feat(posix): implement mkstemp and isatty

[NumberGuan]

What

Implement mkstemp and isatty in libScePosixForWebKit for the homebrew imports reported in #1578.

mkstemp uses the guest path resolver and existing open implementation, creates files exclusively with read/write access and mode 0600, and handles collisions without truncating existing files. Its trailing-X and fixed-name behavior follows FreeBSD 9.

isatty distinguishes terminals, non-terminal files/pipes/sockets (ENOTTY), and invalid descriptors (EBADF), following FreeBSD's terminal check. Windows checks console handles and handles invalid CRT descriptors without aborting.

The socket check calls GuestSocketIsOpen_nid_no_patch, a C host helper whose export survives NID patching. This fixes the patched module load failure (Windows error 127) reported in the review. Internal socket callers keep using the existing registry implementation.

Refs #1578. No dependency on another PR. Console verification and existing Windows file-permission limits are recorded in TechnicalDebt.

Tested

Windows x64, Release, WinLibs MinGW-w64 GCC 15.2.0 UCRT POSIX:

• Eight focused tests passed: POSIX filesystem, filesystem, resolver, strings, UDP, TCP, poll and memory.
• Full project and patched-library builds passed.
• All 115 patched .prx libraries loaded with zero failures using the standalone loader from test(libs): load every patched library with its imports bound #1828; the loader is statically linked and starts without unpatched guest libraries loaded.
• Registration/conventions checks and git diff --check passed. git range-diff confirms the original feature commit is unchanged after rebasing.
• CI on 31b26d7d: Windows and Linux builds and CTest passed, with 489 registered tests / 203 skipped on Windows and 498 / 25 skipped on Linux; zero failures. Conventions passed.
• The regression covers aliases, binary file I/O, unique names, collisions without content loss, fixed names, missing parents, invalid templates, files, pipes, sockets, closed/invalid descriptors and Windows NUL. Terminal tests run when a console or pseudo-terminal is available.
• No homebrew/title execution or PS5 hardware verification.

Checklist

• Based on current main (f1451396); no other open PR implements the same functions
• One topic per PR; follow-ups go in a new PR
• No new comments in code
• No silent stubs or fallbacks added
• No investigation files, images or new dependencies added
• Generic behavior, not specific to one title
• Depends on: none
• AI-assisted: yes, Codex

[github-actions]

Progress report (2e375a5 → f9be276)

📈 System libraries: 85.23% (+0.01%, +2 implemented functions)

✅ 2 implemented

Library	Name
libScePosixForWebKit	isatty_nid_postfix
libScePosixForWebKit	mkstemp_nid_postfix

[github-actions]

Other open pull requests touch the same code. Merging one will break the other, or both implement the same thing. If this one builds on them, list them in Depends on.

Pull request	Conflicting files (lines on main)	Same exports	Same new files
#1605	docs/dev/TechnicalDebt.md L238
#1616		__error_nid_postfix
#1627		__error_nid_postfix
#1641		__error_nid_postfix
#1675		__error_nid_postfix
#1727		__error_nid_postfix
#1729		__error_nid_postfix
#1738		__error_nid_postfix
#1772		__error_nid_postfix
#1823	docs/dev/TechnicalDebt.md L238
#1824	docs/dev/TechnicalDebt.md L238
#1832	core/libs/prx/libkernel/Socket/src/Udp.cpp L182
#1841		__error_nid_postfix
#1860		__error_nid_postfix
#1873	docs/dev/TechnicalDebt.md L238
#1924	docs/dev/TechnicalDebt.md L238

[LeandroLP23]

On Windows the patched libScePosixForWebKit.prx from this PR fails to load, so a title that imports it stops before start-up. OpenGL Showcase (PPSA99005) stops at mkstemp on main (FAIL: unresolved ELF import uEtgPWgPxOk from libScePosixForWebKit.prx); with this PR it no longer gets that far and ends with Failed to load module: ...\libs\libScePosixForWebKit.prx / GetLastError: 127 - The specified procedure could not be found.

The cause is the new call to GuestSockets::IsOpen, a C++ export of libkernel. nid_patcher keeps a host export's name only if libc exports it too, it ends in _nid_no_patch, or it starts with SDL_. Every other export is renamed to its hash (core/libs/nid/src/NidResolver.cpp:40-62). So the patched libkernel.prx no longer has _ZN12GuestSockets6IsOpenEi, while the import in libScePosixForWebKit.prx keeps that name. CI doesn't see it because ctest loads the libraries from libs/unpatched.

Tested fix: export a wrapper extern "C" bool GuestSocketIsOpen_nid_no_patch(int descriptor) from libkernel (as KernelSetSocketPoller_nid_no_patch does in Socket/include/SocketPoll.hpp) and call it from Filesystem.cpp. With that, the module loads, PPSA99005 gets past mkstemp and stops at sceVideoOutGetResolutionStatus (#1714), and the 3 POSIX tests pass.

Windows 11, Radeon 860M, MinGW-w64 GCC 15.2.0, Release, main 4b6ab6b; title relinked with relinker --windows and run with the patched build/core/libs/libs/*.prx.

Tested with AI assistance (Claude Code).

[adriadam10]

Checked the diff, the mkstemp collision/wrap logic (fixed names, all-X suffix, no truncation of existing files), isatty errno mapping against FreeBSD, the TechnicalDebt entry and the _nid_no_patch helper (same pattern as KernelSetSocketPoller_nid_no_patch). guest_posix_filesystem passes locally on Linux; Windows and Linux CI are green on this head. Merging.

Rebased onto current main to resolve the TechnicalDebt conflict with #1823 (both lines kept, no code change).