simplify appendUser

This commit is contained in:
Motiejus Jakštys 2022-02-19 16:56:30 +02:00 committed by Motiejus Jakštys
parent 5f0d9bb176
commit 4e45c6e5a9

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@ -1,6 +1,7 @@
const std = @import("std"); const std = @import("std");
const Allocator = std.mem.Allocator; const Allocator = std.mem.Allocator;
const ArrayList = std.ArrayList;
const cast = std.math.cast; const cast = std.math.cast;
pub const PackedUserSize = @divExact(@bitSizeOf(PackedUser), 8); pub const PackedUserSize = @divExact(@bitSizeOf(PackedUser), 8);
@ -27,81 +28,50 @@ pub const User = struct {
// UserWriter accepts a naive User struct and returns a PackedUser // UserWriter accepts a naive User struct and returns a PackedUser
pub const UserWriter = struct { pub const UserWriter = struct {
// shellIndexFnType is a signature for a function that accepts a shell // shellIndexFnType is a signature for a function that accepts a shell
// string and returns it's index in the global shell section. Passing a // string and returns it's index in the global shell section. Passing a
// function makes tests easier, and removes the Shell dependency of this // function makes tests easier, and removes the Shell dependency of this
// module. // module.
const shellIndexFnType = fn ([]const u8) ?u6; const shellIndexFnType = fn ([]const u8) ?u6;
allocator: Allocator, appendTo: ArrayList(u8),
shellIndexFn: shellIndexFnType, shellIndexFn: shellIndexFnType,
pub fn init(allocator: Allocator, shellIndexFn: shellIndexFnType) UserWriter { pub fn init(appendTo: ArrayList(u8), shellIndexFn: shellIndexFnType) UserWriter {
return UserWriter{ return UserWriter{
.allocator = allocator, .appendTo = appendTo,
.shellIndexFn = shellIndexFn, .shellIndexFn = shellIndexFn,
}; };
} }
const fromUserErr = std.mem.Allocator.Error || error{InvalidRecord}; const fromUserErr = error{InvalidRecord};
pub fn fromUser(self: *UserWriter, user: User) fromUserErr![]const u8 { pub fn appendUser(self: *UserWriter, user: User) !void {
const home_len = std.math.cast(u6, user.home.len - 1) catch return error.InvalidRecord; const home_len = cast(u6, user.home.len - 1) catch return error.InvalidRecord;
const name_len = cast(u5, user.name.len - 1) catch return error.InvalidRecord; const name_len = cast(u5, user.name.len - 1) catch return error.InvalidRecord;
const shell_len = cast(u6, user.shell.len - 1) catch return error.InvalidRecord; const shell_len = cast(u6, user.shell.len - 1) catch return error.InvalidRecord;
const gecos_len = cast(u8, user.gecos.len) catch return error.InvalidRecord; const gecos_len = cast(u8, user.gecos.len) catch return error.InvalidRecord;
var bindata_len: u32 = home_len;
var puser = PackedUser{ var puser = PackedUser{
.uid = @as(u32, user.uid), .uid = user.uid,
.gid = @as(u32, user.gid), .gid = user.gid,
.additional_gids_offset = std.math.maxInt(u29), // needs second pass .additional_gids_offset = std.math.maxInt(u29), // needs second pass
.shell_here = undefined, .shell_here = self.shellIndexFn(user.shell) == null,
.shell_len_or_idx = undefined, .shell_len_or_idx = self.shellIndexFn(user.shell) orelse shell_len,
.home_len = home_len, .home_len = home_len,
.name_is_a_suffix = undefined, .name_is_a_suffix = std.mem.endsWith(u8, user.home, user.name),
.name_len = name_len, .name_len = name_len,
.gecos_len = gecos_len, .gecos_len = gecos_len,
}; };
if (std.mem.endsWith(u8, user.home, user.name)) { try self.appendTo.appendSlice(std.mem.asBytes(&puser));
puser.name_is_a_suffix = true; try self.appendTo.appendSlice(user.home);
} else {
puser.name_is_a_suffix = false;
bindata_len += name_len;
}
bindata_len += gecos_len;
if (self.shellIndexFn(user.shell)) |idx| {
puser.shell_here = false;
puser.shell_len_or_idx = idx;
} else {
puser.shell_here = true;
puser.shell_len_or_idx = shell_len;
bindata_len += shell_len;
}
var result = try self.allocator.alloc(u8, PackedUserSize + bindata_len);
const userPointer = @ptrCast([*]const u8, &puser);
{
var i: u32 = 0;
while (i < PackedUserSize) {
result[i] = userPointer[i];
i += 1;
}
}
std.mem.copy(u8, result, user.home);
if (!puser.name_is_a_suffix) { if (!puser.name_is_a_suffix) {
std.mem.copy(u8, result, user.name); try self.appendTo.appendSlice(user.name);
} }
std.mem.copy(u8, result, user.gecos); try self.appendTo.appendSlice(user.gecos);
if (puser.shell_here) { if (puser.shell_here) {
std.mem.copy(u8, result, user.shell); try self.appendTo.appendSlice(user.shell);
} }
return result;
} }
}; };
@ -121,7 +91,10 @@ fn testShellIndex(shell: []const u8) ?u6 {
} }
test "construct PackedUser blob" { test "construct PackedUser blob" {
var writer = UserWriter.init(testing.allocator, testShellIndex); var buf = ArrayList(u8).init(testing.allocator);
defer buf.deinit();
var writer = UserWriter.init(buf, testShellIndex);
const user1 = User{ const user1 = User{
.uid = 1000, .uid = 1000,
.gid = 1000, .gid = 1000,
@ -138,8 +111,6 @@ test "construct PackedUser blob" {
.home = "/home/service1", .home = "/home/service1",
.shell = "/usr/bin/nologin", .shell = "/usr/bin/nologin",
}; };
const puser1 = try writer.fromUser(user1); try writer.appendUser(user1);
const puser2 = try writer.fromUser(user2); try writer.appendUser(user2);
defer testing.allocator.free(puser1);
defer testing.allocator.free(puser2);
} }