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If FD_CLOEXEC works, create a pipe and use it to report any errors that occur 

while trying to execute the program.
This commit is contained in:
Ned T. Crigler 2008-01-26 03:03:25 +00:00
parent 0b9fe28288
commit 81dfe2ae09
1 changed files with 70 additions and 15 deletions
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85
master.c
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@ -106,7 +106,7 @@ setnonblocking(int fd)
/* Initialize the pty structure. */
static int
init_pty(char **argv)
init_pty(char **argv, int statusfd)
{
/* Use the original terminal's settings. We don't have to set the
** window size here, because the attacher will send it in a packet. */
@ -124,9 +124,18 @@ init_pty(char **argv)
{
/* Child.. Execute the program. */
execvp(*argv, argv);
printf(EOS "\r\n%s: could not execute %s: %s\r\n",
progname, *argv, strerror(errno));
exit(127);
/* Report the error to statusfd if we can, or stdout if we
** can't. */
if (statusfd != -1)
dup2(statusfd, 1);
else
printf(EOS "\r\n");
printf("%s: could not execute %s: %s\r\n", progname,
*argv, strerror(errno));
fflush(stdout);
_exit(127);
}
/* Parent.. Finish up and return */
#ifdef BROKEN_MASTER
@ -396,7 +405,7 @@ client_activity(struct client *p)
/* The master process - It watches over the pty process and the attached */
/* clients. */
static void
master_process(int s, char **argv, int waitattach)
master_process(int s, char **argv, int waitattach, int statusfd)
{
struct client *p, *next;
fd_set readfds;
@ -407,12 +416,8 @@ master_process(int s, char **argv, int waitattach)
** don't care what happens to it. */
setsid();
/* Create a pty in which the process is running. */
if (init_pty(argv) < 0)
{
printf("%s: init_pty: %s\n", progname, strerror(errno));
exit(1);
}
/* Set a trap to unlink the socket when we die. */
atexit(unlink_socket);
/* Set up some signals. */
signal(SIGPIPE, SIG_IGN);
@ -424,6 +429,19 @@ master_process(int s, char **argv, int waitattach)
signal(SIGTERM, die);
signal(SIGCHLD, die);
/* Create a pty in which the process is running. */
if (init_pty(argv, statusfd) < 0)
{
if (statusfd != -1)
dup2(statusfd, 1);
printf("%s: init_pty: %s\n", progname, strerror(errno));
exit(1);
}
/* Close statusfd, since we don't need it anymore. */
if (statusfd != -1)
close(statusfd);
/* Make sure stdin/stdout/stderr point to /dev/null. We are now a
** daemon. */
nullfd = open("/dev/null", O_RDWR);
@ -433,9 +451,6 @@ master_process(int s, char **argv, int waitattach)
if (nullfd > 2)
close(nullfd);
/* Set a trap to unlink the socket when we die. */
atexit(unlink_socket);
/* Loop forever. */
while (1)
{
@ -494,6 +509,7 @@ master_process(int s, char **argv, int waitattach)
int
master_main(char **argv, int waitattach)
{
int fd[2] = {-1, -1};
int s;
pid_t pid;
@ -509,20 +525,59 @@ master_main(char **argv, int waitattach)
return 1;
}
#if defined(F_SETFD) && defined(FD_CLOEXEC)
fcntl(s, F_SETFD, FD_CLOEXEC);
/* If FD_CLOEXEC works, create a pipe and use it to report any errors
** that occur while trying to execute the program. */
if (pipe(fd) >= 0)
{
if (fcntl(fd[0], F_SETFD, FD_CLOEXEC) < 0 ||
fcntl(fd[1], F_SETFD, FD_CLOEXEC) < 0)
{
close(fd[0]);
close(fd[1]);
fd[0] = fd[1] = -1;
}
}
#endif
/* Fork off so we can daemonize and such */
pid = fork();
if (pid < 0)
{
printf("%s: fork: %s\n", progname, strerror(errno));
unlink_socket();
return 1;
}
else if (pid == 0)
{
/* Child - this becomes the master */
master_process(s, argv, waitattach);
if (fd[0] != -1)
close(fd[0]);
master_process(s, argv, waitattach, fd[1]);
return 0;
}
/* Parent - just return. */
#if defined(F_SETFD) && defined(FD_CLOEXEC)
/* Check if an error occurred while trying to execute the program. */
if (fd[0] != -1)
{
char buf[1024];
int len;
close(fd[1]);
len = read(fd[0], buf, sizeof(buf));
if (len > 0)
{
write(2, buf, len);
kill(pid, SIGTERM);
return 1;
}
close(fd[0]);
}
#endif
close(s);
return 0;
}