diff options
| -rw-r--r-- | libc/stdio/popen.c | 70 |
1 files changed, 45 insertions, 25 deletions
diff --git a/libc/stdio/popen.c b/libc/stdio/popen.c index 7a00e570f..bc91bb73b 100644 --- a/libc/stdio/popen.c +++ b/libc/stdio/popen.c @@ -1,46 +1,66 @@ +/* + * 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> - -FILE *popen (const char *command, const char *modes) +FILE *popen (const char *command, const char *mode) { + FILE *fp; int pipe_fd[2]; int pid, reading; + int pr, pnr; - if (pipe(pipe_fd) < 0) - return NULL; - reading = (modes[0] == 'r'); - - pid = vfork(); - if (pid < 0) { - close(pipe_fd[0]); - close(pipe_fd[1]); - return NULL; - } - if (pid == 0) { - close(pipe_fd[!reading]); - close(reading); - if (pipe_fd[reading] != reading) { - dup2(pipe_fd[reading], reading); - close(pipe_fd[reading]); + reading = (mode[0] == 'r'); + if ((!reading && (mode[0] != 'w')) || mode[1]) { + 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); + close(reading); + if (pr != 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); } - - execl("/bin/sh", "sh", "-c", command, (char *) 0); - _exit(255); } - - close(pipe_fd[reading]); - return fdopen(pipe_fd[!reading], modes); + return NULL; } int pclose(FILE *fd) { int waitstat; - if (fclose(fd) != 0) + if (fclose(fd) != 0) { return EOF; + } wait(&waitstat); return waitstat; } + + + |