From 3480b42be1adc7c2876a77e8260049447338c3ff Mon Sep 17 00:00:00 2001
From: Jeremy Allison <jra@samba.org>
Date: Tue, 6 Nov 2007 21:48:01 -0800
Subject: [PATCH] Fix bug where tdb lock call interrupted with an alarm sig
 would not terminate and could lead to runaway smbd processes. Thanks to Dave
 Daugherty @ Centrify for pointing this out to us. Jeremy.

---
 source/lib/replace/replace.h     |  4 ++++
 source/lib/replace/system/wait.h |  4 ++++
 source/lib/util_tdb.c            |  2 ++
 source/tdb/common/lock.c         | 12 ++++++++++++
 source/tdb/common/tdb_private.h  |  2 ++
 source/tdb/include/tdb.h         |  2 ++
 6 files changed, 26 insertions(+)

diff --git a/source/lib/replace/replace.h b/source/lib/replace/replace.h
index b96356ac46..c298b36fcb 100644
--- a/source/lib/replace/replace.h
+++ b/source/lib/replace/replace.h
@@ -79,6 +79,10 @@
 #include <stddef.h>
 #endif
 
+#if !defined(HAVE_VOLATILE)
+#define volatile
+#endif
+
 /**
   this is a warning hack. The idea is to use this everywhere that we
   get the "discarding const" warning from gcc. That doesn't actually
diff --git a/source/lib/replace/system/wait.h b/source/lib/replace/system/wait.h
index 179ef0774e..074675d8a4 100644
--- a/source/lib/replace/system/wait.h
+++ b/source/lib/replace/system/wait.h
@@ -44,4 +44,8 @@
 #define SA_RESETHAND SA_ONESHOT
 #endif
 
+#if !defined(HAVE_SIG_ATOMIC_T_TYPE)
+typedef int sig_atomic_t;
+#endif
+
 #endif
diff --git a/source/lib/util_tdb.c b/source/lib/util_tdb.c
index a1b5bf5bb1..48e34e0b32 100644
--- a/source/lib/util_tdb.c
+++ b/source/lib/util_tdb.c
@@ -68,6 +68,7 @@ static int tdb_chainlock_with_timeout_internal( TDB_CONTEXT *tdb, TDB_DATA key,
 
 	if (timeout) {
 		CatchSignal(SIGALRM, SIGNAL_CAST gotalarm_sig);
+		tdb_setalarm_sigptr(tdb, &gotalarm);
 		alarm(timeout);
 	}
 
@@ -78,6 +79,7 @@ static int tdb_chainlock_with_timeout_internal( TDB_CONTEXT *tdb, TDB_DATA key,
 
 	if (timeout) {
 		alarm(0);
+		tdb_setalarm_sigptr(tdb, NULL);
 		CatchSignal(SIGALRM, SIGNAL_CAST SIG_IGN);
 		if (gotalarm) {
 			DEBUG(0,("tdb_chainlock_with_timeout_internal: alarm (%u) timed out for key %s in tdb %s\n",
diff --git a/source/tdb/common/lock.c b/source/tdb/common/lock.c
index 8a964371d3..3bc0a9cb9e 100644
--- a/source/tdb/common/lock.c
+++ b/source/tdb/common/lock.c
@@ -28,6 +28,11 @@
 
 #include "tdb_private.h"
 
+void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *ptr)
+{
+	tdb->interrupt_sig_ptr = ptr;
+}
+
 /* a byte range locking function - return 0 on success
    this functions locks/unlocks 1 byte at the specified offset.
 
@@ -59,6 +64,13 @@ int tdb_brlock(struct tdb_context *tdb, tdb_off_t offset,
 
 	do {
 		ret = fcntl(tdb->fd,lck_type,&fl);
+
+		/* Check for a sigalarm break. */
+		if (ret == -1 && errno == EINTR &&
+				tdb->interrupt_sig_ptr &&
+				*tdb->interrupt_sig_ptr) {
+			break;
+		}
 	} while (ret == -1 && errno == EINTR);
 
 	if (ret == -1) {
diff --git a/source/tdb/common/tdb_private.h b/source/tdb/common/tdb_private.h
index 10bc6dacdc..8442242326 100644
--- a/source/tdb/common/tdb_private.h
+++ b/source/tdb/common/tdb_private.h
@@ -29,6 +29,7 @@
 #include "system/time.h"
 #include "system/shmem.h"
 #include "system/select.h"
+#include "system/wait.h"
 #include "tdb.h"
 
 #ifndef u32
@@ -170,6 +171,7 @@ struct tdb_context {
 	struct tdb_transaction *transaction;
 	int page_size;
 	int max_dead_records;
+	volatile sig_atomic_t *interrupt_sig_ptr;
 };
 
 
diff --git a/source/tdb/include/tdb.h b/source/tdb/include/tdb.h
index 51bf709f44..3bd30b8f56 100644
--- a/source/tdb/include/tdb.h
+++ b/source/tdb/include/tdb.h
@@ -138,6 +138,8 @@ int tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key);
 int tdb_chainlock_read(struct tdb_context *tdb, TDB_DATA key);
 int tdb_chainunlock_read(struct tdb_context *tdb, TDB_DATA key);
 
+void tdb_setalarm_sigptr(struct tdb_context *tdb, volatile sig_atomic_t *sigptr);
+
 /* Debug functions. Not used in production. */
 void tdb_dump_all(struct tdb_context *tdb);
 int tdb_printfreelist(struct tdb_context *tdb);
-- 
2.34.1