std.Io: Writer and Reader bug fixes related to sendFile, delimiters, Limited, and seeking

build.zig

@@ -81,12 +81,13 @@ pub fn build(b: *std.Build) !void {
     docs_step.dependOn(langref_step);
     docs_step.dependOn(std_docs_step);
 
+    const test_default_only = b.option(bool, "test-default-only", "Limit test matrix to exactly one target configuration") orelse false;
     const skip_debug = b.option(bool, "skip-debug", "Main test suite skips debug builds") orelse false;
-    const skip_release = b.option(bool, "skip-release", "Main test suite skips release builds") orelse false;
+    const skip_release = b.option(bool, "skip-release", "Main test suite skips release builds") orelse test_default_only;
     const skip_release_small = b.option(bool, "skip-release-small", "Main test suite skips release-small builds") orelse skip_release;
     const skip_release_fast = b.option(bool, "skip-release-fast", "Main test suite skips release-fast builds") orelse skip_release;
     const skip_release_safe = b.option(bool, "skip-release-safe", "Main test suite skips release-safe builds") orelse skip_release;
-    const skip_non_native = b.option(bool, "skip-non-native", "Main test suite skips non-native builds") orelse false;
+    const skip_non_native = b.option(bool, "skip-non-native", "Main test suite skips non-native builds") orelse test_default_only;
     const skip_libc = b.option(bool, "skip-libc", "Main test suite skips tests that link libc") orelse false;
     const skip_single_threaded = b.option(bool, "skip-single-threaded", "Main test suite skips tests that are single-threaded") orelse false;
     const skip_compile_errors = b.option(bool, "skip-compile-errors", "Main test suite skips compile error tests") orelse false;
@@ -449,6 +450,7 @@ pub fn build(b: *std.Build) !void {
         .include_paths = &.{},
         .skip_single_threaded = skip_single_threaded,
         .skip_non_native = skip_non_native,
+        .test_default_only = test_default_only,
         .skip_freebsd = skip_freebsd,
         .skip_netbsd = skip_netbsd,
         .skip_windows = skip_windows,
@@ -471,6 +473,7 @@ pub fn build(b: *std.Build) !void {
         .include_paths = &.{},
         .skip_single_threaded = true,
         .skip_non_native = skip_non_native,
+        .test_default_only = test_default_only,
         .skip_freebsd = skip_freebsd,
         .skip_netbsd = skip_netbsd,
         .skip_windows = skip_windows,
@@ -492,6 +495,7 @@ pub fn build(b: *std.Build) !void {
         .include_paths = &.{},
         .skip_single_threaded = true,
         .skip_non_native = skip_non_native,
+        .test_default_only = test_default_only,
         .skip_freebsd = skip_freebsd,
         .skip_netbsd = skip_netbsd,
         .skip_windows = skip_windows,
@@ -513,6 +517,7 @@ pub fn build(b: *std.Build) !void {
         .include_paths = &.{},
         .skip_single_threaded = skip_single_threaded,
         .skip_non_native = skip_non_native,
+        .test_default_only = test_default_only,
         .skip_freebsd = skip_freebsd,
         .skip_netbsd = skip_netbsd,
         .skip_windows = skip_windows,

lib/std/Io/Reader.zig

@@ -481,7 +481,6 @@ pub fn readVecAll(r: *Reader, data: [][]u8) Error!void {
 /// is returned instead.
 ///
 /// See also:
-/// * `peek`
 /// * `toss`
 pub fn peek(r: *Reader, n: usize) Error![]u8 {
     try r.fill(n);
@@ -732,7 +731,7 @@ pub const DelimiterError = error{
 };
 
 /// Returns a slice of the next bytes of buffered data from the stream until
-/// `sentinel` is found, advancing the seek position.
+/// `sentinel` is found, advancing the seek position past the sentinel.
 ///
 /// Returned slice has a sentinel.
 ///
@@ -765,7 +764,7 @@ pub fn peekSentinel(r: *Reader, comptime sentinel: u8) DelimiterError![:sentinel
 }
 
