fdopen - associate a stream with a file descriptor
FILE *fdopen(int fildes, const char *mode);
The fdopen() function associates a stream with a file
The mode argument is a character string having one of the
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
r+ or rb+ or r+b Open a file for update (reading and
w+ or wb+ or w+b Open a file for update (reading and
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 for the
fopen(3C) function, 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 associ-
ated with the new stream is set to the position indicated by
the file offset associated with the file descriptor.
The fdopen() function preserves the offset maximum previ-
ously set for the open file description corresponding to
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.
If fildes refers to a shared memory object, the result of
the fdopen() function is unspecified.
Upon successful completion, fdopen() returns a pointer to a
stream. Otherwise, a null pointer is returned and errno is
set to indicate the error.
The fdopen() function may fail and not set errno if there
are no free stdio streams.
The fdopen() function may fail if:
EBADF The fildes argument is not a valid file descriptor.
The mode argument is not a valid mode.
The number of streams currently open in the calling
process is either FOPEN_MAX or STREAM_MAX.
Insufficient space to allocate a buffer.
The number of streams that a process can have open at one
time is STREAM_MAX. If defined, it has the same value as
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.
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | MT-Safe |
creat(2), dup(2), open(2), pipe(2), fclose(3C), fopen(3C),
Man(1) output converted with