In old packages, zero-length files have zeros for digest (RhBug:1352222)

Commit 8192746196745e15517e49230de183a0211017b6 enabled digest checks
for empty files, which is fine for modern era packages but rpm didn't
always generate a proper digest for them. Handle that as the special
case it is: preserve the digests checks as they are, but additionally
test and accept zeros too for MD5-era zero-length files.

1 files changed, 8 insertions, 0 deletions

diff --git a/lib/rpmfi.c b/lib/rpmfi.c
index 4e89e5888..320296a4d 100644
--- a/lib/rpmfi.c
+++ b/lib/rpmfi.c
@@ -2227,6 +2227,14 @@ int rpmfiArchiveReadToFilePsm(rpmfi fi, FD_t fd, int nodigest, rpmpsm psm)
 	    size_t diglen = rpmDigestLength(digestalgo);
 	    if (memcmp(digest, fidigest, diglen)) {
 		rc = RPMERR_DIGEST_MISMATCH;
+
+		/* ...but in old packages, empty files have zeros for digest */
+		if (rpmfiFSize(fi) == 0 && digestalgo == PGPHASHALGO_MD5) {
+		    uint8_t zeros[diglen];
+		    memset(&zeros, 0, diglen);
+		    if (memcmp(zeros, fidigest, diglen) == 0)
+			rc = 0;
+		}
 	    }
 	} else {
 	    rc = RPMERR_DIGEST_MISMATCH;