std.compress.zstd.Decompress fixes

* std.Io.Reader: appendRemaining no longer supports alignment and has
  different rules about how exceeding limit. Fixed bug where it would
  return success instead of error.StreamTooLong like it was supposed to.

* std.Io.Reader: simplify appendRemaining and appendRemainingUnlimited
  to be implemented based on std.Io.Writer.Allocating

* std.Io.Writer: introduce unreachableRebase

* std.Io.Writer: remove minimum_unused_capacity from Allocating. maybe
  that flexibility could have been handy, but let's see if anyone
  actually needs it. The field is redundant with the superlinear growth
  of ArrayList capacity.

* std.Io.Writer: growingRebase also ensures total capacity on the
  preserve parameter, making it no longer necessary to do
  ensureTotalCapacity at the usage site of decompression streams.

* std.compress.flate.Decompress: fix rebase not taking into account seek

* std.compress.zstd.Decompress: split into "direct" and "indirect" usage
  patterns depending on whether a buffer is provided to init, matching
  how flate works. Remove some overzealous asserts that prevented buffer
  expansion from within rebase implementation.

* std.zig: fix readSourceFileToAlloc returning an overaligned slice
  which was difficult to free correctly.

fixes #24608

1 files changed, 4 insertions, 7 deletions

diff --git a/lib/std/http/test.zig b/lib/std/http/test.zig
index 20c7383650..91a57dbbe2 100644
--- a/lib/std/http/test.zig
+++ b/lib/std/http/test.zig
@@ -149,9 +149,8 @@ test "HTTP server handles a chunked transfer coding request" {
         "content-type: text/plain\r\n" ++
         "\r\n" ++
         "message from server!\n";
-    var tiny_buffer: [1]u8 = undefined; // allows allocRemaining to detect limit exceeded
-    var stream_reader = stream.reader(&tiny_buffer);
-    const response = try stream_reader.interface().allocRemaining(gpa, .limited(expected_response.len));
+    var stream_reader = stream.reader(&.{});
+    const response = try stream_reader.interface().allocRemaining(gpa, .limited(expected_response.len + 1));
     defer gpa.free(response);
     try expectEqualStrings(expected_response, response);
 }
@@ -293,8 +292,7 @@ test "Server.Request.respondStreaming non-chunked, unknown content-length" {
     var stream_writer = stream.writer(&.{});
     try stream_writer.interface.writeAll(request_bytes);
 
-    var tiny_buffer: [1]u8 = undefined; // allows allocRemaining to detect limit exceeded
-    var stream_reader = stream.reader(&tiny_buffer);
+    var stream_reader = stream.reader(&.{});
     const response = try stream_reader.interface().allocRemaining(gpa, .unlimited);
     defer gpa.free(response);
 
@@ -364,8 +362,7 @@ test "receiving arbitrary http headers from the client" {
     var stream_writer = stream.writer(&.{});
     try stream_writer.interface.writeAll(request_bytes);
 
-    var tiny_buffer: [1]u8 = undefined; // allows allocRemaining to detect limit exceeded
-    var stream_reader = stream.reader(&tiny_buffer);
+    var stream_reader = stream.reader(&.{});
     const response = try stream_reader.interface().allocRemaining(gpa, .unlimited);
     defer gpa.free(response);