fsmonitor: avoid signed integer overflow / infinite loop

diff --git a/pack-revindex.c b/pack-revindex.c
index bb521cf7fb2911bc2d3653f46224880f8540f9ab..50891f77a26d6ea65b2c038f4f21ada49255a513 100644 (file)
--- a/pack-revindex.c
+++ b/pack-revindex.c
@@ -119,19 +119,20 @@ static void sort_revindex(struct revindex_entry *entries, unsigned n, off_t max)
  */
 static void create_pack_revindex(struct packed_git *p)
 {
-       unsigned num_ent = p->num_objects;
+       const unsigned num_ent = p->num_objects;
        unsigned i;
        const char *index = p->index_data;
+       const unsigned hashsz = the_hash_algo->rawsz;
 
        ALLOC_ARRAY(p->revindex, num_ent + 1);
        index += 4 * 256;
 
        if (p->index_version > 1) {
                const uint32_t *off_32 =
-                       (uint32_t *)(index + 8 + p->num_objects * (20 + 4));
+                       (uint32_t *)(index + 8 + p->num_objects * (hashsz + 4));
                const uint32_t *off_64 = off_32 + p->num_objects;
                for (i = 0; i < num_ent; i++) {
-                       uint32_t off = ntohl(*off_32++);
+                       const uint32_t off = ntohl(*off_32++);
                        if (!(off & 0x80000000)) {
                                p->revindex[i].offset = off;
                        } else {
@@ -142,16 +143,17 @@ static void create_pack_revindex(struct packed_git *p)
                }
        } else {
                for (i = 0; i < num_ent; i++) {
-                       uint32_t hl = *((uint32_t *)(index + 24 * i));
+                       const uint32_t hl = *((uint32_t *)(index + (hashsz + 4) * i));
                        p->revindex[i].offset = ntohl(hl);
                        p->revindex[i].nr = i;
                }
        }
 
-       /* This knows the pack format -- the 20-byte trailer
+       /*
+        * This knows the pack format -- the hash trailer
         * follows immediately after the last object data.
         */
-       p->revindex[num_ent].offset = p->pack_size - 20;
+       p->revindex[num_ent].offset = p->pack_size - hashsz;
        p->revindex[num_ent].nr = -1;
        sort_revindex(p->revindex, num_ent, p->pack_size);
 }
@@ -166,10 +168,10 @@ int find_revindex_position(struct packed_git *p, off_t ofs)
 {
        int lo = 0;
        int hi = p->num_objects + 1;
-       struct revindex_entry *revindex = p->revindex;
+       const struct revindex_entry *revindex = p->revindex;
 
        do {
-               unsigned mi = lo + (hi - lo) / 2;
+               const unsigned mi = lo + (hi - lo) / 2;
                if (revindex[mi].offset == ofs) {
                        return mi;
                } else if (ofs < revindex[mi].offset)