47 lines
1.2 KiB
C
47 lines
1.2 KiB
C
|
/* This file is part of the sample code and exercises
|
||
|
* used by the class "Advanced Programming in the UNIX
|
||
|
* Environment" taught by Jan Schaumann
|
||
|
* <jschauma@netmeister.org> at Stevens Institute of
|
||
|
* Technology.
|
||
|
*
|
||
|
* This file is in the public domain.
|
||
|
*
|
||
|
* You don't have to, but if you feel like
|
||
|
* acknowledging where you got this code, you may
|
||
|
* reference me by name, email address, or point
|
||
|
* people to the course website:
|
||
|
* https://stevens.netmeister.org/631/
|
||
|
*/
|
||
|
|
||
|
/* This trivial program illustrates the use of access(2). Compile this
|
||
|
* program and run it with /etc/passwd, /etc/master.passwd as arguments;
|
||
|
* then chown and setuid the executable and repeat.
|
||
|
*/
|
||
|
|
||
|
#include <fcntl.h>
|
||
|
#include <stdio.h>
|
||
|
#include <stdlib.h>
|
||
|
#include <unistd.h>
|
||
|
|
||
|
int
|
||
|
main(int argc, char **argv) {
|
||
|
|
||
|
if (argc != 2) {
|
||
|
fprintf(stderr, "%s: usage: %s filename\n", argv[0], argv[0]);
|
||
|
exit(EXIT_FAILURE);
|
||
|
}
|
||
|
|
||
|
if (access(argv[1], R_OK) == -1)
|
||
|
printf("access error for %s\n", argv[1]);
|
||
|
else
|
||
|
printf("access ok for %s\n", argv[1]);
|
||
|
|
||
|
|
||
|
if (open(argv[1], O_RDONLY) == -1)
|
||
|
printf("open error for %s\n", argv[1]);
|
||
|
else
|
||
|
printf("open ok for %s\n", argv[1]);
|
||
|
|
||
|
exit(EXIT_SUCCESS);
|
||
|
}
|