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5d44cd1c8b
If you try to fsck a repository that isn't entirely empty, but that has no inter-object references (ie all the objects are blobs, and don't refer to anything else), git-fsck-objects currently fails. This probably cannot happen in practice, but can be tested with something like git init-db touch dummy git add dummy git fsck-objects where the fsck will die by a divide-by-zero when it tries to look up the references from the one object it found (hash_obj() will do a modulus by refs_hash_size). On some other archiectures (ppc, sparc) the divide-by-zero will go unnoticed, and we'll instead SIGSEGV when we hit the "refs_hash[j]" access. So move the test that should protect against this from mark_reachable() into lookup_object_refs(), which incidentally in the process also fixes mark_reachable() itself (it used to not mark the one object that _was_ reachable, because it decided that it had no refs too early). Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
144 lines
3 KiB
C
144 lines
3 KiB
C
#include "cache.h"
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#include "object.h"
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int track_object_refs = 0;
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static unsigned int refs_hash_size, nr_object_refs;
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static struct object_refs **refs_hash;
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static unsigned int hash_obj(struct object *obj, unsigned int n)
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{
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unsigned int hash = *(unsigned int *)obj->sha1;
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return hash % n;
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}
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static void insert_ref_hash(struct object_refs *ref, struct object_refs **hash, unsigned int size)
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{
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int j = hash_obj(ref->base, size);
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while (hash[j]) {
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j++;
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if (j >= size)
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j = 0;
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}
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hash[j] = ref;
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}
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static void grow_refs_hash(void)
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{
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int i;
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int new_hash_size = (refs_hash_size + 1000) * 3 / 2;
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struct object_refs **new_hash;
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new_hash = xcalloc(new_hash_size, sizeof(struct object_refs *));
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for (i = 0; i < refs_hash_size; i++) {
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struct object_refs *ref = refs_hash[i];
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if (!ref)
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continue;
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insert_ref_hash(ref, new_hash, new_hash_size);
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}
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free(refs_hash);
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refs_hash = new_hash;
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refs_hash_size = new_hash_size;
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}
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static void add_object_refs(struct object *obj, struct object_refs *ref)
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{
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int nr = nr_object_refs + 1;
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if (nr > refs_hash_size * 2 / 3)
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grow_refs_hash();
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ref->base = obj;
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insert_ref_hash(ref, refs_hash, refs_hash_size);
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nr_object_refs = nr;
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}
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struct object_refs *lookup_object_refs(struct object *obj)
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{
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struct object_refs *ref;
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int j;
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/* nothing to lookup */
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if (!refs_hash_size)
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return NULL;
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j = hash_obj(obj, refs_hash_size);
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while ((ref = refs_hash[j]) != NULL) {
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if (ref->base == obj)
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break;
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j++;
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if (j >= refs_hash_size)
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j = 0;
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}
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return ref;
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}
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struct object_refs *alloc_object_refs(unsigned count)
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{
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struct object_refs *refs;
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size_t size = sizeof(*refs) + count*sizeof(struct object *);
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refs = xcalloc(1, size);
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refs->count = count;
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return refs;
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}
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static int compare_object_pointers(const void *a, const void *b)
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{
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const struct object * const *pa = a;
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const struct object * const *pb = b;
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if (*pa == *pb)
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return 0;
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else if (*pa < *pb)
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return -1;
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else
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return 1;
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}
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void set_object_refs(struct object *obj, struct object_refs *refs)
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{
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unsigned int i, j;
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/* Do not install empty list of references */
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if (refs->count < 1) {
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free(refs);
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return;
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}
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/* Sort the list and filter out duplicates */
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qsort(refs->ref, refs->count, sizeof(refs->ref[0]),
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compare_object_pointers);
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for (i = j = 1; i < refs->count; i++) {
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if (refs->ref[i] != refs->ref[i - 1])
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refs->ref[j++] = refs->ref[i];
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}
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if (j < refs->count) {
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/* Duplicates were found - reallocate list */
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size_t size = sizeof(*refs) + j*sizeof(struct object *);
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refs->count = j;
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refs = xrealloc(refs, size);
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}
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for (i = 0; i < refs->count; i++)
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refs->ref[i]->used = 1;
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add_object_refs(obj, refs);
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}
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void mark_reachable(struct object *obj, unsigned int mask)
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{
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const struct object_refs *refs;
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if (!track_object_refs)
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die("cannot do reachability with object refs turned off");
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/* If we've been here already, don't bother */
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if (obj->flags & mask)
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return;
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obj->flags |= mask;
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refs = lookup_object_refs(obj);
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if (refs) {
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unsigned i;
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for (i = 0; i < refs->count; i++)
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mark_reachable(refs->ref[i], mask);
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}
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}
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