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add usergids

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Motiejus Jakštys 2022-03-04 10:37:07 +02:00 committed by Motiejus Jakštys
parent a4e3e08f5f
commit b81072f726
4 changed files with 119 additions and 35 deletions
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7
README.md
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@ -372,11 +372,10 @@ Section creation order:
1. ✅ `bdz_*`. No depdendencies.
1. ✅ `shellIndex`, `shellBlob`. No dependencies.
1. UserGids. No dependencies.
1. Users, but without `additional_gids_offset`. No dependencies.
1. Groupmembers. Depends on Users, ex. `additional_gids_offset`.
1. ✅ userGids. No dependencies.
1. Users. Requires `userGids`.
1. Groupmembers. Requires Users.
1. Groups. Requires Groupmembers.
1. Mutate `Users.additional_gids_offset`. Requires Groupmembers and ShellIndex.
1. `idx_*`. Requires offsets to Groups and Users.
1. Header.

64
src/compress.zig
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@ -5,6 +5,9 @@
// golang's varint implementation.
const std = @import("std");
const ArrayList = std.ArrayList;
const Allocator = std.mem.Allocator;
// compresses a strictly incrementing sorted slice of integers using delta
// compression. Compression is in-place.
pub fn deltaCompress(comptime T: type, elems: []T) error{NotSorted}!void {
@ -48,7 +51,7 @@ test "delta compress/decompress" {
.{ .input = &[_]u8{ 0, 254, 255 }, .want = &[_]u8{ 0, 253, 0 } },
};
for (tests) |t| {
var arr = try std.ArrayList(u8).initCapacity(
var arr = try ArrayList(u8).initCapacity(
testing.allocator,
t.input.len,
);
@ -69,7 +72,7 @@ test "delta compression negative tests" {
&[_]u8{ 0, 1, 1 },
&[_]u8{ 0, 1, 2, 1 },
}) |t| {
var arr = try std.ArrayList(u8).initCapacity(testing.allocator, t.len);
var arr = try ArrayList(u8).initCapacity(testing.allocator, t.len);
defer arr.deinit();
try arr.appendSlice(t);
try testing.expectError(error.NotSorted, deltaCompress(u8, arr.items));
@ -81,7 +84,7 @@ test "delta decompress overflow" {
&[_]u8{ 255, 0 },
&[_]u8{ 0, 128, 127 },
}) |t| {
var arr = try std.ArrayList(u8).initCapacity(testing.allocator, t.len);
var arr = try ArrayList(u8).initCapacity(testing.allocator, t.len);
defer arr.deinit();
try arr.appendSlice(t);
try testing.expectError(error.Overflow, deltaDecompress(u8, arr.items));
@ -142,24 +145,31 @@ pub fn putUvarint(buf: []u8, x: u64) usize {
return i + 1;
}
test "uvarint" {
const uvarint_tests = [_]u64{
0,
1,
2,
10,
20,
63,
64,
65,
127,
128,
129,
255,
256,
257,
1 << 63 - 1,
};
pub fn appendUvarint(arr: *ArrayList(u8), x: u64) Allocator.Error!void {
var buf: [maxVarintLen64]u8 = undefined;
const n = putUvarint(&buf, x);
try arr.appendSlice(buf[0..n]);
}
const uvarint_tests = [_]u64{
0,
1,
2,
10,
20,
63,
64,
65,
127,
128,
129,
255,
256,
257,
1 << 63 - 1,
};
test "putUvarint/uvarint" {
for (uvarint_tests) |x| {
var buf: [maxVarintLen64]u8 = undefined;
const n = putUvarint(buf[0..], x);
@ -170,6 +180,18 @@ test "uvarint" {
}
}
test "appendUvarint" {
for (uvarint_tests) |x| {
var buf = ArrayList(u8).init(testing.allocator);
defer buf.deinit();
try appendUvarint(&buf, x);
const got = try uvarint(buf.items);
try testing.expectEqual(x, got.value);
}
}
test "overflow" {
for ([_][]const u8{
&[_]u8{ 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x2 },

