From 49c0505298c6bde45e136b49a9438c102eb93da1 Mon Sep 17 00:00:00 2001
From: Gerhard Rieger <gerhard@dest-unreach.org>
Date: Fri, 18 Nov 2011 18:07:39 +0100
Subject: [PATCH] fixed sporadic data loss on pid reuse

---
 CHANGES         |  5 +++++
 xio.h           | 12 +++++++-----
 xioinitialize.c |  6 +++++-
 xiosigchld.c    | 25 ++++++++-----------------
 4 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/CHANGES b/CHANGES
index c3cabd2..9ed9651 100644
--- a/CHANGES
+++ b/CHANGES
@@ -44,6 +44,11 @@ corrections:
 	only expected broken messages, not corrupted stack (glibc 2.11.1,
 	Ubuntu 10.4)
 
+	an internal store for child pids was susceptible to pid reuse which
+	could lead to sporadic data loss when both fork option and exec address
+	were used. Thanks to Tetsuya Sodo for reporting this problem and
+	sending a patch
+
 ####################### V 1.7.1.3:
 
 security:
diff --git a/xio.h b/xio.h
index 2110896..6bd6b66 100644
--- a/xio.h
+++ b/xio.h
@@ -1,5 +1,5 @@
 /* source: xio.h */
-/* Copyright Gerhard Rieger 2001-2009 */
+/* Copyright Gerhard Rieger 2001-2011 */
 /* Published under the GNU General Public License V.2, see file COPYING */
 
 #ifndef __xio_h_included
@@ -402,10 +402,12 @@ extern int xioopenhelp(FILE *of, int level);
 
 /* must be outside function for use by childdied handler */
 extern xiofile_t *sock1, *sock2;
-extern pid_t diedunknown1;	/* child died before it is registered */
-extern pid_t diedunknown2;
-extern pid_t diedunknown3;
-extern pid_t diedunknown4;
+#define NUMUNKNOWN 4
+extern pid_t diedunknown[NUMUNKNOWN];	/* child died before it is registered */
+#define diedunknown1 (diedunknown[0])
+#define diedunknown2 (diedunknown[1])
+#define diedunknown3 (diedunknown[2])
+#define diedunknown4 (diedunknown[3])
 
 extern int xiosetsigchild(xiofile_t *xfd, int (*callback)(struct single *));
 extern int xiosetchilddied(void);
diff --git a/xioinitialize.c b/xioinitialize.c
index 15d7d64..43bd875 100644
--- a/xioinitialize.c
+++ b/xioinitialize.c
@@ -1,5 +1,5 @@
 /* source: xioinitialize.c */
-/* Copyright Gerhard Rieger 2001-2008 */
+/* Copyright Gerhard Rieger 2001-2011 */
 /* Published under the GNU General Public License V.2, see file COPYING */
 
 /* this file contains the source for the initialize function */
@@ -172,7 +172,11 @@ static int xio_nokill(xiofile_t *sock) {
    returns 0 on success or != 0 if an error occurred */
 int xio_forked_inchild(void) {
    int result = 0;
+   int i;
 
+   for (i=0; i<NUMUNKNOWN; ++i) {
+      diedunknown[i] = 0;
+   }
    xiodroplocks();
 #if WITH_FIPS
    if (xio_reset_fips_mode() != 0) {
diff --git a/xiosigchld.c b/xiosigchld.c
index 510463c..7d6f486 100644
--- a/xiosigchld.c
+++ b/xiosigchld.c
@@ -1,5 +1,5 @@
 /* source: xiosigchld.c */
-/* Copyright Gerhard Rieger 2001-2008 */
+/* Copyright Gerhard Rieger 2001-2011 */
 /* Published under the GNU General Public License V.2, see file COPYING */
 
 /* this is the source of the extended child signal handler */
@@ -10,10 +10,8 @@
 
 
 /*!! with socat, at most 4 exec children exist */
-pid_t diedunknown1;	/* child died before it is registered */
-pid_t diedunknown2;
-pid_t diedunknown3;
-pid_t diedunknown4;
+pid_t diedunknown[NUMUNKNOWN];	/* children that died before they were registered */
+size_t nextunknown;
 
 
 /* register for a xio filedescriptor a callback (handler).
@@ -114,19 +112,12 @@ void childdied(int signum) {
    }
    if (i == XIO_MAXSOCK) {
 	 Info2("childdied(%d): cannot identify child %d", signum, pid);
-	 if (diedunknown1 == 0) {
-	    diedunknown1 = pid;
-	    Debug("saving pid in diedunknown1");
-	 } else if (diedunknown2 == 0) {
-	    diedunknown2 = pid;
-	    Debug("saving pid in diedunknown2");
-	 } else if (diedunknown3 == 0) {
-	     diedunknown3 = pid;
-	    Debug("saving pid in diedunknown3");
-	 } else {
-	    diedunknown4 = pid;
-	    Debug("saving pid in diedunknown4");
+	 if (nextunknown == NUMUNKNOWN) {
+	    nextunknown = 0;
 	 }
+	 diedunknown[nextunknown++] = pid;
+	 Debug1("saving pid in diedunknown%u",
+		nextunknown/*sic, for compatibility*/);
       }
 
    if (WIFEXITED(status)) {