NAME

fchmod — change mode of a file

SYNOPSIS

#include <sys/stat.h>

int fchmod(int fildes, mode_t mode);

DESCRIPTION

The fchmod () function shall be equivalent to chmod(3) except that the file whose permissions are changed is specified by the file descriptor fildes.

[SHM] If fildes references a shared memory object, the fchmod () function need only affect the S_IRUSR, S_IWUSR, S_IRGRP, S_IWGRP, S_IROTH, and S_IWOTH file permission bits.

[TYM] If fildes references a typed memory object, the behavior of fchmod () is unspecified.

If fildes refers to a socket, the behavior of fchmod () is unspecified.

[OB XSR] If fildes refers to a STREAM (which is fattach(3) -ed into the file system name space) the call returns successfully, doing nothing.

RETURN VALUE

Upon successful completion, fchmod () shall return 0. Otherwise, it shall return -1 and set errno to indicate the error.

ERRORS

The fchmod () function shall fail if:

[EBADF]

The fildes argument is not an open file descriptor.

[EPERM]

The effective user ID does not match the owner of the file and the process does not have appropriate privileges.

[EROFS]

The file referred to by fildes resides on a read-only file system.

The fchmod () function may fail if:

[EINTR]

[XSI] The fchmod () function was interrupted by a signal.

[EINVAL]

[XSI] The value of the mode argument is invalid.

[EINVAL]

The fildes argument refers to a pipe and the implementation disallows execution of fchmod () on a pipe.

The following sections are informative.

EXAMPLES

#include <sys/stat.h>
#include <fcntl.h>


mode_t mode;
int    fildes;
...
fildes = open("/home/cnd/mod1", O_RDWR);
fchmod(fildes, S_IRWXU | S_IRWXG | S_IROTH | S_IWOTH);

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

chmod(3), chown(3), creat(3), fcntl(3), fstatat(3), fstatvfs(3), mknod(3), open(3), read(3), write(3)

XBD <sys/stat.h>

CHANGE HISTORY

First released in Issue 4, Version 2.

Issue 5

Moved from X/OPEN UNIX extension to BASE and aligned with fchmod () in the POSIX Realtime Extension. Specifically, the second paragraph of the DESCRIPTION is added and a second instance of [EINVAL] is defined in the list of optional errors.

Issue 6

The DESCRIPTION is updated for alignment with IEEE Std 1003.1j-2000 by stating that fchmod () behavior is unspecified for typed memory objects.

End of informative text.