fdopen(3S)
NAME
fdopen − associate a stream with a file descriptor
SYNOPSIS
#include <stdio.h>
FILE ∗fdopen(int fildes, const char ∗mode);
DESCRIPTION
The fdopen() function associates a stream with a file descriptor fildes, whose value must be less than 255.
The mode argument is a character string having one of the following values:
| r or rb | open a file for reading |
| w or wb | open a file for writing |
| a or ab | open a file for writing at end of file |
| r+ or rb+ or r+b | open a file for update (reading and writing) |
| w+ or wb+ or w+b | open a file for update (reading and writing) |
| a+ or ab+ or a+b | open a file for update (reading and writing) at end of file |
The meaning of these flags is exactly as specified in fopen(3S), except that modes beginning with w do not cause truncation of the file.
The mode of the stream must be allowed by the file access mode of the open file. The file position indicator associated with the new stream is set to the position indicated by the file offset associated with the file descriptor.
fdopen() will preserve the offset maximum previously set for the open file description corresponding to fildes.
The error and end-of-file indicators for the stream are cleared. The fdopen() function may cause the st_atime field of the underlying file to be marked for update.
RETURN VALUES
Upon successful completion, fdopen() returns a pointer to a stream. Otherwise, a null pointer is returned and errno is set to indicate the error.
fdopen() may fail and not set errno if there are no free stdio streams.
ERRORS
The fdopen() function may fail if:
EBADF The fildes argument is not a valid file descriptor.
EINVAL The mode argument is not a valid mode.
EMFILE FOPEN_MAX streams are currently open in the calling process.
EMFILE STREAM_MAX streams are currently open in the calling process.
ENOMEM
Insufficient space to allocate a buffer.
USAGE
STREAM_MAX is the number of streams that one process can have open at one time. If defined, it has the same value as FOPEN_MAX.
File descriptors are obtained from calls like open(2), dup(2), creat(2) or pipe(2), which open files but do not return streams. Streams are necessary input for almost all of the Section 3S library routines.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | MT-Safe |
SEE ALSO
creat(2), dup(2), open(2), pipe(2), fclose(3S), fopen(3S), attributes(5)
SunOS 5.6 — Last change: 30 Dec 1996