[Queuse]

What

Translate newly reported host CRT errno in ordinary-stream fread, fgetc, getc_unlocked and fgets, including failure to flush pending output when switching an update stream to reading. An empty nonblocking pipe exposes Linux EAGAIN 11 where the guest expects 35. Preserve incoming guest errno when no new native error is reported, including EOF and sticky errors, and retain partial results, byte bounds and directory-error handling.

Rebased after #10324 merged, preserving main's stream-orientation calls. The agreed integration order is fulfilled; this change has no remaining runtime dependency.

Tested

Head 0873e3d4e976d1b85790fac939e51bf2ab728abf, refreshed against main d63781e9ce826dd5445b35b91960bb576f4834ae.

• Windows 11 / WinLibs GCC 15.2.0 and Ubuntu WSL / GCC 15.2.0, glibc 2.43, Release: affected native library/dependency/test builds pass. file_position, file_stream_status, file_streams, guest_standard_streams and guest_fwide pass 5/5 on each OS.
• Linux independent checks against the produced libc module pass 34 actual-module cases: 30 ordinary-read controls and four failed write-to-read transitions, covering nonblocking errors, partial results, sticky errors and successful controls. Three focused native executables also pass as an unprivileged user in a temporary directory. POSIX pipe exhaustion is not run on Windows.
• The original implementation exposes native 11 in the regression and independent negative controls; the correction reports guest 35.
• Canonical overlap comparisons remain incomplete for feat(aot): consolidate native ARM64 compiler, runtime and consumers #5021, fix(libs): share Sony CRT handler and lconv state between libc and libSceAmpr #7081, feat(libc): scan 16-bit wide conversions on Linux #7386, feat(libc): support archive-backed stdio reads #7447, fix(libc): support character reads from random device streams #8150, feat(libc): add std::__sce_v2::_Random_device, _Fiopen and setw #9526, fix(libc): share multibyte state in fgetwc #10405, feat(libkernel): cancel blocked POSIX reads with owned operations #12682, fix(libkernel): preserve blocking sockets over nonblocking native transport #12688, feat(libkernel): cancel blocked POSIX writes with partial progress #12700, feat(libkernel): support deferred cancellation in POSIX accept #12965, fix(relinker): match AppContent utility import to provider #13486 and the other stream-errno PR because those scanned branches conflict with main. Their complete shared-file topic diffs were manually compared; none duplicates this error conversion. The refreshed read/write branches compose cleanly with each other. The read fixture's include/call placement also composes cleanly with feat(libc): implement fcloseall with tracked stream lifetimes #11831, avoiding its former insertion overlap.
• Conventions and whitespace checks pass. No title, console, GPU, full-product, performance or hosted CI result is claimed.

Checklist

• Based on current main; no other open PR implements the same functions
• One topic per PR; follow-ups go in a new PR
• No comments in code except technical debt
• Unimplemented paths throw (NotImplemented_nid_no_patch); silent stubs are listed under Silent stubs in their library's technical debt file
• No notes, investigation .md files or images added to the repository (attach them to this PR)
• New third-party code is a submodule built from source
• Generic behaviour, not specific to one title
• Depends on: none
• Fixes: none
• Unblocks: none
• GPUs tested: n/a
• AI-assisted: yes

[github-actions]

Some comparisons could not be completed because a pull request conflicts with the base branch. Review these shared files manually before concluding that there is no overlap.

Pull request	Shared files not compared
PR 5021	core/libs/prx/libc/src/StandardStreams.cpp
PR 7081	core/libs/prx/libc/src/FileAndHeap.cpp
PR 7386	core/libs/tests/FileStreams.cpp
PR 7447	core/libs/prx/libc/src/FileAndHeap.cpp
PR 8150	core/libs/prx/libc/src/StandardStreams.cpp core/libs/tests/FileStreams.cpp
PR 9526	core/libs/prx/libc/src/FileAndHeap.cpp
PR 10405	core/libs/prx/libc/src/FileAndHeap.cpp core/libs/prx/libc/src/StandardStreams.cpp
PR 11621	core/libs/prx/libc/src/FileAndHeap.cpp
PR 11831	core/libs/prx/libc/src/FileAndHeap.cpp core/libs/tests/FileStreams.cpp
PR 11848	core/libs/prx/libc/src/FileAndHeap.cpp
PR 12036	core/libs/tests/FileStreams.cpp
PR 12057	core/libs/prx/libc/src/StandardStreams.cpp core/libs/tests/FileStreams.cpp
PR 12184	core/libs/prx/libc/src/FileAndHeap.cpp
PR 12271	core/libs/prx/libc/src/FileAndHeap.cpp
PR 12292	core/libs/prx/libc/src/StandardStreams.cpp
PR 12560	core/libs/prx/libc/src/FileAndHeap.cpp
PR 12598	core/libs/prx/libc/src/FileAndHeap.cpp
PR 12682	core/libs/prx/libc/src/FileAndHeap.cpp
PR 12688	core/libs/prx/libc/src/FileAndHeap.cpp
PR 12700	core/libs/prx/libc/src/FileAndHeap.cpp
PR 12920	core/libs/prx/libc/src/StandardStreams.cpp
PR 12965	core/libs/prx/libc/src/FileAndHeap.cpp
PR 13119	core/libs/tests/FileStreams.cpp
PR 13828	core/libs/prx/libc/src/FileAndHeap.cpp
PR 14863	core/libs/prx/libc/src/StandardStreams.cpp
PR 14878	core/libs/prx/libc/src/StandardStreams.cpp core/libs/tests/FileStreams.cpp