Add stricter and clearer error-checking in png2ff and ff2png

As known from sbase, we want to manually flush stdout to see if all
data has been passed on.

2 files changed, 56 insertions, 27 deletions

diff --git a/ff2png.c b/ff2png.c
index ad39720..548c7dd 100644
--- a/ff2png.c
+++ b/ff2png.c
@@ -1,6 +1,7 @@
 /* See LICENSE file for copyright and license details. */
 #include <arpa/inet.h>
 
+#include <errno.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -8,17 +9,18 @@
 
 #include <png.h>
 
-#define HEADER_FORMAT "farbfeld########"
+#define HEADER "farbfeld########"
 
 int
 main(int argc, char *argv[])
 {
 	png_structp png_struct_p;
 	png_infop png_info_p;
-	uint8_t hdr[16];
-	uint16_t tmp16, *png_row;
-	png_uint_32 width, height, i;
 	png_size_t png_row_len, j;
+	png_uint_32 width, height, i;
+	int ret = 0;
+	uint16_t tmp16, *png_row;
+	uint8_t hdr[16];
 
 	if (argc > 1) {
 		fprintf(stderr, "usage: %s\n", argv[0]);
@@ -26,42 +28,47 @@ main(int argc, char *argv[])
 	}
 
 	/* header */
-	if (fread(hdr, 1, strlen(HEADER_FORMAT), stdin) != strlen(HEADER_FORMAT)) {
-		fprintf(stderr, "failed to read from stdin or input too short\n");
+	if (fread(hdr, 1, strlen(HEADER), stdin) != strlen(HEADER)) {
+		fprintf(stderr, "%s: incomplete header\n", argv[0]);
 		return 1;
 	}
 	if (memcmp("farbfeld", hdr, strlen("farbfeld"))) {
-		fprintf(stderr, "invalid magic in header\n");
+		fprintf(stderr, "%s: invalid magic value\n", argv[0]);
 		return 1;
 	}
 	width = ntohl(*((uint32_t *)(hdr + 8)));
 	height = ntohl(*((uint32_t *)(hdr + 12)));
 
 	/* load png */
-	png_struct_p = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
+	png_struct_p = png_create_write_struct(PNG_LIBPNG_VER_STRING,
+                                               NULL, NULL, NULL);
 	png_info_p = png_create_info_struct(png_struct_p);
 
-	if (!png_struct_p || !png_info_p || setjmp(png_jmpbuf(png_struct_p))) {
-		fprintf(stderr, "failed to initialize libpng\n");
+	if (!png_struct_p || !png_info_p) {
+		fprintf(stderr, "%s: failed to initialize libpng\n", argv[0]);
 		return 1;
 	}
+	if (setjmp(png_jmpbuf(png_struct_p)))
+		return 1;
 	png_init_io(png_struct_p, stdout);
-	png_set_IHDR(png_struct_p, png_info_p, width, height, 16, PNG_COLOR_TYPE_RGB_ALPHA,
-		     PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
+	png_set_IHDR(png_struct_p, png_info_p, width, height, 16,
+	             PNG_COLOR_TYPE_RGB_ALPHA, PNG_INTERLACE_NONE,
+	             PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
 	png_write_info(png_struct_p, png_info_p);
 
 	/* write rows */
 	png_row_len = strlen("RGBA") * width * sizeof(uint16_t);
-	png_row = malloc(png_row_len);
-	if (!png_row) {
-		fprintf(stderr, "failed to allocate row-buffer\n");
+	if (!(png_row = malloc(png_row_len))) {
+		fprintf(stderr, "%s: malloc: ", argv[0]);
+		perror(NULL);
 		return 1;
 	}
-
 	for (i = 0; i < height; ++i) {
 		for (j = 0; j < png_row_len / sizeof(uint16_t); ++j) {
-			if (fread(&tmp16, 1, sizeof(uint16_t), stdin) != sizeof(uint16_t)) {
-				fprintf(stderr, "unexpected EOF or row-skew\n");
+			if (fread(&tmp16, 1, sizeof(uint16_t), stdin) !=
+			    sizeof(uint16_t)) {
+				fprintf(stderr, "%s: unexpected EOF\n",
+				        argv[0]);
 				return 1;
 			}
 			png_row[j] = tmp16;
@@ -70,10 +77,19 @@ main(int argc, char *argv[])
 	}
 	png_write_end(png_struct_p, NULL);
 
-	/* clean up */
-	png_free_data(png_struct_p, png_info_p, PNG_FREE_ALL, -1);
 	png_destroy_write_struct(&png_struct_p, NULL);
-	free(png_row);
 
-	return 0;
+	/* flush output */
+	if (fflush(stdout)) {
+		fprintf(stderr, "%s: fflush stdout: ", argv[0]);
+		perror(NULL);
+		ret = 1;
+	}
+	if (fclose(stdout) && !ret) {
+		fprintf(stderr, "%s: fclose stdout: ", argv[0]);
+		perror(NULL);
+		ret = 1;
+	}
+
+	return ret;
 }
diff --git a/png2ff.c b/png2ff.c
index 0835d34..4f4fc83 100644
--- a/png2ff.c
+++ b/png2ff.c
@@ -1,6 +1,7 @@
 /* See LICENSE file for copyright and license details. */
 #include <arpa/inet.h>
 
+#include <errno.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -13,7 +14,7 @@ main(int argc, char *argv[])
 	png_structp png_struct_p;
 	png_infop png_info_p;
 	png_bytepp png_row_p;
-	int depth, color;
+	int depth, color, ret = 0;
 	uint32_t width, height, png_row_len, tmp32, r, i;
 	uint16_t tmp16;
 
@@ -28,7 +29,7 @@ main(int argc, char *argv[])
 	png_info_p = png_create_info_struct(png_struct_p);
 
 	if (!png_struct_p || !png_info_p) {
-		fprintf(stderr, "failed to initialize libpng\n");
+		fprintf(stderr, "%s: failed to initialize libpng\n", argv[0]);
 		return 1;
 	}
 	if (setjmp(png_jmpbuf(png_struct_p)))
@@ -48,7 +49,7 @@ main(int argc, char *argv[])
 	png_row_p = png_get_rows(png_struct_p, png_info_p);
 
 	/* write header */
-	fprintf(stdout, "farbfeld");
+	fputs("farbfeld", stdout);
 	tmp32 = htonl(width);
 	fwrite(&tmp32, sizeof(uint32_t), 1, stdout);
 	tmp32 = htonl(height);
@@ -75,11 +76,23 @@ main(int argc, char *argv[])
 		}
 		break;
 	default:
-		fprintf(stderr, "format error\n");
+		fprintf(stderr, "%s: format error\n", argv[0]);
 		return 1;
 	}
 
 	png_destroy_read_struct(&png_struct_p, &png_info_p, NULL);
 
-	return 0;
+	/* flush output */
+	if (fflush(stdout)) {
+		fprintf(stderr, "%s: fflush stdout: ", argv[0]);
+		perror(NULL);
+		ret = 1;
+	}
+	if (fclose(stdout) && !ret) {
+		fprintf(stderr, "%s: fclose stdout: ", argv[0]);
+		perror(NULL);
+		ret = 1;
+	}
+
+	return ret;
 }