replace PackedUserHash with simple PackedUser
passing hashes is OK
This commit is contained in:
Motiejus Jakštys
parent
c78a2c0def
commit
1751f6c996
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@ -251,13 +251,13 @@ pub fn usersSection(
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const userOffset = try math.cast(u32, blob.items.len);
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std.debug.assert(userOffset & 7 == 0);
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idx2offset[i] = userOffset;
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try userImport.PackedUserHash.packTo(
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try userImport.PackedUser.packTo(
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&blob,
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user,
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gids.idx2offset[i],
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shells.indices,
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);
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try pad.arrayList(&blob, userImport.PackedUserHash.alignment_bits);
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try pad.arrayList(&blob, userImport.PackedUser.alignment_bits);
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}
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return UsersSection{
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.idx2offset = idx2offset,
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395
src/user.zig
395
src/user.zig
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@ -10,6 +10,7 @@ const mem = std.mem;
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const math = std.math;
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const Allocator = mem.Allocator;
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const ArrayList = std.ArrayList;
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const StringHashMap = std.StringHashMap;
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// Idx2ShellProto is a function prototype that, given a shell's index (in
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// global shell section), will return a shell string. Matches ShellReader.get.
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@ -78,231 +79,221 @@ pub fn Shell2Index(T: type) type {
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};
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}
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pub const PackedUserHash = packedUser(std.StringHashMap(u6));
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pub const PackedUser = struct {
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const Self = @This();
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fn packedUser(comptime ShellIndexType: type) type {
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return struct {
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const Self = @This();
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pub const alignment_bits = 3;
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pub const alignment_bits = 3;
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const Inner = packed struct {
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uid: u32,
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gid: u32,
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padding: u2 = 0,
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shell_len_or_idx: u6,
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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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const Inner = packed struct {
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uid: u32,
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gid: u32,
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padding: u2 = 0,
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shell_len_or_idx: u6,
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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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fn homeLen(self: *const Inner) usize {
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return @as(u32, self.home_len) + 1;
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}
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fn nameStart(self: *const Inner) usize {
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const name_len = self.nameLen();
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if (self.name_is_a_suffix) {
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return self.homeLen() - name_len;
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} else return self.homeLen();
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}
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fn nameLen(self: *const Inner) usize {
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return @as(u32, self.name_len) + 1;
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}
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fn gecosStart(self: *const Inner) usize {
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if (self.name_is_a_suffix) {
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return self.homeLen();
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} else return self.homeLen() + self.nameLen();
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}
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fn gecosLen(self: *const Inner) usize {
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return self.gecos_len;
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}
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fn maybeShellStart(self: *const Inner) usize {
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assert(self.shell_here);
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return self.gecosStart() + self.gecosLen();
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}
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fn shellLen(self: *const Inner) usize {
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return @as(u32, self.shell_len_or_idx) + 1;
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}
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// stringLength returns the length of the blob storing string values.
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fn stringLength(self: *const Inner) usize {
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var result: usize = self.homeLen() + self.gecosLen();
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if (!self.name_is_a_suffix)
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result += self.nameLen();
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if (self.shell_here)
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result += self.shellLen();
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return result;
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}
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};
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// PackedUser does not allocate; it re-interprets the "bytes" blob
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// field. Both of those fields are pointers to "our representation" of
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// that field.
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inner: *const Inner,
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bytes: []const u8,
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additional_gids_offset: u64,
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pub const Entry = struct {
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user: Self,
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next: ?[]const u8,
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};
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// TODO(motiejus) provide a way to return an entry without decoding the
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// additional_gids_offset:
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// - will not return the 'next' slice.
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// - cannot throw an Overflow error.
