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Techatrix merged 1 commit into from
Jul 12, 2025
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Silence the Writergate #59

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178 changes: 144 additions & 34 deletions known-folders.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -337,7 +337,11 @@ const TestingSystem = struct {
if (std.mem.eql(u8, key, kv.key)) return kv.value;
}
system.deinit();
std.debug.panic("the result of `getenv(\"{}\")` must explicitly specified in the TestingSystem", .{std.zig.fmtEscapes(key)});
if (@hasDecl(std.zig, "fmtString")) {
std.debug.panic("the result of `getenv(\"{f}\")` must explicitly specified in the TestingSystem", .{std.zig.fmtString(key)});
} else {
std.debug.panic("the result of `getenv(\"{}\")` must explicitly specified in the TestingSystem", .{std.zig.fmtEscapes(key)});
}
}

/// Asserts that the file is specified in `TestingSystem.files`.
Expand All @@ -349,7 +353,11 @@ const TestingSystem = struct {
if (std.mem.eql(u8, file_path, kv.path)) break kv;
} else {
system.deinit();
std.debug.panic("`openFile(\"{0}\", \"{1}\")` has been called on an unexpected file", .{ std.zig.fmtEscapes(dir_path), std.zig.fmtEscapes(sub_path) });
if (@hasDecl(std.zig, "fmtString")) {
std.debug.panic("`openFile(\"{0f}\", \"{1f}\")` has been called on an unexpected file", .{ std.zig.fmtString(dir_path), std.zig.fmtString(sub_path) });
} else {
std.debug.panic("`openFile(\"{0}\", \"{1}\")` has been called on an unexpected file", .{ std.zig.fmtEscapes(dir_path), std.zig.fmtEscapes(sub_path) });
}
};

const data = kv.data orelse return error.FileNotFound;
Expand Down Expand Up @@ -435,40 +443,12 @@ fn xdgUserDirLookup(
try system.openFile(home_dir, ".config/user-dirs.dirs");
defer file.close();

var fbr = std.io.bufferedReaderSize(512, file.reader());
const reader = fbr.reader();
var buffer: [xdg_user_dir_lookup_line_buffer_size + 1]u8 = undefined;
var line_it: if (@hasDecl(std.fs.File, "stdin")) LineIterator else OldLineIterator = .init(file);

var user_dir: ?[]u8 = null;
outer: while (true) {
var buffer: [xdg_user_dir_lookup_line_buffer_size + 1]u8 = undefined;

// Similar to `readUntilDelimiterOrEof` but also writes a null-terminator
var line: [:0]u8 = for (&buffer, 0..) |*out, index| {
const byte = reader.readByte() catch |err| switch (err) {
error.EndOfStream => if (index == 0) break :outer else '\n',
else => |e| return e,
};
if (byte == '\n') {
out.* = 0;
break buffer[0..index :0];
}
out.* = byte;
} else blk: {
// This happens when the line is longer than 511 characters
// There are four possible ways to handle this:
// - use dynamic allocation to acquire enough storage
// - return an error
// - skip the line
// - truncate the line
//
// The xdg-user-dir implementation chooses to trunacte the line.
// See "getPath - user-dirs.dirs - very long line" test

try reader.skipUntilDelimiterOrEof('\n');

buffer[buffer.len - 1] = 0;
break :blk buffer[0 .. buffer.len - 1 :0];
};
while (try line_it.next(&buffer)) |line_capture| {
var line = line_capture;

while (line[0] == ' ' or line[0] == '\t')
line = line[1..];
Expand Down Expand Up @@ -549,6 +529,108 @@ fn xdgUserDirLookup(
return user_dir;
}

const OldLineIterator = struct {
fbr: std.io.BufferedReader(4096, std.fs.File.Reader),

fn init(file: std.fs.File) OldLineIterator {
return .{
.fbr = std.io.bufferedReader(file.reader()),
};
}

fn next(it: *OldLineIterator, buffer: []u8) std.posix.ReadError!?[:0]const u8 {
const reader = it.fbr.reader();

