On Linux a guest stderr redirect also moves the host's: guest
descriptors are host descriptors, and the guest stderr stream wraps the
host stderr FILE. After dup2(fd, 2), or freopen(path, mode, stderr) with
full buffering, the libc terminate report, the host fprintf(stderr)
diagnostics and libstdc++'s terminate message go into the title's pipe
or file, and abort() discards what is still buffered. RetroArch
(PPSA99169) reopens stderr onto app0/trace.txt with full buffering, so
its stop on main left no message anywhere.
Before the first guest redirect of descriptor 2 (libkernel dup2, libc
freopen of a stream on descriptor 2), keep a close-on-exec duplicate of
the host descriptor 2 and point the host stderr at an unbuffered stream
on it. The guest stream keeps its own FILE and follows the redirect.
The libc terminate report writes to the kept descriptor with write()
instead of the stderr stream, and libkernel's sceKernelDebugOutText uses
the same kept descriptor.
The guest fgets handed the size straight to the host. With a size of 0
glibc and the Windows runtime return NULL without setting errno or the
stream error indicator, and a negative size goes to the Windows
invalid-parameter path. FreeBSD's fgets checks n <= 0 before reading:
it sets __SERR on the stream, sets errno to EINVAL and returns NULL,
leaving the buffer and the file position untouched.
fgets_nid_postfix now does the same before calling the host. The
FileStream flag it uses was only set for encoding errors so far and is
renamed from SetEncodingError/encodingError to SetError/guestError; it
already stays set until clearerr like __SERR.
guest_standard_streams checks sizes 0, -1 and INT_MIN (NULL, errno 22,
error indicator set and cleared by clearerr, buffer and position
untouched) and that a following read still returns the line; it fails
without the change.
Fixes#3084
AI-assisted: yes
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Use unlocked POSIX EOF/error queries after unlocked byte operations so status synchronization cannot reacquire the stream lock. Keep the verified UCRT status calls on Windows, and cover byte, status, error, and held-lock behavior.
Co-authored-by: MarcZX100 <marczxrr@gmail.com>
Dean
marshmll
David
Ondra97
MarcZX100
fablevoid
Romans Pokrovskis
xXPBSXx
SamG-Coder
boykopovar