1UNLOCKED_STDIO(3)          Linux Programmer's Manual         UNLOCKED_STDIO(3)
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NAME

6       getc_unlocked, getchar_unlocked, putc_unlocked, putchar_unlocked - non‐
7       locking stdio functions
8

SYNOPSIS

10       #include <stdio.h>
11
12       int getc_unlocked(FILE *stream);
13       int getchar_unlocked(void);
14       int putc_unlocked(int c, FILE *stream);
15       int putchar_unlocked(int c);
16
17       void clearerr_unlocked(FILE *stream);
18       int feof_unlocked(FILE *stream);
19       int ferror_unlocked(FILE *stream);
20       int fileno_unlocked(FILE *stream);
21       int fflush_unlocked(FILE *stream);
22       int fgetc_unlocked(FILE *stream);
23       int fputc_unlocked(int c, FILE *stream);
24       size_t fread_unlocked(void *ptr, size_t size, size_t n,
25                             FILE *stream);
26       size_t fwrite_unlocked(const void *ptr, size_t size, size_t n,
27                             FILE *stream);
28
29       char *fgets_unlocked(char *s, int n, FILE *stream);
30       int fputs_unlocked(const char *s, FILE *stream);
31
32       #include <wchar.h>
33
34       wint_t getwc_unlocked(FILE *stream);
35       wint_t getwchar_unlocked(void);
36       wint_t fgetwc_unlocked(FILE *stream);
37       wint_t fputwc_unlocked(wchar_t wc, FILE *stream);
38       wint_t putwc_unlocked(wchar_t wc, FILE *stream);
39       wint_t putwchar_unlocked(wchar_t wc);
40       wchar_t *fgetws_unlocked(wchar_t *ws, int n, FILE *stream);
41       int fputws_unlocked(const wchar_t *ws, FILE *stream);
42
43   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
44
45       getc_unlocked(), getchar_unlocked(), putc_unlocked(),
46       putchar_unlocked():
47           /* Since glibc 2.24: */ _POSIX_C_SOURCE >= 199309L
48               || /* Glibc versions <= 2.23: */ _POSIX_C_SOURCE
49               || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
50
51       clearerr_unlocked(), feof_unlocked(), ferror_unlocked(),
52       fileno_unlocked(), fflush_unlocked(), fgetc_unlocked(),
53       fputc_unlocked(), fread_unlocked(), fwrite_unlocked():
54           /* Glibc since 2.19: */ _DEFAULT_SOURCE
55               || /* Glibc versions <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
56
57       fgets_unlocked(), fputs_unlocked(), getwc_unlocked(),
58       getwchar_unlocked(), fgetwc_unlocked(), fputwc_unlocked(),
59       putwchar_unlocked(), fgetws_unlocked(), fputws_unlocked():
60           _GNU_SOURCE
61

DESCRIPTION

63       Each  of these functions has the same behavior as its counterpart with‐
64       out the "_unlocked" suffix, except that they do not use  locking  (they
65       do  not set locks themselves, and do not test for the presence of locks
66       set by others) and hence are thread-unsafe.  See flockfile(3).
67

ATTRIBUTES

69       For  an  explanation  of  the  terms  used   in   this   section,   see
70       attributes(7).
71
72       ┌─────────────────────┬───────────────┬───────────────────────┐
73       │Interface            │ Attribute     │ Value                 │
74       ├─────────────────────┼───────────────┼───────────────────────┤
75       │getc_unlocked(),     │ Thread safety │ MT-Safe race:stream   │
76       │putc_unlocked(),     │               │                       │
77       │clearerr_unlocked(), │               │                       │
78       │fflush_unlocked(),   │               │                       │
79       │fgetc_unlocked(),    │               │                       │
80       │fputc_unlocked(),    │               │                       │
81       │fread_unlocked(),    │               │                       │
82       │fwrite_unlocked(),   │               │                       │
83       │fgets_unlocked(),    │               │                       │
84       │fputs_unlocked(),    │               │                       │
85       │getwc_unlocked(),    │               │                       │
86       │fgetwc_unlocked(),   │               │                       │
87       │fputwc_unlocked(),   │               │                       │
88       │putwc_unlocked(),    │               │                       │
89       │fgetws_unlocked(),   │               │                       │
90       │fputws_unlocked()    │               │                       │
91       ├─────────────────────┼───────────────┼───────────────────────┤
92       │getchar_unlocked(),  │ Thread safety │ MT-Unsafe race:stdin  │
93       │getwchar_unlocked()  │               │                       │
94       ├─────────────────────┼───────────────┼───────────────────────┤
95       │putchar_unlocked(),  │ Thread safety │ MT-Unsafe race:stdout │
96       │putwchar_unlocked()  │               │                       │
97       ├─────────────────────┼───────────────┼───────────────────────┤
98       │feof_unlocked(),     │ Thread safety │ MT-Safe               │
99       │ferror_unlocked(),   │               │                       │
100       │fileno_unlocked()    │               │                       │
101       └─────────────────────┴───────────────┴───────────────────────┘

CONFORMING TO

103       The     four     functions     getc_unlocked(),     getchar_unlocked(),
104       putc_unlocked(),    putchar_unlocked()    are   in   POSIX.1-2001   and
105       POSIX.1-2008.
106
107       The nonstandard *_unlocked() variants occur on a few UNIX systems,  and
108       are available in recent glibc.  They should probably not be used.
109

SEE ALSO

111       flockfile(3), stdio(3)
112

COLOPHON

114       This  page  is  part of release 4.16 of the Linux man-pages project.  A
115       description of the project, information about reporting bugs,  and  the
116       latest     version     of     this    page,    can    be    found    at
117       https://www.kernel.org/doc/man-pages/.
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121                                  2017-09-15                 UNLOCKED_STDIO(3)
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