libc fprintf implementation for stdout,stderr case (needed from undertale)

src/core/hle/libraries/libc/libc.cpp

@@ -109,9 +109,12 @@ void libcSymbolsRegister(SymbolsResolver* sym) {
     LIB_FUNCTION("hcuQgD53UxM", "libc", 1, "libc", 1, 1, printf);
     LIB_FUNCTION("Q2V+iqvjgC0", "libc", 1, "libc", 1, 1, vsnprintf);
     LIB_FUNCTION("YQ0navp+YIc", "libc", 1, "libc", 1, 1, puts);
+    LIB_FUNCTION("fffwELXNVFA", "libc", 1, "libc", 1, 1, fprintf);
 
     // misc
     LIB_OBJ("P330P3dFF68", "libc", 1, "libc", 1, 1, &g_need_sceLibc);
+    LIB_OBJ("2sWzhYqFH4E","libc", 1, "libc", 1, 1,stdout);
+    LIB_OBJ("H8AprKeZtNg", "libc", 1, "libc", 1, 1, stderr); 
     LIB_FUNCTION("bzQExy189ZI", "libc", 1, "libc", 1, 1, init_env);
     LIB_FUNCTION("XKRegsFpEpk", "libc", 1, "libc", 1, 1, catchReturnFromMain);
     LIB_FUNCTION("-QgqOT5u2Vk", "libc", 1, "libc", 1, 1, _Assert);

src/core/hle/libraries/libc/libc_stdio.cpp

@@ -1,10 +1,25 @@
 #include "libc_stdio.h"
 
+#include <debug.h>
+#include <Util/log.h>
+
 namespace Core::Libraries::LibC {
+constexpr bool log_file_libc = true;  // disable it to disable logging
+
 int PS4_SYSV_ABI printf(VA_ARGS) {
     VA_CTX(ctx);
     return printf_ctx(&ctx);
 }
+int PS4_SYSV_ABI fprintf(FILE* file, VA_ARGS) {
+    int fd = _fileno(file);
+    if (fd == 1 || fd == 2) {  // output stdout and stderr to console
+        VA_CTX(ctx);
+        return printf_ctx(&ctx);
+    }
+    LOG_ERROR_IF(log_file_libc, "libc:Unimplemented fprintf case\n");
+    BREAKPOINT();
+    return 0;
+}
 
 int PS4_SYSV_ABI vsnprintf(char* s, size_t n, const char* format, VaList* arg) { return vsnprintf_ctx(s, n, format, arg); }
 

src/core/hle/libraries/libc/libc_stdio.h

@@ -8,4 +8,5 @@ namespace Core::Libraries::LibC {
 int PS4_SYSV_ABI printf(VA_ARGS);
 int PS4_SYSV_ABI vsnprintf(char* s, size_t n, const char* format, VaList* arg);
 int PS4_SYSV_ABI puts(const char* s);
+int PS4_SYSV_ABI fprintf(FILE* file, VA_ARGS);
 }  // namespace Core::Libraries::LibC