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Turbo NSS
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Turbo NSS
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---------
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---------
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Turbonss is a plugin for GNU Name Service Switch (NSS) functionality of GNU C
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Turbonss is a plugin for GNU Name Service Switch ([NSS][nsswitch])
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Library (glibc). Turbonss implements lookup for `user` and `passwd` database
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functionality of GNU C Library (glibc). Turbonss implements lookup for `user`
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entries (i.e. system users, groups, and group memberships). It's main goal is
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and `passwd` database entries (i.e. system users, groups, and group
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performance, with focus on making [`id(1)`][id] run as fast as possible.
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memberships). It's main goal is to run [`id(1)`][id] as fast as possible.
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Turbonss is optimized for reading. If the data changes in any way, the whole
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Turbonss is optimized for reading. If the data changes in any way, the whole
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file will need to be regenerated (and tooling only supports only full
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file will need to be regenerated. Therefore, it was created, and best suited,
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generation). It was created, and best suited, for environments that have a
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for environments that have a central user & group database which then needs to
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central user & group database which then needs to be distributed to many
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be distributed to many servers/services, and the data does not change very
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servers/services, and the data does not change very often (e.g. hourly).
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often (e.g. hourly).
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To understand more about name service switch, start with
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This is the fastest known NSS passwd/group implementation for *reads*. On a
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[`nsswitch.conf(5)`][nsswitch].
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corpus with 10k users, 10k groups and 500 average members per group, `id` takes
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17 seconds with the glibc default implementation, 10-17 milliseconds with a
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pre-cached `nscd`, ~8 milliseconds with `turbonss`.
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Design & constraints
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Project status
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--------------------
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--------------
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To be fast, the user/group database (later: DB) has to be small
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The project is finished and is not recommended for production; just use nscd.
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([background][data-oriented-design]). It encodes user & group information in a
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Turbonss duly implements the full user/group API in `src/libnss.zig`: feel free
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way that minimizes the DB size, and reduces jumping across the DB ("chasing
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to copy that.
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pointers and thrashing CPU cache").
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To understand how this is done efficiently, let's analyze the
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Yours truly (the author) worked on this for about 7 months. And when this was
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[`getpwnam_r(3)`][getpwnam_r] in high level. This API call accepts a username
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finished it turned out that just slapping nscd on top of the existing NSS
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and returns the following user information:
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implementation is almost as fast as this.
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```
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struct passwd {
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char *pw_name; /* username */
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char *pw_passwd; /* user password */
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uid_t pw_uid; /* user ID */
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gid_t pw_gid; /* group ID */
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char *pw_gecos; /* user information */
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char *pw_dir; /* home directory */
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char *pw_shell; /* shell program */
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};
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```
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Turbonss, among others, implements this call, and takes the following steps to
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resolve a username to a `struct passwd*`:
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- Open the DB (using `mmap`) and interpret it's first 64 bytes as a `*struct
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Header`. The header stores offsets to the sections of the file. This needs to
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be done once, when the NSS library is loaded.
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- Hash the username using a perfect hash function. Perfect hash function
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returns a number `n ∈ [0,N-1]`, where N is the total number of users.
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- Jump to the `n`'th location in the `idx_name2user` section, which contains
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the index `i` to the user's information.
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- Jump to the location `i` of section `Users`, which stores the full user
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information.
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- Decode the user information (which is all in a continuous memory block) and
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return it to the caller.
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In total, that's one hash for the username (~150ns), two pointer jumps within
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the group file (to sections `idx_name2user` and `Users`), and, now that the
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user record is found, `memcpy` for each field.
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The turbonss DB file is be `mmap`-ed, making it simple to jump across the file
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using pointer arithmetic. This also reduces memory usage, as the mmap'ed
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regions are shared. Turbonss reads do not consume any heap space.
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Tight packing places some constraints on the underlying data:
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- Permitted length of username and groupname: 1-32 bytes.
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- Permitted length of shell and home: 1-256 bytes.
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- Permitted comment ("gecos") length: 0-255 bytes.
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- User name, groupname, gecos and shell must be utf8-encoded.
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- User and Groups sections are up to 2^35B (~34GB) large. Assuming an "average"
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user record takes 50 bytes, this section would fit ~660M users. The
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worst-case upper bound is left as an exercise to the reader.
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Sorting is stable. In v0:
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- Groups are sorted by gid, ascending.
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- Users are sorted by their name, ascending by the unicode codepoints
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(locale-independent).
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Checking out and building
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-------------------------
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```
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$ git clone --recursive https://git.sr.ht/~motiejus/turbonss
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```
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Alternatively, if you forgot `--recursive`:
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```
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$ git submodule update --init
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```
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And run tests:
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```
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$ zig build test
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```
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Test the so
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-----------
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Build:
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zig build -Dtarget=x86_64-linux-gnu.2.31 -Dcpu=x86_64_v3 -Drelease-fast=true -Dstrip=true
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Generate `db.turbo`:
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zig-out/bin/turbonss-unix2db --passwd /etc/passwd --group /etc/group
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zig-out/bin/turbonss-analyze db.turbo
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<...>
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Run a test container:
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$ docker run -ti --rm --privileged -v `pwd`:/etc/turbonss -w /etc/turbonss debian:bullseye
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# cp zig-out/lib/libnss_turbo.so.2 /lib/x86_64-linux-gnu
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# sed -i 's/\(\(passwd\|group\).*files\)$/\1 turbo/' /etc/nsswitch.conf
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And knock yourself out:
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getent passwd
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getent group
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id root
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This is probably not very interesting; you may want to take a larger corpus of
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/etc/passwd and /etc/group for more interesting results.
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Dependencies
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Dependencies
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------------
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------------
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This project uses [git subtrac][git-subtrac] for managing dependencies. They
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1. Stage1 of the nightly zig compiler.
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work just like regular submodules, except all the refs of the submodules are in
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2. [cmph][cmph]: bundled with this repository.
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this repository. Repeat after me: all the submodules are in this repository.
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So if you have a copy of this repo, dependencies will not disappear.
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remarks on `id(1)`
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Trying it out
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------------------
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-------------
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A known implementation runs id(1) at ~250 rps sequentially on ~20k users and
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Clone, compile and test first:
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~10k groups. Our rps target is much higher.
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To better reason about the trade-offs, it is useful to understand how `id(1)`
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$ git clone --recursive https://git.sr.ht/~motiejus/turbonss
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is implemented, in rough terms:
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$ zig build -fstage1 test
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- lookup user by name ([`getpwent_r(3)`][getpwent]).
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$ zig build -fstage1 -Dtarget=x86_64-linux-gnu.2.31 -Dcpu=x86_64_v3 -Drelease-safe=true
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- get all gids for the user ([`getgrouplist(3)`][getgrouplist]). Note: it is
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actually using `initgroups_dyn`, accepts a uid, and is very poorly
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documented.
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- for each additional gid, get the `struct group*`
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([`getgrgid_r(3)`][getgrgid_r]).
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Assuming a member is in ~100 groups on average, to reach 10k id/s translates to
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One may choose different options, depending on requirements. Here are some
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1M group lookups per second. We need to convert gid to a group index, and group
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hints:
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index to a group gid/name quickly.
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Caveat: `struct group` contains an array of pointers to names of group members
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1. `-Dcpu=<...>` for the CPU
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(`char **gr_mem`). However, `id` does not use that information, resulting in
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[microarchitecture](https://en.wikipedia.org/wiki/X86-64#Microarchitecture_levels).
