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![Jeff King](/assets/img/avatar_default.png)
The "struct object" type implements basic object polymorphism. Individual instances are allocated as concrete types (or as a union type that can store any object), and a "struct object *" can be cast into its real type after examining its "type" enum. This means it is dangerous to have a type field that does not match the allocation (e.g., setting the type field of a "struct blob" to "OBJ_COMMIT" would mean that a reader might read past the allocated memory). In most of the current code this is not a problem; the first thing we do after allocating an object is usually to set its type field by passing it to create_object. However, the virtual commits we create in merge-recursive.c do not ever get their type set. This does not seem to have caused problems in practice, though (presumably because we always pass around a "struct commit" pointer and never even look at the type). We can fix this oversight and also make it harder for future code to get it wrong by setting the type directly in the object allocation functions. This will also make it easier to fix problems with commit index allocation, as we know that any object allocated by alloc_commit_node will meet the invariant that an object with an OBJ_COMMIT type field will have a unique index number. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
170 lines
3.9 KiB
C
170 lines
3.9 KiB
C
#include "cache.h"
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#include "tag.h"
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#include "commit.h"
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#include "tree.h"
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#include "blob.h"
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#define PGP_SIGNATURE "-----BEGIN PGP SIGNATURE-----"
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#define PGP_MESSAGE "-----BEGIN PGP MESSAGE-----"
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const char *tag_type = "tag";
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struct object *deref_tag(struct object *o, const char *warn, int warnlen)
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{
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while (o && o->type == OBJ_TAG)
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if (((struct tag *)o)->tagged)
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o = parse_object(((struct tag *)o)->tagged->sha1);
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else
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o = NULL;
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if (!o && warn) {
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if (!warnlen)
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warnlen = strlen(warn);
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error("missing object referenced by '%.*s'", warnlen, warn);
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}
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return o;
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}
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struct object *deref_tag_noverify(struct object *o)
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{
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while (o && o->type == OBJ_TAG) {
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o = parse_object(o->sha1);
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if (o && o->type == OBJ_TAG && ((struct tag *)o)->tagged)
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o = ((struct tag *)o)->tagged;
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else
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o = NULL;
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}
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return o;
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}
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struct tag *lookup_tag(const unsigned char *sha1)
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{
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struct object *obj = lookup_object(sha1);
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if (!obj)
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return create_object(sha1, alloc_tag_node());
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if (!obj->type)
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obj->type = OBJ_TAG;
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if (obj->type != OBJ_TAG) {
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error("Object %s is a %s, not a tag",
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sha1_to_hex(sha1), typename(obj->type));
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return NULL;
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}
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return (struct tag *) obj;
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}
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static unsigned long parse_tag_date(const char *buf, const char *tail)
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{
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const char *dateptr;
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while (buf < tail && *buf++ != '>')
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/* nada */;
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if (buf >= tail)
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return 0;
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dateptr = buf;
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while (buf < tail && *buf++ != '\n')
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/* nada */;
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if (buf >= tail)
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return 0;
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/* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
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return strtoul(dateptr, NULL, 10);
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}
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int parse_tag_buffer(struct tag *item, const void *data, unsigned long size)
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{
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unsigned char sha1[20];
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char type[20];
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const char *bufptr = data;
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const char *tail = bufptr + size;
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const char *nl;
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if (item->object.parsed)
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return 0;
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item->object.parsed = 1;
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if (size < 64)
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return -1;
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if (memcmp("object ", bufptr, 7) || get_sha1_hex(bufptr + 7, sha1) || bufptr[47] != '\n')
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return -1;
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bufptr += 48; /* "object " + sha1 + "\n" */
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if (!starts_with(bufptr, "type "))
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return -1;
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bufptr += 5;
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nl = memchr(bufptr, '\n', tail - bufptr);
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if (!nl || sizeof(type) <= (nl - bufptr))
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return -1;
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strncpy(type, bufptr, nl - bufptr);
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type[nl - bufptr] = '\0';
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bufptr = nl + 1;
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if (!strcmp(type, blob_type)) {
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item->tagged = &lookup_blob(sha1)->object;
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} else if (!strcmp(type, tree_type)) {
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item->tagged = &lookup_tree(sha1)->object;
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} else if (!strcmp(type, commit_type)) {
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item->tagged = &lookup_commit(sha1)->object;
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} else if (!strcmp(type, tag_type)) {
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item->tagged = &lookup_tag(sha1)->object;
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} else {
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error("Unknown type %s", type);
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item->tagged = NULL;
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}
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if (bufptr + 4 < tail && starts_with(bufptr, "tag "))
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; /* good */
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else
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return -1;
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bufptr += 4;
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nl = memchr(bufptr, '\n', tail - bufptr);
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if (!nl)
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return -1;
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item->tag = xmemdupz(bufptr, nl - bufptr);
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bufptr = nl + 1;
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if (bufptr + 7 < tail && starts_with(bufptr, "tagger "))
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item->date = parse_tag_date(bufptr, tail);
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else
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item->date = 0;
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return 0;
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}
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int parse_tag(struct tag *item)
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{
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enum object_type type;
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void *data;
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unsigned long size;
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int ret;
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if (item->object.parsed)
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return 0;
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data = read_sha1_file(item->object.sha1, &type, &size);
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if (!data)
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return error("Could not read %s",
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sha1_to_hex(item->object.sha1));
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if (type != OBJ_TAG) {
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free(data);
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return error("Object %s not a tag",
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sha1_to_hex(item->object.sha1));
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}
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ret = parse_tag_buffer(item, data, size);
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free(data);
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return ret;
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}
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/*
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* Look at a signed tag object, and return the offset where
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* the embedded detached signature begins, or the end of the
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* data when there is no such signature.
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*/
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size_t parse_signature(const char *buf, unsigned long size)
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{
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char *eol;
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size_t len = 0;
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while (len < size && !starts_with(buf + len, PGP_SIGNATURE) &&
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!starts_with(buf + len, PGP_MESSAGE)) {
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eol = memchr(buf + len, '\n', size - len);
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len += eol ? eol - (buf + len) + 1 : size - len;
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}
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return len;
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}
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