[Gnucash-changes] r14235 - gnucash/trunk - Add wait_for_gzip to avoid reading from a file that is still being

[Andreas Köhler]

Author: andi5
Date: 2006-05-29 03:08:28 -0400 (Mon, 29 May 2006)
New Revision: 14235
Trac: http://svn.gnucash.org/trac/changeset/14235

Modified:
   gnucash/trunk/ChangeLog
   gnucash/trunk/src/backend/file/io-gncxml-v2.c
Log:
Add wait_for_gzip to avoid reading from a file that is still being
written to by a child process, a race condition at the end of the xml
import druid.


Modified: gnucash/trunk/ChangeLog
===================================================================
--- gnucash/trunk/ChangeLog	2006-05-29 06:02:00 UTC (rev 14234)
+++ gnucash/trunk/ChangeLog	2006-05-29 07:08:28 UTC (rev 14235)
@@ -1,3 +1,9 @@
+2006-05-29  Andreas Köhler  <andi5.py at gmx.net>
+
+	* src/backend/file/io-gncxml-v2.c: Add wait_for_gzip to avoid
+	  reading from a file that is still being written to by a child
+	  process, a race condition at the end of the xml import druid.
+
 2006-05-28  David Hampton  <hampton at employees.org>
 
 	* src/pixmaps/gnucash_splash.png: New splash screen from Joshua

Modified: gnucash/trunk/src/backend/file/io-gncxml-v2.c
===================================================================
--- gnucash/trunk/src/backend/file/io-gncxml-v2.c	2006-05-29 06:02:00 UTC (rev 14234)
+++ gnucash/trunk/src/backend/file/io-gncxml-v2.c	2006-05-29 07:08:28 UTC (rev 14235)
@@ -28,6 +28,7 @@
 #include <unistd.h>
 #include <zlib.h>
 #include <errno.h>
+#include <sys/wait.h>
 
 #include "gnc-engine.h"
 #include "gnc-pricedb-p.h"
@@ -51,6 +52,8 @@
 
 static QofLogModule log_module = GNC_MOD_IO;
 
+static pid_t gzip_child_pid = 0;
+
 /* Callback structure */
 struct file_backend {
   gboolean        ok;
@@ -1282,6 +1285,10 @@
     int filedes[2];
     pid_t pid;
 
+    /* avoid reading from file that is still being written to
+       by a child process */
+    g_assert(gzip_child_pid == 0);
+
     if (pipe(filedes) < 0) {
       PWARN("Pipe call failed. Opening uncompressed file.");
       return fopen(filename, perms);
@@ -1320,6 +1327,10 @@
     }
 
     default: /* parent */
+      if (compress) {
+        /* the calling code must wait_for_gzip() */
+        gzip_child_pid = pid;
+      }
       sleep(2);
       if (compress) {
         close(filedes[0]);
@@ -1335,6 +1346,20 @@
 #endif
 }
 
+static gboolean
+wait_for_gzip()
+{
+    pid_t retval;
+
+    if (gzip_child_pid == 0)
+        return TRUE;
+
+    retval = waitpid(gzip_child_pid, NULL, WUNTRACED);
+    gzip_child_pid = 0;
+
+    return retval != -1;
+}
+
 gboolean
 gnc_book_write_to_xml_file_v2(
     QofBook *book,
@@ -1358,6 +1383,9 @@
         return FALSE;
     }
 
+    if (compress)
+        return wait_for_gzip();
+
     return TRUE;
 }