UNLOCKED_STDIO

Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
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NAME

getc_unlocked, getchar_unlocked, putc_unlocked, putchar_unlocked - nonlocking 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);

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);

char *fgets_unlocked(char *s, int n, FILE *stream);
int fputs_unlocked(const char *s, FILE *stream);

#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);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

getc_unlocked(), getchar_unlocked(), putc_unlocked(), putchar_unlocked():

/* Since glibc 2.24: */ _POSIX_C_SOURCE >= 199309L
    || /* Glibc versions <= 2.23: */ _POSIX_C_SOURCE
    || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE

clearerr_unlocked(), feof_unlocked(), ferror_unlocked(), fileno_unlocked(), fflush_unlocked(), fgetc_unlocked(), fputc_unlocked(), fread_unlocked(), fwrite_unlocked():

/* Glibc since 2.19: */ _DEFAULT_SOURCE
    || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE

fgets_unlocked(), fputs_unlocked(), getwc_unlocked(), getwchar_unlocked(), fgetwc_unlocked(), fputwc_unlocked(), putwchar_unlocked(), fgetws_unlocked(), fputws_unlocked():

_GNU_SOURCE

 

DESCRIPTION

Each of these functions has the same behavior 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).  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

Interface	Attribute	Value
getc_unlocked(), putc_unlocked(), clearerr_unlocked(), fflush_unlocked(), fgetc_unlocked(), fputc_unlocked(), fread_unlocked(), fwrite_unlocked(), fgets_unlocked(), fputs_unlocked(), getwc_unlocked(), fgetwc_unlocked(), fputwc_unlocked(), putwc_unlocked(), fgetws_unlocked(), fputws_unlocked()	Thread safety	MT-Safe race:stream
getchar_unlocked(), getwchar_unlocked()	Thread safety	MT-Unsafe race:stdin
putchar_unlocked(), putwchar_unlocked()	Thread safety	MT-Unsafe race:stdout
feof_unlocked(), ferror_unlocked(), fileno_unlocked()	Thread safety	MT-Safe

 

CONFORMING TO

The four functions getc_unlocked(), getchar_unlocked(), putc_unlocked(), putchar_unlocked() are in POSIX.1-2001 and POSIX.1-2008.

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

SEE ALSO

flockfile(3), stdio(3)  

COLOPHON

This page is part of release 4.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

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Index

NAME

SYNOPSIS

DESCRIPTION

ATTRIBUTES

CONFORMING TO

SEE ALSO

COLOPHON