fix(libc): export daemon

VLC (PPSA85300) imports daemon (Wn6I3wVATUE) and fails to load because
no library exports it. Forking into the background is not supported,
so it throws if called. VLC 3.0 calls daemon only when its daemon
option is set, and the title starts libVLC with --ignore-config and
without --daemon.

core/libs/prx/libc/CMakeLists.txt

@@ -263,6 +263,15 @@ if(BUILD_TESTING)
         set_tests_properties(guest_memrchr PROPERTIES ENVIRONMENT_MODIFICATION
             "PATH=path_list_prepend:$<TARGET_FILE_DIR:libc>")
     endif()
+    add_test_executable(guest_daemon_tests ${LIBS_INCLUDE_DIR}/tests/GuestDaemon.cpp)
+    target_include_directories(guest_daemon_tests PRIVATE ${LIBS_INCLUDE_DIR})
+    target_link_libraries(guest_daemon_tests PRIVATE libc)
+    configure_windows_unwind(guest_daemon_tests)
+    add_test(NAME guest_daemon COMMAND guest_daemon_tests)
+    if(WIN32)
+        set_tests_properties(guest_daemon PROPERTIES ENVIRONMENT_MODIFICATION
+            "PATH=path_list_prepend:$<TARGET_FILE_DIR:libc>")
+    endif()
     add_test_executable(guest_lifecycle_tests ${LIBS_INCLUDE_DIR}/tests/GuestLifecycle.cpp)
     target_include_directories(guest_lifecycle_tests PRIVATE ${LIBS_INCLUDE_DIR})
     target_link_libraries(guest_lifecycle_tests PRIVATE libc)

core/libs/prx/libc/src/Process.cpp

@@ -196,4 +196,11 @@ int APS5_VABI at_quick_exit_nid_postfix(GuestExitCallback func) {
     _Exit_nid_postfix(status);
 }
 
+int APS5_VABI daemon_nid_postfix(int noChdir, int noClose) {
+    (void)noChdir;
+    (void)noClose;
+    NotImplemented_nid_no_patch("daemon: forking into the background");
+    return -1;
+}
+
 }

core/libs/tests/GuestDaemon.cpp

@@ -0,0 +1,19 @@
+#include "prx/libc/include/general/VabiMacros.hpp"
+#include <cstdlib>
+#include <stdexcept>
+#include <string>
+extern "C" int APS5_VABI daemon_nid_postfix(int, int);
+static void Require(bool value) { if (!value) std::abort(); }
+static bool ReportsNotImplemented(int noChdir, int noClose) {
+    try {
+        daemon_nid_postfix(noChdir, noClose);
+    } catch (const std::runtime_error& error) {
+        return std::string(error.what()) == "daemon: forking into the background not implemented";
+    }
+    return false;
+}
+int main() {
+    Require(ReportsNotImplemented(1, 0));
+    Require(ReportsNotImplemented(0, 0));
+    Require(ReportsNotImplemented(1, 1));
+}

