unlocked_stdio(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | ATTRIBUTES | CONFORMING TO | SEE ALSO | COLOPHON

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

NAME         top

       getc_unlocked, getchar_unlocked, putc_unlocked, putchar_unlocked
       - nonlocking stdio functions

SYNOPSIS         top

       #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 *restrict ptr, size_t size, size_t n,
                             FILE *restrict stream);
       size_t fwrite_unlocked(const void *restrict ptr, size_t size, size_t n,
                             FILE *restrict stream);

       char *fgets_unlocked(char *restrict s, int n, FILE *restrict stream);
       int fputs_unlocked(const char *restrict s, FILE *restrict 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 *restrict ws, int n,
                             FILE *restrict stream);
       int fputws_unlocked(const wchar_t *restrict ws,
                             FILE *restrict 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 <= 2.23: */ _POSIX_C_SOURCE
               || /* Glibc <= 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 <= 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         top

       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         top

       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         top

       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         top

       flockfile(3), stdio(3)

COLOPHON         top

       This page is part of release 5.11 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/.

                               2021-03-22              UNLOCKED_STDIO(3)

Pages that refer to this page: ferror(3)fflush(3)fgetc(3)fgetwc(3)fgetws(3)fileno(3)flockfile(3)fputwc(3)fputws(3)fread(3)gets(3)getwchar(3)puts(3)putwchar(3)stdio(3)