/* * Modified 3/03/2001 Manuel Novoa III * * Added check for legal mode arg. * Call fdopen and check return value before forking. * Reduced code size by using variables pr and pnr instead of array refs. */ #include <stdio.h> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <errno.h> /* uClinux-2.0 has vfork, but Linux 2.0 doesn't */ #include <sys/syscall.h> #if ! defined __NR_vfork #define vfork fork #endif FILE *popen (const char *command, const char *mode) { FILE *fp; int pipe_fd[2]; int pid, reading; int pr, pnr; reading = (mode[0] == 'r'); if ((!reading && (mode[0] != 'w')) || mode[1]) { __set_errno(EINVAL); /* Invalid mode arg. */ } else if (pipe(pipe_fd) == 0) { pr = pipe_fd[reading]; pnr = pipe_fd[1-reading]; if ((fp = fdopen(pnr, mode)) != NULL) { if ((pid = vfork()) == 0) { /* vfork -- child */ close(pnr); if (pr != reading) { close(reading); dup2(pr, reading); close(pr); } execl("/bin/sh", "sh", "-c", command, (char *) 0); _exit(255); /* execl failed! */ } else { /* vfork -- parent or failed */ close(pr); if (pid > 0) { /* vfork -- parent */ return fp; } else { /* vfork -- failed! */ fclose(fp); } } } else { /* fdopen failed */ close(pr); close(pnr); } } return NULL; } int pclose(FILE *fd) { int waitstat; if (fclose(fd) != 0) { return EOF; } if (wait(&waitstat) == -1) return -1; return waitstat; }