| 1 | #include <errno.h>
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| 2 | #include <fcntl.h>
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| 3 | #include <signal.h>
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| 4 | #include <string.h>
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| 5 | #include <sys/stat.h>
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| 6 | #include <unistd.h>
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| 7 |
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| 8 | int
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| 9 | main(int argc, char **argv)
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| 10 | {
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| 11 | int fd;
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| 12 | sigset_t blocked;
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| 13 |
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| 14 | /* Try invoking this program first on its own, then again using either
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| 15 | * strace or the debugger. Without the patch for #3417 applied you should
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| 16 | * find it terminates normally in the first case but gets stuck in an ioctl
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| 17 | * and runs forever in the second. With the patch applied it terminates
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| 18 | * normally in both cases. */
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| 19 |
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| 20 | /* Open our controlling terminal */
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| 21 | fd = open("/dev/tty", O_RDWR | O_NOCTTY);
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| 22 |
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| 23 | /* If our process-group ID is not the same as our process ID (i.e. we're
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| 24 | * running with a debugger attached), move to our own (background) process
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| 25 | * group */
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| 26 | if (getpid() != tcgetpgrp(fd))
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| 27 | setpgid(0, 0);
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| 28 |
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| 29 | /* Block SIGTTOU (in this thread only) */
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| 30 | sigemptyset(&blocked);
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| 31 | sigaddset(&blocked, SIGTTOU);
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| 32 | pthread_sigmask(SIG_BLOCK, &blocked, NULL);
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| 33 |
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| 34 | /* Now set the terminal's foreground process group to our own.
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| 35 | *
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| 36 | * Normally this should cause a SIGTTOU signal to be sent to us if we're
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| 37 | * running in the background (within the debugger), but since we've already
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| 38 | * blocked this signal it should not be generated. */
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| 39 | tcsetpgrp(fd, getpgrp());
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| 40 |
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| 41 | /* Clean up and exit */
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| 42 | close(fd);
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| 43 |
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| 44 | return 0;
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| 45 | }
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