29 lines
648 B
C
29 lines
648 B
C
|
#include <unistd.h>
|
||
|
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
#include <fcntl.h>
|
||
|
|
#include <string.h>
|
||
|
|
|
||
|
|
|
||
|
|
void main(int argc, char *argv[]) {
|
||
|
|
char buf[1024];
|
||
|
|
int fd;
|
||
|
|
char *filename = argv[1];
|
||
|
|
|
||
|
|
if (access(filename, R_OK) != 0) {
|
||
|
|
//printf("file '%s' not accessible by user\n", filename);
|
||
|
|
exit(-1); // original user lacks permission
|
||
|
|
}
|
||
|
|
|
||
|
|
// file at path `filename` exists and is readable
|
||
|
|
// by the original user (i.e., not just by root)
|
||
|
|
memset(buf, 0, 1024);
|
||
|
|
fd = open(filename, O_RDONLY);
|
||
|
|
if (fd == -1) {
|
||
|
|
//perror("error in open()");
|
||
|
|
} else {
|
||
|
|
read(fd, buf, 1024);
|
||
|
|
printf("%s", buf);
|
||
|
|
}
|
||
|
|
}
|