1.
#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <pthread.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <errno.h>
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pthread_mutex_t file_lock = PTHREAD_MUTEX_INITIALIZER;
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void th_funz(void* arg)
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{
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int rc;
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int fd;
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FILE* f;
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char* point;
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int nread = 1;
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int *id = (int*) arg;
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rc = pthread_mutex_lock(&file_lock);
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if (rc) perror("pthread_mutex_lock");
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printf("th %d comes..\n", *id);
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sleep(4);
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rc = pthread_mutex_unlock(&file_lock);
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if (rc) perror("pthread_mutex_unlock");
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}
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int main()
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{
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pthread_t th1, th2, th3;
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int rc;
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int uno= 1, due = 2, tre= 3;
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rc = pthread_create(&th1, NULL, th_funz, (void*) &uno);
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if (rc < 0) perror("pthread_create()");
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rc = pthread_create(&th2, NULL, th_funz, (void*) &due);
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if (rc < 0) perror("pthread_create()");
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rc = pthread_create(&th3, NULL, th_funz, (void*) &tre);
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if (rc < 0) perror("pthread_create()");
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pthread_join(th1, NULL);
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pthread_join(th2, NULL);
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pthread_join(th3, NULL);
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return 0;
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}
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when i debug this sample program with gdb and set a breakpoint into pthread_mutex_lock() line
63.
i got sigtrap:(gdb) b prova.c:26
64.
Breakpoint 1 at 0x8048547: file prova.c, line 26.
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(gdb) r
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Starting program: /progetto/fd_threads/prova
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[Thread debugging using libthread_db enabled]
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[New Thread -1208653568 (LWP 20212)]
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[New Thread -1209922640 (LWP 20215)]
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[Switching to Thread -1209922640 (LWP 20215)]
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Breakpoint 1, th_funz (arg=0xbfb86994) at prova.c:26
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26 rc = pthread_mutex_lock(&file_lock);
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(gdb) n
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[New Thread -1218311248 (LWP 20216)]
76.
77.
Program received signal SIGTRAP, Trace/breakpoint trap.
78.
[Switching to Thread -1208653568 (LWP 20212)]
my gdb version is 6.3-debian
thx everybody!