// Similar to `readUntilDelimiterOrEof` but also writes a null-terminator
for (buffer, 0..) |*out, index| {
const byte = reader.readByte() catch |err| switch (err) {
error.EndOfStream => if (index == 0) return null else '\n',
else => |e| return e,
};
if (byte == '\n') {
out.* = 0;
return buffer[0..index :0];
}
out.* = byte;
} else {
// This happens when the line is longer than 511 characters
// There are four possible ways to handle this:
// - use dynamic allocation to acquire enough storage
// - return an error
// - skip the line
// - truncate the line
//
// The xdg-user-dir implementation chooses to trunacte the line.
// See "getPath - user-dirs.dirs - very long line" test

try reader.skipUntilDelimiterOrEof('\n');

buffer[buffer.len - 1] = 0;
return buffer[0 .. buffer.len - 1 :0];
}
}
};

const LineIterator = struct {
file_reader: std.fs.File.Reader,
keep_reading: bool,
discard_until_newline: bool,

fn init(file: std.fs.File) LineIterator {
return .{
.file_reader = file.reader(undefined),
.keep_reading = true,
.discard_until_newline = false,
};
}

fn next(it: *LineIterator, buffer: []u8) std.posix.ReadError!?[:'\n']const u8 {
if (!it.keep_reading) return null;

const reader = &it.file_reader.interface;
reader.buffer = buffer[0 .. buffer.len - 1]; // leave space for the sentinel

if (it.discard_until_newline) {
it.discard_until_newline = false;
_ = reader.discardDelimiterInclusive('\n') catch |discard_err| switch (discard_err) {
error.ReadFailed => return it.file_reader.err.?,
error.EndOfStream => return null,
};
}

return reader.takeSentinel('\n') catch |err| switch (err) {
error.ReadFailed => return it.file_reader.err.?,
error.EndOfStream => {
if (reader.bufferedLen() == 0)
return null; // trailing newline

// This is the last line
buffer[reader.end] = '\n';
const line = buffer[reader.seek..reader.end :'\n'];
it.keep_reading = false;
return line;
},
error.StreamTooLong => {
// This happens when the line is longer than 511 characters
// There are four possible ways to handle this:
// - use dynamic allocation to acquire enough storage
// - return an error
// - skip the line
// - truncate the line
//
// The xdg-user-dir implementation chooses to trunacte the line.
// See "getPath - user-dirs.dirs - very long line" test

buffer[reader.end] = '\n';
const line = buffer[reader.seek..reader.end :'\n'];
it.discard_until_newline = true;

return line;
},
};
}
};

/// Contains the GUIDs for each available known-folder on windows
const WindowsFolderSpec = union(enum) {
by_guid: std.os.windows.GUID,
Expand Down Expand Up @@ -891,6 +973,34 @@ test "getPath - user-dirs.dirs - duplicate config" {
});
}

test "getPath - user-dirs.dirs - trailing newline" {
if (builtin.os.tag == .windows) return error.SkipZigTest;

var system: TestingSystem = .{
.config = .{ .xdg_on_mac = true },
.env_map = &.{
.{ .key = "HOME", .value = "/home/janedoe" },
.{ .key = "XDG_CONFIG_HOME", .value = "/home/janedoe/custom" },

.{ .key = "XDG_VIDEOS_DIR", .value = null },
},
.files = &.{.{
.path = "/home/janedoe/custom/user-dirs.dirs",
.data =
\\XDG_VIDEOS_DIR="/mnt/Videos"
\\
,
}},
};
defer system.deinit();

try testGetPath(.{
.system = system,
.folder = .videos,
.expected = "/mnt/Videos",
});
}

test "getPath - user-dirs.dirs - escaped path" {
if (builtin.os.tag == .windows) return error.SkipZigTest;

Expand Down
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