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turbonss/lib/User.zig

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Zig

const std = @import("std");
const mem = std.mem;
const fmt = std.fmt;
const maxInt = std.math.maxInt;
const Allocator = mem.Allocator;
const ArrayList = std.ArrayList;
const BoundedArray = std.BoundedArray;
const User = @This();
const PackedUser = @import("PackedUser.zig");
const validate = @import("validate.zig");
uid: u32,
gid: u32,
name: []const u8,
gecos: []const u8,
home: []const u8,
shell: []const u8,
// deep-clones a User record with a given Allocator.
pub fn clone(
self: *const User,
allocator: Allocator,
) error{OutOfMemory}!User {
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.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);
mem.copy(u8, stringdata[shell_start..], self.shell);
return User{
.uid = self.uid,
.gid = self.gid,
.name = stringdata[0..self.name.len],
.gecos = stringdata[gecos_start .. gecos_start + self.gecos.len],
.home = stringdata[home_start .. home_start + self.home.len],
.shell = stringdata[shell_start .. shell_start + self.shell.len],
};
}
const line_fmt = "{s}:x:{d}:{d}:{s}:{s}:{s}\n";
const max_line_len = fmt.count(line_fmt, .{
max_user.uid,
max_user.gid,
max_user.gecos,
max_user.home,
max_user.shell,
});
// toPasswdLine formats the user in /etc/passwd format, including the EOL
fn toLine(self: *const User) BoundedArray(u8, max_line_len) {
var result = BoundedArray(u8, max_line_len);
fmt.bufPrint(result.slice(), line_fmt, .{
self.uid,
self.gid,
self.gecos,
self.home,
self.shell,
});
return result;
}
// fromLine accepts a line of /etc/passwd (with or without the EOL) and makes a
// User.
fn fromLine(allocator: Allocator, line: []const u8) error{ InvalidRecord, OutOfMemory }!User {
var it = mem.split(u8, line, ":");
const uids = it.next() orelse return error.InvalidRecord;
const gids = it.next() orelse return error.InvalidRecord;
const name = it.next() orelse return error.InvalidRecord;
const gecos = it.next() orelse return error.InvalidRecord;
const home = it.next() orelse return error.InvalidRecord;
const shell = it.next() orelse return error.InvalidRecord;
// the line must be exhaustive.
if (it.next() != null) return error.InvalidRecord;
const uid = fmt.parseInt(u32, uids) orelse return error.InvalidRecord;
const gid = fmt.parseInt(u32, gids) orelse return error.InvalidRecord;
try validate.utf8(name);
try validate.utf8(gecos);
try validate.utf8(home);
try validate.utf8(shell);
const user = User{
.uid = uid,
.gid = gid,
.name = name,
.gecos = gecos,
.home = home,
.shell = shell,
};
return try user.clone(allocator);
}
fn strlen(self: *const User) usize {
return self.name.len +
self.gecos.len +
self.home.len +
self.shell.len;
}
// length of all string-data fields, assuming they are zero-terminated.
// Includes one character for "password".
pub fn strlenZ(self: *const User) usize {
return self.strlen() +
4 + // '\0' of name, gecos, home and shell
2; // password: 'x\0'
}
pub fn deinit(self: *User, allocator: Allocator) void {
const slice = self.home.ptr[0..self.strlen()];
allocator.free(slice);
self.* = undefined;
}
pub fn fromReader(allocator: Allocator, reader: anytype) ![]User {
var users = ArrayList(User).init(allocator);
var scratch = ArrayList(u8).init(allocator);
defer scratch.deinit();
while (true) {
const line = reader.readUntilDelimiterArrayList(&scratch, '\n', maxInt(usize));
_ = line;
}
_ = users;
}
const testing = std.testing;
pub const max_user = User{
.uid = maxInt(u32),
.gid = maxInt(u32),
.name = "Name" ** 8,
.gecos = "realname" ** 255 ++ "realnam",
.home = "Home" ** 16,
.shell = "She.LllL" ** 32,
};
test "max_user and max_str_len are consistent" {
const total_len = max_user.name.len +
max_user.gecos.len +
max_user.home.len +
max_user.shell.len;
try testing.expectEqual(total_len, PackedUser.max_str_len);
}
test "User.clone" {
var allocator = testing.allocator;
const user = User{
.uid = 1000,
.gid = 1000,
.name = "vidmantas",
.gecos = "Vidmantas Kaminskas",
.home = "/home/vidmantas",
.shell = "/bin/bash",
};
var user2 = try user.clone(allocator);
defer user2.deinit(allocator);
try testing.expectEqualStrings(user.shell, "/bin/bash");
}