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read amplification, sometimes by 10-100x. Therefore, if `argv[0] == "id"`, our
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2. `-Drelease-fast=true` for max speed
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implementation of [`getgrid_r(3)`][getgrid] returns the `struct group*` without
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3. `-Drelease-small=true` for smallest binary sizes.
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the members. This speeds up `id` by about 10x on a known NSS implementation.
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4. `-Dstrip=true` to strip debug symbols.
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Relatedly, because [`getgrid_r(3)`][getgrid] does not need the group members,
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Test it on a real system
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the group members are stored in a different DB section, reducing the `Groups`
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------------------------
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section and making more of it fit the CPU caches.
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Turbonss header
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`db.turbo` is the TurboNSS database file. To create one from `/etc/group` and
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---------------
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`/etc/passwd`, use `turbonss-unix2db`:
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The turbonss header looks like this:
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$ zig-out/bin/turbonss-unix2db --passwd /etc/passwd --group /etc/group
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$ zig-out/bin/turbonss-analyze db.turbo
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<...>
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```
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Run and configure a test container that uses `turbonss` instead of the default
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OFFSET TYPE NAME DESCRIPTION
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`files`:
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0 [4]u8 magic f0 9f a4 b7
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4 u8 version 0
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5 u8 endian 0 for little, 1 for big
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6 u8 nblocks_shell_blob max value: 63
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7 u8 num_shells max value: 63
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8 u32 num_groups number of group entries
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12 u32 num_users number of passwd entries
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16 u32 nblocks_bdz_gid bdz_gid section block count
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20 u32 nblocks_bdz_groupname
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24 u32 nblocks_bdz_uid
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28 u32 nblocks_bdz_username
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32 u64 nblocks_groups
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40 u64 nblocks_users
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48 u64 nblocks_groupmembers
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56 u64 nblocks_additional_gids
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64 u64 getgr_bufsize
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72 u64 getpw_bufsize
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80 [48]u8 padding
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```
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`magic` is 0xf09fa4b7, and `version` must be `0`. All integers are
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$ docker run -ti --rm -v `pwd`:/etc/turbonss -w /etc/turbonss debian:bullseye
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native-endian. `nblocks_*` is the count of blocks of a particular section; this
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# cp zig-out/lib/libnss_turbo.so.2 /lib/x86_64-linux-gnu/
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helps calculate the offsets to all sections.
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# sed -i '/passwd\|group/ s/files/turbo/' /etc/nsswitch.conf
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Some numbers, like `nblocks_shell_blob`, `num_shells`, would fit to smaller
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And run the commands:
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number of bytes. However, interpreting `[2]u6` with `xxd(1)` is harder than
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interpreting `[2]u8`. Therefore we are using the space we have to make these
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integers byte-wide.
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`getgr_bufsize` and `getpw_bufsize` is a hint for the caller of `getgr*` and
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$ getent passwd
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`getpw*`-family calls. This is the recommended size of the buffer, so the
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$ getent group
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caller does not receive `ENOMEM`.
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$ id root
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Primitive types
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More users and groups
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---------------
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---------------------
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`User` and `Group` entries are sorted by the order they were received in the input
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`turbonss-makecorpus` can synthesize more `users` and `groups`:
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file. All entries are aligned to 8 bytes. All `User` and `Group` entries are
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referred by their byte offset in the `Users` and `Groups` section relative to
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the beginning of the section.
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```
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# ./zig-out/bin/turbonss-makecorpus
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const PackedGroup = packed struct {
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wrote users=10000 groups=10000 avg-members=1000 to .
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gid: u32,
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# cat group >> /etc/group
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padding: u3,
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# cat passwd >> /etc/passwd
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groupname_len: u5,
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# time id u_1000000
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}
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<...>
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```
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real 0m17.380s
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user 0m13.117s
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sys 0m4.263s
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PackedGroup is followed by the group name (of length `groupname_len`), followed
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17 seconds for an `id` command! Well, there are indeed many users and groups.
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by a varint-compressed offset to the groupmembers section, followed by 8b padding.
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Let's see how turbonss fares with it:
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PackedUser is a bit more involved:
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# zig-out/bin/turbonss-unix2db --group /etc/group --passwd /etc/passwd
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total 10968512 bytes. groups=10019 users=10039
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# ls -hs /etc/group /etc/passwd db.turbo
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48M /etc/group 668K /etc/passwd 11M db.turbo
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# sed -i '/passwd\|group/ s/files/turbo/' /etc/nsswitch.conf
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# time id u_1000000
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real 0m0.008s
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user 0m0.000s
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sys 0m0.008s
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```
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That's ~1500x improvement for the `id` command (and notice about 4X compression
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pub const PackedUser = packed struct {
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ratio compared to plain files). If the number of users and groups is increased
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uid: u32,
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by 10x (to 100k each), the difference becomes even crazier:
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gid: u32,
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shell_len_or_idx: u8,
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shell_here: bool,
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name_is_a_suffix: bool,
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home_len: u6,
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name_len: u5,
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gecos_len: u11,
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}
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```
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... followed by `userdata: []u8`:
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# time id u_1000000
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- home.
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<...>
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- name (optional).
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real 3m42.281s
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- gecos.
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user 2m30.482s
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- shell (optional).
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sys 0m55.840s
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- `additional_gids_offset`: varint.
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# sed -i '/passwd\|group/ s/files/turbo/' /etc/nsswitch.conf
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# time id u_1000000
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<...>
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real 0m0.008s
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user 0m0.000s
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sys 0m0.008s
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First byte of home is stored right after the `gecos_len` field, and its length
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Documentation
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is `home_len`. The same logic applies to all the `stringdata` fields: there is
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-------------
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a way to calculate their relative position from the length of the fields before
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them.
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PackedUser employs two data-oriented compression techniques:
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Architecture is detailed in `docs/architecture.md`
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- shells are often shared across different users, see the "Shells" section.
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Development notes are in `docs/development.md`
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- `name` is frequently a suffix of `home`. For example, `/home/vidmantas` and
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`vidmantas`. In this case storing both name and home is wasteful. Therefore
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name has two options:
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1. `name_is_a_suffix=true`: name is a suffix of the home dir. Then `name`
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starts at the `home_len - name_len`'th byte of `home`, and ends at the same
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place as `home`.
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2. `name_is_a_suffix=false`: name begins one byte after home, and it's length
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is `name_len`.
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The last field `additional_gids_offset: varint` points to the `additional_gids`
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section for this user.
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Shells
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------
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Normally there is a limited number of separate shells even in huge user
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databases. A few examples: `/bin/bash`, `/usr/bin/nologin`, `/bin/zsh` among
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others. Therefore, "shells" have an optimization: they can be pointed by in the
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external list, or, if they are unique to the user, reside among the user's
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data.
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255 most popular shells (i.e. referred to by at least two User entries) are
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stored externally in "Shells" area. The less popular ones are stored with
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userdata.
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Shells section consists of two sub-sections: the index and the blob. The index
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is an array of offsets: the i'th shell starts at `offsets[i]` byte, and ends at
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`offsets[i+1]` byte. If there is at least one shell in the shell section, the
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index contains a sentinel index as the last element, which signifies the position
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of the last byte of the shell blob.
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`shell_here=true` in the User struct means the shell is stored with userdata,
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and it's length is `shell_len_or_idx`. `shell_here=false` means it is stored in
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the `Shells` section, and it's index is `shell_len_or_idx` (and the actual
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string start and end offsets are resolved as described in the paragraph above).