docs/dev/TechnicalDebt.md

@@ -531,6 +531,7 @@ Throughout the project, every function at every stage either **does exactly what
 - [s_call_b64](../../core/shader/recompiler/Translation/src/ScalarInstructions.cpp) saves `PC + 4` over `GetShaderBase` and branches to `PC + 4 + signext(SIMM16) * 4`, following [AMD RDNA2 ISA](https://gpuopen.com/download/rdna2-shader-instruction-set-architecture.pdf) sections 3.6.3, 12.2 and 12.3. Forward callees after `s_endpgm` are decoded. Measured on RDNA2 (gfx1036) in wave32 and wave64 with SIMM16 = 3: the link pair receives `PC + 4`, the branch goes to `PC + 4 + signext(SIMM16) * 4`, and `s_setpc_b64` of the link returns to the instruction after the call. Execution on the PS5 (gfx1013) and title compatibility for these bounded scalar calls remain unverified; `s_rfe_b64` still throws in translation.
 - [sceVideodec2CreateDecoder](../../core/libs/prx/libSceVideodec2/Export.cpp) (libSceVideodec2) decodes HEVC (codec type 974921) and VP9 (2382845) through FFmpeg, besides H.264. The tags come from SharpProspero's `Videodec2CodecType` and EVO-PLAYER-PS5's `sce_videodec2.h`, which records them from hardware runs. HEVC input is converted from length-prefixed NAL units to Annex B as for H.264, and VP9 frames are passed through. Output is the same 8-bit NV12 for every codec; a decoder for HEVC Main10 or VP9 Profile 2 is created, but a frame deeper than 8 bits throws, since the console's 10-bit output layout is unknown, and `QueryDecoderMemoryInfo` reports the 8-bit frame size for it. `sceVideodec2GetPictureInfo` and `sceVideodec2GetAvcPictureInfo` throw for HEVC and VP9 pictures, which use other layouts (`SceVideodec2HevcPictureInfo`, `SceVideodec2Vp9PictureInfo`), and `sceVideodec2GetHevcPictureInfo` and `sceVideodec2GetVp9PictureInfo` are not exported
 - [syslog](../../core/libs/prx/libc/src/Syslog.cpp) (libc) writes each message to `stderr` as `[syslog:<priority>] <message>`, with a newline added when missing, instead of sending it to the console's system log. Priority and facility handling follow FreeBSD's `vsyslog`: `%m` expands to the guest errno's message, unknown bits are reported (as priority 0x23, since FreeBSD passes `LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID` as the priority) and masked, a missing facility becomes `LOG_USER`, and errno is preserved. `openlog`, `setlogmask` and `closelog` are not implemented, so the identity, options and mask they set are not applied
+- [daemon](../../core/libs/prx/libc/src/Process.cpp) (libc) throws: forking into the background is not supported. PPSA85300 imports it and fails to load without it. VLC 3.0 calls it only when its `daemon` option is set ([libvlc.c](https://github.com/videolan/vlc/blob/6de05adcbaf2e8b85fe86aad4169393098628119/src/libvlc.c#L190-L197)), and the title starts libVLC with `--ignore-config` and without `--daemon` ([player.cc](https://github.com/ZiZc3/VLC/blob/f3253020a64368153233ede29183014c0b6c8979/src/player.cc#L960-L981))
 - [sigaction](../../core/libs/prx/libkernel/System/src/Signals.cpp) (libkernel) records the handler, flags and mask of every signal from 1 to 128 and reports them back, following FreeBSD's `sigaction` (`EINVAL` for other signals, and for a handler on `SIGKILL` or `SIGSTOP`); `signal` records its handler with `SA_RESTART`, as FreeBSD's libc does. Only handlers without `SA_SIGINFO` on the signals `signal` already delivers (`SIGINT`, `SIGILL`, `SIGABRT`, `SIGFPE`, `SIGSEGV`, `SIGTERM`) run, the same way `signal` handlers do; their mask and flags are not applied. `SA_SIGINFO` handlers and other signals (`SIGBUS`, `SIGHUP`, ...) are recorded but never called, since that needs FreeBSD's `siginfo_t` and `ucontext_t`; `raise` of an `SA_SIGINFO` handler on a signal `signal` delivers throws instead of terminating, and `raise` of the other signals still returns `EINVAL`
 - [kill](../../core/libs/prx/libkernel/System/src/Signals.cpp) (libkernel) follows FreeBSD's `kern_kill` and `killpg1` for the only guest process: `EINVAL` for signals outside 0 to 128, signal 0 only checks that the target exists, and its own pid, 0 and minus its own pid (the guest is taken to lead its own process group) signal it through `raise`, so they share `raise`'s limits above. Any other pid, and -1, which skips the caller, report `ESRCH`, so `EPERM` is never reported
 - [sceKernelFcntl](../../core/libs/prx/libkernel/File/src/Open.cpp) (libkernel) handles socket descriptors through the POSIX `fcntl` export (`F_GETFL`, `F_SETFL` with `O_NONBLOCK`) and returns its guest errno as `SCE_KERNEL_ERROR_*`, the form the other `sceKernel` file exports use; the command semantics follow FreeBSD's [fcntl](https://github.com/freebsd/freebsd-src/blob/stable/11/sys/kern/kern_descrip.c), and a closed descriptor returns `SCE_KERNEL_ERROR_EBADF`. File descriptors throw: their open flags are not tracked, and `F_DUPFD`, `F_GETFD` and `F_SETFD` are unsupported on all descriptors. The return values and error codes are unverified on a console