Evrim Cicek a7b52084ec fix(libc): set up streams for writing after a read as FreeBSD does on Windows ...

On Windows the UCRT drops a write that directly follows a read on an r+,
w+ or a+ stream: fputc and fprintf report success, fwrite returns 0 and
fputs returns EOF, all without the error indicator, and the file is left
unchanged, also after an fflush. On a stream open only for reading, fputc
after a read reports success as well.

Writes now first do what FreeBSD 11.4's __swsetup does: a stream open only
for reading fails with EBADF and sets the error indicator, and an update
stream that is reading drops its read buffer and ungetc data, clears end
of file and writes at the descriptor's offset. This covers fwrite, fputs,
fputc, putc_unlocked, fprintf, fprintf_s, fputwc, fputws, fwprintf,
fwprintf_s, puts and wprintf, and printf, vprintf and printf_s, which
write to standard output through PrintWindows and now return -1 there
instead of throwing.

Linux is unchanged: glibc writes at the stream position, which the libc
technical debt now records.

2026-10-26 21:53:56 +03:00

..

dev

fix(libc): set up streams for writing after a read as FreeBSD does on Windows

2026-10-26 21:53:56 +03:00

user

Merge pull request #9408 from rursache/feat/macos-trace-imports

2026-10-26 11:27:51 +01:00