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Variable-length integers (varints)
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----------------------------------
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Varint is an efficiently encoded integer (packed for small values). Same as
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|
||||||
[protocol buffer varints][varint], except the largest possible value is `u64`.
|
|
||||||
They compress integers well. Varints are stored for group memberships.
|
|
||||||
|
|
||||||
Group memberships
|
|
||||||
-----------------
|
|
||||||
|
|
||||||
There are two group memberships at play:
|
|
||||||
|
|
||||||
1. Given a group (gid/name), resolve the members' names (e.g. `getgrgid`).
|
|
||||||
2. Given a username, resolve user's group gids (for `initgroups(3)`).
|
|
||||||
|
|
||||||
When group's memberships are resolved in (1), the same call also requires other
|
|
||||||
group information: gid and group name. Therefore it makes sense to store a
|
|
||||||
pointer to the group members in the group information itself. However, the
|
|
||||||
memberships are not *always* necessary (see remarks about `id(1)`), therefore
|
|
||||||
the memberships will be stored separately, outside of the groups section.
|
|
||||||
|
|
||||||
Similarly, when user's groups are resolved in (2), they are not always necessary
|
|
||||||
(i.e. not part of `struct user*`), therefore the memberships themselves are
|
|
||||||
stored out of bound.
|
|
||||||
|
|
||||||
`groupmembers` and `additional_gids` store group and user memberships
|
|
||||||
respectively. Membership IDs are packed — not necessitating random access, thus
|
|
||||||
suitable for compression.
|
|
||||||
|
|
||||||
- `groupmembers` consists of a number X followed by a list of offsets to User
|
|
||||||
records, because `getgr*` returns pointers to membernames, thus a name has to
|
|
||||||
be immediately resolvable.
|
|
||||||
- `additional_gids` is a list of gids, because `initgroups_dyn` (and friends)
|
|
||||||
returns an array of gids.
|
|
||||||
|
|
||||||
Each entry of `groupmembers` and `additional_gids` starts with a varint N,
|
|
||||||
which is the number of upcoming elements. Then N delta-compressed varints,
|
|
||||||
which are:
|
|
||||||
|
|
||||||
- **additional_gids** a list of gids.
|
|
||||||
- **groupmembers** byte-offsets to the User records in the `users` section.
|
|
||||||
|
|
||||||
Indices
|
|
||||||
-------
|
|
||||||
|
|
||||||
Now that we've sketched the implementation of `id(3)`, it's clearer to
|
|
||||||
understand which operations need to be fast; in order of importance:
|
|
||||||
|
|
||||||
1. lookup gid -> group info (this is on hot path in id) without members.
|
|
||||||
2. lookup username -> user's groups.
|
|
||||||
3. lookup uid -> user.
|
|
||||||
4. lookup groupname -> group.
|
|
||||||
5. lookup username -> user.
|
|
||||||
|
|
||||||
These indices can use perfect hashing like [bdz from cmph][cmph]: a perfect
|
|
||||||
hash hashes a list of bytes to a sequential list of integers. Perfect hashing
|
|
||||||
algorithms require some space, and take some time to calculate ("hashing
|
|
||||||
duration"). I've tested BDZ, which hashes `[][]u8` to a sequential list of
|
|
||||||
integers (not preserving order) and CHM, preserves order. BDZ accepts an
|
|
||||||
optional argument `3 <= b <= 10`.
|
|
||||||
|
|
||||||
* BDZ algorithm requires (b=3, 900KB, b=7, 338KB, b=10, 306KB) for 1M values.
|
|
||||||
* Latency to resolve 1M keys: (170ms, 180ms, 230ms, respectively).
|
|
||||||
* Packed vs non-packed latency differences are not meaningful.
|
|
||||||
|
|
||||||
CHM retains order, however, 1M keys weigh 8MB. 10k keys are ~20x larger with
|
|
||||||
CHM than with BDZ, eliminating the benefit of preserved ordering: we can just
|
|
||||||
have a separate index.
|
|
||||||
|
|
||||||
None of the tested perfect hashing algorithms makes the distinction between
|
|
||||||
existing (in the initial dictionary) and new keys. In other words, HASH(value)
|
|
||||||
will be pointing to a number `n ∈ [0,N-1]`, regardless whether the value was in
|
|
||||||
the initial dictionary. Therefore one must always confirm, after calculating
|
|
||||||
the hash, that the key matches what's been hashed.
|
|
||||||
|
|
||||||
`idx_*` sections are of type `[]u32` and are pointing from `hash(key)` to the
|
|
||||||
respective `Groups` and `Users` entries (from the beginning of the respective
|
|
||||||
section). Since User and Group records are 8-byte aligned, the actual offset to
|
|
||||||
the record is acquired by right-shifting this value by 3 bits.
|
|
||||||
|
|
||||||
Database file structure
|
|
||||||
-----------------------
|
|
||||||
|
|
||||||
Each section is padded to 64 bytes.
|
|
||||||
|
|
||||||
```
|
|
||||||
SECTION SIZE DESCRIPTION
|
|
||||||
header 128 see "Turbonss header" section
|
|
||||||
bdz_gid ? bdz(gid)
|
|
||||||
bdz_groupname ? bdz(groupname)
|
|
||||||
bdz_uid ? bdz(uid)
|
|
||||||
bdz_username ? bdz(username)
|
|
||||||
idx_gid2group len(group)*4 bdz->offset Groups
|
|
||||||
idx_groupname2group len(group)*4 bdz->offset Groups
|
|
||||||
idx_uid2user len(user)*4 bdz->offset Users
|
|
||||||
idx_name2user len(user)*4 bdz->offset Users
|
|
||||||
shell_index len(shells)*2 shell index array
|
|
||||||
shell_blob <= 65280 shell data blob (max 255*256 bytes)
|
|
||||||
groups ? packed Group entries (8b padding)
|
|
||||||
users ? packed User entries (8b padding)
|
|
||||||
groupmembers ? per-group delta varint memberlist (no padding)
|
|
||||||
additional_gids ? per-user delta varint gidlist (no padding)
|
|
||||||
```
|
|
||||||
|
|
||||||
Section creation order:
|
|
||||||
|
|
||||||
1. ✅ `bdz_*`.
|
|
||||||
1. ✅ `shell_index`, `shell_blob`.
|
|
||||||
1. ✅ `additional_gids`.
|
|
||||||
1. ✅ `users` requires `additional_gids` and shell.
|
|
||||||
1. ✅ `groupmembers` requires `users`.
|
|
||||||
1. ✅ `groups` requires `groupmembers`.
|
|
||||||
1. ✅ `idx_*`. requires offsets to `groups` and `users`.
|
|
||||||
1. ✅ Header.
|
|
||||||
|
|
||||||
For v2
|
|
||||||
------
|
|
||||||
|
|
||||||
These are desired for the next DB format:
|
|
||||||
- Compress strings with fsst.
|
|
||||||
- Trim first 4 bytes from the cmph headers.
