1FCLOSE(3P) POSIX Programmer's Manual FCLOSE(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 fclose — close a stream
13
15 #include <stdio.h>
16 int fclose(FILE *stream);
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20 The functionality described on this reference page is aligned with the
21 ISO C standard. Any conflict between the requirements described here
22 and the ISO C standard is unintentional. This volume of POSIX.1‐2017
23 defers to the ISO C standard.
24 The fclose() function shall cause the stream pointed to by stream to be
26 flushed and the associated file to be closed. Any unwritten buffered
27 data for the stream shall be written to the file; any unread buffered
28 data shall be discarded. Whether or not the call succeeds, the stream
29 shall be disassociated from the file and any buffer set by the setbuf()
30 or setvbuf() function shall be disassociated from the stream. If the
31 associated buffer was automatically allocated, it shall be deallocated.
32 If the file is not already at EOF, and the file is one capable of seek‐
34 ing, the file offset of the underlying open file description shall be
35 set to the file position of the stream if the stream is the active han‐
36 dle to the underlying file description.
37 The fclose() function shall mark for update the last data modification
39 and last file status change timestamps of the underlying file, if the
40 stream was writable, and if buffered data remains that has not yet been
41 written to the file. The fclose() function shall perform the equivalent
42 of a close() on the file descriptor that is associated with the stream
43 pointed to by stream.
44 After the call to fclose(), any use of stream results in undefined
46 behavior.
47
49 Upon successful completion, fclose() shall return 0; otherwise, it
50 shall return EOF and set errno to indicate the error.
51
53 The fclose() function shall fail if:
54 EAGAIN The O_NONBLOCK flag is set for the file descriptor underlying
56 stream and the thread would be delayed in the write operation.
57 EBADF The file descriptor underlying stream is not valid.
59 EFBIG An attempt was made to write a file that exceeds the maximum
61 file size.
62 EFBIG An attempt was made to write a file that exceeds the file size
64 limit of the process.
65 EFBIG The file is a regular file and an attempt was made to write at
67 or beyond the offset maximum associated with the corresponding
68 stream.
69 EINTR The fclose() function was interrupted by a signal.
71 EIO The process is a member of a background process group attempting
73 to write to its controlling terminal, TOSTOP is set, the calling
74 thread is not blocking SIGTTOU, the process is not ignoring
75 SIGTTOU, and the process group of the process is orphaned. This
76 error may also be returned under implementation-defined condi‐
77 tions.
78 ENOMEM The underlying stream was created by open_memstream() or
80 open_wmemstream() and insufficient memory is available.
81 ENOSPC There was no free space remaining on the device containing the
83 file or in the buffer used by the fmemopen() function.
84 EPIPE An attempt is made to write to a pipe or FIFO that is not open
86 for reading by any process. A SIGPIPE signal shall also be sent
87 to the thread.
88 The fclose() function may fail if:
90 ENXIO A request was made of a nonexistent device, or the request was
92 outside the capabilities of the device.
93 The following sections are informative.
95
97 None.
98
100 Since after the call to fclose() any use of stream results in undefined
101 behavior, fclose() should not be used on stdin, stdout, or stderr
102 except immediately before process termination (see the Base Definitions
103 volume of POSIX.1‐2017, Section 3.303, Process Termination), so as to
104 avoid triggering undefined behavior in other standard interfaces that
105 rely on these streams. If there are any atexit() handlers registered by
106 the application, such a call to fclose() should not occur until the
107 last handler is finishing. Once fclose() has been used to close stdin,
108 stdout, or stderr, there is no standard way to reopen any of these
109 streams.
110 Use of freopen() to change stdin, stdout, or stderr instead of closing
112 them avoids the danger of a file unexpectedly being opened as one of
113 the special file descriptors STDIN_FILENO, STDOUT_FILENO, or
114 STDERR_FILENO at a later time in the application.
115
117 None.
118
120 None.
121
123 Section 2.5, Standard I/O Streams, atexit(), close(), fmemopen(),
124 fopen(), freopen(), getrlimit(), open_memstream(), ulimit()
125 The Base Definitions volume of POSIX.1‐2017, <stdio.h>
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129 Portions of this text are reprinted and reproduced in electronic form
130 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
131 table Operating System Interface (POSIX), The Open Group Base Specifi‐
132 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
133 Electrical and Electronics Engineers, Inc and The Open Group. In the
134 event of any discrepancy between this version and the original IEEE and
135 The Open Group Standard, the original IEEE and The Open Group Standard
136 is the referee document. The original Standard can be obtained online
137 at http://www.opengroup.org/unix/online.html .
138 Any typographical or formatting errors that appear in this page are
140 most likely to have been introduced during the conversion of the source
141 files to man page format. To report such errors, see https://www.ker‐
142 nel.org/doc/man-pages/reporting_bugs.html .
143IEEE/The Open Group 2017 FCLOSE(3P)