refactoring UserReader
This commit is contained in:
Motiejus Jakštys
parent
751b51b859
commit
2154205711
301
src/user.zig
301
src/user.zig
@ -35,46 +35,28 @@ pub const PackedUser = struct {
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name_len: u5,
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gecos_len: u8,
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pub fn homeLen(self: *const PackedUser) usize {
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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 fn nameLen(self: *const PackedUser) usize {
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return @as(u32, self.name_len) + 1;
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}
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pub fn gecosLen(self: *const PackedUser) usize {
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return self.gecos_len;
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}
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pub fn shellLen(self: *const PackedUser) usize {
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return @as(u32, self.shell_len_or_idx) + 1;
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}
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// blobLength returns the length of the blob storing string values.
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pub fn blobLength(self: *const Inner) usize {
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var result: usize = self.homeLen();
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if (!self.name_is_a_suffix) {
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result += self.nameLen();
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}
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result += self.gecosLen();
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if (self.shell_here) {
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result += self.shellLen();
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}
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return result;
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}
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pub fn namePos(self: *const Inner) usize {
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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.inner.homeLen() - name_len;
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return self.homeLen() - name_len;
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} else {
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return self.homeLen();
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}
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}
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pub fn gecosPos(self: *const Inner) usize {
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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 gecosLen(self: *const Inner) usize {
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return self.gecos_len;
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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 {
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@ -82,27 +64,83 @@ pub const PackedUser = struct {
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}
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}
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pub fn maybeShellPos(self: *const Inner) usize {
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fn maybeShellStart(self: *const Inner) usize {
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assert(self.shell_here);
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return self.gecosPos() + self.gecosLen();
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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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// blobLength returns the length of the blob storing string values.
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fn blobLength(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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}
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if (self.shell_here) {
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result += self.shellLen();
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}
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return result;
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}
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};
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inner: Inner,
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inner: *const Inner,
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userdata: []const u8,
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pub fn fromBytes(bytes: []const u8) PackedUser {
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pub const Entry = struct {
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user: PackedUser,
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next: ?[]const u8,
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};
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pub fn fromBytes(bytes: []const u8) Entry {
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const inner = std.mem.bytesAsValue(
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PackedUser,
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Inner,
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// https://github.com/ziglang/zig/issues/10958
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bytes[0..@sizeOf(Inner)][0..@sizeOf(Inner)],
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bytes[0..@sizeOf(Inner)],
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);
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const startBlob = InnerSize;
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const endBlob = startBlob + inner.blobLength();
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return PackedUser{
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const nextStart = pad.roundUp(usize, PackedUserAlignmentBits, endBlob);
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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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}
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std.debug.print("\n", .{});
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std.debug.print("startBlob: {d}\n", .{startBlob});
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std.debug.print("endBlob: {d}\n", .{endBlob});
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std.debug.print("nextStart: {d}\n", .{nextStart});
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std.debug.print("len(userdata): {d}\n", .{bytes[startBlob..endBlob].len});
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std.debug.print("uid: {d}\n", .{inner.uid});
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std.debug.print("gid: {d}\n", .{inner.gid});
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std.debug.print("additional_gids_offset: {d}\n", .{inner.additional_gids_offset});
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std.debug.print("shell_here: {d}\n", .{inner.shell_here});
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std.debug.print("shell_len_or_idx: {d}\n", .{inner.shell_len_or_idx});
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std.debug.print("home_len: {d}\n", .{inner.home_len});
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std.debug.print("name_is_a_suffix: {d}\n", .{inner.name_is_a_suffix});
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std.debug.print("name_len: {d}\n", .{inner.name_len});
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std.debug.print("gecos_len: {d}\n", .{inner.gecos_len});
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std.debug.print("userdata: {s}\n", .{bytes[startBlob..endBlob]});
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std.debug.print("userdata[0]: {c}\n", .{bytes[startBlob]});
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std.debug.print("userdata[1]: {c}\n", .{bytes[startBlob + 1]});
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std.debug.print("userdata[2]: {c}\n", .{bytes[startBlob + 2]});
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std.debug.print("userdata[3]: {c}\n", .{bytes[startBlob + 3]});
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std.debug.print("userdata[4]: {c}\n", .{bytes[startBlob + 4]});
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std.debug.print("userdata[5]: {c}\n", .{bytes[startBlob + 5]});
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std.debug.print("userdata[6]: {c}\n", .{bytes[startBlob + 6]});
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std.debug.print("userdata[7]: {c}\n", .{bytes[startBlob + 7]});
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return Entry{
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.user = PackedUser{
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.inner = inner,
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.userdata = bytes[startBlob..endBlob],
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},
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.next = next,
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};
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}
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@ -122,12 +160,10 @@ pub const PackedUser = struct {
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// packTo packs the User record and copies it to the given byte slice. The
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// slice must have at least maxRecordSize() bytes available.
