Segmentation fault for little or no data

backend/blockf.c

@@ -514,6 +514,31 @@ int data_encode_blockf(unsigned char source[], int subset_selector[], int blockm
 		
 	} while (exit_status == 0);
 	
+	if(current_row == 0) { 
+		/* fill up the first row */
+		for(c = column_position; c <= *(columns_needed); c++) {
+			if(current_mode == MODEA) {
+				blockmatrix[current_row][c] = 100; /* Code B */
+				current_mode = MODEB;
+			} else {
+				blockmatrix[current_row][c] = 101; /* Code A */
+				current_mode = MODEA;
+			}
+		}
+		current_row++;
+		/* add a second row */
+		subset_selector[current_row] = MODEA;
+		current_mode = MODEA;
+		for(c = 0; c <= *(columns_needed) - 2; c++) {
+			if(current_mode == MODEA) {
+				blockmatrix[current_row][c] = 100; /* Code B */
+				current_mode = MODEB;
+			} else {
+				blockmatrix[current_row][c] = 101; /* Code A */
+				current_mode = MODEA;
+			}
+		}
+	}
 	*(rows_needed) = current_row + 1;
 	
 	return error_number;
@@ -602,7 +627,6 @@ int codablock(struct zint_symbol *symbol, unsigned char source[])
 	min_module_height = (0.55 * (columns_needed + 3)) + 3;
 	if(min_module_height < 8) { min_module_height = 8; }
 	
-	
 	/* Encode the Row Indicator in the First Row of the Symbol - Table D2 */
 	if(subset_selector[0] == 99) {
 		/* Code C */
@@ -643,6 +667,13 @@ int codablock(struct zint_symbol *symbol, unsigned char source[])
 	for(i = 0; i < rows_needed; i++) {
 		int writer, flip_flop;
 		
+		printf("row %d: ",i);
+		printf("103 %d %d [", subset_selector[i], row_indicator[i]);
+		for(j = 0; j < columns_needed; j++) {
+			printf("%d ",blockmatrix[i][j]);
+		}
+		printf("] %d 106\n", row_check[i]);
+		
 		strcpy(row_pattern, "");
 		/* Start character */
 		concat(row_pattern, C128Table[103]); /* Always Start A */
@@ -650,18 +681,14 @@ int codablock(struct zint_symbol *symbol, unsigned char source[])
 		concat(row_pattern, C128Table[subset_selector[i]]);
 		concat(row_pattern, C128Table[row_indicator[i]]);
 		
-		/*printf("103 %d %d ", subset_selector[i], row_indicator[i]);*/
-		
 		for(j = 0; j < columns_needed; j++) {
 			concat(row_pattern, C128Table[blockmatrix[i][j]]);
-			/*printf("%d ",blockmatrix[i][j]);*/
 		}
 		
 		concat(row_pattern, C128Table[row_check[i]]);
 		
 		/* Stop character */
 		concat(row_pattern, C128Table[106]);
-		/*printf("%d 106\n", row_check[i]);*/
 		
 		/* Write the information into the symbol */
 		writer = 0;

backend/code16k.c

@@ -275,6 +275,10 @@ int code16k(struct zint_symbol *symbol, unsigned char source[])
 	rows_needed = (i/5);
 	if(i%5 > 0) { rows_needed++; }
 	
+	if(rows_needed == 1) {
+		rows_needed = 2;
+	}
+	
 	/* start with the mode character - Table 2 */
 	m = 0;
 	switch(set[0]) {
@@ -393,16 +397,19 @@ int code16k(struct zint_symbol *symbol, unsigned char source[])
 		}
 	} while (read < ustrlen(source));
 
-	
 	pads_needed = 5 - ((bar_characters + 2) % 5);
 	if(pads_needed == 5) {
 		pads_needed = 0;
 	}
+	if((bar_characters + pads_needed) < 8) {
+		pads_needed += 8 - (bar_characters + pads_needed);
+	}
 	for(i = 0; i < pads_needed; i++) {
 		values[bar_characters] = 106;
 		bar_characters++;
 	}
 	
+	/* Calculate check digits */
 	first_sum = 0;
 	second_sum = 0;
 	for(i = 0; i < bar_characters; i++)
@@ -424,6 +431,7 @@ int code16k(struct zint_symbol *symbol, unsigned char source[])
 		concat(width_pattern, "1");
 		for(i = 0; i < 5; i++) {
 			concat(width_pattern, C16KTable[values[(current_row * 5) + i]]);
+			
 		}
 		concat(width_pattern, C16KStartStop[C16KStopValues[current_row]]);
 

backend/library.c

@@ -137,8 +137,13 @@ int ZBarcode_Encode(struct zint_symbol *symbol, unsigned char *input)
 	int error_number, error_buffer;
 	error_number = 0;
 
-	/* First check the symbology field */
+	if(ustrlen(input) == 0) {
+		strcpy(symbol->errtxt, "No input data [Z00]");
+		error_tag(symbol->errtxt, ERROR_INVALID_DATA);
+		return ERROR_INVALID_DATA;
+	}
 	
+	/* First check the symbology field */
 	if(symbol->symbology < 1) { strcpy(symbol->errtxt, "Symbology out of range, using Code 128 [Z01]"); symbol->symbology = BARCODE_CODE128; error_number = WARN_INVALID_OPTION; }
 
 	/* symbol->symbologys 1 to 86 are defined by tbarcode */
@@ -262,11 +267,9 @@ int ZBarcode_Encode(struct zint_symbol *symbol, unsigned char *input)
 		case BARCODE_DAFT: error_number = daft_code(symbol, input); break;
 		case BARCODE_EAN14: error_number = ean_14(symbol, input); break;
 	}
-	
 	if(error_number == 0) {
 		error_number = error_buffer;
 	}
-	
 	error_tag(symbol->errtxt, error_number);
 	return error_number;
 }
@@ -318,6 +321,7 @@ int ZBarcode_Print_Rotated(struct zint_symbol *symbol, int rotate_angle)
 		output[2] = symbol->outfile[strlen(symbol->outfile) - 1];
 		output[3] = '\0';
 		to_upper((unsigned char*)output);
+
 #ifndef NO_PNG
 		if(!(strcmp(output, "PNG"))) {
 			error_number = png_handle(symbol, rotate_angle);