On 2020-08-16 15:58, Wes Hardaker wrote:
> Magnus Fromreide <ma...@lysator.liu.se> writes:
>
>> That is a more lenient option than just dropping it so I think 'happy with
>> dropping it' covers this variant. On the other hand I usually am far from
>> the most conservative one in discussions like this one.
>
> I think off by default makes a lot more sense than an out-right removal.
How about restoring uClinux support with the patch below? parse_cmd() and
dup() are called before fork(). That change makes it possible to use a
regular pipe between the parent and the child, even when using vfork(). The
patch below has been tested on Linux (but not on uClinux).
Thanks,
Bart.
diff --git a/agent/mibgroup/util_funcs.c b/agent/mibgroup/util_funcs.c
index f39ea1adcd89..d42277b18f7e 100644
--- a/agent/mibgroup/util_funcs.c
+++ b/agent/mibgroup/util_funcs.c
@@ -458,53 +458,60 @@ int
get_exec_pipes(const char *cmd, int *fdIn, int *fdOut, netsnmp_pid_t *pid)
{
#if defined(HAVE_EXECV)
- int fd[2][2];
+ int fd[2][2], stdin_fd, stdout_fd, stderr_fd;
char **argv, *args;
+ argv = parse_cmd(&args, cmd);
+ if (!argv) {
+ DEBUGMSGTL(("util_funcs", "get_exec_pipes(): argv == NULL\n"));
+ return 0;
+ }
/*
- * Setup our pipes
+ * Setup pipes
*/
if (pipe(fd[0]) || pipe(fd[1])) {
setPerrorstatus("pipe");
return 0;
}
- if ((*pid = fork()) == 0) { /* First handle for the child */
- close(fd[0][1]);
- close(fd[1][0]);
- close(0);
- if (dup(fd[0][0]) != 0) {
- setPerrorstatus("dup 0");
- return 0;
- }
- close(fd[0][0]);
- close(1);
- if (dup(fd[1][1]) != 1) {
- setPerrorstatus("dup 1");
- return 0;
- }
- close(fd[1][1]);
-
- /*
- * write standard output and standard error to pipe.
- */
+ /* Save stdin, stdout and stderr */
+ stdin_fd = dup(STDIN_FILENO);
+ stdout_fd = dup(STDOUT_FILENO);
+ stderr_fd = dup(STDERR_FILENO);
+ /* Redirect stdin, stdout and stderr to the child side of the pipe */
+ if (dup2(fd[0][0], STDIN_FILENO) != 0) {
+ setPerrorstatus("dup 0");
+ return 0;
+ }
+ if (dup2(fd[1][1], STDOUT_FILENO) != 1) {
+ setPerrorstatus("dup 1");
+ return 0;
+ }
+ NETSNMP_IGNORE_RESULT(dup2(STDOUT_FILENO, STDERR_FILENO));
+#ifdef __uClinux__
+ if ((*pid = vfork()) == 0) {
+#else
+ if ((*pid = fork()) == 0) {
/*
* close all non-standard open file descriptors
*/
- netsnmp_close_fds(1);
- NETSNMP_IGNORE_RESULT(dup(1)); /* stderr */
+ netsnmp_close_fds(STDOUT_FILENO);
+#endif
- argv = parse_cmd(&args, cmd);
- if (!argv) {
- DEBUGMSGTL(("util_funcs", "get_exec_pipes(): argv == NULL\n"));
- return 0;
- }
- DEBUGMSGTL(("util_funcs", "get_exec_pipes(): argv[0] = %s\n",
argv[0]));
+ /* Child process */
execv(argv[0], argv);
perror(argv[0]);
free(argv);
free(args);
- exit(1);
+ return 1;
} else {
+ /* Parent process. */
+ /* Restore stdin, stdout and stderr */
+ dup2(stdin_fd, STDIN_FILENO);
+ close(stdin_fd);
+ dup2(stdout_fd, STDOUT_FILENO);
+ close(stdout_fd);
+ dup2(stderr_fd, STDERR_FILENO);
+ close(stderr_fd);
close(fd[0][0]);
close(fd[1][1]);
if (*pid < 0) {
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