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[libc] Acquire the lock for scanf files #67357

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Merged
merged 1 commit into from
Sep 25, 2023
Merged

[libc] Acquire the lock for scanf files #67357

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22 changes: 19 additions & 3 deletions libc/src/stdio/scanf_core/vfscanf_internal.h
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,14 @@ namespace internal {

#ifndef LIBC_COPT_STDIO_USE_SYSTEM_FILE

LIBC_INLINE void flockfile(FILE *f) {
reinterpret_cast<__llvm_libc::File *>(f)->lock();
}

LIBC_INLINE void funlockfile(FILE *f) {
reinterpret_cast<__llvm_libc::File *>(f)->unlock();
}

LIBC_INLINE int getc(void *f) {
unsigned char c;
auto result = reinterpret_cast<__llvm_libc::File *>(f)->read_unlocked(&c, 1);
Expand All @@ -33,7 +41,7 @@ LIBC_INLINE int getc(void *f) {
}

LIBC_INLINE void ungetc(int c, void *f) {
reinterpret_cast<__llvm_libc::File *>(f)->ungetc(c);
reinterpret_cast<__llvm_libc::File *>(f)->ungetc_unlocked(c);
}

LIBC_INLINE int ferror_unlocked(FILE *f) {
Expand All @@ -42,13 +50,19 @@ LIBC_INLINE int ferror_unlocked(FILE *f) {

#else // defined(LIBC_COPT_STDIO_USE_SYSTEM_FILE)

// Since ungetc_unlocked isn't always available, we don't acquire the lock for
// system files.
LIBC_INLINE void flockfile(::FILE *) { return; }

LIBC_INLINE void funlockfile(::FILE *) { return; }

LIBC_INLINE int getc(void *f) { return ::getc(reinterpret_cast<::FILE *>(f)); }

LIBC_INLINE void ungetc(int c, void *f) {
::ungetc(c, reinterpret_cast<::FILE *>(f));
}

LIBC_INLINE int ferror_unlocked(::FILE *f) { return ::ferror_unlocked(f); }
LIBC_INLINE int ferror_unlocked(::FILE *f) { return ::ferror(f); }

#endif // LIBC_COPT_STDIO_USE_SYSTEM_FILE

Expand All @@ -59,10 +73,12 @@ namespace scanf_core {
LIBC_INLINE int vfscanf_internal(::FILE *__restrict stream,
const char *__restrict format,
internal::ArgList &args) {
internal::flockfile(stream);
scanf_core::Reader reader(stream, &internal::getc, internal::ungetc);
int retval = scanf_core::scanf_main(&reader, format, args);
if (retval == 0 && internal::ferror_unlocked(stream))
return EOF;
retval = EOF;
internal::funlockfile(stream);

return retval;
}
Expand Down