|
|
||||||
|
|
||||||
Profiling
|
|
||||||
---------
|
|
||||||
|
|
||||||
Prepare `profile.data`:
|
|
||||||
|
|
||||||
```
|
|
||||||
zig build -Drelease-small=true && \
|
|
||||||
perf record --call-graph=dwarf \
|
|
||||||
zig-out/bin/turbonss-unix2db --passwd passwd2 --group group2
|
|
||||||
```
|
|
||||||
|
|
||||||
Perf interactive:
|
|
||||||
|
|
||||||
```
|
|
||||||
perf report -i perf.data
|
|
||||||
```
|
|
||||||
|
|
||||||
Flame graph:
|
|
||||||
|
|
||||||
```
|
|
||||||
perf script | inferno-collapse-perf | inferno-flamegraph > profile.svg
|
|
||||||
```
|
|
||||||
|
|
||||||
[git-subtrac]: https://apenwarr.ca/log/20191109
|
[git-subtrac]: https://apenwarr.ca/log/20191109
|
||||||
[cmph]: http://cmph.sourceforge.net/
|
|
||||||
[id]: https://linux.die.net/man/1/id
|
|
||||||
[nsswitch]: https://linux.die.net/man/5/nsswitch.conf
|
[nsswitch]: https://linux.die.net/man/5/nsswitch.conf
|
||||||
[data-oriented-design]: https://media.handmade-seattle.com/practical-data-oriented-design/
|
[id]: https://linux.die.net/man/1/id
|
||||||
[getpwnam_r]: https://linux.die.net/man/3/getpwnam_r
|
[cmph]: http://cmph.sourceforge.net/
|
||||||
[varint]: https://developers.google.com/protocol-buffers/docs/encoding#varints
|
|
||||||
[getpwent]: https://www.man7.org/linux/man-pages/man3/getpwent_r.3.html
|
|
||||||
[getgrouplist]: https://www.man7.org/linux/man-pages/man3/getgrouplist.3.html
|
|
||||||
[getgrid]: https://www.man7.org/linux/man-pages/man3/getgrid_r.3.html
|
|
||||||
|
|
|
||||||
|
|
@ -0,0 +1,327 @@
|
||||||
|
Design & constraints
|
||||||
|
--------------------
|
||||||
|
|
||||||
|
To be fast, the user/group database (later: DB) has to be small
|
||||||
|
([background][data-oriented-design]). It encodes user & group information in a
|
||||||
|
way that minimizes the DB size, and reduces jumping across the DB ("chasing
|
||||||
|
pointers and thrashing CPU cache").
|
||||||
|
|
||||||
|
To understand how this is done efficiently, let's analyze the
|
||||||
|
[`getpwnam_r(3)`][getpwnam_r] in high level. This API call accepts a username
|
||||||
|
and returns the following user information:
|
||||||
|
|
||||||
|
```
|
||||||
|
struct passwd {
|
||||||
|
char *pw_name; /* username */
|
||||||
|
char *pw_passwd; /* user password */
|
||||||
|
uid_t pw_uid; /* user ID */
|
||||||
|
gid_t pw_gid; /* group ID */
|
||||||
|
char *pw_gecos; /* user information */
|
||||||
|
char *pw_dir; /* home directory */
|
||||||
|
char *pw_shell; /* shell program */
|
||||||
|
};
|
||||||
|
```
|
||||||
|
|
||||||
|
Turbonss, among others, implements this call, and takes the following steps to
|
||||||
|
resolve a username to a `struct passwd*`:
|
||||||
|
|
||||||
|
- Open the DB (using `mmap`) and interpret it's first 64 bytes as a `*struct
|
||||||
|
Header`. The header stores offsets to the sections of the file. This needs to
|
||||||
|
be done once, when the NSS library is loaded.
|
||||||
|
- Hash the username using a perfect hash function. Perfect hash function
|
||||||
|
returns a number `n ∈ [0,N-1]`, where N is the total number of users.
|
||||||
|
- Jump to the `n`'th location in the `idx_name2user` section, which contains
|
||||||
|
the index `i` to the user's information.
|
||||||
|
- Jump to the location `i` of section `Users`, which stores the full user
|
||||||
|
information.
|
||||||
|
- Decode the user information (which is all in a continuous memory block) and
|
||||||
|
return it to the caller.
|
||||||
|
|
||||||
|
In total, that's one hash for the username (~150ns), two pointer jumps within
|
||||||
|
the group file (to sections `idx_name2user` and `Users`), and, now that the
|
||||||
|
user record is found, `memcpy` for each field.
|
||||||
|
|
||||||
|
The turbonss DB file is be `mmap`-ed, making it simple to jump across the file
|
||||||
|
using pointer arithmetic. This also reduces memory usage, as the mmap'ed
|
||||||
|
regions are shared. Turbonss reads do not consume any heap space.
|
||||||
|
|
||||||
|
Tight packing places some constraints on the underlying data:
|
||||||
|
|
||||||
|
- Permitted length of username and groupname: 1-32 bytes.
|
||||||
|
- Permitted length of shell and home: 1-256 bytes.
|
||||||
|
- Permitted comment ("gecos") length: 0-255 bytes.
|
||||||
|
- User name, groupname, gecos and shell must be utf8-encoded.
|
||||||
|
- User and Groups sections are up to 2^35B (~34GB) large. Assuming an "average"
|
||||||
|
user record takes 50 bytes, this section would fit ~660M users. The
|
||||||
|
worst-case upper bound is left as an exercise to the reader.
|
||||||
|
|
||||||
|
Sorting is stable. In v0:
|
||||||
|
- Groups are sorted by gid, ascending.
|
||||||
|
- Users are sorted by their name, ascending by the unicode codepoints
|
||||||
|
(locale-independent).
|
||||||
|
|
||||||
|
remarks on `id(1)`
|
||||||
|
------------------
|
||||||
|
|
||||||
|
A known implementation runs id(1) at ~250 rps sequentially on ~20k users and
|
||||||
|
~10k groups. Our rps target is much higher.
|
||||||
|
|
||||||
|
To better reason about the trade-offs, it is useful to understand how `id(1)`
|
||||||
|
is implemented, in rough terms:
|
||||||
|
- lookup user by name ([`getpwent_r(3)`][getpwent]).
|
||||||
|
- get all gids for the user ([`getgrouplist(3)`][getgrouplist]). Note: it is
|
||||||
|
actually using `initgroups_dyn`, accepts a uid, and is very poorly
|
||||||
|
documented.
|
||||||
|
- for each additional gid, get the `struct group*`
|
||||||
|
([`getgrgid_r(3)`][getgrgid_r]).
|
||||||
|
|
||||||
|
Assuming a member is in ~100 groups on average, to reach 10k id/s translates to
|
||||||
|
1M group lookups per second. We need to convert gid to a group index, and group
|
||||||
|
index to a group gid/name quickly.
|
||||||
|
|
||||||
|
Caveat: `struct group` contains an array of pointers to names of group members
|
||||||
|
(`char **gr_mem`). However, `id` does not use that information, resulting in
|
||||||
|
read amplification, sometimes by 10-100x. Therefore, if `argv[0] == "id"`, our
|
||||||
|
implementation of [`getgrid_r(3)`][getgrid] returns the `struct group*` without
|
||||||
|
the members. This speeds up `id` by about 10x on a known NSS implementation.
|
||||||
|
|
||||||
|
Relatedly, because [`getgrid_r(3)`][getgrid] does not need the group members,
|
||||||
|
the group members are stored in a different DB section, reducing the `Groups`
|
||||||
|
section and making more of it fit the CPU caches.
|
||||||
|
|
||||||
|
Turbonss header
|
||||||
|
---------------
|
||||||
|
|
||||||
|
The turbonss header looks like this:
|
||||||
|
|
||||||
|
```
|
||||||
|
OFFSET TYPE NAME DESCRIPTION
|
||||||
|
0 [4]u8 magic f0 9f a4 b7
|
||||||
|
4 u8 version 0
|
||||||
|
5 u8 endian 0 for little, 1 for big
|
||||||
|
6 u8 nblocks_shell_blob max value: 63
|
||||||
|
7 u8 num_shells max value: 63
|
||||||
|
8 u32 num_groups number of group entries
|
||||||
|
12 u32 num_users number of passwd entries
|
||||||
|
16 u32 nblocks_bdz_gid bdz_gid section block count
|
||||||
|
20 u32 nblocks_bdz_groupname
|
||||||
|
24 u32 nblocks_bdz_uid
|
||||||
|
28 u32 nblocks_bdz_username
|
||||||
|
32 u64 nblocks_groups
|
||||||
|
40 u64 nblocks_users
|
||||||
|
48 u64 nblocks_groupmembers
|
||||||
|
56 u64 nblocks_additional_gids
|
||||||
|
64 u64 getgr_bufsize
|
||||||
|
72 u64 getpw_bufsize
|
||||||
|
80 [48]u8 padding
|
||||||
|
```
|
||||||
|
|
||||||
|
`magic` is 0xf09fa4b7, and `version` must be `0`. All integers are
|
||||||
|
native-endian. `nblocks_*` is the count of blocks of a particular section; this
|
||||||
|
helps calculate the offsets to all sections.
