unlocked_stdio(3) - Linux man page
Name
*_unlocked - non-locking stdio functionsSynopsis
#include <stdio.h> int getc_unlocked(FILE *stream);int getchar_unlocked(void);int putc_unlocked(int c, FILE *stream);int putchar_unlocked(int c); #define _BSD_SOURCE /* or _SVID_SOURCE or _GNU_SOURCE */#include <stdio.h> void clearerr_unlocked(FILE *stream);int feof_unlocked(FILE *stream);int ferror_unlocked(FILE *stream);int fileno_unlocked(FILE *stream);int fflush_unlocked(FILE *stream);int fgetc_unlocked(FILE *stream);int fputc_unlocked(int c, FILE *stream);size_t fread_unlocked(void *ptr, size_t size, size_t n, FILE *stream);size_t fwrite_unlocked(const void *ptr, size_t size, size_t n, FILE *stream); #define _GNU_SOURCE#include <stdio.h> char *fgets_unlocked(char *s, int n, FILE *stream);int fputs_unlocked(const char *s, FILE *stream); #define _GNU_SOURCE#include <wchar.h> wint_t getwc_unlocked(FILE *stream);wint_t getwchar_unlocked(void);wint_t fgetwc_unlocked(FILE *stream);wint_t fputwc_unlocked(wchar_t wc, FILE *stream);wint_t putwc_unlocked(wchar_t wc, FILE *stream);wint_t putwchar_unlocked(wchar_t wc);wchar_t *fgetws_unlocked(wchar_t *ws, int n, FILE *stream);int fputws_unlocked(const wchar_t *ws, FILE *stream);
Description
Each of these functions has the same behaviour as its counterpart without the '_unlocked' suffix, except that they do not use locking (they do not set locks themselves, and do not test for the presence of locks set by others) and hence are thread-unsafe. See flockfile(3).Conforming to
The four functions getc_unlocked(), getchar_unlocked(), putc_unlocked(), putchar_unlocked() are in POSIX.1-2001.The nonstandard *_unlocked() variants occur on a few Unix systems, and are available in recent glibc. They should probably not be used.