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pub fn packTo(bufPtr: *[]u8, user: User, shellIndexFn: shellIndexFnType) error{InvalidRecord}!void {
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// The slice is passed as a pointer, so it can be mutated.
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pub fn packTo(buf: *[]u8, user: User, shellIndexFn: shellIndexFnType) error{InvalidRecord}!void {
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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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var buf = bufPtr.*;
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const bufStart = @ptrToInt(buf.ptr);
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const home_len = try downCast(u6, user.home.len - 1);
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const name_len = try downCast(u5, user.name.len - 1);
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const shell_len = try downCast(u6, user.shell.len - 1);
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@ -150,37 +186,41 @@ pub const PackedUser = struct {
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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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buf.len += innerBytes.len +
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var pos: usize = buf.*.len;
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buf.*.len += InnerSize +
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user.home.len +
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user.gecos.len;
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mem.copy(u8, buf[0..innerBytes.len], innerBytes);
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buf = buf[innerBytes.len..];
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mem.copy(u8, buf[0..user.home.len], user.home);
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buf = buf[user.home.len..];
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// innerBytes.len is longer than InnerSize. We want to copy
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// only the InnerSize-number of bytes.
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mem.copy(u8, buf.*[pos .. pos + InnerSize], innerBytes[0..InnerSize]);
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pos += InnerSize;
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mem.copy(u8, buf.*[pos .. pos + user.home.len], user.home);
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pos += user.home.len;
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if (!inner.name_is_a_suffix) {
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buf.len += user.name.len;
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mem.copy(u8, buf[0..user.name.len], user.name);
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buf = buf[user.name.len..];
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buf.*.len += user.name.len;
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mem.copy(u8, buf.*[pos .. pos + user.name.len], user.name);
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pos += user.name.len;
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}
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mem.copy(u8, buf, user.gecos);
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buf = buf[user.gecos.len..];
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mem.copy(u8, buf.*[pos .. pos + user.gecos.len], user.gecos);
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pos += user.gecos.len;
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if (inner.shell_here) {
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buf.len += user.shell.len;
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mem.copy(u8, buf[0..user.shell.len], user.shell);
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buf = buf[user.shell.len..];
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buf.*.len += user.shell.len;
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mem.copy(u8, buf.*[pos .. pos + user.shell.len], user.shell);
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pos += user.shell.len;
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}
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const bufLen = @ptrToInt(buf.ptr) - bufStart;
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const padding = pad.roundUpPadding(u64, PackedUserAlignmentBits, bufLen);
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buf.len += padding;
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mem.set(u8, buf[0..padding], 0);
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const padding = pad.roundUpPadding(u64, PackedUserAlignmentBits, pos);
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buf.*.len += padding;
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mem.set(u8, buf.*[pos .. pos + padding], 0);
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}
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// maxSize is the maximum number of records a PackedUser can take
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// (struct + userdata).
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pub fn maxSize() usize {
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comptime {
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const unpadded = InnerSize +
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std.math.maxInt(u6) + // home
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std.math.maxInt(u5) + // name
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@ -188,26 +228,35 @@ pub const PackedUser = struct {
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std.math.maxInt(u8); // gecos
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return pad.roundUp(u64, PackedUserAlignmentBits, unpadded);
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}
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}
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pub fn uid(self: *const PackedUser) u32 {
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return self.inner.uid;
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}
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pub fn gid(self: *const PackedUser) u32 {
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return self.inner.gid;
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}
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pub fn home(self: *const PackedUser) []const u8 {
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return self.userdata[0..self.inner.homeLen()];
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}
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pub fn name(self: *const PackedUser) []const u8 {
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const name_pos = self.inner.namePos();
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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.userdata[name_pos .. name_pos + name_len];
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}
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pub fn gecos(self: *const PackedUser) []const u8 {
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const gecos_pos = self.inner.gecosPos();
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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.userdata[gecos_pos .. gecos_pos + gecos_len];
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}
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pub fn shell(self: *const PackedUser, shellIndex: shellIndexProto) []const u8 {
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if (self.inner.shell_here) {
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const shell_pos = self.inner.maybeShellPos();
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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.userdata[shell_pos .. shell_pos + shell_len];
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}
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@ -215,98 +264,27 @@ pub const PackedUser = struct {
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}
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};
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pub const UserReader = struct {
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section: []const u8,
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shellIndex: shellIndexProto,
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pub const PackedEntry = struct {
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packed_user: *PackedUser,
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section: []const u8,
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};
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pub fn init(section: []u8, shellIndex: shellIndexProto) UserReader {
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return UserReader{
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pub fn userIterator(section: []const u8, shellIndex: shellIndexProto) Iterator {
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return Iterator{
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.section = section,
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.shellIndex = shellIndex,
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};
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}
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pub const Entry = struct {
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user: User,
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nextOffset: usize,
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};
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// atOffset returns a ?User in a given offset of the User section. Also,
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// the offset to the next user.
