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udevd: cleanup std{in,our,err} on startup

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It occurs, when root-partition has no /dev/console, meaning that kernel
could not open it, and such udevd is started without open filedescriptors
0 1 2. In that case udevd openes its sockets (netlink and control). They
get fds between 0 and 2. Later duping /dev/null to 0 1 2 closes the sockets
and replaces them with /dev/null.

The error condition can also be reproduced by starting udevd with this
command-line:
  udevd --daemon <&- >&- 2>&-
This commit is contained in:
Matthias Schwarzott 2007-03-13 22:27:21 +01:00 committed by Kay Sievers
parent d7eeab1194
commit 5edec024b1
1 changed files with 19 additions and 11 deletions
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30
udevd.c
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@ -989,6 +989,19 @@ int main(int argc, char *argv[], char *envp[])
goto exit; goto exit;
} }
/* make sure std{in,out,err} fd's are in a sane state */
fd = open("/dev/null", O_RDWR);
if (fd < 0) {
fprintf(stderr, "cannot open /dev/null\n");
err("cannot open /dev/null");
}
if (fd > STDIN_FILENO)
dup2(fd, STDIN_FILENO);
if (write(STDOUT_FILENO, 0, 0) < 0)
dup2(fd, STDOUT_FILENO);
if (write(STDERR_FILENO, 0, 0) < 0)
dup2(fd, STDERR_FILENO);
/* init sockets to receive events */ /* init sockets to receive events */
if (init_udevd_socket() < 0) { if (init_udevd_socket() < 0) {
if (errno == EADDRINUSE) { if (errno == EADDRINUSE) {
@ -1064,17 +1077,12 @@ int main(int argc, char *argv[], char *envp[])
} }
} }
/* redirect std fd's */ /* redirect std{out,err} fd's */
fd = open("/dev/null", O_RDWR); if (!verbose)
if (fd >= 0) { dup2(fd, STDOUT_FILENO);
dup2(fd, STDIN_FILENO); dup2(fd, STDERR_FILENO);
if (!verbose) if (fd > STDERR_FILENO)
dup2(fd, STDOUT_FILENO); close(fd);
dup2(fd, STDERR_FILENO);
if (fd > STDERR_FILENO)
close(fd);
} else
err("error opening /dev/null: %s", strerror(errno));
/* set scheduling priority for the daemon */ /* set scheduling priority for the daemon */
setpriority(PRIO_PROCESS, 0, UDEVD_PRIORITY); setpriority(PRIO_PROCESS, 0, UDEVD_PRIORITY);