47 lines
1.2 KiB
C
47 lines
1.2 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 trivial program illustrates the use of access(2). Compile this
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* program and run it with /etc/passwd, /etc/master.passwd as arguments;
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* then chown and setuid the executable and repeat.
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*/
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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int
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main(int argc, char **argv) {
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if (argc != 2) {
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fprintf(stderr, "%s: usage: %s filename\n", argv[0], argv[0]);
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exit(EXIT_FAILURE);
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}
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if (access(argv[1], R_OK) == -1)
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printf("access error for %s\n", argv[1]);
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else
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printf("access ok for %s\n", argv[1]);
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if (open(argv[1], O_RDONLY) == -1)
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printf("open error for %s\n", argv[1]);
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else
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printf("open ok for %s\n", argv[1]);
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exit(EXIT_SUCCESS);
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}
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