zig

commit 4f639ff8805b33fa6c75416eddfb205e3a04e09a (tree)
parent 5e986fef1fa5cf04f3547cc4f5a8c0f490ea1d3d
Author: Kendall Condon <goon.pri.low@gmail.com>
Date:   Tue, 12 Aug 2025 15:48:45 -0400

http: fix handling of limit in chunkedSendFile

`limit` in chunkedSendFile applies only to the file, not the entire
chunk. `limit` in sendFileHeader does not include the header.

Additionally adds a comment to clarify what `limit` applies to in
sendFileHeader and fixed a small bug in it (`drain` is able to return
less then `header.len`).

Diffstat:
M
lib/std/Io/Writer.zig
 | 
4
+++-
M
lib/std/http.zig
 | 
7
+++++--

2 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/lib/std/Io/Writer.zig b/lib/std/Io/Writer.zig
@@ -868,6 +868,8 @@ pub fn sendFile(w: *Writer, file_reader: *File.Reader, limit: Limit) FileError!u
 }
 
 /// Returns how many bytes from `header` and `file_reader` were consumed.
+///
+/// `limit` only applies to `file_reader`.
 pub fn sendFileHeader(
     w: *Writer,
     header: []const u8,
@@ -882,7 +884,7 @@ pub fn sendFileHeader(
     }
     const buffered_contents = limit.slice(file_reader.interface.buffered());
     const n = try w.vtable.drain(w, &.{ header, buffered_contents }, 1);
-    file_reader.interface.toss(n - header.len);
+    file_reader.interface.toss(n -| header.len);
     return n;
 }
 
diff --git a/lib/std/http.zig b/lib/std/http.zig
@@ -1021,8 +1021,11 @@ pub const BodyWriter = struct {
                     continue :l 1;
                 },
                 else => {
-                    const new_limit = limit.min(.limited(chunk_len - 2));
-                    const n = try out.sendFileHeader(w.buffered(), file_reader, new_limit);
+                    const chunk_limit: std.Io.Limit = .limited(chunk_len - 2);
+                    const n = if (chunk_limit.subtract(w.buffered().len)) |sendfile_limit|
+                        try out.sendFileHeader(w.buffered(), file_reader, sendfile_limit.min(limit))
+                    else
+                        try out.write(chunk_limit.slice(w.buffered()));
                     chunked.chunk_len = chunk_len - n;
                     return w.consume(n);
                 },