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openrc-shutdown: simplify broadcast function

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Get rid of the alarm/setjmp/longjmp.
Trust that the kernel will not block with O_NDELAY.
Use write() instead of stdio.

Bug: https://bugs.gentoo.org/923326
Signed-off-by: Mike Gilbert <floppym@gentoo.org>
This commit is contained in:
Mike Gilbert 2024-05-23 15:28:39 -04:00 committed by William Hubbs
parent 096cf6bbc2
commit 53071ceb13
1 changed files with 10 additions and 45 deletions
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55
src/openrc-shutdown/broadcast.c
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@ -17,8 +17,6 @@
#include <fcntl.h>
#include <paths.h>
#include <pwd.h>
#include <signal.h>
#include <setjmp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
@ -37,15 +35,6 @@
# define _PATH_DEV "/dev/"
#endif
static sigjmp_buf jbuf;
/*
* Alarm handler
*/
RC_NORETURN static void handler(int arg RC_UNUSED)
{
siglongjmp(jbuf, 1);
}
static void getuidtty(char **userp, char **ttyp)
{
@ -120,19 +109,13 @@ void broadcast(char *text)
char *user;
struct utsname name;
time_t t;
char *date;
char *date;
char *p;
char *line = NULL;
struct sigaction sa;
int flags;
int len;
int fd;
char *term = NULL;
struct utmpx *utmp;
/*
* These are set across the sigsetjmp call, so they can't be stored on
* the stack, otherwise they might be clobbered.
*/
static int fd;
static FILE *tp;
getuidtty(&user, &tty);
@ -149,8 +132,8 @@ void broadcast(char *text)
if (p)
*p = 0;
xasprintf(&line, "\007\r\nBroadcast message from %s@%s %s(%s):\r\n\r\n",
user, name.nodename, tty, date);
len = xasprintf(&line, "\007\r\nBroadcast message from %s@%s %s(%s):\r\n\r\n%s",
user, name.nodename, tty, date, text);
free(tty);
/*
@ -159,11 +142,6 @@ void broadcast(char *text)
if (fork() != 0)
return;
memset(&sa, 0, sizeof(sa));
sa.sa_handler = handler;
sigemptyset(&sa.sa_mask);
sigaction(SIGALRM, &sa, NULL);
setutxent();
while ((utmp = getutxent()) != NULL) {
@ -178,25 +156,12 @@ void broadcast(char *text)
continue;
}
/*
* Open it non-delay
*/
if (sigsetjmp(jbuf, 1) == 0) {
alarm(2);
flags = O_WRONLY|O_NDELAY|O_NOCTTY;
if (file_isatty(term) && (fd = open(term, flags)) >= 0) {
if (isatty(fd) && (tp = fdopen(fd, "w")) != NULL) {
fputs(line, tp);
fputs(text, tp);
fflush(tp);
}
}
}
alarm(0);
if (fd >= 0)
/* Open it non-delay */
if (file_isatty(term) && (fd = open(term, O_WRONLY|O_NDELAY|O_NOCTTY)) >= 0) {
if (isatty(fd))
write(fd, line, len);
close(fd);
if (tp != NULL)
fclose(tp);
}
free(term);
}
endutxent();