Changeset: 82bf5eb519ea for MonetDB
URL: http://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=82bf5eb519ea
Modified Files:
tools/merovingian/daemon/controlrunner.c
tools/merovingian/daemon/handlers.c
Branch: Oct2014
Log Message:
Block SIGCHLD signals when forking for create -p.
By blocking SIGCHLD signals when forking and subsequently waiting for
the forked child when handling the create -p command, and by also
ignoring SIGCHLD signals if there is no child ready to be waited for,
we hopefully fix bug 3603.
diffs (64 lines):
diff --git a/tools/merovingian/daemon/controlrunner.c
b/tools/merovingian/daemon/controlrunner.c
--- a/tools/merovingian/daemon/controlrunner.c
+++ b/tools/merovingian/daemon/controlrunner.c
@@ -399,6 +399,13 @@ static void ctl_handle_client(
} else {
if (*p != '\0') {
pid_t child;
+ sigset_t blocksig;
+ /* temporarily block SIGCHLD
signals until
+ * we've waited for the child
we're about to
+ * create. See bug
http://bugs.monetdb.org/3603. */
+ sigemptyset(&blocksig);
+ sigaddset(&blocksig, SIGCHLD);
+ sigprocmask(SIG_BLOCK,
&blocksig, (sigset_t *) 0);
if ((child = fork()) == 0) {
FILE *secretf;
size_t len;
@@ -408,6 +415,10 @@ static void ctl_handle_client(
int setlen = 0;
char *sadbfarm;
+ sigemptyset(&blocksig);
+ sigaddset(&blocksig,
SIGCHLD);
+
sigprocmask(SIG_UNBLOCK, &blocksig, (sigset_t *) 0);
+
if ((err =
msab_getDBfarm(&sadbfarm)) != NULL) {
Mfprintf(_mero_ctlerr, "%s: internal error: %s\n",
origin, err);
@@ -456,9 +467,18 @@ static void ctl_handle_client(
}
exit(0); /* return to
the parent */
- } else {
+ } else if (child > 0) {
/* wait for the child
to finish */
waitpid(child, NULL, 0);
+ sigemptyset(&blocksig);
+ sigaddset(&blocksig,
SIGCHLD);
+
sigprocmask(SIG_UNBLOCK, &blocksig, (sigset_t *) 0);
+ } else {
+ sigemptyset(&blocksig);
+ sigaddset(&blocksig,
SIGCHLD);
+
sigprocmask(SIG_UNBLOCK, &blocksig, (sigset_t *) 0);
+ Mfprintf(_mero_ctlout,
"%s: forking failed\n",
+
origin);
}
}
diff --git a/tools/merovingian/daemon/handlers.c
b/tools/merovingian/daemon/handlers.c
--- a/tools/merovingian/daemon/handlers.c
+++ b/tools/merovingian/daemon/handlers.c
@@ -169,7 +169,11 @@ childhandler(int sig, siginfo_t *si, voi
/* wait for the child to get properly terminated, hopefully filling
* in the siginfo struct on FreeBSD */
- wait(NULL);
+ if (waitpid(-1, NULL, WNOHANG) <= 0) {
+ /* if no child has exited, we may have already waited for it
+ * in e.g. ctl_handle_client() */
+ return;
+ }
if (si->si_code != CLD_EXITED &&
si->si_code != CLD_KILLED &&
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