wchmod

Name

wchmod - changes permissions of a file

Library

libc.lib

Synopsis

#include <wchar.h>

#include <sys/stat.h>

#include <sys/types.h>

int wchmod (const wchar_t *path, mode_t mode);

Return values

Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

Detailed description

The file permission bits of the wide character file-name specified by path are changed to mode. The wchmod system call verifies that the process owner (user) either owns the file specified by path is the super-user.

A mode is created from or’d permission bit masks defined in

#include <sys/stat.h>:

#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 */
#ifndef __BSD_VISIBLE
#define S_ISTXT 0001000    /* sticky bit */
#endif

Note : sticky bit and setuid on exec bit are not supported, permission values for users is considered while premissions values for group and others are ignored(As there is no concept of group and others). An attempt to change file permission to write-only changes the file permission to read-write. Permissions for directory will be ignored.

Examples

#include <wchar.h>              /* wchmode, wfopen */
#include <sys/stat.h>           /* S_IWUSR */
#include <stdio.h>              /* printf */
int main()
{
        FILE * wfp = wfopen(L"fileName.txt", L"wb");            /* create file */
        if(wfp)
                {
                fclose(wfp);                                    /* close file */
                int ret = wchmod(L"fileName", S_IWUSR);         /* change mode */
                if(ret < 0)
                        {
                        printf("error changing mode");
                        return -1;
                        }
                else
                        {
                        printf("mode changed");
                        }
                }
        else
        {
        printf("error creating file");
        return -1;
        }
        return 0;
}

Output

mode changed

Errors

The wchmod system call will fail and the file mode will be unchanged if:

[`EINVAL`]
	Invalid argument.
[`ENAMETOOLONG`]
	A component of a pathname exceeded 255 characters.
[`ENOENT`]
	The named file does not exist.
[`EACCES`]
	Search permission is denied for a component of the path prefix.

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