unlocked_stdio

UNLOCKED_STDIO(3)          Linux Programmer's Manual         UNLOCKED_STDIO(3)



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(),     │ Thread safety │ MT-Safe race:stream   │
       │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()    │               │                       │
       ├─────────────────────┼───────────────┼───────────────────────┤
       │getchar_unlocked(),  │ Thread safety │ MT-Unsafe race:stdin  │
       │getwchar_unlocked()  │               │                       │
       ├─────────────────────┼───────────────┼───────────────────────┤
       │putchar_unlocked(),  │ Thread safety │ MT-Unsafe race:stdout │
       │putwchar_unlocked()  │               │                       │
       ├─────────────────────┼───────────────┼───────────────────────┤
       │feof_unlocked(),     │ Thread safety │ MT-Safe               │
       │ferror_unlocked(),   │               │                       │
       │fileno_unlocked()    │               │                       │
       └─────────────────────┴───────────────┴───────────────────────┘
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 5.02 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/.



                                  2017-09-15                 UNLOCKED_STDIO(3)