52 lines
1.3 KiB
C
52 lines
1.3 KiB
C
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/* This file is part of the sample code and exercises
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* used by the class "Advanced Programming in the UNIX
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* Environment" taught by Jan Schaumann
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* <jschauma@netmeister.org> at Stevens Institute of
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* Technology.
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*
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* This file is in the public domain.
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*
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* You don't have to, but if you feel like
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* acknowledging where you got this code, you may
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* reference me by name, email address, or point
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* people to the course website:
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* https://stevens.netmeister.org/631/
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*/
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/* This simple program illustrates the use of the chmod(2) system call,
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* and how it can be used to set explicit/absolute modes or to selectively
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* enable individual modes.
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*
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* Set your umask to 077, create file and file1, then run this command.
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <stdio.h>
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#include <stdlib.h>
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int
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main() {
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struct stat sbuf;
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if (stat("file", &sbuf) == -1) {
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perror("can't stat file");
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exit(EXIT_FAILURE);
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}
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/* turn off owner read permissions and turn on setgid */
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if (chmod("file", (sbuf.st_mode & ~S_IRUSR) | S_ISGID) == -1) {
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perror("can't chmod file");
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exit(EXIT_FAILURE);
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}
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/* set absolute mode to rw-r--r-- */
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if (chmod("file1", S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) == -1) {
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perror("can't chmod file1");
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exit(EXIT_FAILURE);
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}
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exit(EXIT_SUCCESS);
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}
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