|
||||||
|
|
||||||
|
Some numbers, like `nblocks_shell_blob`, `num_shells`, would fit to smaller
|
||||||
|
number of bytes. However, interpreting `[2]u6` with `xxd(1)` is harder than
|
||||||
|
interpreting `[2]u8`. Therefore we are using the space we have to make these
|
||||||
|
integers byte-wide.
|
||||||
|
|
||||||
|
`getgr_bufsize` and `getpw_bufsize` is a hint for the caller of `getgr*` and
|
||||||
|
`getpw*`-family calls. This is the recommended size of the buffer, so the
|
||||||
|
caller does not receive `ENOMEM`.
|
||||||
|
|
||||||
|
Primitive types
|
||||||
|
---------------
|
||||||
|
|
||||||
|
`User` and `Group` entries are sorted by the order they were received in the input
|
||||||
|
file. All entries are aligned to 8 bytes. All `User` and `Group` entries are
|
||||||
|
referred by their byte offset in the `Users` and `Groups` section relative to
|
||||||
|
the beginning of the section.
|
||||||
|
|
||||||
|
```
|
||||||
|
const PackedGroup = packed struct {
|
||||||
|
gid: u32,
|
||||||
|
padding: u3,
|
||||||
|
groupname_len: u5,
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
PackedGroup is followed by the group name (of length `groupname_len`), followed
|
||||||
|
by a varint-compressed offset to the groupmembers section, followed by 8b padding.
|
||||||
|
|
||||||
|
PackedUser is a bit more involved:
|
||||||
|
|
||||||
|
```
|
||||||
|
pub const PackedUser = packed struct {
|
||||||
|
uid: u32,
|
||||||
|
gid: u32,
|
||||||
|
shell_len_or_idx: u8,
|
||||||
|
shell_here: bool,
|
||||||
|
name_is_a_suffix: bool,
|
||||||
|
home_len: u6,
|
||||||
|
name_len: u5,
|
||||||
|
gecos_len: u11,
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
... followed by `userdata: []u8`:
|
||||||
|
- home.
|
||||||
|
- name (optional).
|
||||||
|
- gecos.
|
||||||
|
- shell (optional).
|
||||||
|
- `additional_gids_offset`: varint.
|
||||||
|
|
||||||
|
First byte of home is stored right after the `gecos_len` field, and its length
|
||||||
|
is `home_len`. The same logic applies to all the `stringdata` fields: there is
|
||||||
|
a way to calculate their relative position from the length of the fields before
|
||||||
|
them.
|
||||||
|
|
||||||
|
PackedUser employs two data-oriented compression techniques:
|
||||||
|
- shells are often shared across different users, see the "Shells" section.
|
||||||
|
- `name` is frequently a suffix of `home`. For example, `/home/vidmantas` and
|
||||||
|
`vidmantas`. In this case storing both name and home is wasteful. Therefore
|
||||||
|
name has two options:
|
||||||
|
1. `name_is_a_suffix=true`: name is a suffix of the home dir. Then `name`
|
||||||
|
starts at the `home_len - name_len`'th byte of `home`, and ends at the same
|
||||||
|
place as `home`.
|
||||||
|
2. `name_is_a_suffix=false`: name begins one byte after home, and it's length
|
||||||
|
is `name_len`.
|
||||||
|
|
||||||
|
The last field `additional_gids_offset: varint` points to the `additional_gids`
|
||||||
|
section for this user.
|
||||||
|
|
||||||
|
Shells
|
||||||
|
------
|
||||||
|
|
||||||
|
Normally there is a limited number of separate shells even in huge user
|
||||||
|
databases. A few examples: `/bin/bash`, `/usr/bin/nologin`, `/bin/zsh` among
|
||||||
|
others. Therefore, "shells" have an optimization: they can be pointed by in the
|
||||||
|
external list, or, if they are unique to the user, reside among the user's
|
||||||
|
data.
|
||||||
|
|
||||||
|
255 most popular shells (i.e. referred to by at least two User entries) are
|
||||||
|
stored externally in "Shells" area. The less popular ones are stored with
|
||||||
|
userdata.
|
||||||
|
|
||||||
|
Shells section consists of two sub-sections: the index and the blob. The index
|
||||||
|
is an array of offsets: the i'th shell starts at `offsets[i]` byte, and ends at
|
||||||
|
`offsets[i+1]` byte. If there is at least one shell in the shell section, the
|
||||||
|
index contains a sentinel index as the last element, which signifies the position
|
||||||
|
of the last byte of the shell blob.
|
||||||
|
|
||||||
|
`shell_here=true` in the User struct means the shell is stored with userdata,
|
||||||
|
and it's length is `shell_len_or_idx`. `shell_here=false` means it is stored in
|
||||||
|
the `Shells` section, and it's index is `shell_len_or_idx` (and the actual
|
||||||
|
string start and end offsets are resolved as described in the paragraph above).
|
||||||
|
|
||||||
|
Variable-length integers (varints)
|
||||||
|
----------------------------------
|
||||||
|
|
||||||
|
Varint is an efficiently encoded integer (packed for small values). Same as
|
||||||
|
[protocol buffer varints][varint], except the largest possible value is `u64`.
|
||||||
|
They compress integers well. Varints are stored for group memberships.
|
||||||
|
|
||||||
|
Group memberships
|
||||||
|
-----------------
|
||||||
|
|
||||||
|
There are two group memberships at play:
|
||||||
|
|
||||||
|
1. Given a group (gid/name), resolve the members' names (e.g. `getgrgid`).
|
||||||
|
2. Given a username, resolve user's group gids (for `initgroups(3)`).
|
||||||
|
|
||||||
|
When group's memberships are resolved in (1), the same call also requires other
|
||||||
|
group information: gid and group name. Therefore it makes sense to store a
|
||||||
|
pointer to the group members in the group information itself. However, the
|
||||||
|
memberships are not *always* necessary (see remarks about `id(1)`), therefore
|
||||||
|
the memberships will be stored separately, outside of the groups section.
|
||||||
|
|
||||||
|
Similarly, when user's groups are resolved in (2), they are not always necessary
|
||||||
|
(i.e. not part of `struct user*`), therefore the memberships themselves are
|
||||||
|
stored out of bound.
|
||||||
|
|
||||||
|
`groupmembers` and `additional_gids` store group and user memberships
|
||||||
|
respectively. Membership IDs are packed — not necessitating random access, thus
|
||||||
|
suitable for compression.
|
||||||
|
|
||||||
|
- `groupmembers` consists of a number X followed by a list of offsets to User
|
||||||
|
records, because `getgr*` returns pointers to membernames, thus a name has to
|
||||||
|
be immediately resolvable.
|
||||||
|
- `additional_gids` is a list of gids, because `initgroups_dyn` (and friends)
|
||||||
|
returns an array of gids.
