Fix various memory leaks

Bugfixes thanks to Alex Haley <ahaley42@users.sf.net>

backend/bmp.c

@@ -236,5 +236,6 @@ int bmp_pixel_plot(struct zint_symbol *symbol, int image_height, int image_width
     fwrite(bitmap_file_start, file_header.file_size, 1, bmp_file);
     fclose(bmp_file);
     
+    free(bitmap_file_start);
     return 0;
 }

backend/gif.c

@@ -497,6 +497,7 @@ int gif_pixel_plot(struct zint_symbol *symbol, int image_height, int image_width
         image_height * image_width);
     if (byte_out <= 0)
     {
+        fclose(gif_file);
         return ZINT_ERROR_MEMORY;
     }
     fwrite(lzwoutbuf, byte_out, 1, gif_file);

backend/library.c

@@ -105,6 +105,8 @@ void ZBarcode_Delete(struct zint_symbol *symbol) {
     if (symbol->rendered != NULL) {
         struct zint_render_line *line, *l;
         struct zint_render_string *string, *s;
+        struct zint_render_ring *ring, *r;
+        struct zint_render_hexagon *hexagon, *h;
 
         // Free lines
         line = symbol->rendered->lines;
@@ -122,6 +124,22 @@ void ZBarcode_Delete(struct zint_symbol *symbol) {
             free(s);
         }
         
+        // Free Rings
+        ring = symbol->rendered->rings;
+        while (ring) {
+            r = ring;
+            ring = ring->next;
+            free(r);
+        }
+        
+        // Free Hexagons
+        hexagon = symbol->rendered->hexagons;
+        while (hexagon) {
+            h = hexagon;
+            hexagon = hexagon->next;
+            free(h);
+        }
+
         // Free Render
         free(symbol->rendered);
     }

backend/ps.c

@@ -115,20 +115,24 @@ int ps_plot(struct zint_symbol *symbol) {
 
     if (strlen(symbol->fgcolour) != 6) {
         strcpy(symbol->errtxt, "Malformed foreground colour target");
+        fclose(feps);
         return ZINT_ERROR_INVALID_OPTION;
     }
     if (strlen(symbol->bgcolour) != 6) {
         strcpy(symbol->errtxt, "Malformed background colour target");
+        fclose(feps);
         return ZINT_ERROR_INVALID_OPTION;
     }
     error_number = is_sane(SSET, (unsigned char*) symbol->fgcolour, strlen(symbol->fgcolour));
     if (error_number == ZINT_ERROR_INVALID_DATA) {
         strcpy(symbol->errtxt, "Malformed foreground colour target");
+        fclose(feps);
         return ZINT_ERROR_INVALID_OPTION;
     }
     error_number = is_sane(SSET, (unsigned char*) symbol->bgcolour, strlen(symbol->bgcolour));
     if (error_number == ZINT_ERROR_INVALID_DATA) {
         strcpy(symbol->errtxt, "Malformed background colour target");
+        fclose(feps);
         return ZINT_ERROR_INVALID_OPTION;
     }
     locale = setlocale(LC_ALL, "C");

backend/raster.c

@@ -341,6 +341,7 @@ int plot_raster_maxicode(struct zint_symbol *symbol, int rotate_angle, int data_
     /* Apply scale options by creating another pixel buffer */
     if (!(scaled_pixelbuf = (char *) malloc(scale_width * scale_height))) {
         printf("Insufficient memory for pixel buffer");
+        free(pixelbuf);
         return ZINT_ERROR_ENCODING_PROBLEM;
     } else {
         for (i = 0; i < (scale_width * scale_height); i++) {
@@ -902,6 +903,7 @@ int plot_raster_default(struct zint_symbol *symbol, int rotate_angle, int data_t
 
     /* Apply scale options by creating another pixel buffer */
     if (!(scaled_pixelbuf = (char *) malloc(scale_width * scale_height))) {
+        free(pixelbuf);
         printf("Insufficient memory for pixel buffer");
         return ZINT_ERROR_ENCODING_PROBLEM;
     } else {

backend/svg.c

@@ -111,20 +111,24 @@ int svg_plot(struct zint_symbol *symbol) {
 
     if (strlen(symbol->fgcolour) != 6) {
         strcpy(symbol->errtxt, "Malformed foreground colour target");
+        fclose(fsvg);
         return ZINT_ERROR_INVALID_OPTION;
     }
     if (strlen(symbol->bgcolour) != 6) {
         strcpy(symbol->errtxt, "Malformed background colour target");
+        fclose(fsvg);
         return ZINT_ERROR_INVALID_OPTION;
     }
     error_number = is_sane(SSET, (unsigned char*) symbol->fgcolour, strlen(symbol->fgcolour));
     if (error_number == ZINT_ERROR_INVALID_DATA) {
         strcpy(symbol->errtxt, "Malformed foreground colour target");
+        fclose(fsvg);
         return ZINT_ERROR_INVALID_OPTION;
     }
     error_number = is_sane(SSET, (unsigned char*) symbol->bgcolour, strlen(symbol->bgcolour));
     if (error_number == ZINT_ERROR_INVALID_DATA) {
         strcpy(symbol->errtxt, "Malformed background colour target");
+        fclose(fsvg);
         return ZINT_ERROR_INVALID_OPTION;
     }
     locale = setlocale(LC_ALL, "C");