 /// Returns a slice of the next bytes of buffered data from the stream until
-/// `delimiter` is found, advancing the seek position.
+/// `delimiter` is found, advancing the seek position past the delimiter.
 ///
 /// Returned slice includes the delimiter as the last byte.
 ///
@@ -793,32 +792,42 @@ pub fn takeDelimiterInclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
 /// * `peekDelimiterExclusive`
 /// * `takeDelimiterInclusive`
 pub fn peekDelimiterInclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
-    const buffer = r.buffer[0..r.end];
-    const seek = r.seek;
-    if (std.mem.indexOfScalarPos(u8, buffer, seek, delimiter)) |delimiter_index| {
-        @branchHint(.likely);
-        return buffer[seek .. delimiter_index + 1];
+    {
+        const contents = r.buffer[0..r.end];
+        const seek = r.seek;
+        if (std.mem.findScalarPos(u8, contents, seek, delimiter)) |end| {
+            @branchHint(.likely);
+            return contents[seek .. end + 1];
+        }
     }
-    // TODO take a parameter for max search length rather than relying on buffer capacity
-    try rebase(r, r.buffer.len);
-    while (r.buffer.len - r.end != 0) {
-        const existing_buffered_len = r.end - r.seek;
-        const end_cap = r.buffer[r.end..];
-        var writer: Writer = .fixed(end_cap);
-        const n = r.vtable.stream(r, &writer, .limited(end_cap.len)) catch |err| switch (err) {
-            error.WriteFailed => unreachable,
-            else => |e| return e,
-        };
-        r.end += n;
-        if (std.mem.indexOfScalarPos(u8, r.buffer[0..r.end], r.seek + existing_buffered_len, delimiter)) |delimiter_index| {
-            return r.buffer[r.seek .. delimiter_index + 1];
+    while (true) {
+        const content_len = r.end - r.seek;
+        if (r.buffer.len - content_len == 0) break;
+        try fillMore(r);
+        const seek = r.seek;
+        const contents = r.buffer[0..r.end];
+        if (std.mem.findScalarPos(u8, contents, seek + content_len, delimiter)) |end| {
+            return contents[seek .. end + 1];
         }
     }
-    return error.StreamTooLong;
+    // It might or might not be end of stream. There is no more buffer space
+    // left to disambiguate. If `StreamTooLong` was added to `RebaseError` then
+    // this logic could be replaced by removing the exit condition from the
+    // above while loop. That error code would represent when `buffer` capacity
+    // is too small for an operation, replacing the current use of asserts.
+    var failing_writer = Writer.failing;
+    while (r.vtable.stream(r, &failing_writer, .limited(1))) |n| {
+        assert(n == 0);
+    } else |err| switch (err) {
+        error.WriteFailed => return error.StreamTooLong,
+        error.ReadFailed => |e| return e,
+        error.EndOfStream => |e| return e,
+    }
 }
 
 /// Returns a slice of the next bytes of buffered data from the stream until
-/// `delimiter` is found, advancing the seek position up to the delimiter.
+/// `delimiter` is found, advancing the seek position up to (but not past)
+/// the delimiter.
 ///
 /// Returned slice excludes the delimiter. End-of-stream is treated equivalent
 /// to a delimiter, unless it would result in a length 0 return value, in which
@@ -832,20 +841,13 @@ pub fn peekDelimiterInclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
 /// Invalidates previously returned values from `peek`.
 ///
 /// See also:
+/// * `takeDelimiter`
 /// * `takeDelimiterInclusive`
 /// * `peekDelimiterExclusive`
 pub fn takeDelimiterExclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
-    const result = r.peekDelimiterInclusive(delimiter) catch |err| switch (err) {
-        error.EndOfStream => {
-            const remaining = r.buffer[r.seek..r.end];
-            if (remaining.len == 0) return error.EndOfStream;
-            r.toss(remaining.len);
-            return remaining;
-        },
-        else => |e| return e,
-    };
+    const result = try r.peekDelimiterExclusive(delimiter);
     r.toss(result.len);
-    return result[0 .. result.len - 1];
+    return result;
 }
 
 /// Returns a slice of the next bytes of buffered data from the stream until
@@ -866,7 +868,7 @@ pub fn takeDelimiterExclusive(r: *Reader, delimiter: u8) DelimiterError![]u8 {
 /// * `takeDelimiterInclusive`
 /// * `takeDelimiterExclusive`
 pub fn takeDelimiter(r: *Reader, delimiter: u8) error{ ReadFailed, StreamTooLong }!?[]u8 {
-    const result = r.peekDelimiterInclusive(delimiter) catch |err| switch (err) {
+    const inclusive = r.peekDelimiterInclusive(delimiter) catch |err| switch (err) {
         error.EndOfStream => {
             const remaining = r.buffer[r.seek..r.end];
             if (remaining.len == 0) return null;
@@ -875,8 +877,8 @@ pub fn takeDelimiter(r: *Reader, delimiter: u8) error{ ReadFailed, StreamTooLong
         },
         else => |e| return e,
     };
-    r.toss(result.len + 1);
-    return result[0 .. result.len - 1];
+    r.toss(inclusive.len);
+    return inclusive[0 .. inclusive.len - 1];
 }
 
