Fix for ticket #110.

wonder · wonder · commit c74003e8fe25 · 2007-10-24T18:10:18.000Z
To protect the process from being terminated by GRASS (>= 6.3), we use setjmp/longjmp functions. git-svn-id: http://svn.osgeo.org/qgis/trunk/qgis@7299 c8812cc2-4d05-0410-92ff-de0c093fc19c
diff --git a/src/plugins/grass/qgsgrassselect.cpp b/src/plugins/grass/qgsgrassselect.cpp
@@ -394,8 +394,19 @@ QStringList QgsGrassSelect::vectorLayers ( QString gisdbase,
     QgsGrass::resetError();
     Vect_set_open_level (2);
     struct Map_info map;
-    int level = Vect_open_old_head (&map, (char *) mapName.ascii(), 
-	                            (char *) mapset.ascii());
+    int level;
+    
+    // Mechanism to recover from fatal errors in GRASS
+    // Since fatal error routine in GRASS >= 6.3 terminates the process,
+    // we use setjmp() to set recovery place in case of a fatal error.
+    // Call to setjmp() returns 0 first time. In case of fatal error,
+    // our error routine uses longjmp() to come back to this context,
+    // this time setjmp() will return non-zero value and we can continue...
+    if (setjmp(QgsGrass::fatalErrorEnv()) == 0)
+    {
+      level = Vect_open_old_head (&map, (char *) mapName.ascii(), 
+                                (char *) mapset.ascii());
+    }
 
     if ( QgsGrass::getError() == QgsGrass::FATAL ) {
 	std::cerr << "Cannot open GRASS vector: " << QgsGrass::getErrorMessage().toLocal8Bit().data() << std::endl;
diff --git a/src/providers/grass/qgsgrass.cpp b/src/providers/grass/qgsgrass.cpp
@@ -347,18 +347,26 @@ QString QgsGrass::mMapsetLock;
 QString QgsGrass::mGisrc;
 QString QgsGrass::mTmp;
 
+jmp_buf QgsGrass::mFatalErrorEnv;
+
 int QgsGrass::error_routine ( char *msg, int fatal) {
   return error_routine((const char*) msg, fatal);
 }
 
 int QgsGrass::error_routine ( const char *msg, int fatal) {
     std::cerr << "error_routine (fatal = " << fatal << "): " << msg << std::endl;
 
-    if ( fatal ) error = FATAL;
-    else error = WARNING;
-
     error_message = msg;
 
+    if ( fatal )
+    { 
+      error = FATAL;
+      // we have to do a long jump here, otherwise GRASS >= 6.3 will kill our process
+      longjmp(mFatalErrorEnv, 1);
+    }
+    else
+      error = WARNING;
+
     return 1;
 }
 
@@ -374,6 +382,12 @@ QString QgsGrass::getErrorMessage ( void ) {
     return error_message;
 }
 
+jmp_buf& QgsGrass::fatalErrorEnv()
+{
+    return mFatalErrorEnv;
+}
+
+
 QString QgsGrass::openMapset ( QString gisdbase, QString location, QString mapset )
 {
 #ifdef QGISDEBUG
diff --git a/src/providers/grass/qgsgrass.h b/src/providers/grass/qgsgrass.h
@@ -22,6 +22,8 @@ extern "C" {
 #include <grass/form.h>
 }
 
+#include <setjmp.h>
+
 /*!
    Methods for C library initialization and error handling.
 */
@@ -151,7 +153,10 @@ class QgsGrass {
     static int versionMinor();
     static int versionRelease();
     static QString versionString();
+    
+    static jmp_buf& fatalErrorEnv();
 
+  
 private:
     static int initialized; // Set to 1 after initialization 
     static bool active; // is active mode
@@ -175,7 +180,10 @@ class QgsGrass {
     // Current mapset GISRC file path
     static QString mGisrc;  
     // Temporary directory where GISRC and sockets are stored
-    static QString mTmp;  
+    static QString mTmp;
+      
+    // Context saved before a call to routine that can produce a fatal error
+    static jmp_buf mFatalErrorEnv;
 };
 
 #endif // QGSGRASS_H
