UNLOCKED_STDIO

Section: Linux Programmer's Manual (3)
Updated: 2001-10-18
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NAME

*_unlocked - non-locking stdio functions

SYNOPSIS

#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. The nonstandard *_unlocked() variants occur on a few Unix systems, and are available in recent glibc. They should probably not be used.