 /// Returns a slice of the next bytes of buffered data from the stream until
@@ -1403,6 +1405,9 @@ test peekSentinel {
     var r: Reader = .fixed("ab\nc");
     try testing.expectEqualStrings("ab", try r.peekSentinel('\n'));
     try testing.expectEqualStrings("ab", try r.peekSentinel('\n'));
+    r.toss(3);
+    try testing.expectError(error.EndOfStream, r.peekSentinel('\n'));
+    try testing.expectEqualStrings("c", try r.peek(1));
 }
 
 test takeDelimiterInclusive {
@@ -1417,22 +1422,52 @@ test peekDelimiterInclusive {
     try testing.expectEqualStrings("ab\n", try r.peekDelimiterInclusive('\n'));
     r.toss(3);
     try testing.expectError(error.EndOfStream, r.peekDelimiterInclusive('\n'));
+    try testing.expectEqualStrings("c", try r.peek(1));
 }
 
 test takeDelimiterExclusive {
     var r: Reader = .fixed("ab\nc");
+
     try testing.expectEqualStrings("ab", try r.takeDelimiterExclusive('\n'));
+    try testing.expectEqualStrings("", try r.takeDelimiterExclusive('\n'));
+    try testing.expectEqualStrings("", try r.takeDelimiterExclusive('\n'));
+    try testing.expectEqualStrings("\n", try r.take(1));
+
     try testing.expectEqualStrings("c", try r.takeDelimiterExclusive('\n'));
     try testing.expectError(error.EndOfStream, r.takeDelimiterExclusive('\n'));
 }
 
 test peekDelimiterExclusive {
     var r: Reader = .fixed("ab\nc");
+
     try testing.expectEqualStrings("ab", try r.peekDelimiterExclusive('\n'));
     try testing.expectEqualStrings("ab", try r.peekDelimiterExclusive('\n'));
-    r.toss(3);
+    r.toss(2);
+    try testing.expectEqualStrings("", try r.peekDelimiterExclusive('\n'));
+    try testing.expectEqualStrings("\n", try r.take(1));
+
     try testing.expectEqualStrings("c", try r.peekDelimiterExclusive('\n'));
     try testing.expectEqualStrings("c", try r.peekDelimiterExclusive('\n'));
+    r.toss(1);
+    try testing.expectError(error.EndOfStream, r.peekDelimiterExclusive('\n'));
+}
+
+test takeDelimiter {
+    var r: Reader = .fixed("ab\nc\n\nd");
+    try testing.expectEqualStrings("ab", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("c", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("d", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqual(null, try r.takeDelimiter('\n'));
+    try testing.expectEqual(null, try r.takeDelimiter('\n'));
+
+    r = .fixed("ab\nc\n\nd\n"); // one trailing newline does not affect behavior
+    try testing.expectEqualStrings("ab", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("c", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqualStrings("d", (try r.takeDelimiter('\n')).?);
+    try testing.expectEqual(null, try r.takeDelimiter('\n'));
+    try testing.expectEqual(null, try r.takeDelimiter('\n'));
 }
 
 test streamDelimiter {

lib/std/Io/Reader/Limited.zig

@@ -27,6 +27,7 @@ pub fn init(reader: *Reader, limit: Limit, buffer: []u8) Limited {
 
 fn stream(r: *Reader, w: *Writer, limit: Limit) Reader.StreamError!usize {
     const l: *Limited = @fieldParentPtr("interface", r);
+    if (l.remaining == .nothing) return error.EndOfStream;
     const combined_limit = limit.min(l.remaining);
     const n = try l.unlimited.stream(w, combined_limit);
     l.remaining = l.remaining.subtract(n).?;
@@ -51,8 +52,51 @@ test stream {
 
