79 lines
2.6 KiB
Zig
79 lines
2.6 KiB
Zig
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const builtin = @import("builtin");
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const Os = builtin.Os;
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const os = @import("index.zig");
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const io = @import("../io.zig");
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/// POSIX function which gets a uid from username.
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pub fn getUserId(name: []const u8) -> %u32 {
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return switch (builtin.os) {
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Os.linux, Os.darwin, Os.macosx, Os.ios => posixGetUserId(name),
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else => @compileError("Unsupported OS"),
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};
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}
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const State = enum {
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Start,
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WaitForNextLine,
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SkipPassword,
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ReadId,
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};
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error UserNotFound;
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error CorruptPasswordFile;
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pub fn posixGetUserId(name: []const u8) -> %u32 {
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var in_stream = %return io.InStream.open("/etc/passwd", null);
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defer in_stream.close();
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var buf: [os.page_size]u8 = undefined;
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var name_index: usize = 0;
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var state = State.Start;
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var uid: u32 = 0;
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while (true) {
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const amt_read = %return in_stream.read(buf[0..]);
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for (buf[0..amt_read]) |byte| {
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switch (state) {
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State.Start => switch (byte) {
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':' => {
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state = if (name_index == name.len) State.SkipPassword else State.WaitForNextLine;
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},
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'\n' => return error.CorruptPasswordFile,
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else => {
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if (name_index == name.len or name[name_index] != byte) {
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state = State.WaitForNextLine;
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}
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name_index += 1;
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},
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},
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State.WaitForNextLine => switch (byte) {
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'\n' => {
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name_index = 0;
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state = State.Start;
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},
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else => continue,
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},
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State.SkipPassword => switch (byte) {
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'\n' => return error.CorruptPasswordFile,
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':' => {
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state = State.ReadId;
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},
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else => continue,
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},
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State.ReadId => switch (byte) {
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'\n', ':' => return uid,
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else => {
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const digit = switch (byte) {
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'0' ... '9' => byte - '0',
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else => return error.CorruptPasswordFile,
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};
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if (@mulWithOverflow(u32, uid, 10, &uid)) return error.CorruptPasswordFile;
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if (@addWithOverflow(u32, uid, digit, &uid)) return error.CorruptPasswordFile;
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},
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},
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}
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}
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if (amt_read < buf.len) return error.UserNotFound;
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}
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}
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