[PATCH 1/2] fsck: use strbuf_getline() to read skiplist file

["René Scharfe" <l.s.r@web.de>]

The char array named "buffer" is unlikely to contain a NUL character, so
printing its contents using %s in a die() format is unsafe.  Clang's
ASan reports running over the end of buffer in the recently added
skiplist tests in t5504-fetch-receive-strict.sh as a result.

Use an idiomatic strbuf_getline() loop instead, which ensures the buffer
is always NUL-terminated.  As a side-effect this also adds support for
skiplist files with CRLF line endings.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
---
  fsck.c | 23 ++++++++++-------------
  1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/fsck.c b/fsck.c
index a0cee0be59..83f4562390 100644
--- a/fsck.c
+++ b/fsck.c
@@ -183,8 +183,9 @@ static int fsck_msg_type(enum fsck_msg_id msg_id,
  static void init_skiplist(struct fsck_options *options, const char *path)
  {
  	static struct oid_array skiplist = OID_ARRAY_INIT;
-	int sorted, fd;
-	char buffer[GIT_MAX_HEXSZ + 1];
+	int sorted;
+	FILE *fp;
+	struct strbuf sb = STRBUF_INIT;
  	struct object_id oid;
  
  	if (options->skiplist)
@@ -194,25 +195,21 @@ static void init_skiplist(struct fsck_options *options, const char *path)
  		options->skiplist = &skiplist;
  	}
  
-	fd = open(path, O_RDONLY);
-	if (fd < 0)
+	fp = fopen(path, "r");
+	if (!fp)
  		die("Could not open skip list: %s", path);
-	for (;;) {
+	while (!strbuf_getline(&sb, fp)) {
  		const char *p;
-		int result = read_in_full(fd, buffer, sizeof(buffer));
-		if (result < 0)
-			die_errno("Could not read '%s'", path);
-		if (!result)
-			break;
-		if (parse_oid_hex(buffer, &oid, &p) || *p != '\n')
-			die("Invalid SHA-1: %s", buffer);
+		if (parse_oid_hex(sb.buf, &oid, &p) || *p != '\0')
+			die("Invalid SHA-1: %s", sb.buf);
  		oid_array_append(&skiplist, &oid);
  		if (sorted && skiplist.nr > 1 &&
  				oidcmp(&skiplist.oid[skiplist.nr - 2],
  				       &oid) > 0)
  			sorted = 0;
  	}
-	close(fd);
+	fclose(fp);
+	strbuf_release(&sb);
  
  	if (sorted)
  		skiplist.sorted = 1;
-- 
2.18.0