syntax cosmetics

docs/architecture.md

@@ -132,10 +132,11 @@ 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.
+`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 (shifted by 3 bits due to the 8-byte
+alignment) in the `Users` and `Groups` section relative to the beginning of the
+section.
 
 ```
 const PackedGroup = packed struct {
@@ -146,7 +147,8 @@ const PackedGroup = packed struct {
 ```
 
 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.
+by a varint-compressed offset to the groupmembers section, followed by padding
+upto 8 bytes.
 
 PackedUser is a bit more involved:
 
@@ -177,9 +179,9 @@ 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:
+- `name` is frequently a suffix of `home`. For example, `home=/home/vidmantas`
+  and `name=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`.

src/DB.zig

@@ -702,10 +702,10 @@ fn bdzIdx(
     keys: []const T,
     idx2offset: []const u32,
 ) error{OutOfMemory}![]align(8) const u32 {
-    const search_fn = switch (T) {
+    const search_fn = comptime switch (T) {
         u32 => bdz.search_u32,
         []const u8 => bdz.search,
-        else => unreachable,
+        else => @compileError("unexpected type " ++ @typeName(T)),
     };
     assert(keys.len <= math.maxInt(u32));
     var result = try allocator.alignedAlloc(u32, 8, keys.len);

src/Group.zig

@@ -74,7 +74,6 @@ pub fn fromReader(allocator: Allocator, reader: anytype) FromReaderError![]Group
 
     var i: usize = 0;
     while (true) : (i += 1) {
-        // TODO: catch and interpret different errors
         const max = std.math.maxInt(u32);
         reader.readUntilDelimiterArrayList(&line, '\n', max) catch |err| switch (err) {
             error.EndOfStream => break,

src/libnss.zig

@@ -220,7 +220,7 @@ fn getgrgid_r(
     const omit_members = state.omit_members;
 
     var buf = buffer[0..buflen];
-    var cgroup = db.getgrgid(gid, buf, omit_members) catch |err| switch (err) {
+    const cgroup = db.getgrgid(gid, buf, omit_members) catch |err| switch (err) {
         error.BufferTooSmall => {
             errnop.* = @enumToInt(os.E.RANGE);
             return c.NSS_STATUS_TRYAGAIN;
@@ -262,17 +262,16 @@ fn getgrnam_r(
     const omit_members = state.omit_members;
     const nameSlice = mem.sliceTo(name, 0);
     var buf = buffer[0..buflen];
-    var cgroup = db.getgrnam(nameSlice, buf, omit_members) catch |err| switch (err) {
+    const cgroup = db.getgrnam(nameSlice, buf, omit_members) catch |err| switch (err) {
         error.BufferTooSmall => {
             errnop.* = @enumToInt(os.E.RANGE);
             return c.NSS_STATUS_TRYAGAIN;
         },
     };
-    const got_cgroup = cgroup orelse {
+    group.* = cgroup orelse {
         errnop.* = @enumToInt(os.E.NOENT);
         return c.NSS_STATUS_NOTFOUND;
     };
-    group.* = got_cgroup;
     return c.NSS_STATUS_SUCCESS;
 }
 
@@ -286,11 +285,10 @@ fn setpwent(state: *State) c.enum_nss_status {
     state.getpwent_iterator_mu.lock();
     defer state.getpwent_iterator_mu.unlock();
 
-    const db = state.file.db;
     state.getpwent_iterator = PackedUser.iterator(
-        db.users,
-        db.header.num_users,
-        db.shellReader(),
+        state.file.db.users,
+        state.file.db.header.num_users,
+        state.file.db.shellReader(),
     );
     return c.NSS_STATUS_SUCCESS;
 }