FSETPOS(3P) POSIX Programmer's Manual FSETPOS(3P)
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
fsetpos — set current file position
#include <stdio.h> int fsetpos(FILE *stream, const fpos_t *pos);
The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2017 defers to the ISO C standard. The fsetpos() function shall set the file position and state indicators for the stream pointed to by stream according to the value of the object pointed to by pos, which the application shall ensure is a value obtained from an earlier call to fgetpos() on the same stream. If a read or write error occurs, the error indicator for the stream shall be set and fsetpos() fails. A successful call to the fsetpos() function shall clear the end- of-file indicator for the stream and undo any effects of ungetc() on the same stream. After an fsetpos() call, the next operation on an update stream may be either input or output. The behavior of fsetpos() on devices which are incapable of seeking is implementation-defined. The value of the file offset associated with such a device is undefined. The fsetpos() function shall not change the setting of errno if successful.
The fsetpos() function shall return 0 if it succeeds; otherwise, it shall return a non-zero value and set errno to indicate the error.
The fsetpos() function shall fail if, either the stream is unbuffered or the stream's buffer needed to be flushed, and the call to fsetpos() causes an underlying lseek() or write() to be invoked, and: EAGAIN The O_NONBLOCK flag is set for the file descriptor and the thread would be delayed in the write operation. EBADF The file descriptor underlying the stream file is not open for writing or the stream's buffer needed to be flushed and the file is not open. EFBIG An attempt was made to write a file that exceeds the maximum file size. EFBIG An attempt was made to write a file that exceeds the file size limit of the process. EFBIG The file is a regular file and an attempt was made to write at or beyond the offset maximum associated with the corresponding stream. EINTR The write operation was terminated due to the receipt of a signal, and no data was transferred. EIO A physical I/O error has occurred, or the process is a member of a background process group attempting to perform a write() to its controlling terminal, TOSTOP is set, the calling thread is not blocking SIGTTOU, the process is not ignoring SIGTTOU, and the process group of the process is orphaned. This error may also be returned under implementation-defined conditions. ENOSPC There was no free space remaining on the device containing the file. EPIPE An attempt was made to write to a pipe or FIFO that is not open for reading by any process; a SIGPIPE signal shall also be sent to the thread. ESPIPE The file descriptor underlying stream is associated with a pipe, FIFO, or socket. The fsetpos() function may fail if: ENXIO A request was made of a nonexistent device, or the request was outside the capabilities of the device. The following sections are informative.
Section 2.5, Standard I/O Streams, fopen(3p), ftell(3p), lseek(3p), rewind(3p), ungetc(3p), write(3p) The Base Definitions volume of POSIX.1‐2017, stdio.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any
discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .
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Pages that refer to this page: stdio.h(0p), fseek(3p), ungetc(3p), ungetwc(3p)