|
||||||
|
|
||||||
|
Each entry of `groupmembers` and `additional_gids` starts with a varint N,
|
||||||
|
which is the number of upcoming elements. Then N delta-compressed varints,
|
||||||
|
which are:
|
||||||
|
|
||||||
|
- **additional_gids** a list of gids.
|
||||||
|
- **groupmembers** byte-offsets to the User records in the `users` section.
|
||||||
|
|
||||||
|
Indices
|
||||||
|
-------
|
||||||
|
|
||||||
|
Now that we've sketched the implementation of `id(3)`, it's clearer to
|
||||||
|
understand which operations need to be fast; in order of importance:
|
||||||
|
|
||||||
|
1. lookup gid -> group info (this is on hot path in id) without members.
|
||||||
|
2. lookup username -> user's groups.
|
||||||
|
3. lookup uid -> user.
|
||||||
|
4. lookup groupname -> group.
|
||||||
|
5. lookup username -> user.
|
||||||
|
|
||||||
|
These indices can use perfect hashing like [bdz from cmph][cmph]: a perfect
|
||||||
|
hash hashes a list of bytes to a sequential list of integers. Perfect hashing
|
||||||
|
algorithms require some space, and take some time to calculate ("hashing
|
||||||
|
duration"). I've tested BDZ, which hashes `[][]u8` to a sequential list of
|
||||||
|
integers (not preserving order) and CHM, preserves order. BDZ accepts an
|
||||||
|
optional argument `3 <= b <= 10`.
|
||||||
|
|
||||||
|
* BDZ algorithm requires (b=3, 900KB, b=7, 338KB, b=10, 306KB) for 1M values.
|
||||||
|
* Latency to resolve 1M keys: (170ms, 180ms, 230ms, respectively).
|
||||||
|
* Packed vs non-packed latency differences are not meaningful.
|
||||||
|
|
||||||
|
CHM retains order, however, 1M keys weigh 8MB. 10k keys are ~20x larger with
|
||||||
|
CHM than with BDZ, eliminating the benefit of preserved ordering: we can just
|
||||||
|
have a separate index.
|
||||||
|
|
||||||
|
None of the tested perfect hashing algorithms makes the distinction between
|
||||||
|
existing (in the initial dictionary) and new keys. In other words, HASH(value)
|
||||||
|
will be pointing to a number `n ∈ [0,N-1]`, regardless whether the value was in
|
||||||
|
the initial dictionary. Therefore one must always confirm, after calculating
|
||||||
|
the hash, that the key matches what's been hashed.
|
||||||
|
|
||||||
|
`idx_*` sections are of type `[]u32` and are pointing from `hash(key)` to the
|
||||||
|
respective `Groups` and `Users` entries (from the beginning of the respective
|
||||||
|
section). Since User and Group records are 8-byte aligned, the actual offset to
|
||||||
|
the record is acquired by right-shifting this value by 3 bits.
|
||||||
|
|
||||||
|
Database file structure
|
||||||
|
-----------------------
|
||||||
|
|
||||||
|
Each section is padded to 64 bytes.
|
||||||
|
|
||||||
|
```
|
||||||
|
SECTION SIZE DESCRIPTION
|
||||||
|
header 128 see "Turbonss header" section
|
||||||
|
bdz_gid ? bdz(gid)
|
||||||
|
bdz_groupname ? bdz(groupname)
|
||||||
|
bdz_uid ? bdz(uid)
|
||||||
|
bdz_username ? bdz(username)
|
||||||
|
idx_gid2group len(group)*4 bdz->offset Groups
|
||||||
|
idx_groupname2group len(group)*4 bdz->offset Groups
|
||||||
|
idx_uid2user len(user)*4 bdz->offset Users
|
||||||
|
idx_name2user len(user)*4 bdz->offset Users
|
||||||
|
shell_index len(shells)*2 shell index array
|
||||||
|
shell_blob <= 65280 shell data blob (max 255*256 bytes)
|
||||||
|
groups ? packed Group entries (8b padding)
|
||||||
|
users ? packed User entries (8b padding)
|
||||||
|
groupmembers ? per-group delta varint memberlist (no padding)
|
||||||
|
additional_gids ? per-user delta varint gidlist (no padding)
|
||||||
|
```
|
||||||
|
|
||||||
|
[cmph]: http://cmph.sourceforge.net/
|
||||||
|
[id]: https://linux.die.net/man/1/id
|
||||||
|
[data-oriented-design]: https://media.handmade-seattle.com/practical-data-oriented-design/
|
||||||
|
[getpwnam_r]: https://linux.die.net/man/3/getpwnam_r
|
||||||
|
[varint]: https://developers.google.com/protocol-buffers/docs/encoding#varints
|
||||||
|
[getpwent]: https://www.man7.org/linux/man-pages/man3/getpwent_r.3.html
|
||||||
|
[getgrouplist]: https://www.man7.org/linux/man-pages/man3/getgrouplist.3.html
|
||||||
|
[getgrid]: https://www.man7.org/linux/man-pages/man3/getgrid_r.3.html
|
||||||
|
|
@ -0,0 +1,37 @@
|
||||||
|
Profiling
|
||||||
|
---------
|
||||||
|
|
||||||
|
Prepare `profile.data`:
|
||||||
|
|
||||||
|
```
|
||||||
|
zig build -Drelease-small=true && \
|
||||||
|
perf record --call-graph=dwarf \
|
||||||
|
zig-out/bin/turbonss-unix2db --passwd passwd --group group
|
||||||
|
```
|
||||||
|
|
||||||
|
Perf interactive:
|
||||||
|
|
||||||
|
```
|
||||||
|
perf report -i perf.data
|
||||||
|
```
|
||||||
|
|
||||||
|
Flame graph:
|
||||||
|
|
||||||
|
```
|
||||||
|
perf script | inferno-collapse-perf | inferno-flamegraph > profile.svg
|
||||||
|
```
|
||||||
|
|
||||||
|
For v2
|
||||||
|
------
|
||||||
|
|
||||||
|
These are desired for the next DB format:
|
||||||
|
- Compress strings with fsst.
|
||||||
|
- Trim first 4 bytes from the cmph headers.
|
||||||
|
|
||||||
|
Dependencies
|
||||||
|
------------
|
||||||
|
|
||||||
|
This project uses [git subtrac][git-subtrac] for managing dependencies. They
|
||||||
|
work just like regular submodules, except all the refs of the submodules are in
|
||||||
|
this repository. Repeat after me: all the submodules are in this repository.
|
||||||
|
So if you have a copy of this repo, dependencies will not disappear.
|
||||||
|
|
@ -1,305 +0,0 @@
|
||||||
const std = @import("std");
|
|
||||||
const fs = std.fs;
|
|
||||||
const io = std.io;
|
|
||||||
const mem = std.mem;
|
|
||||||
const os = std.os;
|
|
||||||
const heap = std.heap;
|
|
||||||
const math = std.math;
|
|
||||||
const fmt = std.fmt;
|
|
||||||
const json = std.json;
|
|
||||||
const ArrayList = std.ArrayList;
|
|
||||||
const ArrayListUnmanaged = std.ArrayListUnmanaged;
|
|
||||||
const Allocator = std.mem.Allocator;
|
|
||||||
const StringArrayHashMap = std.StringArrayHashMap;
|
|
||||||
|
|
||||||
const flags = @import("flags.zig");
|
|
||||||
const User = @import("User.zig");
|
|
||||||
const PackedUser = @import("PackedUser.zig");
|
|
||||||
const Group = @import("Group.zig");
|
|
||||||
const Corpus = @import("Corpus.zig");
|
|
||||||
const DB = @import("DB.zig");
|
|
||||||
const ErrCtx = @import("ErrCtx.zig");
|
|
||||||
|
|
||||||
const usage =
|
|
||||||
\\usage: turbonss-unix2systemd [OPTION]...
