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unlocked_stdio
<html> <head> <title>unlocked_stdio</title> <META NAME="KEYWORDS" CONTENT="unlocked_stdio"> </head> <body BGCOLOR="#ffffff" LINK="#0000ff" VLINK="#0000ff" ALINK="#0000ff" TEXT="#000000"> <center> <h1><b>unlocked_stdio</b></h1></center> <PRE> <STRONG><A HREF="/man3/UNLOCKED_STDIO">UNLOCKED_STDIO(3)</A></STRONG> Linux Programmer's Manual <STRONG><A HREF="/man3/UNLOCKED_STDIO">UNLOCKED_STDIO(3)</A></STRONG> NAME getc_unlocked, getchar_unlocked, putc_unlocked, putchar_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); 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 <STRONG><A HREF="/man7/feature_test_macros">feature_test_macros(7)</A></STRONG>): getc_unlocked(), getchar_unlocked(), putc_unlocked(), putchar_un- locked(): /* 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_un- locked(), 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_un- locked(), fgetwc_unlocked(), fputwc_unlocked(), putwchar_unlocked(), fgetws_unlocked(), fputws_unlocked(): _GNU_SOURCE DESCRIPTION Each of these functions has the same behavior as its counterpart with- out 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 <STRONG><A HREF="/man3/flockfile">flockfile(3)</A></STRONG>. ATTRIBUTES For an explanation of the terms used in this section, see at- <STRONG><A HREF="/man7/tributes">tributes(7)</A></STRONG>. +---------------------+---------------+-----------------------+ |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_un- locked(), 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 <STRONG><A HREF="/man3/flockfile">flockfile(3)</A></STRONG>, <STRONG><A HREF="/man3/stdio">stdio(3)</A></STRONG> COLOPHON This page is part of release 5.05 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 <STRONG><A HREF="/man3/UNLOCKED_STDIO">UNLOCKED_STDIO(3)</A></STRONG></PRE> <center> <h6>Man Pages Copyright Respective Owners. Site Copyright (C) 1994 - 2025 <a href="http://www.he.net">Hurricane Electric</a>. All Rights Reserved.</h6></center> </body> </html>