Hi , Please find the code snippet of popen() from the source code that I have (We are working on an OS that is derived from FreeBSD 4.1) . I don't think I have the thread safe version .
------------------------- FILE * popen(command, type) const char *command, *type; { struct pid *cur; FILE *iop; int pdes[2], pid, twoway; char *argv[4]; struct pid *p; /* * Lite2 introduced two-way popen() pipes using socketpair(). * FreeBSD's pipe() is bidirectional, so we use that. */ if (strchr(type, '+')) { twoway = 1; type = "r+"; } else { twoway = 0; if ((*type != 'r' && *type != 'w') || type[1]) return (NULL); } if (pipe(pdes) < 0) return (NULL); if ((cur = malloc(sizeof(struct pid))) == NULL) { (void)_close(pdes[0]); (void)_close(pdes[1]); return (NULL); } argv[0] = "sh"; argv[1] = "-c"; argv[2] = (char *)command; argv[3] = NULL; switch (pid = vfork()) { case -1: /* Error. */ (void)_close(pdes[0]); (void)_close(pdes[1]); free(cur); return (NULL); /* NOTREACHED */ case 0: /* Child. */ if (*type == 'r') { /* * The dup2() to STDIN_FILENO is repeated to avoid * writing to pdes[1], which might corrupt the * parent's copy. This isn't good enough in * general, since the _exit() is no return, so * the compiler is free to corrupt all the local * variables. */ (void)_close(pdes[0]); if (pdes[1] != STDOUT_FILENO) { (void)dup2(pdes[1], STDOUT_FILENO); (void)_close(pdes[1]); if (twoway) (void)dup2(STDOUT_FILENO, STDIN_FILENO); } else if (twoway && (pdes[1] != STDIN_FILENO)) (void)dup2(pdes[1], STDIN_FILENO); } else { if (pdes[0] != STDIN_FILENO) { (void)dup2(pdes[0], STDIN_FILENO); (void)_close(pdes[0]); } (void)_close(pdes[1]); } for (p = pidlist; p; p = p->next) { (void)_close(fileno(p->fp)); } execve(_PATH_BSHELL, argv, environ); _exit(127); /* NOTREACHED */ } --- ---- } -------------------------------------------------- We had cases where our RAID applications (multi-threaded ) failed with invocations of popen() . Initially we handpicked the popen() calls and replaced it with actual code of the functions but it was simply too much work and little gain . So we decided to backport a thread-safe version . (If the above code is not thread-safe then we will have a bigger problem at hand .) --Dip On 7/5/05, Dan Nelson <[EMAIL PROTECTED]> wrote: > In the last episode (Jul 05), Dipjyoti Saikia said: > > I am working on an OS derived for BSD 4.1 . I am trying to backport > > a thread-safe version of popen() from BSD 4.10 . > > popen should be threadsafe as of rev 1.17 (2003-01-03) of > /usr/src/lib/libc/gen/popen.c . It was merged into the 4.* branch in > rev 1.14.2.1 (2004/12/15). The PR is bin/50770 . Do you have a > testcase that causes it to fail? > > -- > Dan Nelson > [EMAIL PROTECTED] > _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"