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pub fn fromBytes(bytes: []const u8) error{Overflow}!Entry {
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const inner = mem.bytesAsValue(Inner, bytes[0..@sizeOf(Inner)]);
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const start_blob = @sizeOf(Inner);
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const end_strings = start_blob + inner.stringLength();
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const gids_offset = try compress.uvarint(bytes[end_strings..]);
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const end_blob = end_strings + gids_offset.bytes_read;
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const nextStart = pad.roundUp(usize, alignment_bits, end_blob);
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var next: ?[]const u8 = null;
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if (nextStart < bytes.len)
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next = bytes[nextStart..];
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return Entry{
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.user = Self{
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.inner = inner,
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.bytes = bytes[start_blob..end_blob],
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.additional_gids_offset = gids_offset.value,
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},
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.next = next,
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};
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fn homeLen(self: *const Inner) usize {
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return @as(u32, self.home_len) + 1;
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}
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pub const Iterator = struct {
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section: ?[]const u8,
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shellIndex: Idx2ShellProto,
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pub fn next(it: *Iterator) error{Overflow}!?Self {
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if (it.section) |section| {
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const entry = try Self.fromBytes(section);
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it.section = entry.next;
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return entry.user;
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}
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return null;
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}
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};
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pub fn iterator(section: []const u8, idxFn: Idx2ShellProto) Iterator {
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return Iterator{ .section = section, .shellIndex = idxFn };
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fn nameStart(self: *const Inner) usize {
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const name_len = self.nameLen();
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if (self.name_is_a_suffix) {
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return self.homeLen() - name_len;
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} else return self.homeLen();
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}
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// packTo packs the User record and copies it to the given byte slice.
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// The slice must have at least maxRecordSize() bytes available. The
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// slice is passed as a pointer, so it can be mutated.
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pub fn packTo(
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arr: *ArrayList(u8),
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user: User,
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additional_gids_offset: u64,
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idxFn: ShellIndexType,
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) error{ InvalidRecord, OutOfMemory }!void {
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std.debug.assert(arr.items.len & 7 == 0);
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// function arguments are consts. We need to mutate the underlying
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// slice, so passing it via pointer instead.
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const home_len = try validate.downCast(u6, user.home.len - 1);
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const name_len = try validate.downCast(u5, user.name.len - 1);
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const shell_len = try validate.downCast(u6, user.shell.len - 1);
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const gecos_len = try validate.downCast(u8, user.gecos.len);
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try validate.utf8(user.home);
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try validate.utf8(user.name);
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try validate.utf8(user.shell);
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try validate.utf8(user.gecos);
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const inner = Inner{
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.uid = user.uid,
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.gid = user.gid,
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.shell_here = idxFn.get(user.shell) == null,
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.shell_len_or_idx = idxFn.get(user.shell) orelse shell_len,
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.home_len = home_len,
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.name_is_a_suffix = mem.endsWith(u8, user.home, user.name),
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.name_len = name_len,
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.gecos_len = gecos_len,
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};
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const innerBytes = mem.asBytes(&inner);
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try arr.*.appendSlice(innerBytes[0..@sizeOf(Inner)]);
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try arr.*.appendSlice(user.home);
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if (!inner.name_is_a_suffix)
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try arr.*.appendSlice(user.name);
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try arr.*.appendSlice(user.gecos);
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if (inner.shell_here)
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try arr.*.appendSlice(user.shell);
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try compress.appendUvarint(arr, additional_gids_offset);
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fn nameLen(self: *const Inner) usize {
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return @as(u32, self.name_len) + 1;
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}
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pub fn uid(self: Self) u32 {
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return self.inner.uid;
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fn gecosStart(self: *const Inner) usize {
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if (self.name_is_a_suffix) {
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return self.homeLen();
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} else return self.homeLen() + self.nameLen();
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}
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pub fn gid(self: Self) u32 {
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return self.inner.gid;
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fn gecosLen(self: *const Inner) usize {
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return self.gecos_len;
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}
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pub fn additionalGidsOffset(self: Self) u64 {
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return self.additional_gids_offset;
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fn maybeShellStart(self: *const Inner) usize {
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assert(self.shell_here);
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return self.gecosStart() + self.gecosLen();
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}
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pub fn home(self: Self) []const u8 {
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return self.bytes[0..self.inner.homeLen()];
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fn shellLen(self: *const Inner) usize {
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return @as(u32, self.shell_len_or_idx) + 1;
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}
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pub fn name(self: Self) []const u8 {
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const name_pos = self.inner.nameStart();
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const name_len = self.inner.nameLen();
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return self.bytes[name_pos .. name_pos + name_len];
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}
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pub fn gecos(self: Self) []const u8 {
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const gecos_pos = self.inner.gecosStart();
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const gecos_len = self.inner.gecosLen();
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return self.bytes[gecos_pos .. gecos_pos + gecos_len];
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}
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pub fn shell(self: Self, idxFn: Idx2ShellProto) []const u8 {
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if (self.inner.shell_here) {
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const shell_pos = self.inner.maybeShellStart();
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const shell_len = self.inner.shellLen();
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return self.bytes[shell_pos .. shell_pos + shell_len];
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}
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return idxFn(self.inner.shell_len_or_idx);
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// stringLength returns the length of the blob storing string values.
