farbfeld

commit 3fa775e1dfd5dc38648f88c2f385be1f0fe45605
parent c494437937ee01c6d3eb5b630a15e207aae76c25
Author: Alexander Krotov <ilabdsf@yandex.ru>
Date:   Thu, 19 May 2016 01:21:58 +0300

Improve fread error handling in ff2*

In case of unexpected end of file errno is not set, and strerror(errno)
returns "Success". Caller should distinguish between error and EOF by
calling ferror(3) as described in fread(3).

Diffstat:
M
ff2jpg.c
 | 
14
++++++++++----
M
ff2png.c
 | 
7
+++++--
M
ff2ppm.c
 | 
14
++++++++++----

3 files changed, 25 insertions(+), 10 deletions(-)
diff --git a/ff2jpg.c b/ff2jpg.c
@@ -80,8 +80,7 @@ main(int argc, char *argv[])
 
 	/* header */
 	if (fread(hdr, sizeof(*hdr), 4, stdin) != 4) {
-		fprintf(stderr, "%s: fread: %s\n", argv0, strerror(errno));
-		return 1;
+		goto readerr;
 	}
 	if (memcmp("farbfeld", hdr, sizeof("farbfeld") - 1)) {
 		fprintf(stderr, "%s: invalid magic value\n", argv0);
@@ -124,8 +123,7 @@ main(int argc, char *argv[])
 	/* write rows */
 	for (i = 0; i < height; ++i) {
 		if (fread(row, sizeof(uint16_t), rowlen, stdin) != rowlen) {
-			fprintf(stderr, "%s: fread: %s\n", argv0, strerror(errno));
-			return 1;
+			goto readerr;
 		}
 		for (j = 0, k = 0; j < rowlen; j += 4, k += 3) {
 			a = ntohs(row[j + 3]);
@@ -142,4 +140,12 @@ main(int argc, char *argv[])
 	jpeg_destroy_compress(&cinfo);
 
 	return 0;
+readerr:
+	if (ferror(stdin)) {
+		fprintf(stderr, "%s: fread: %s\n", argv0, strerror(errno));
+	} else {
+		fprintf(stderr, "%s: unexpected end of file\n", argv0);
+	}
+
+	return 1;
 }
diff --git a/ff2png.c b/ff2png.c
@@ -81,8 +81,11 @@ main(int argc, char *argv[])
 
 	return 0;
 readerr:
-	fprintf(stderr, "%s: fread: ", argv0);
-	perror(NULL);
+	if (ferror(stdin)) {
+		fprintf(stderr, "%s: fread: %s\n", argv0, strerror(errno));
+	} else {
+		fprintf(stderr, "%s: unexpected end of file\n", argv0);
+	}
 
 	return 1;
 }
diff --git a/ff2ppm.c b/ff2ppm.c
@@ -60,8 +60,7 @@ main(int argc, char *argv[])
 
 	/* header */
 	if (fread(hdr, sizeof(*hdr), 4, stdin) != 4) {
-		fprintf(stderr, "%s: fread: %s\n", argv0, strerror(errno));
-		return 1;
+		goto readerr;
 	}
 	if (memcmp("farbfeld", hdr, sizeof("farbfeld") - 1)) {
 		fprintf(stderr, "%s: invalid magic value\n", argv0);
@@ -90,8 +89,7 @@ main(int argc, char *argv[])
 	/* write rows */
 	for (i = 0; i < height; ++i) {
 		if (fread(row, sizeof(uint16_t), rowlen, stdin) != rowlen) {
-			fprintf(stderr, "%s: fread: %s\n", argv0, strerror(errno));
-			return 1;
+			goto readerr;
 		}
 		for (j = 0, k = 0; j < rowlen; j += 4, k += 3) {
 			a = ntohs(row[j + 3]);
@@ -108,4 +106,12 @@ main(int argc, char *argv[])
 	}
 
 	return 0;
+readerr:
+	if (ferror(stdin)) {
+		fprintf(stderr, "%s: fread: %s\n", argv0, strerror(errno));
+	} else {
+		fprintf(stderr, "%s: unexpected end of file\n", argv0);
+	}
+
+	return 1;
 }