sbase

commit deb8a16527b235840fd04787463590ccf5198d07
parent 29649762b3602f4ce54ca8bb282524e5f1a92b92
Author: Hiltjo Posthuma <hiltjo@codemadness.org>
Date:   Fri,  8 May 2015 22:01:37 +0200

tar: fix checksum calculation (signed/unsigned issue)

some archives gave the error: "malformed tar archive"

test file where this occurred:
   http://nl.alpinelinux.org/alpine/v3.1/main/x86_64/apk-tools-static-2.5.0_rc1-r0.apk

Diffstat:
M
tar.c
 | 
4
++--

1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tar.c b/tar.c
@@ -237,7 +237,7 @@ archive(const char *path)
 
 	memset(h->chksum, ' ', sizeof(h->chksum));
 	for (i = 0, chksum = 0; i < sizeof(*h); i++)
-		chksum += b[i];
+		chksum += (unsigned char)b[i];
 	putoctal(h->chksum, chksum, sizeof(h->chksum));
 	ewrite(tarfd, b, BLKSIZ);
 
@@ -412,7 +412,7 @@ chktar(struct header *h)
 		goto bad;
 	memset(h->chksum, ' ', sizeof(h->chksum));
 	for (i = 0, s2 = 0; i < sizeof(*h); i++)
-		s2 += p[i];
+		s2 += (unsigned char)p[i];
 	if (s1 != s2)
 		goto bad;
 	memcpy(h->chksum, tmp, sizeof(h->chksum));