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The
function sets the file permission bits of the file specified by the pathname
to sets the permission bits of the specified file descriptor verifies
that the process owner (user) either owns the file specified by (or or
is the super-user. A mode is created from permission bit masks defined in
#define S_IRWXU 0000700 /* RWX mask for owner */ #define S_IRUSR 0000400
/* R for owner */ #define S_IWUSR 0000200 /* W for owner */ #define
S_IXUSR 0000100 /* X for owner */
#define S_IRWXG 0000070 /* RWX
mask for group */ #define S_IRGRP 0000040 /* R for group */ #define
S_IWGRP 0000020 /* W for group */ #define S_IXGRP 0000010 /* X for
group */
#define S_IRWXO 0000007 /* RWX mask for other */ #define S_IROTH
0000004 /* R for other */ #define S_IWOTH 0000002 /* W for other
*/ #define S_IXOTH 0000001 /* X for other */
#define S_ISUID 0004000
/* set user id on execution */ #define S_ISGID 0002000 /* set group
id on execution */ #define S_ISVTX 0001000 /* save swapped text even
after use */ The (the indicates to the system which executable files
are shareable (the default) and the system maintains the program text of
the files in the swap area. The sticky bit may only be set by the super
user on shareable executable files. If mode (the ‘sticky bit’) is set on
a directory, an unprivileged user may not delete or rename files of other
users in that directory. The sticky bit may be set by any user on a directory
which the user owns or has appropriate permissions. For more details of
the properties of the sticky bit, see Writing or changing the owner of
a file turns off the set-user-id and set-group-id bits unless the user is the
super-user. This makes the system somewhat more secure by protecting set-user-id
(set-group-id) files from remaining set-user-id (set-group-id) if they are modified,
at the expense of a degree of compatibility.
Upon successful
completion, a value of 0 is returned. Otherwise, a value of -1 is returned
and is set to indicate the error.
will fail and the file mode will
be unchanged if: A component of the path prefix is not a directory. A
component of a pathname exceeded characters, or an entire path name exceeded
characters. The named file does not exist. Search permission is denied
for a component of the path prefix. Too many symbolic links were encountered
in translating the pathname. The effective user ID does not match the owner
of the file and the effective user ID is not the super-user. The named file
resides on a read-only file system. points outside the process’s allocated
address space. An I/O error occurred while reading from or writing to the
file system. will fail if: The descriptor is not valid. refers to
a socket, not to a file. The file resides on a read-only file system. An
I/O error occurred while reading from or writing to the file system.
The function is expected to conform to
The
function call appeared in
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