 fn discard(r: *Reader, limit: Limit) Reader.Error!usize {
     const l: *Limited = @fieldParentPtr("interface", r);
+    if (l.remaining == .nothing) return error.EndOfStream;
     const combined_limit = limit.min(l.remaining);
     const n = try l.unlimited.discard(combined_limit);
     l.remaining = l.remaining.subtract(n).?;
     return n;
 }
+
+test "end of stream, read, hit limit exactly" {
+    var f: Reader = .fixed("i'm dying");
+    var l = f.limited(.limited(4), &.{});
+    const r = &l.interface;
+
+    var buf: [2]u8 = undefined;
+    try r.readSliceAll(&buf);
+    try r.readSliceAll(&buf);
+    try std.testing.expectError(error.EndOfStream, l.interface.readSliceAll(&buf));
+}
+
+test "end of stream, read, hit limit after partial read" {
+    var f: Reader = .fixed("i'm dying");
+    var l = f.limited(.limited(5), &.{});
+    const r = &l.interface;
+
+    var buf: [2]u8 = undefined;
+    try r.readSliceAll(&buf);
+    try r.readSliceAll(&buf);
+    try std.testing.expectError(error.EndOfStream, l.interface.readSliceAll(&buf));
+}
+
+test "end of stream, discard, hit limit exactly" {
+    var f: Reader = .fixed("i'm dying");
+    var l = f.limited(.limited(4), &.{});
+    const r = &l.interface;
+
+    try r.discardAll(2);
+    try r.discardAll(2);
+    try std.testing.expectError(error.EndOfStream, l.interface.discardAll(2));
+}
+
+test "end of stream, discard, hit limit after partial read" {
+    var f: Reader = .fixed("i'm dying");
+    var l = f.limited(.limited(5), &.{});
+    const r = &l.interface;
+
+    try r.discardAll(2);
+    try r.discardAll(2);
+    try std.testing.expectError(error.EndOfStream, l.interface.discardAll(2));
+}

lib/std/Io/Writer.zig

@@ -923,10 +923,12 @@ pub fn sendFileHeader(
     return n;
 }
 
-/// Asserts nonzero buffer capacity.
+/// Asserts nonzero buffer capacity and nonzero `limit`.
 pub fn sendFileReading(w: *Writer, file_reader: *File.Reader, limit: Limit) FileReadingError!usize {
+    assert(limit != .nothing);
     const dest = limit.slice(try w.writableSliceGreedy(1));
-    const n = try file_reader.read(dest);
+    const n = try file_reader.interface.readSliceShort(dest);
+    if (n == 0) return error.EndOfStream;
     w.advance(n);
     return n;
 }
@@ -2778,7 +2780,8 @@ pub const Allocating = struct {
         if (additional == 0) return error.EndOfStream;
         a.ensureUnusedCapacity(limit.minInt64(additional)) catch return error.WriteFailed;
         const dest = limit.slice(a.writer.buffer[a.writer.end..]);
-        const n = try file_reader.read(dest);
+        const n = try file_reader.interface.readSliceShort(dest);
+        if (n == 0) return error.EndOfStream;
         a.writer.end += n;
         return n;
     }
@@ -2849,18 +2852,40 @@ test "allocating sendFile" {
 
     const file = try tmp_dir.dir.createFile("input.txt", .{ .read = true });
     defer file.close();
-    var r_buffer: [256]u8 = undefined;
+    var r_buffer: [2]u8 = undefined;
     var file_writer: std.fs.File.Writer = .init(file, &r_buffer);
-    try file_writer.interface.writeByte('h');
+    try file_writer.interface.writeAll("abcd");
     try file_writer.interface.flush();
 
     var file_reader = file_writer.moveToReader();
     try file_reader.seekTo(0);
+    try file_reader.interface.fill(2);
 
     var allocating: Writer.Allocating = .init(testing.allocator);
     defer allocating.deinit();
+    try allocating.ensureUnusedCapacity(1);
+    try testing.expectEqual(4, allocating.writer.sendFileAll(&file_reader, .unlimited));
+    try testing.expectEqualStrings("abcd", allocating.writer.buffered());
+}
+
+test sendFileReading {
+    var tmp_dir = testing.tmpDir(.{});
+    defer tmp_dir.cleanup();
+
+    const file = try tmp_dir.dir.createFile("input.txt", .{ .read = true });
+    defer file.close();
+    var r_buffer: [2]u8 = undefined;
+    var file_writer: std.fs.File.Writer = .init(file, &r_buffer);
+    try file_writer.interface.writeAll("abcd");
+    try file_writer.interface.flush();
 
-    _ = try file_reader.interface.streamRemaining(&allocating.writer);
+    var file_reader = file_writer.moveToReader();
+    try file_reader.seekTo(0);
+    try file_reader.interface.fill(2);
+
+    var w_buffer: [1]u8 = undefined;
+    var discarding: Writer.Discarding = .init(&w_buffer);
+    try testing.expectEqual(4, discarding.writer.sendFileReadingAll(&file_reader, .unlimited));
 }
 
 test writeStruct {