From f6b2e0b167ed19aedef11c686441c8cfa284c1e1 Mon Sep 17 00:00:00 2001
From: Gerhard Rieger <gerhard@dest-unreach.org>
Date: Sun, 22 Jul 2012 17:43:24 +0200
Subject: [PATCH] fixed sporadic data loss on pid reuse

---
 CHANGES         |  5 +++++
 xioinitialize.c |  6 +++++-
 xiosigchld.c    | 31 +++++++++++--------------------
 xiosigchld.h    | 14 ++++++++------
 4 files changed, 29 insertions(+), 27 deletions(-)

diff --git a/CHANGES b/CHANGES
index 40a149d..7b9125b 100644
--- a/CHANGES
+++ b/CHANGES
@@ -70,6 +70,11 @@ corrections:
 	development had been aware that localtime() is not thread safe but had
 	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
 
 	docu mentions option so-bindtodev but correct name is so-bindtodevice. 
 	Thanks to Jim Zimmerman for reporting.
diff --git a/xioinitialize.c b/xioinitialize.c
index 0ab09c3..35d258f 100644
--- a/xioinitialize.c
+++ b/xioinitialize.c
@@ -1,5 +1,5 @@
 /* source: xioinitialize.c */
-/* Copyright Gerhard Rieger 2001-2008 */
+/* Copyright Gerhard Rieger 2001-2012 */
 /* Published under the GNU General Public License V.2, see file COPYING */
 
 /* this file contains the source for the initialize function */
@@ -206,7 +206,11 @@ 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 3414d55..d9bc47e 100644
--- a/xiosigchld.c
+++ b/xiosigchld.c
@@ -1,5 +1,5 @@
 /* source: xiosigchld.c */
-/* Copyright Gerhard Rieger 2001-2008 */
+/* Copyright Gerhard Rieger 2001-2012 */
 /* Published under the GNU General Public License V.2, see file COPYING */
 
 /* this is the source of the extended child signal handler */
@@ -27,11 +27,9 @@ static struct _xiosigchld_child * _xiosigchld_find(pid_t pid);
 static struct _xiosigchld_child xio_childpids[XIO_MAXCHILDPIDS];
 
 #if 1 /*!!!*/
-/*!! with socat, at most 4 managed children exist */
-pid_t diedunknown1;	/* child died before it is registered */
-pid_t diedunknown2;
-pid_t diedunknown3;
-pid_t diedunknown4;
+/*!! with socat 1, at most 4 managed children existed */
+pid_t diedunknown[NUMUNKNOWN]; /* children that died before they were registered */
+size_t nextunknown;
 #endif
 
 
@@ -135,21 +133,14 @@ void childdied(int signum
       ++i;
    }
    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");
-	 }
+      Info2("childdied(%d): cannot identify child %d", signum, pid);
+      if (nextunknown == NUMUNKNOWN) {
+	 nextunknown = 0;
       }
+      diedunknown[nextunknown++] = pid;
+      Debug1("saving pid in diedunknown%u",
+	     nextunknown/*sic, for compatibility*/);
+   }
 #else
    entry = _xiosigchld_find(pid);
    if (entry == NULL) {
diff --git a/xiosigchld.h b/xiosigchld.h
index 8b28f76..e0e38ee 100644
--- a/xiosigchld.h
+++ b/xiosigchld.h
@@ -1,14 +1,16 @@
-/* $Id$ */
-/* Copyright Gerhard Rieger 2006 */
+/* source: xiosigchld.h */
+/* Copyright Gerhard Rieger 2012 */
 /* Published under the GNU General Public License V.2, see file COPYING */
 
 #ifndef __xiosigchld_h
 #define __xiosigchld_h 1
 
-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 void childdied(int signum