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fn stringLength(self: *const Inner) usize {
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var result: usize = self.homeLen() + self.gecosLen();
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if (!self.name_is_a_suffix)
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result += self.nameLen();
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if (self.shell_here)
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result += self.shellLen();
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return result;
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}
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};
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}
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// PackedUser does not allocate; it re-interprets the "bytes" blob
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// field. Both of those fields are pointers to "our representation" of
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// that field.
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inner: *const Inner,
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bytes: []const u8,
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additional_gids_offset: u64,
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pub const Entry = struct {
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user: Self,
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next: ?[]const u8,
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};
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// TODO(motiejus) provide a way to return an entry without decoding the
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// additional_gids_offset:
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// - will not return the 'next' slice.
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// - cannot throw an Overflow error.
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pub fn fromBytes(bytes: []const u8) error{Overflow}!Entry {
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const inner = mem.bytesAsValue(Inner, bytes[0..@sizeOf(Inner)]);
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const start_blob = @sizeOf(Inner);
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const end_strings = start_blob + inner.stringLength();
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const gids_offset = try compress.uvarint(bytes[end_strings..]);
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const end_blob = end_strings + gids_offset.bytes_read;
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const nextStart = pad.roundUp(usize, alignment_bits, end_blob);
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var next: ?[]const u8 = null;
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if (nextStart < bytes.len)
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next = bytes[nextStart..];
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return Entry{
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.user = Self{
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.inner = inner,
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.bytes = bytes[start_blob..end_blob],
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.additional_gids_offset = gids_offset.value,
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},
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.next = next,
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};
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}
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pub const Iterator = struct {
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section: ?[]const u8,
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shellIndex: Idx2ShellProto,
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pub fn next(it: *Iterator) error{Overflow}!?Self {
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if (it.section) |section| {
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const entry = try Self.fromBytes(section);
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it.section = entry.next;
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return entry.user;
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}
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return null;
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}
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};
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pub fn iterator(section: []const u8, idxFn: Idx2ShellProto) Iterator {
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return Iterator{ .section = section, .shellIndex = idxFn };
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}
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// packTo packs the User record and copies it to the given byte slice.
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// The slice must have at least maxRecordSize() bytes available. The
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// slice is passed as a pointer, so it can be mutated.
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pub fn packTo(
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arr: *ArrayList(u8),
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user: User,
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additional_gids_offset: u64,
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idxFn: StringHashMap(u6),
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) error{ InvalidRecord, OutOfMemory }!void {
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std.debug.assert(arr.items.len & 7 == 0);
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// function arguments are consts. We need to mutate the underlying
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// slice, so passing it via pointer instead.