|
|
||||||
\\
|
|
||||||
\\Options:
|
|
||||||
\\ -h Print this help message and exit
|
|
||||||
\\ --passwd Path to passwd file (default: passwd)
|
|
||||||
\\ --group Path to group file (default: group)
|
|
||||||
\\ --outdir Path to output directory (default: ./userdb)
|
|
||||||
\\
|
|
||||||
;
|
|
||||||
|
|
||||||
pub fn main() !void {
|
|
||||||
// This line is here because of https://github.com/ziglang/zig/issues/7807
|
|
||||||
const argv: []const [*:0]const u8 = os.argv;
|
|
||||||
const gpa = heap.raw_c_allocator;
|
|
||||||
|
|
||||||
const stderr = io.getStdErr().writer();
|
|
||||||
const stdout = io.getStdOut().writer();
|
|
||||||
|
|
||||||
const return_code = execute(gpa, stdout, stderr, argv[1..]);
|
|
||||||
os.exit(return_code);
|
|
||||||
}
|
|
||||||
|
|
||||||
fn execute(
|
|
||||||
allocator: Allocator,
|
|
||||||
stdout: anytype,
|
|
||||||
stderr: anytype,
|
|
||||||
argv: []const [*:0]const u8,
|
|
||||||
) u8 {
|
|
||||||
const result = flags.parse(argv, &[_]flags.Flag{
|
|
||||||
.{ .name = "-h", .kind = .boolean },
|
|
||||||
.{ .name = "--passwd", .kind = .arg },
|
|
||||||
.{ .name = "--group", .kind = .arg },
|
|
||||||
.{ .name = "--outdir", .kind = .arg },
|
|
||||||
}) catch {
|
|
||||||
stderr.writeAll(usage) catch {};
|
|
||||||
return 1;
|
|
||||||
};
|
|
||||||
|
|
||||||
if (result.boolFlag("-h")) {
|
|
||||||
stdout.writeAll(usage) catch return 1;
|
|
||||||
return 0;
|
|
||||||
}
|
|
||||||
|
|
||||||
if (result.args.len != 0) {
|
|
||||||
stderr.print("ERROR: unknown option '{s}'\n", .{result.args[0]}) catch {};
|
|
||||||
stderr.writeAll(usage) catch {};
|
|
||||||
return 1;
|
|
||||||
}
|
|
||||||
|
|
||||||
const passwd_fname = result.argFlag("--passwd") orelse "passwd";
|
|
||||||
const group_fname = result.argFlag("--group") orelse "group";
|
|
||||||
const outdir = result.argFlag("--outdir") orelse "./userdb";
|
|
||||||
|
|
||||||
// to catch an error set file.OpenError, wait for
|
|
||||||
// https://github.com/ziglang/zig/issues/2473
|
|
||||||
var errc = ErrCtx{};
|
|
||||||
var passwd_file = fs.cwd().openFile(passwd_fname, .{ .mode = .read_only }) catch |err|
|
|
||||||
return fail(errc.wrapf("open '{s}'", .{passwd_fname}), stderr, err);
|
|
||||||
defer passwd_file.close();
|
|
||||||
|
|
||||||
var group_file = fs.cwd().openFile(group_fname, .{ .mode = .read_only }) catch |err|
|
|
||||||
return fail(errc.wrapf("open '{s}'", .{group_fname}), stderr, err);
|
|
||||||
defer group_file.close();
|
|
||||||
|
|
||||||
var passwdReader = io.bufferedReader(passwd_file.reader()).reader();
|
|
||||||
var users = User.fromReader(allocator, &errc, passwdReader) catch |err|
|
|
||||||
return fail(errc.wrap("read users"), stderr, err);
|
|
||||||
defer {
|
|
||||||
for (users) |*user| user.deinit(allocator);
|
|
||||||
allocator.free(users);
|
|
||||||
}
|
|
||||||
|
|
||||||
var groupReader = io.bufferedReader(group_file.reader()).reader();
|
|
||||||
var groups = Group.fromReader(allocator, groupReader) catch |err|
|
|
||||||
return fail(errc.wrap("read groups"), stderr, err);
|
|
||||||
defer {
|
|
||||||
for (groups) |*group| group.deinit(allocator);
|
|
||||||
allocator.free(groups);
|
|
||||||
}
|
|
||||||
|
|
||||||
const user2groups = StringArrayHashMap(ArrayListUnmanaged([]const u8)).init(allocator);
|
|
||||||
defer {
|
|
||||||
var it = user2groups.iterator();
|
|
||||||
while (it.next()) |entry|
|
|
||||||
entry.value_ptr.*.deinit(allocator);
|
|
||||||
user2groups.deinit();
|
|
||||||
}
|
|
||||||
fillMemberships(allocator, groups, &user2groups);
|
|
||||||
|
|
||||||
try os.mkdirZ(outdir, 0o755) catch |err| switch (err) {
|
|
||||||
error.PathAlreadyExists => {},
|
|
||||||
else => |err| return err,
|
|
||||||
};
|
|
||||||
|
|
||||||
var dir = try fs.cwd().openDir(outdir, .{});
|
|
||||||
|
|
||||||
try makePasswd(dir, users.items);
|
|
||||||
try makeGroups(dir, groups.items);
|
|
||||||
|
|
||||||
return 0;
|
|
||||||
}
|
|
||||||
|
|
||||||
const JSONPasswd = struct {
|
|
||||||
uid: u32,
|
|
||||||
gid: u32,
|
|
||||||
userName: []const u8, // pw_name
|
|
||||||
realName: []const u8, // pw_gecos
|
|
||||||
homeDirectory: []const u8,
|
|
||||||
shell: []const u8,
|
|
||||||
memberOf: []const []const u8,
|
|
||||||
};
|
|
||||||
|
|
||||||
fn makePasswd(
|
|
||||||
dir: fs.Dir,
|
|
||||||
users: []User,
|
|
||||||
memberships: *const StringArrayHashMap(ArrayListUnmanaged([]const u8)),
|
|
||||||
) !void {
|
|
||||||
var namebuf: [PackedUser.max_name_len + ".user".len:0]u8 = undefined;
|
|
||||||
var symlinkbuf: [fmt.count("{d}.user", math.maxInt(u32)):0]u8 = undefined;
|
|
||||||
|
|
||||||
for (users) |user| {
|
|
||||||
const member_of = if (memberships.get(user.name)) |m|
|
|
||||||
m.items
|
|
||||||
else
|
|
||||||
[]const []const u8{};
|
|
||||||
|
|
||||||
const u = JSONPasswd{
|
|
||||||
.uid = user.uid,
|
|
||||||
.gid = user.gid,
|
|
||||||
.userName = user.name,
|
|
||||||
.realName = user.gecos,
|
|
||||||
.homeDirectory = user.home,
|
|
||||||
.shell = user.shell,
|
|
||||||
.memberOf = member_of,
|
|
||||||
};
|
|
||||||
|
|
||||||
const fname = try fmt.bufPrintZ(namebuf, "{s}.user", user.name);
|
|
||||||
var f = try dir.createFileZ(fname, .{});
|
|
||||||
defer f.close();
|
|
||||||
|
|
||||||
var wr = io.bufferedWriter(f.writer());
|
|
||||||
try json.stringify(u, .{}, wr);
|
|
||||||
try wr.flush();
|
|
||||||
|
|
||||||
const symlinkname = try fmt.bufPrintZ(symlinkbuf, "{d}.user", user.uid);
|
|
||||||
try os.symlinkatZ(fname, dir.fd, symlinkname);
