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copied!<p>I have a rather strange issue here or I am be ignorant of the way it works, but any way I have the program below that creates the semaphore properly and runs to the end for the first time. But SEGFaults at sem_wait, if the semaphore already exists. I am running this on 64bit Fedora 17. Does this have to do anything with the error?</p> <pre><code>#include <stdio.h> /* printf() */ #include <stdlib.h> /* exit(), malloc(), free() */ #include <sys/types.h> /* key_t, sem_t, pid_t */ #include <sys/shm.h> /* shmat(), IPC_RMID */ #include <errno.h> /* errno, ECHILD */ #include <semaphore.h> /* sem_open(), sem_destroy(), sem_wait().. */ #include <fcntl.h> /* O_CREAT, O_EXEC */ int main() { sem_t *mysem; int oflag = O_CREAT | O_EXCL; mode_t mode = 0777; const char semname[] = "mysem"; unsigned int value = 1; int sts; mysem = sem_open(semname, oflag, mode, value); //sem_unlink(semname); if(mysem == (void *)-1) { printf("sem_open() failed"); exit(1); } printf("opened a semaphore successful\n"); if(!sem_wait(mysem)) { /*locked */ printf("worked\n"); } else { printf("error\n"); } return 0; } </code></pre> <p><strong>Contents of /dev/shm sem.mysem</strong></p> <pre><code>Program received signal SIGSEGV, Segmentation fault. 0x000000332980d5f0 in sem_wait () from /lib64/libpthread.so.0 Missing separate debuginfos, use: debuginfo-install glibc-2.15-58.fc17.x86_64 (gdb) where #0 0x000000332980d5f0 in sem_wait () from /lib64/libpthread.so.0 #1 0x000000000040074a in main () at str2.c:31 </code></pre> <p>Strange issue is that when I delete the semaphore in /dev/shm or uncomment sem_unlink it works every time. Am I doing something wrong here or do I need to run a sem_post somewhere?</p> <p>thanks.</p>

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