81
src/sections.zig
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@ -108,6 +108,7 @@ const Corpus = struct {
var username2groups = StringHashMap(
ArrayListUnmanaged(*const Group),
).init(baseAllocator);
for (groups) |*group| {
var members = try allocator.alloc(*const User, group.members.count());
members.len = 0;
@ -143,9 +144,11 @@ const Corpus = struct {
sort.sort(*const Group, userGroups.items, {}, cmpGroupPtr);
var username2groups_final = StringHashMap([]*const Group).init(allocator);
for (users) |user| {
const userGroups = username2groups.get(user.name).?.toOwnedSlice(allocator);
try username2groups_final.put(user.name, userGroups);
var it = username2groups.iterator();
while (it.next()) |elem| {
const username = elem.key_ptr.*;
const usergroups = elem.value_ptr.*.toOwnedSlice(allocator);
try username2groups_final.put(username, usergroups);
}
username2groups.deinit();
@ -228,6 +231,53 @@ pub const Sections = struct {
};
}
pub const UserGids = struct {
// username -> offset in blob
name2offset: StringHashMap(u32),
// compressed user gids blob. A blob contains N <= users.len items,
// an item is:
// len: varint
// gid: [varint]varint,
// ... and the gid list is delta-compressed.
blob: []u8,
};
const userGidsErr = Allocator.Error || error{Overflow};
pub fn userGids(self: *const Sections) userGidsErr!UserGids {
var arena = std.heap.ArenaAllocator.init(self.allocator);
defer arena.deinit();
var blob = ArrayList(u8).init(self.allocator);
var name2offset = StringHashMap(u32).init(self.allocator);
for (self.corpus.users) |user| {
const usergroups_maybe = self.corpus.username2groups.get(user.name);
if (usergroups_maybe == null)
continue;
const usergroups = usergroups_maybe.?;
try name2offset.putNoClobber(user.name, try math.cast(u32, blob.items.len));
var userBlob = try ArrayList(u8).initCapacity(arena.allocator(), usergroups.len * 2);
var deltaCompressedGids = try arena.allocator().alloc(u32, usergroups.len);
deltaCompressedGids.len = usergroups.len;
for (usergroups) |group, i| {
deltaCompressedGids[i] = group.gid;
}
compress.deltaCompress(u32, deltaCompressedGids) catch |err| switch (err) {
error.NotSorted => unreachable,
};
try compress.appendUvarint(&userBlob, usergroups.len);
for (deltaCompressedGids) |gid| {
try compress.appendUvarint(&userBlob, gid);
}
try blob.appendSlice(userBlob.toOwnedSlice());
}
return UserGids{
.name2offset = name2offset,
.blob = blob.toOwnedSlice(),
};
}
pub fn groupMembers(self: *const Sections) Allocator.Error!GroupMembers {
var buf: [compress.maxVarintLen64]u8 = undefined;
var offsets = ArrayListUnmanaged(usize).initCapacity(
@ -306,6 +356,13 @@ fn testCorpus(allocator: Allocator) !Corpus {
.gecos = "",
.home = "/",
.shell = "/",
}, User{
.uid = 65534,
.gid = 65534,
.name = "nobody",
.gecos = "nobody",
.home = "/nonexistent",
.shell = "/usr/sbin/nologin",
} };
var members1 = try groupImport.someMembers(
@ -348,8 +405,9 @@ test "test corpus" {
defer corpus.deinit();
try testing.expectEqualStrings(corpus.users[0].name, "Name" ** 8);
try testing.expectEqualStrings(corpus.users[1].name, "svc-bar");
try testing.expectEqualStrings(corpus.users[2].name, "vidmantas");
try testing.expectEqualStrings(corpus.users[1].name, "nobody");
try testing.expectEqualStrings(corpus.users[2].name, "svc-bar");
try testing.expectEqualStrings(corpus.users[3].name, "vidmantas");
try testing.expectEqual(corpus.name2user.get("404"), null);
try testing.expectEqual(corpus.name2user.get("vidmantas").?.uid, 128);
@ -370,7 +428,8 @@ test "test corpus" {
try testing.expectEqual(groupsOfVidmantas[0].gid, 0);
try testing.expectEqual(groupsOfVidmantas[1].gid, 128);
try testing.expectEqual(groupsOfVidmantas[2].gid, 9999);
try testing.expectEqual(corpus.username2groups.get("404"), null);
try testing.expectEqual(corpus.username2groups.get("nobody"), null);
try testing.expectEqual(corpus.username2groups.get("doesnotexist"), null);
}
test "test sections" {
@ -392,9 +451,13 @@ test "test sections" {
const bdz_username = try sections.bdzUsername();
defer allocator.free(bdz_username);
const shellSections = try sections.shellSections();
defer allocator.free(shellSections.index);
defer allocator.free(shellSections.blob);
const shell_sections = try sections.shellSections();
defer allocator.free(shell_sections.index);
defer allocator.free(shell_sections.blob);
var user_gids = try sections.userGids();
defer user_gids.name2offset.deinit();
defer allocator.free(user_gids.blob);
}
test "pack gids" {

2
src/user.zig
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@ -31,7 +31,7 @@ pub const User = struct {
const stringdata = try allocator.alloc(u8, self.strlen());
const gecos_start = self.name.len;
const home_start = gecos_start + self.gecos.len;
const shell_start = home_start + self.shell.len;
const shell_start = home_start + self.home.len;
mem.copy(u8, stringdata[0..self.name.len], self.name);
mem.copy(u8, stringdata[gecos_start..], self.gecos);
mem.copy(u8, stringdata[home_start..], self.home);