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.

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(), except that modes beginning with w do not cause truncation of the file.

Additional values for the mode argument may be supported by an implementation.

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.

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.

The fdopen() function will preserve the offset maximum previously set for the open file description corresponding to fildes.

 RETURN VALUE

Upon successful completion, fdopen() returns a pointer to a stream. Otherwise, a null pointer is returned and errno is set to indicate the error.

 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.

 EXAMPLES

None.

 APPLICATION USAGE

File descriptors are obtained from calls like open(), dup(), creat() or pipe(), which open files but do not return streams.

 FUTURE DIRECTIONS

None.

 SEE ALSO

fclose(), fopen(), open(), <stdio.h>, Standard I/O Streans.

DERIVATION

Derived from Issue 1 of the SVID.