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diff --git a/man-pages-posix-2017/man3p/freopen.3p b/man-pages-posix-2017/man3p/freopen.3p new file mode 100644 index 0000000..1d23344 --- /dev/null +++ b/man-pages-posix-2017/man3p/freopen.3p @@ -0,0 +1,365 @@ +'\" et +.TH FREOPEN "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual" +.\" +.SH PROLOG +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. +.\" +.SH NAME +freopen +\(em open a stream +.SH SYNOPSIS +.LP +.nf +#include <stdio.h> +.P +FILE *freopen(const char *restrict \fIpathname\fP, const char *restrict \fImode\fP, + FILE *restrict \fIstream\fP); +.fi +.SH DESCRIPTION +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\(hy2017 defers to the ISO\ C standard. +.P +The +\fIfreopen\fR() +function shall first attempt to flush the stream associated with +.IR stream +as if by a call to +.IR fflush ( stream ). +Failure to flush the stream successfully shall be ignored. If +.IR pathname +is not a null pointer, +\fIfreopen\fR() +shall close any file descriptor associated with +.IR stream . +Failure to close the file descriptor successfully shall be ignored. +The error and end-of-file indicators for the stream shall be +cleared. +.P +The +\fIfreopen\fR() +function shall open the file whose pathname is the string pointed to by +.IR pathname +and associate the stream pointed to by +.IR stream +with it. The +.IR mode +argument shall be used just as in +\fIfopen\fR(). +.P +The original stream shall be closed regardless of whether the +subsequent open succeeds. +.P +If +.IR pathname +is a null pointer, the +\fIfreopen\fR() +function shall attempt to change the mode of the stream to that +specified by +.IR mode , +as if the name of the file currently associated with the stream had +been used. In this case, the file descriptor associated with the stream +need not be closed if the call to +\fIfreopen\fR() +succeeds. It is implementation-defined which changes of mode are +permitted (if any), and under what circumstances. +.P +After a successful call to the +\fIfreopen\fR() +function, the orientation of the stream shall be cleared, +the encoding rule shall be cleared, +and the associated +.BR mbstate_t +object shall be set to describe an initial conversion state. +.P +If +.IR pathname +is not a null pointer, or if +.IR pathname +is a null pointer and the specified mode change necessitates the file +descriptor associated with the stream to be closed and reopened, the +file descriptor associated with the reopened stream shall be allocated +and opened as if by a call to +\fIopen\fR() +with the following flags: +.TS +center box tab(!); +cB | cB +l | l. +\fIfreopen\fP(\^) Mode!\fIopen\fP(\^) Flags +_ +\fIr\fR or \fIrb\fR!O_RDONLY +\fIw\fR or \fIwb\fR!O_WRONLY|O_CREAT|O_TRUNC +\fIa\fR or \fIab\fR!O_WRONLY|O_CREAT|O_APPEND +\fIr+\fR or \fIrb+\fR or \fIr+b\fR!O_RDWR +\fIw+\fR or \fIwb+\fR or \fIw+b\fR!O_RDWR|O_CREAT|O_TRUNC +\fIa+\fR or \fIab+\fR or \fIa+b\fR!O_RDWR|O_CREAT|O_APPEND +.TE +.SH "RETURN VALUE" +Upon successful completion, +\fIfreopen\fR() +shall return the value of +.IR stream . +Otherwise, a null pointer shall be returned, +and +.IR errno +shall be set to indicate the error. +.SH ERRORS +The +\fIfreopen\fR() +function shall fail if: +.TP +.BR EACCES +Search permission is denied on a component of the path prefix, or the +file exists and the permissions specified by +.IR mode +are denied, or the file does not exist and write permission is denied +for the parent directory of the file to be created. +.TP +.BR EBADF +The file descriptor underlying the stream is not a valid file +descriptor when +.IR pathname +is a null pointer. +.TP +.BR EINTR +A signal was caught during +\fIfreopen\fR(). +.TP +.BR EISDIR +The named file is a directory and +.IR mode +requires write access. +.TP +.BR ELOOP +A loop exists in symbolic links encountered during resolution of the +.IR path +argument. +.TP +.BR EMFILE +All file descriptors available to the process are currently open. +.TP +.BR ENAMETOOLONG +.br +The length of a component of a pathname is longer than +{NAME_MAX}. +.TP +.BR ENFILE +The maximum allowable number of files is currently open in the system. +.TP +.BR ENOENT +The +.IR mode +string begins with +.BR 'r' +and a component of +.IR pathname +does not name an existing file, or +.IR mode +begins with +.BR 'w' +or +.BR 'a' +and a component of the path prefix of +.IR pathname +does not name an existing file, or +.IR pathname +is an empty string. +.TP +.BR ENOENT " or " ENOTDIR +.br +The +.IR pathname +argument contains at least one non-\c +<slash> +character and ends with one or more