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
fn makeGroups(dir: fs.Dir, groups: []Group) !void {
|
|
||||||
_ = dir;
|
|
||||||
_ = groups;
|
|
||||||
}
|
|
||||||
|
|
||||||
fn fail(errc: *ErrCtx, stderr: anytype, err: anytype) u8 {
|
|
||||||
const err_chain = errc.unwrap().constSlice();
|
|
||||||
stderr.print("ERROR {s}: {s}\n", .{ @errorName(err), err_chain }) catch {};
|
|
||||||
return 1;
|
|
||||||
}
|
|
||||||
|
|
||||||
fn fillMemberships(
|
|
||||||
allocator: Allocator,
|
|
||||||
groups: ArrayList(Group),
|
|
||||||
user2groups: *StringArrayHashMap(ArrayListUnmanaged([]const u8)),
|
|
||||||
) void {
|
|
||||||
for (groups) |group| {
|
|
||||||
for (group.members) |member| {
|
|
||||||
const member_groups = try user2groups.getOrPut(allocator, member.name);
|
|
||||||
if (!member_groups.found_existing)
|
|
||||||
member_groups.value_ptr.* = ArrayListUnmanaged([]const u8){};
|
|
||||||
member_groups.value_ptr.*.append(group.name);
|
|
||||||
}
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
const testing = std.testing;
|
|
||||||
|
|
||||||
test "turbonss-unix2systemd invalid argument" {
|
|
||||||
const allocator = testing.allocator;
|
|
||||||
const args = &[_][*:0]const u8{"--invalid-argument"};
|
|
||||||
var stderr = ArrayList(u8).init(allocator);
|
|
||||||
defer stderr.deinit();
|
|
||||||
var stdout = ArrayList(u8).init(allocator);
|
|
||||||
defer stdout.deinit();
|
|
||||||
|
|
||||||
const exit_code = execute(allocator, stdout.writer(), stderr.writer(), args[0..]);
|
|
||||||
try testing.expectEqual(@as(u8, 1), exit_code);
|
|
||||||
try testing.expect(mem.startsWith(
|
|
||||||
u8,
|
|
||||||
stderr.items,
|
|
||||||
"ERROR: unknown option '--invalid-argument'",
|
|
||||||
));
|
|
||||||
}
|
|
||||||
|
|
||||||
test "turbonss-unix2systemd trivial error: missing passwd file" {
|
|
||||||
const allocator = testing.allocator;
|
|
||||||
const args = &[_][*:0]const u8{
|
|
||||||
"--passwd",
|
|
||||||
"/does/not/exist/passwd",
|
|
||||||
"--group",
|
|
||||||
"/does/not/exist/group",
|
|
||||||
};
|
|
||||||
var stderr = ArrayList(u8).init(allocator);
|
|
||||||
defer stderr.deinit();
|
|
||||||
var stdout = ArrayList(u8).init(allocator);
|
|
||||||
defer stdout.deinit();
|
|
||||||
|
|
||||||
const exit_code = execute(allocator, stdout.writer(), stderr.writer(), args[0..]);
|
|
||||||
try testing.expectEqual(@as(u8, 1), exit_code);
|
|
||||||
try testing.expectEqualStrings(stderr.items, "ERROR FileNotFound: open '/does/not/exist/passwd'\n");
|
|
||||||
}
|
|
||||||
|
|
||||||
test "turbonss-unix2systemd fail" {
|
|
||||||
var errc = ErrCtx{};
|
|
||||||
var buf = ArrayList(u8).init(testing.allocator);
|
|
||||||
defer buf.deinit();
|
|
||||||
var wr = buf.writer();
|
|
||||||
const exit_code = fail(errc.wrapf("invalid user 'foo'", .{}), wr, error.NotSure);
|
|
||||||
try testing.expectEqual(exit_code, 1);
|
|
||||||
try testing.expectEqualStrings(buf.items, "ERROR NotSure: invalid user 'foo'\n");
|
|
||||||
}
|
|
||||||
|
|
||||||
test "turbonss-unix2db smoke test" {
|
|
||||||
const allocator = testing.allocator;
|
|
||||||
var stderr = ArrayList(u8).init(allocator);
|
|
||||||
defer stderr.deinit();
|
|
||||||
var stdout = ArrayList(u8).init(allocator);
|
|
||||||
defer stdout.deinit();
|
|
||||||
|
|
||||||
var corpus = try Corpus.testCorpus(allocator);
|
|
||||||
defer corpus.deinit();
|
|
||||||
|
|
||||||
var tmp = testing.tmpDir(.{});
|
|
||||||
// TODO: defer
|
|
||||||
errdefer tmp.cleanup();
|
|
||||||
|
|
||||||
const tmp_path = blk: {
|
|
||||||
const relative_path = try fs.path.join(allocator, &[_][]const u8{
|
|
||||||
"zig-cache",
|
|
||||||
"tmp",
|
|
||||||
tmp.sub_path[0..],
|
|
||||||
});
|
|
||||||
const real_path = try fs.realpathAlloc(allocator, relative_path);
|
|
||||||
allocator.free(relative_path);
|
|
||||||
break :blk real_path;
|
|
||||||
};
|
|
||||||
defer allocator.free(tmp_path);
|
|
||||||
|
|
||||||
const passwdPath = try fs.path.joinZ(allocator, &[_][]const u8{ tmp_path, "passwd" });
|
|
||||||
defer allocator.free(passwdPath);
|
|
||||||
const groupPath = try fs.path.joinZ(allocator, &[_][]const u8{ tmp_path, "group" });
|
|
||||||
defer allocator.free(groupPath);
|
|
||||||
const outDir = try fs.path.joinZ(allocator, &[_][]const u8{ tmp_path, "outdir" });
|
|
||||||
defer allocator.free(outDir);
|
|
||||||
|
|
||||||
const passwd_fd = try os.open(passwdPath, os.O.CREAT | os.O.WRONLY, 0o644);
|
|
||||||
const group_fd = try os.open(groupPath, os.O.CREAT | os.O.WRONLY, 0o644);
|
|
||||||
|
|
||||||
var i: usize = 0;
|
|
||||||
while (i < corpus.users.len) : (i += 1) {
|
|
||||||
const user = corpus.users.get(i);
|
|
||||||
const line = user.toLine().constSlice();
|
|
||||||
_ = try os.write(passwd_fd, line);
|
|
||||||
}
|
|
||||||
os.close(passwd_fd);
|
|
||||||
|
|
||||||
var group_writer = (fs.File{ .handle = group_fd }).writer();
|
|
||||||
i = 0;
|
|
||||||
while (i < corpus.groups.len) : (i += 1)
|
|
||||||
try corpus.groups.get(i).writeTo(group_writer);
|
|
||||||
os.close(group_fd);
|
|
||||||
|
|
||||||
const args = &[_][*:0]const u8{
|
|
||||||
"--passwd", passwdPath,
|
|
||||||
"--group", groupPath,
|
|
||||||
"--outdir", outDir,
|
|
||||||
};
|
|
||||||
|
|
||||||
const exit_code = execute(allocator, stdout.writer(), stderr.writer(), args);
|
|
||||||
try testing.expectEqualStrings("total 1664 bytes. groups=5 users=4\n", stderr.items);
|
|
||||||
try testing.expectEqual(@as(u8, 0), exit_code);
|
|
||||||
}
|
|
||||||
Loading…
Reference in New Issue