83 lines
1.5 KiB
C
83 lines
1.5 KiB
C
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#include <sys/types.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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#include <fcntl.h>
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void
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fail_if_still_open(int fd)
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{
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if(fd == 0){
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printf("atoi failed\n");
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exit(2);
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}
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if(fcntl(fd, F_GETFD) != -1){
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printf("fd %d is still open\n", fd);
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exit(3);
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}
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}
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int
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main(int argc, char *argv[])
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{
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int sync[2];
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int outfd;
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int nullfd;
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int tmp;
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char *eargv[7], *p;
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char buf[128];
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if(argc == 1){
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printf("cat /proc/%d/fd\n", getpid());
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pipe(sync);
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outfd = dup(1);
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nullfd = open("/dev/null", O_WRONLY);
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tmp = fcntl(sync[0], F_DUPFD_CLOEXEC, 1);
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close(sync[0]);
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sync[0] = tmp;
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tmp = fcntl(sync[1], F_DUPFD_CLOEXEC, 1);
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close(sync[1]);
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sync[1] = tmp;
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tmp = fcntl(outfd, F_DUPFD_CLOEXEC, 1);
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close(outfd);
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outfd = tmp;
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tmp = fcntl(nullfd, F_DUPFD_CLOEXEC, 1);
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close(nullfd);
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nullfd = tmp;
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eargv[0] = argv[0];
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p = buf;
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eargv[1] = p;
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p += 1+sprintf(p, "%d", sync[0]);
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eargv[2] = p;
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p += 1+sprintf(p, "%d", sync[1]);
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eargv[3] = p;
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p += 1+sprintf(p, "%d", outfd);
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eargv[4] = p;
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p += 1+sprintf(p, "%d", nullfd);
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eargv[5] = NULL;
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execvp(argv[0], eargv);
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printf("execvp returned\n");
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exit(100);
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} else if(argc != 5){
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printf("argc = %d (should be 5)\n", argc);
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exit(1);
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}
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printf("argc = %d; fds: %s %s %s %s\n", argc, argv[1], argv[2], argv[3], argv[4] );
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sync[0] = atoi(argv[1]);
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sync[1] = atoi(argv[2]);
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outfd = atoi(argv[3]);
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nullfd = atoi(argv[4]);
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fail_if_still_open(sync[0]);
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fail_if_still_open(sync[1]);
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fail_if_still_open(outfd);
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fail_if_still_open(nullfd);
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exit(0);
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}
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