From: Andreas Stieger <astieger@suse.com>
Date: Mon, 8 May 2017 21:51:28 +0200
Subject: some IO improvements
References: https://github.com/cr-marcstevens/sha1collisiondetection/pull/28

---
 src/main.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Index: sha1collisiondetection-stable-v1.0.3/src/main.c
===================================================================
--- sha1collisiondetection-stable-v1.0.3.orig/src/main.c	2017-05-22 18:17:51.339889238 +0200
+++ sha1collisiondetection-stable-v1.0.3/src/main.c	2017-05-22 18:18:14.471988044 +0200
@@ -8,6 +8,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <errno.h>
 #include <libgen.h>
 
 #include "sha1.h"
@@ -23,7 +24,7 @@ int main(int argc, char** argv)
 
 	if (argc < 2)
 	{
-		printf("Usage: %s <file>\n", basename(argv[0]));
+		fprintf(stderr, "Usage: %s <file>\n", basename(argv[0]));
 		return 1;
 	}
 
@@ -37,10 +38,14 @@ int main(int argc, char** argv)
 			SHA1DCSetDetectReducedRoundCollision(&ctx2, 1);
 		}
 
-		fd = fopen(argv[i], "rb");
+		if(!strcmp(argv[i],"-")) {
+			fd = stdin;
+		} else {
+			fd = fopen(argv[i], "rb");
+		}
 		if (fd == NULL)
 		{
-			printf("cannot open file: %s\n", argv[i]);
+			fprintf(stderr, "cannot open file: %s: %s\n", argv[i], strerror(errno));
 			return 1;
 		}
 
@@ -53,12 +58,12 @@ int main(int argc, char** argv)
 		}
 		if (ferror(fd))
 		{
-			printf("error while reading file: %s\n", argv[i]);
+			fprintf(stderr, "error while reading file: %s: %s\n", argv[i], strerror(errno));
 			return 1;
 		}
 		if (!feof(fd))
 		{
-			printf("not end of file?: %s\n",argv[i]);
+			fprintf(stderr, "not end of file?: %s: %s\n", argv[i], strerror(errno));
 			return 1;
 		}
 
Index: sha1collisiondetection-stable-v1.0.3/README.md
===================================================================
--- sha1collisiondetection-stable-v1.0.3.orig/README.md	2017-05-22 18:17:51.339889238 +0200
+++ sha1collisiondetection-stable-v1.0.3/README.md	2017-05-22 18:17:54.539902741 +0200
@@ -51,6 +51,7 @@ Examples:
 ```
 bin/sha1dcsum test/sha1_reducedsha_coll.bin test/shattered-1.pdf
 bin/sha1dcsum_partialcoll test/sha1reducedsha_coll.bin test/shattered-1.pdf
+pipe_data | bin/sha1dcsum -
 ```
 
 ## Library usage