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Make interrupt handler async-safe

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Calling printf() in a signal handler can be dangerous, so avoid it by
writing directly which is guaranteed to be safe according to signal(7).

Signed-off-by: Dan McGee <dan@archlinux.org>
This commit is contained in:
Dan McGee 2008-10-12 21:07:49 -05:00
parent f0e1846b51
commit 30851a24ff
1 changed files with 22 additions and 8 deletions
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30
src/pacman/pacman.c
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@ -36,6 +36,7 @@
#include <sys/utsname.h> /* uname */
#include <locale.h> /* setlocale */
#include <time.h> /* time_t */
#include <errno.h>
#if defined(PACMAN_DEBUG) && defined(HAVE_MCHECK_H)
#include <mcheck.h> /* debug tracing (mtrace) */
#endif
@ -211,21 +212,34 @@ static void cleanup(int ret) {
exit(ret);
}
/** Write function that correctly handles EINTR.
*/
static ssize_t xwrite(int fd, const void *buf, size_t count)
{
ssize_t ret;
while((ret = write(fd, buf, count)) == -1 && errno == EINTR);
return(ret);
}
/** Catches thrown signals. Performs necessary cleanup to ensure database is
* in a consistant state.
* @param signum the thrown signal
*/
static RETSIGTYPE handler(int signum)
{
if(signum==SIGSEGV)
{
/* write a log message and write to stderr */
pm_printf(PM_LOG_ERROR, _("segmentation fault\n"));
pm_fprintf(stderr, PM_LOG_ERROR,
_("Internal pacman error: Segmentation fault.\n"
"Please submit a full bug report with --debug if appropriate.\n"));
int out = fileno(stdout);
int err = fileno(stderr);
if(signum == SIGSEGV) {
const char *msg1 = "error: segmentation fault\n";
const char *msg2 = "Internal pacman error: Segmentation fault.\n"
"Please submit a full bug report with --debug if appropriate.\n";
/* write a error message to out, the rest to err */
xwrite(out, msg1, strlen(msg1));
xwrite(err, msg2, strlen(msg2));
exit(signum);
} else if((signum == SIGINT)) {
const char *msg = "\nInterrupt signal received\n";
xwrite(err, msg, strlen(msg));
if(alpm_trans_interrupt() == 0) {
/* a transaction is being interrupted, don't exit pacman yet. */
return;
@ -233,7 +247,7 @@ static RETSIGTYPE handler(int signum)
/* no commiting transaction, we can release it now and then exit pacman */
alpm_trans_release();
/* output a newline to be sure we clear any line we may be on */
printf("\n");
xwrite(out, "\n", 1);
}
cleanup(signum);
}