trailing +<slash> +characters. If +.IR pathname +without the trailing +<slash> +characters would name an existing file, an +.BR [ENOENT] +error shall not occur. +.TP +.BR ENOSPC +The directory or file system that would contain the new file cannot be +expanded, the file does not exist, and it was to be created. +.TP +.BR ENOTDIR +A component of the path prefix names an existing file that is neither +a directory nor a symbolic link to a directory, or the +.IR pathname +argument contains at least one non-\c +<slash> +character and ends with one or more trailing +<slash> +characters and the last pathname component names an existing file that +is neither a directory nor a symbolic link to a directory. +.TP +.BR ENXIO +The named file is a character special or block special file, and the +device associated with this special file does not exist. +.TP +.BR EOVERFLOW +The named file is a regular file and the size of the file cannot be +represented correctly in an object of type +.BR off_t . +.TP +.BR EROFS +The named file resides on a read-only file system and +.IR mode +requires write access. +.P +The +\fIfreopen\fR() +function may fail if: +.TP +.BR EBADF +The mode with which the file descriptor underlying the stream was +opened does not support the requested mode when +.IR pathname +is a null pointer. +.TP +.BR EINVAL +The value of the +.IR mode +argument is not valid. +.TP +.BR ELOOP +More than +{SYMLOOP_MAX} +symbolic links were encountered during resolution of the +.IR path +argument. +.TP +.BR ENAMETOOLONG +.br +The length of a pathname exceeds +{PATH_MAX}, +or pathname resolution of a symbolic link produced an intermediate +result with a length that exceeds +{PATH_MAX}. +.TP +.BR ENOMEM +Insufficient storage space is available. +.TP +.BR ENXIO +A request was made of a nonexistent device, or the request was outside +the capabilities of the device. +.TP +.BR ETXTBSY +The file is a pure procedure (shared text) file that is being executed +and +.IR mode +requires write access. +.LP +.IR "The following sections are informative." +.SH EXAMPLES +.SS "Directing Standard Output to a File" +.P +The following example logs all standard output to the +.BR /tmp/logfile +file. +.sp +.RS 4 +.nf + +#include <stdio.h> +\&... +FILE *fp; +\&... +fp = freopen ("/tmp/logfile", "a+", stdout); +\&... +.fi +.P +.RE +.SH "APPLICATION USAGE" +The +\fIfreopen\fR() +function is typically used to attach the pre-opened +.IR streams +associated with +.IR stdin , +.IR stdout , +and +.IR stderr +to other files. +.P +Since implementations are not required to support any stream mode changes +when the +.IR pathname +argument is NULL, portable applications cannot rely on the use of +\fIfreopen\fR() +to change the stream mode, and use of this feature is discouraged. The +feature was originally added to the ISO\ C standard in order to facilitate changing +.IR stdin +and +.IR stdout +to binary mode. Since a +.BR 'b' +character in the mode has no effect on POSIX systems, this use of the +feature is unnecessary in POSIX applications. However, even though the +.BR 'b' +is ignored, a successful call to +.IR freopen \c +(NULL, "\fIwb\fR", \fIstdout\fR) does have an effect. In particular, +for regular files it truncates the file and sets the file-position +indicator for the stream to the start of the file. It is possible that +these side-effects are an unintended consequence of the way the feature +is specified in the ISO/IEC\ 9899:\|1999 standard, but unless or until the ISO\ C standard is changed, +applications which successfully call +.IR freopen \c +(NULL, "\fIwb\fR", \fIstdout\fR) will behave in unexpected ways on +conforming systems in situations such as: +.sp +.RS 4 +.nf + +{ appl file1; appl file2; } > file3 +.fi +.P +.RE +.P +which will result in +.BR file3 +containing only the output from the second invocation of +.IR appl . +.SH RATIONALE +None. +.SH "FUTURE DIRECTIONS" +None. +.SH "SEE ALSO" +.IR "Section 2.5" ", " "Standard I/O Streams", +.IR "\fIfclose\fR\^(\|)", +.IR "\fIfdopen\fR\^(\|)", +.IR "\fIfflush\fR\^(\|)", +.IR "\fIfmemopen\fR\^(\|)", +.IR "\fIfopen\fR\^(\|)", +.IR "\fImbsinit\fR\^(\|)", +.IR "\fIopen\fR\^(\|)", +.IR "\fIopen_memstream\fR\^(\|)" +.P +The Base Definitions volume of POSIX.1\(hy2017, +.IR "\fB<stdio.h>\fP" +.\" +.SH COPYRIGHT +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 . +.PP +Any typographical or formatting errors that appear +in this page are most likely +to have been introduced during the conversion of the source files to +man page format. To report such errors, see +https://www.kernel.org/doc/man-pages/reporting_bugs.html . |