compext/Png.c: late image_index allocation

nx-X11/programs/Xserver/hw/nxagent/compext/Png.c

@@ -253,17 +253,6 @@ char *PngCompressData(XImage *image, int *compressed_size)
   NXColorTable color_table[NB_COLOR_MAX];
   CARD8       *image_index;
 
-  image_index = (CARD8 *) malloc((image -> height) * (image -> width) * sizeof(CARD8));
-
-  /*
-   * TODO: Be sure the padded bytes are cleaned.
-   * It would be better to set to zero the bytes
-   * that are not aligned to the word boundary
-   * at the end of the procedure.
-   */
-
-  memset(image_index, 0, (image -> height) * (image -> width) * sizeof(CARD8));
-
   *compressed_size = 0;
 
   pngDataLen = 0;
@@ -283,7 +272,6 @@ char *PngCompressData(XImage *image, int *compressed_size)
                 bitsPerPixel);
     #endif
 
-    free(image_index);
     return NULL;
   }
 
@@ -316,7 +304,6 @@ char *PngCompressData(XImage *image, int *compressed_size)
     fprintf(stderr, "******PngCompressData: PANIC! Failed creating the png_create_write_struct.\n");
     #endif
 
-    free(image_index);
     return NULL;
   }
 
@@ -329,7 +316,6 @@ char *PngCompressData(XImage *image, int *compressed_size)
     #endif
 
     png_destroy_write_struct(&png_ptr, NULL);
-    free(image_index);
 
     return NULL;
   }
@@ -341,7 +327,6 @@ char *PngCompressData(XImage *image, int *compressed_size)
     #endif
 
     png_destroy_write_struct(&png_ptr, &info_ptr);
-    free(image_index);
 
     return NULL;
   }
@@ -364,8 +349,6 @@ char *PngCompressData(XImage *image, int *compressed_size)
                 PNG_DEST_SIZE(w, h));
     #endif
 
-    free(image_index);
-
     return NULL;
   }
 
@@ -383,6 +366,24 @@ char *PngCompressData(XImage *image, int *compressed_size)
     return NULL;
   }
 
+  image_index = (CARD8 *) calloc(1, (image -> height) * (image -> width) * sizeof(CARD8));
+  if (image_index == NULL)
+  {
+    #ifdef PANIC
+    fprintf(stderr, "******PngCompressData: PANIC! Could not alloc image_index.\n");
+    #endif
+
+    free(pngCompBuf);
+    return NULL;
+  }
+
+  /*
+   * TODO: Be sure the padded bytes are cleaned.
+   * It would be better to set to zero the bytes
+   * that are not aligned to the word boundary
+   * at the end of the procedure.
+   */
+
   png_set_compression_level(png_ptr, PNG_Z_LEVEL);
 
   if (bitsPerPixel == 16)