fix(libc): return NULL from fgets for a size below 2 as the console does

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

@@ -231,13 +231,9 @@ int APS5_VABI ungetc_nid_postfix(int value, FileStream* stream) {
     return result;
 }
 char* APS5_VABI fgets_nid_postfix(char* buffer, int size, FileStream* stream) {
+    if (size < 2) return nullptr;
     if (stream && !stream->IsOpen()) { errno = 9; return nullptr; }
     if (stream) stream->Orientation(-1);
-    if (size <= 0) {
-        stream->SetError();
-        errno = 22;
-        return nullptr;
-    }
     auto* native = GetNativeStream(stream);
     if (!stream->SwitchToReading()) return nullptr;
     auto* result = std::fgets(buffer, size, native);

core/libs/tests/GuestFwide.cpp

@@ -184,7 +184,7 @@ int main(int argc, char** argv) {
     stream = open(argv[2], "w+b");
     Require(stream != nullptr, "could not reopen guest stream");
     Require(getLine(line, 0, stream) == nullptr, "fgets with size 0 should fail");
-    Require(wide(stream, 0) == -1, "fgets should orient the stream even for size 0");
+    Require(wide(stream, 0) == 0, "fgets with a size below 2 should leave the stream unoriented");
     Require(close(stream) == 0, "could not close stream after fgets");
     stream = open(argv[2], "w+b");
     Require(stream != nullptr, "could not reopen guest stream");

core/libs/tests/GuestStandardStreams.cpp

@@ -303,12 +303,8 @@ static void CheckFgetsSize() {
         std::memset(buffer, '!', sizeof(buffer));
         *__error_nid_postfix() = 0;
         Require(fgets_nid_postfix(buffer, size, &stream) == nullptr);
-        Require(*__error_nid_postfix() == 22 && ferror_nid_postfix(&stream) != 0 && feof_nid_postfix(&stream) == 0);
+        Require(*__error_nid_postfix() == 0 && ferror_nid_postfix(&stream) == 0 && feof_nid_postfix(&stream) == 0);
         Require(buffer[0] == '!' && ftello_nid_postfix(&stream) == 0);
-        Require(ferror_nid_postfix(&stream) != 0);
-        clearerr_nid_postfix(&stream);
-
-        Require(ferror_nid_postfix(&stream) == 0);
     }
     char line[8]{};
     Require(fgets_nid_postfix(line, sizeof(line), &stream) == line && std::strcmp(line, "line\n") == 0);
@@ -322,9 +318,15 @@ static void CheckFgetsSizeOne() {
     rewind_nid_postfix(&stream);
     char buffer[8];
     std::memset(buffer, '!', sizeof(buffer));
-    Require(fgets_nid_postfix(buffer, 1, &stream) == buffer && buffer[0] == '\0' && buffer[1] == '!');
+    *__error_nid_postfix() = 0;
+    Require(fgets_nid_postfix(buffer, 1, &stream) == nullptr && buffer[0] == '!' && *__error_nid_postfix() == 0);
     Require(ftello_nid_postfix(&stream) == 0 && ferror_nid_postfix(&stream) == 0 && feof_nid_postfix(&stream) == 0);
     Require(fgets_nid_postfix(buffer, sizeof(buffer), &stream) == buffer && std::strcmp(buffer, "line\n") == 0);
+    Require(fgets_nid_postfix(buffer, sizeof(buffer), &stream) == nullptr && feof_nid_postfix(&stream) != 0);
+    std::memset(buffer, '!', sizeof(buffer));
+    *__error_nid_postfix() = 0;
+    Require(fgets_nid_postfix(buffer, 1, &stream) == nullptr && buffer[0] == '!' && *__error_nid_postfix() == 0);
+    Require(ftello_nid_postfix(&stream) == 5 && ferror_nid_postfix(&stream) == 0 && feof_nid_postfix(&stream) != 0);
     stream.Close();
 }
 

docs/dev/debt/libc.md

@@ -107,7 +107,7 @@
 
 - [strtoq](../../../core/libs/prx/libc/src/Strings.cpp) (libc, NID `yUUOxgk8Dmc`) is the BSD "quad" alias of `strtoll` and forwards to it, as FreeBSD 11.4 [strtoq.c](https://github.com/freebsd/freebsd-src/blob/8c639945a44588f6cfdddfb057bb5aad88735da0/lib/libc/stdlib/strtoq.c) does. The console export is not verified; the sibling `strtouq` is already here.
 
-- [fwide](../../../core/libs/prx/libc/src/StandardStreams.cpp) (libc) - the `printf` and `wprintf` families, `perror` and `putw` orient a stream as C11 7.21.2p4 requires, where FreeBSD 11.4's `vfprintf.c`, `vfwprintf.c`, `perror.c` and `putw.c` have no `ORIENT`; nothing is measured on a console. Otherwise it follows [FreeBSD 11.4 fwide.c](https://github.com/freebsd/freebsd-src/blob/8c639945a44588f6cfdddfb057bb5aad88735da0/lib/libc/stdio/fwide.c#L38-L51) and `ORIENT`: the first byte or wide read, write, unget or scan orients a stream, also when `fgets`, `fgetws` or `ungetwc` then fail on their arguments; a zero-length `fread` or `fwrite` does not, and a successful `freopen` clears it. Mixed byte and wide calls still run. The export is in the [PS5 3.20 inventory](https://github.com/DNNDHH/PS5-3.20_Libs/blob/b2a77c09cd71c01f34c790cfbe98c751a13262ad/libSceLibcInternal.c#L17666)
+- [fwide](../../../core/libs/prx/libc/src/StandardStreams.cpp) (libc) - the `printf` and `wprintf` families, `perror` and `putw` orient a stream as C11 7.21.2p4 requires, where FreeBSD 11.4's `vfprintf.c`, `vfwprintf.c`, `perror.c` and `putw.c` have no `ORIENT`; nothing is measured on a console. Otherwise it follows [FreeBSD 11.4 fwide.c](https://github.com/freebsd/freebsd-src/blob/8c639945a44588f6cfdddfb057bb5aad88735da0/lib/libc/stdio/fwide.c#L38-L51) and `ORIENT`: the first byte or wide read, write, unget or scan orients a stream, also when `fgetws` or `ungetwc` then fail on their arguments, but not `fgets` with a size below 2, which returns before it touches the stream as the console's `fgets` does; a zero-length `fread` or `fwrite` does not, and a successful `freopen` clears it. Mixed byte and wide calls still run. The export is in the [PS5 3.20 inventory](https://github.com/DNNDHH/PS5-3.20_Libs/blob/b2a77c09cd71c01f34c790cfbe98c751a13262ad/libSceLibcInternal.c#L17666)
 
 ### Functional