Standard C Library Functions freopen(3C)
NAME
freopen - open a stream
SYNOPSIS
#include
FILE *freopen(const char *filename, const char *mode, FILE *stream);
DESCRIPTION
The freopen() function first attempts to flush the stream
and close any file descriptor associated with stream. Failure to flush or close the file successfully is ignored.The error and end-of-file indicators for the stream are
cleared.The freopen() function opens the file whose pathname is the
string pointed to by filename and associates the stream pointed to by stream with it. The mode argument is used just as in fopen(3C). If filename is a null pointer and the application comformsto SUSv3 (see standards(5)), the freopen() function attempts
to change the mode of the stream to that specified by mode, as though the name of the file currently associated with the stream had been used. The following changes of mode are permitted, depending upon the access mode of the file descriptor underlying the stream: o When + is specified, the file descriptor mode mustbe O_RDWR.
o When r is specified, the file descriptor mode mustbe O_RDONLY or O_RDWR.
o When a or w is specified, the file descriptor modemust be O_WRONLY or O_RDWR.
If the filename is a null pointer and the application doesnot comform to SUSv3, freopen() returns a null pointer.
The original stream is closed regardless of whether the sub-
sequent open succeeds.After a successful call to the freopen() function, the
orientation of the stream is cleared, the encoding rule iscleared, and the associated mbstate_t object is set to
SunOS 5.11 Last change: 24 Jul 2002 1
Standard C Library Functions freopen(3C)
describe an initial conversion state. The largest value that can be represented correctly in anobject of type off_t will be established as the offset max-
imum in the open file description.RETURN VALUES
Upon successful completion, freopen() returns the value of
stream. Otherwise, a null pointer is returned and errno is set to indicate the error.ERRORS
The freopen() function will fail if:
EACCES Search permission is denied on a component of the path prefix, or the file exists and the permissions specified by mode are denied, or the file does not exist and writepermission is denied for the parent direc-
tory of the file to be created. EBADF The application comforms to SUSv3, the filename argument is a null pointer, and either the underlying file descriptor is notvalid or the mode specified when the under-
lying file descriptor was opened does not support the file access modes requested by the mode argument. EFAULT The application does not comform to SUSv3 and the filename argument is a null pointer.EINTR A signal was caught during freopen().
EISDIR The named file is a directory and mode requires write access. ELOOP Too many symbolic links were encountered in resolving path.EMFILE There are {OPEN_MAX} file descriptors
currently open in the calling process.SunOS 5.11 Last change: 24 Jul 2002 2
Standard C Library Functions freopen(3C)
ENAMETOOLONG The length of the filename exceeds
{PATH_MAX} or a pathname component is longer
than {NAME_MAX}.
ENFILE The maximum allowable number of files is currently open in the system. ENOENT A component of filename does not name an existing file or filename is an empty string.ENOSPC The directory or file system that would con-
tain the new file cannot be expanded, the file does not exist, and it was to be created. ENOTDIR A component of the path prefix is not a directory. ENXIO The named file is a character special orblock special file, and the device associ-
ated with this special file does not exist.EOVERFLOW The current value of the file position can-
not be represented correctly in an object oftype off_t.
EROFS The named file resides on a read-only file
system and mode requires write access.The freopen() function may fail if:
EINVAL The value of the mode argument is not valid.ENAMETOOLONG Pathname resolution of a symbolic link pro-
duced an intermediate result whose lengthexceeds {PATH_MAX}.
ENOMEM Insufficient storage space is available.SunOS 5.11 Last change: 24 Jul 2002 3
Standard C Library Functions freopen(3C)
ENXIO A request was made of a non-existent device,
or the request was outside the capabilities of the device. ETXTBSY The file is a pure procedure (shared text) file that is being executed and mode requires write access.USAGE
The freopen() function is typically used to attach the preo-
pened streams associated with stdin, stdout and stderr to other files. By default stderr is unbuffered, but the use offreopen() will cause it to become buffered or line-buffered.
The freopen() function has a transitional interface for 64-
bit file offsets. See lf64(5).ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| MT-Level | MT-Safe |
|_____________________________|_____________________________|
| Standard | See standards(5). ||_____________________________|_____________________________|
SEE ALSO
fclose(3C), fdopen(3C), fopen(3C), stdio(3C), attributes(5), lf64(5), standards(5)SunOS 5.11 Last change: 24 Jul 2002 4