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const home_len = try validate.downCast(u6, user.home.len - 1);
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const name_len = try validate.downCast(u5, user.name.len - 1);
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const shell_len = try validate.downCast(u6, user.shell.len - 1);
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const gecos_len = try validate.downCast(u8, user.gecos.len);
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try validate.utf8(user.home);
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try validate.utf8(user.name);
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try validate.utf8(user.shell);
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try validate.utf8(user.gecos);
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const inner = Inner{
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.uid = user.uid,
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.gid = user.gid,
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.shell_here = idxFn.get(user.shell) == null,
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.shell_len_or_idx = idxFn.get(user.shell) orelse shell_len,
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.home_len = home_len,
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.name_is_a_suffix = mem.endsWith(u8, user.home, user.name),
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.name_len = name_len,
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.gecos_len = gecos_len,
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};
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const innerBytes = mem.asBytes(&inner);
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try arr.*.appendSlice(innerBytes[0..@sizeOf(Inner)]);
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try arr.*.appendSlice(user.home);
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if (!inner.name_is_a_suffix)
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try arr.*.appendSlice(user.name);
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try arr.*.appendSlice(user.gecos);
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if (inner.shell_here)
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try arr.*.appendSlice(user.shell);
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try compress.appendUvarint(arr, additional_gids_offset);
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}
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pub fn uid(self: Self) u32 {
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return self.inner.uid;
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}
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pub fn gid(self: Self) u32 {
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return self.inner.gid;
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}
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pub fn additionalGidsOffset(self: Self) u64 {
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return self.additional_gids_offset;
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}
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pub fn home(self: Self) []const u8 {
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return self.bytes[0..self.inner.homeLen()];
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}
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pub fn name(self: Self) []const u8 {
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const name_pos = self.inner.nameStart();
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const name_len = self.inner.nameLen();
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return self.bytes[name_pos .. name_pos + name_len];
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}
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pub fn gecos(self: Self) []const u8 {
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const gecos_pos = self.inner.gecosStart();
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const gecos_len = self.inner.gecosLen();
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return self.bytes[gecos_pos .. gecos_pos + gecos_len];
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}
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pub fn shell(self: Self, idxFn: Idx2ShellProto) []const u8 {
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if (self.inner.shell_here) {
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const shell_pos = self.inner.maybeShellStart();
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const shell_len = self.inner.shellLen();
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return self.bytes[shell_pos .. shell_pos + shell_len];
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}
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return idxFn(self.inner.shell_len_or_idx);
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}
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};
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const testing = std.testing;
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test "PackedUser internal and external alignment" {
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try testing.expectEqual(
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@sizeOf(PackedUserHash.Inner) * 8,
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@bitSizeOf(PackedUserHash.Inner),
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@sizeOf(PackedUser.Inner) * 8,
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@bitSizeOf(PackedUser.Inner),
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);
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}
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const TestShellIndex = struct {
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pub fn get(_: *const TestShellIndex, shell: []const u8) ?u6 {
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if (mem.eql(u8, shell, "/bin/bash")) {
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return 0;
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} else if (mem.eql(u8, shell, "/bin/zsh")) {
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return 1;
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}
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return null;
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}
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};
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const PackedUserTest = packedUser(TestShellIndex);
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fn testShellIndex(allocator: Allocator) StringHashMap(u6) {
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var result = StringHashMap(u6).init(allocator);
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result.put("/bin/bash", 0) catch unreachable;
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result.put("/bin/zsh", 1) catch unreachable;
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return result;
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}
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fn testShell(index: u6) []const u8 {
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return switch (index) {
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@ -345,13 +336,15 @@ test "construct PackedUser section" {
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.home = "/",
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.shell = "/",
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} };
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var shellIndex = testShellIndex(testing.allocator);
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defer shellIndex.deinit();
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for (users) |user| {
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try PackedUserTest.packTo(&buf, user, math.maxInt(u64), TestShellIndex{});
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try pad.arrayList(&buf, PackedUserHash.alignment_bits);
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try PackedUser.packTo(&buf, user, math.maxInt(u64), shellIndex);
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try pad.arrayList(&buf, PackedUser.alignment_bits);
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}
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var i: u29 = 0;
|
||||
var it1 = PackedUserTest.iterator(buf.items, testShell);
|
||||
var it1 = PackedUser.iterator(buf.items, testShell);
|
||||
while (try it1.next()) |user| : (i += 1) {
|
||||
try testing.expectEqual(users[i].uid, user.uid());
|
||||
try testing.expectEqual(users[i].gid, user.gid());
|
||||
|
|
|
|||
Loading…
Reference in New Issue