40 lines
1.4 KiB
C
40 lines
1.4 KiB
C
// Demonstrate umask: restrictions on permissions for freshly created
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// files with open()/creat() files
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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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#include <sys/stat.h>
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#include <fcntl.h>
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#include <string.h>
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int main(int argc, char *argv[]){
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mode_t new_mask = 0000; // allow any permissions
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mode_t old_mask = umask(new_mask); // set umask to
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int perms = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP;;
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int flags = O_WRONLY | O_CREAT;
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int out_fd = -1;
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char *message = NULL;
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// Write to first file
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out_fd = open("readable1.txt",flags,perms ); // create file
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message = "here is some text to write"; // what to write
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write(out_fd, message, strlen(message)); // do the write
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close(out_fd); // sloppy close
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// readable1.txt should have perms: -rw-rw----
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new_mask = 0077; // don't allow permissions to be set for group or other
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old_mask = umask(new_mask);
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// Write to first file
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out_fd = open("readable2.txt",flags,perms); // open for writing and create if needed, PERMISSIONS
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message = "more text for writing"; // what to write
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write(out_fd, message, strlen(message)); // do the write
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close(out_fd); // sloppy close
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// readable1.txt should have perms: -rw-------
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// No group perms as umask stopped this
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return 0;
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}
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