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pub fn atOffset(self: *UserReader, index: usize) ?Entry {
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if (index == self.section.len) return null;
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assert(index < self.section.len);
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const endUser = index + @sizeOf(PackedUser);
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var u = std.mem.bytesAsValue(
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PackedUser,
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self.section[index..endUser][0..@sizeOf(PackedUser)],
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);
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const startBlob = endUser;
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const endBlob = startBlob + u.blobLength();
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const section = self.section[startBlob..endBlob];
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const home = section[0..u.homeLen()];
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var name: []const u8 = undefined;
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var pos: usize = undefined;
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if (u.name_is_a_suffix) {
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const name_start = u.homeLen() - u.nameLen();
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name = section[name_start..u.homeLen()];
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pos = u.homeLen();
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} else {
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const name_start = u.homeLen();
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name = section[name_start .. name_start + u.nameLen()];
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pos = name_start + u.nameLen();
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}
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const gecos = section[pos .. pos + u.gecosLen()];
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pos += u.gecosLen();
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var shell: []const u8 = undefined;
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if (u.shell_here) {
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shell = section[pos .. pos + u.shellLen()];
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} else {
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shell = self.shellIndex(u.shell_len_or_idx);
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}
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return Entry{
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.user = User{
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.uid = u.uid,
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.gid = u.gid,
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.name = name,
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.gecos = gecos,
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.home = home,
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.shell = shell,
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},
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.nextOffset = pad.roundUp(usize, PackedUserAlignmentBits, endBlob),
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};
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}
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pub const Iterator = struct {
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ur: *UserReader,
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offset: usize = 0,
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section: ?[]const u8,
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shellIndex: shellIndexProto,
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pub fn next(it: *Iterator) ?User {
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if (it.ur.atOffset(it.offset)) |result| {
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it.offset = result.nextOffset;
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return result.user;
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pub fn next(it: *Iterator) ?PackedUser {
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if (it.section) |section| {
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const entry = PackedUser.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(self: *UserReader) Iterator {
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return Iterator{
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.ur = self,
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.offset = 0,
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};
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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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@ -340,6 +318,7 @@ test "construct PackedUser section" {
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var buf = ArrayList(u8).init(testing.allocator);
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defer buf.deinit();
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std.debug.print("\n", .{});
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const users = [_]User{ User{
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.uid = 1000,
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.gid = 1000,
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@ -356,27 +335,33 @@ test "construct PackedUser section" {
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.shell = "/usr/bin/nologin",
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}, User{
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.uid = 0,
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.gid = 4294967295,
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.name = "n" ** 32,
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.gecos = "g" ** 255,
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.home = "h" ** 64,
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.shell = "s" ** 64,
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.gid = math.maxInt(u32),
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.name = "Name" ** 8,
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.gecos = "Gecos" ** 51,
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.home = "Home" ** 16,
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.shell = "She.l..l" ** 8,
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}, User{
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.uid = 1002,
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.gid = 1002,
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.name = "svc-bar",
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.gecos = "",
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.home = "/",
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.shell = "/",
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} };
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for (users) |user| {
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try buf.ensureUnusedCapacity(PackedUser.maxSize());
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try PackedUser.packTo(&buf.items, user, testShellIndex);
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}
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//var rd = UserReader.init(buf.items, testShell);
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//var it = rd.iterator();
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//var i: u32 = 0;
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//while (it.next()) |user| : (i += 1) {
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// try testing.expectEqual(users[i].uid, user.uid);
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// try testing.expectEqual(users[i].gid, user.gid);
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// try testing.expectEqualStrings(users[i].name, user.name);
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// try testing.expectEqualStrings(users[i].gecos, user.gecos);
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// try testing.expectEqualStrings(users[i].home, user.home);
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// try testing.expectEqualStrings(users[i].shell, user.shell);
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//}
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var it = userIterator(buf.items, testShell);
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var i: u32 = 0;
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while (it.next()) |user| : (i += 1) {
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try testing.expectEqual(users[i].uid, user.uid());
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try testing.expectEqual(users[i].gid, user.gid());
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try testing.expectEqualStrings(users[i].name, user.name());
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try testing.expectEqualStrings(users[i].gecos, user.gecos());
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try testing.expectEqualStrings(users[i].home, user.home());
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try testing.expectEqualStrings(users[i].shell, user.shell(testShell));
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}
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try testing.expectEqual(users.len, i);
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}
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