X-Git-Url: http://nsz.repo.hu/git/?p=musl;a=blobdiff_plain;f=src%2Fstdio%2Fpopen.c;h=28ff23fd1614422bdbeb907529b08c7ec5c6b413;hp=1d33e9d692fae195b41af7ca8179e972c155c710;hb=1d92cddb1e1ed4b6cc0e55461727561e7a2522e0;hpb=0b44a0315b47dd8eced9f3b7f31580cf14bbfc01

diff --git a/src/stdio/popen.c b/src/stdio/popen.c
index 1d33e9d6..28ff23fd 100644
--- a/src/stdio/popen.c
+++ b/src/stdio/popen.c
@@ -1,43 +1,73 @@
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h>
+#include <spawn.h>
 #include "stdio_impl.h"
+#include "syscall.h"
+
+extern char **__environ;
 
 FILE *popen(const char *cmd, const char *mode)
 {
-	int p[2];
-	int op;
+	int p[2], op, e;
 	pid_t pid;
 	FILE *f;
-	const char *modes = "rw", *mi = strchr(modes, *mode);
+	posix_spawn_file_actions_t fa;
 
-	if (mi) {
-		op = mi-modes;
+	if (*mode == 'r') {
+		op = 0;
+	} else if (*mode == 'w') {
+		op = 1;
 	} else {
 		errno = EINVAL;
 		return 0;
 	}
 	
-	if (pipe(p)) return NULL;
+	if (pipe2(p, O_CLOEXEC)) return NULL;
 	f = fdopen(p[op], mode);
 	if (!f) {
-		close(p[0]);
-		close(p[1]);
+		__syscall(SYS_close, p[0]);
+		__syscall(SYS_close, p[1]);
 		return NULL;
 	}
-	
-	pid = fork();
-	switch (pid) {
-	case -1:
-		fclose(f);
-		close(p[0]);
-		close(p[1]);
-		return NULL;
-	case 0:
-		dup2(p[1-op], 1-op);
-		close(p[0]);
-		close(p[1]);
-		execl("/bin/sh", "sh", "-c", cmd, (char *)0);
-		_exit(127);
+	FLOCK(f);
+
+	/* If the child's end of the pipe happens to already be on the final
+	 * fd number to which it will be assigned (either 0 or 1), it must
+	 * be moved to a different fd. Otherwise, there is no safe way to
+	 * remove the close-on-exec flag in the child without also creating
+	 * a file descriptor leak race condition in the parent. */
+	if (p[1-op] == 1-op) {
+		int tmp = fcntl(F_DUPFD_CLOEXEC, 1-op, 0);
+		if (tmp < 0) {
+			e = errno;
+			goto fail;
+		}
+		__syscall(SYS_close, p[1-op]);
+		p[1-op] = tmp;
 	}
-	close(p[1-op]);
-	f->pipe_pid = pid;
-	return f;
+
+	e = ENOMEM;
+	if (!posix_spawn_file_actions_init(&fa)) {
+		if (!posix_spawn_file_actions_adddup2(&fa, p[1-op], 1-op)) {
+			if (!(e = posix_spawn(&pid, "/bin/sh", &fa, 0,
+			    (char *[]){ "sh", "-c", (char *)cmd, 0 }, __environ))) {
+				posix_spawn_file_actions_destroy(&fa);
+				f->pipe_pid = pid;
+				if (!strchr(mode, 'e'))
+					fcntl(p[op], F_SETFD, 0);
+				__syscall(SYS_close, p[1-op]);
+				FUNLOCK(f);
+				return f;
+			}
+		}
+		posix_spawn_file_actions_destroy(&fa);
+	}
+fail:
+	fclose(f);
+	__syscall(SYS_close, p[1-op]);
+
+	errno = e;
+	return 0;
 }