x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SETMODE(3bsd) LOCAL SETMODE(3bsd)
NAME
getmode, setmode -- modify mode bits
LIBRARY
library ``libbsd''
SYNOPSIS
#include <unistd.h>
(See libbsd(7) for include usage.)
void *
setmode(const char *mode_str);
mode_t
getmode(const void *set, mode_t mode);
DESCRIPTION
The setmode() function accepts a string representation of a file mode
change, compiles it to binary form, and returns an abstract representa-
tion that may be passed to getmode(). The string may be an numeric
(octal) or symbolic string of the form accepted by chmod(1), and may rep-
resent either an exact mode to set or a change to make to the existing
mode.
The getmode() function adjusts the file permission bits given by mode
according to the compiled change representation set, and returns the
adjusted mode. While only the permission bits are altered, other parts
of the file mode, particularly the type, may be examined.
Because some of the possible symbolic values are defined relative to the
file creation mask, setmode() may call umask(2), temporarily changing the
mask. If this occurs, the file creation mask will be restored before
setmode() returns. If the calling program changes the value of its file
creation mask after calling setmode(), setmode() must be called again to
recompile the mode string if getmode() is to modify future file modes
correctly.
If the mode passed to setmode() is invalid, setmode() returns NULL.
The value returned from setmode() is obtained from malloc() and should be
returned to the system with free() when the program is done with it, gen-
erally after a call to getmode().
EXAMPLES
The effects of the shell command `chmod a+x myscript.sh' can be dupli-
cated as follows:
const char *file = "myscript.sh";
struct stat st;
mode_t newmode;
stat(file, &st);
newmode = getmode(setmode("a+x"), st.st_mode);
chmod(file, newmode);
ERRORS
The setmode() function may fail and set errno for any of the errors spec-
ified for the library routines malloc(3) or strtol(3). In addition,
setmode() will fail and set errno to:
[EINVAL] The mode argument does not represent a valid mode.
SEE ALSO
chmod(1), stat(2), umask(2), malloc(3)
HISTORY
The getmode() and setmode() functions first appeared in 4.4BSD.
BUGS
The type of set should really be some opaque struct type used only by
these functions rather than void *.
BSD January 4, 2009 BSD
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