+/*
+ * 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;
}
+
+
+