Bug 214191 - crash printing pages with spacer images.

r=roland.mainz, sr=bzbarsky

gfx/src/ps/nsPostScriptObj.cpp

@@ -2573,6 +2573,16 @@ PRInt32 sRow, eRow, rStep;
   if(bytes_Per_Pix == 1)
     return ;
 
+  aImage->LockImagePixels(PR_FALSE);
+  theBits = aImage->GetBits();
+
+  /* image data might not be available (ex: spacer image) */
+  if (!theBits)
+  {
+    aImage->UnlockImagePixels(PR_FALSE);
+    return;
+  }
+
   rowData = aImage->GetLineStride();
   height = aImage->GetHeight();
   width = aImage->GetWidth();
@@ -2591,8 +2601,6 @@ PRInt32 sRow, eRow, rStep;
   fprintf(f, " { currentfile rowdata readhexstring pop }\n");
   fprintf(f, " image\n");
 
-  aImage->LockImagePixels(PR_FALSE);
-  theBits = aImage->GetBits();
   n = 0;
   if ( ( isTopToBottom = aImage->GetIsRowOrderTopToBottom()) == PR_TRUE ) {
 	sRow = height - 1;
@@ -2658,6 +2666,16 @@ PRInt32 sRow, eRow, rStep;
   if(bytes_Per_Pix == 1)
     return ;
 
+  aImage->LockImagePixels(PR_FALSE);
+  theBits = aImage->GetBits();
+
+  /* image data might not be available (ex: spacer image) */
+  if (!theBits)
+  {
+    aImage->UnlockImagePixels(PR_FALSE);
+    return;
+  }
+
   rowData = aImage->GetLineStride();
   height = aImage->GetHeight();
   width = aImage->GetWidth();
@@ -2676,8 +2694,6 @@ PRInt32 sRow, eRow, rStep;
   fprintf(f, " { currentfile rowdata readhexstring pop }\n");
   fprintf(f, " false 3 colorimage\n");
 
-  aImage->LockImagePixels(PR_FALSE);
-  theBits = aImage->GetBits();
   n = 0;
   if ( ( isTopToBottom = aImage->GetIsRowOrderTopToBottom()) == PR_TRUE ) {
 	sRow = height - 1;

gfx/src/xprint/nsXPrintContext.cpp

@@ -1061,6 +1061,13 @@ nsXPrintContext::DrawImageBitsScaled(xGC *xgc, nsIImage *aImage,
   PRInt32  aSrcHeight    = aImage->GetHeight();
   PRUint8 *composed_bits = nsnull;
 
+ /* image data might not be available (ex: spacer image) */
+  if (!image_bits)
+  {
+    aImage->UnlockImagePixels(PR_FALSE);
+    return NS_OK;
+  }
+ 
   // Use client-side alpha image composing - plain X11 can only do 1bit alpha 
   // stuff - this method adds 8bit alpha support, too...
   if( alphaBits != nsnull )
@@ -1139,6 +1146,13 @@ nsXPrintContext::DrawImage(xGC *xgc, nsIImage *aImage,
   PRUint8 *image_bits    = aImage->GetBits();
   PRUint8 *composed_bits = nsnull;
   PRInt32  row_bytes     = aImage->GetLineStride();
+
+  /* image data might not be available (ex: spacer image) */
+  if (!image_bits)
+  {
+    aImage->UnlockImagePixels(PR_FALSE);
+    return NS_OK;
+  }
   
   // Use client-side alpha image composing - plain X11 can only do 1bit alpha
   // stuff - this method adds 8bit alpha support, too...