_umask_s
Sets the default file-permission mask. A version of _umask with security enhancements as described in Security Features in the CRT.
errno_t _umask_s(
int mode,
int * pOldMode
);
Parameters
[in] mode
Default permission setting.[out] oldMode
The previous value of the permission setting.
Return Value
Returns an error code if Mode does not specify a valid mode or the pOldMode pointer is NULL.
Error Conditions
mode |
pOldMode |
Return Value |
Contents of oldMode |
|---|---|---|---|
any |
NULL |
EINVAL |
not modified |
invalid mode |
any |
EINVAL |
not modified |
If one of the above conditions occurs, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, _umask_s returns EINVAL and sets errno to EINVAL.
Remarks
The _umask_s function sets the file-permission mask of the current process to the mode specified by mode*.* The file-permission mask modifies the permission setting of new files created by _creat, _open, or _sopen. If a bit in the mask is 1, the corresponding bit in the file's requested permission value is set to 0 (disallowed). If a bit in the mask is 0, the corresponding bit is left unchanged. The permission setting for a new file is not set until the file is closed for the first time.
The integer expression pmode contains one or both of the following manifest constants, defined in SYS\STAT.H:
_S_IWRITE
Writing permitted._S_IREAD
Reading permitted._S_IREAD | _S_IWRITE
Reading and writing permitted.
When both constants are given, they are joined with the bitwise-OR operator ( | ). If the mode argument is _S_IREAD, reading is not allowed (the file is write-only). If the mode argument is _S_IWRITE, writing is not allowed (the file is read-only). For example, if the write bit is set in the mask, any new files will be read-only. Note that with MS-DOS and the Windows operating systems, all files are readable; it is not possible to give write-only permission. Therefore, setting the read bit with _umask_s has no effect on the file's modes.
If pmode is not a combination of one of the manifest constants or incorporates an alternate set of constants, the function will simply ignore those.
Requirements
Routine |
Required header |
|---|---|
_umask_s |
<io.h> and <sys/stat.h> and <sys/types.h> |
For additional compatibility information, see Compatibility in the Introduction.
Example
// crt_umask_s.c
/* This program uses _umask_s to set
* the file-permission mask so that all future
* files will be created as read-only files.
* It also displays the old mask.
*/
#include <sys/stat.h>
#include <sys/types.h>
#include <io.h>
#include <stdio.h>
int main( void )
{
int oldmask, err;
/* Create read-only files: */
err = _umask_s( _S_IWRITE, &oldmask );
if (err)
{
printf("Error setting the umask.\n");
exit(1);
}
printf( "Oldmask = 0x%.4x\n", oldmask );
}
Oldmask = 0x0000
.NET Framework Equivalent
System::IO::File::SetAttributes