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(), putchar_un‐
46       locked():
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(), fileno_un‐
52       locked(), fflush_unlocked(), fgetc_unlocked(), fputc_unlocked(),
53       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(), getwchar_un‐
58       locked(), fgetwc_unlocked(), fputwc_unlocked(), putwchar_unlocked(),
59       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  at‐
70       tributes(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(),   putc_un‐
104       locked(), putchar_unlocked() are in POSIX.1-2001 and POSIX.1-2008.
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106       The  nonstandard *_unlocked() variants occur on a few UNIX systems, and
107       are available in recent glibc.  They should probably not be used.
108

SEE ALSO

110       flockfile(3), stdio(3)
111

COLOPHON

113       This page is part of release 5.10 of the Linux  man-pages  project.   A
114       description  of  the project, information about reporting bugs, and the
115       latest    version    of    this    page,    can     be     found     at
116       https://www.kernel.org/doc/man-pages/.
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120                                  2017-09-15                 UNLOCKED_STDIO(3)
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