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23 January 2022, 05:21:09 UTC
Revision 5035242c4785bd23c53827a1656b5f97394f724e authored by Junio C Hamano on 08 June 2007, 08:19:13 UTC, committed by Junio C Hamano on 08 June 2007, 08:19:13 UTC 
checkout: do not get confused with ambiguous tag/branch names
 
Although it is not advisable, we have always allowed a branch
and a tag to have the same basename (i.e. it is not illegal to
have refs/heads/frotz and refs/tags/frotz at the same time).
When talking about a specific commit, the interpretation of
'frotz' has always been "use tag and then check branch",
although we warn when ambiguities exist.

However "git checkout $name" is defined to (1) first see if it
matches the branch name, and if so switch to that branch; (2)
otherwise it is an instruction to detach HEAD to point at the
commit named by $name.  We did not follow this definition when
$name appeared under both refs/heads/ and refs/tags/ -- we
switched to the branch but read the tree from the tagged commit,
which was utterly bogus.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 23fcdc7
Raw File
Tip revision: 5035242c4785bd23c53827a1656b5f97394f724e authored by Junio C Hamano on 08 June 2007, 08:19:13 UTC
checkout: do not get confused with ambiguous tag/branch names
Tip revision: 5035242
show-index.c 
#include "cache.h"
#include "pack.h"

int main(int argc, char **argv)
{
	int i;
	unsigned nr;
	unsigned int version;
	static unsigned int top_index[256];

	if (fread(top_index, 2 * 4, 1, stdin) != 1)
		die("unable to read header");
	if (top_index[0] == htonl(PACK_IDX_SIGNATURE)) {
		version = ntohl(top_index[1]);
		if (version < 2 || version > 2)
			die("unknown index version");
		if (fread(top_index, 256 * 4, 1, stdin) != 1)
			die("unable to read index");
	} else {
		version = 1;
		if (fread(&top_index[2], 254 * 4, 1, stdin) != 1)
			die("unable to read index");
	}
	nr = 0;
	for (i = 0; i < 256; i++) {
		unsigned n = ntohl(top_index[i]);
		if (n < nr)
			die("corrupt index file");
		nr = n;
	}
	if (version == 1) {
		for (i = 0; i < nr; i++) {
			unsigned int offset, entry[6];

			if (fread(entry, 4 + 20, 1, stdin) != 1)
				die("unable to read entry %u/%u", i, nr);
			offset = ntohl(entry[0]);
			printf("%u %s\n", offset, sha1_to_hex((void *)(entry+1)));
		}
	} else {
		unsigned off64_nr = 0;
		struct {
			unsigned char sha1[20];
			uint32_t crc;
			uint32_t off;
		} *entries = xmalloc(nr * sizeof(entries[0]));
		for (i = 0; i < nr; i++)
			if (fread(entries[i].sha1, 20, 1, stdin) != 1)
				die("unable to read sha1 %u/%u", i, nr);
		for (i = 0; i < nr; i++)
			if (fread(&entries[i].crc, 4, 1, stdin) != 1)
				die("unable to read crc %u/%u", i, nr);
		for (i = 0; i < nr; i++)
			if (fread(&entries[i].off, 4, 1, stdin) != 1)
				die("unable to read 32b offset %u/%u", i, nr);
		for (i = 0; i < nr; i++) {
			uint64_t offset;
			uint32_t off = ntohl(entries[i].off);
			if (!(off & 0x80000000)) {
				offset = off;
			} else {
				uint32_t off64[2];
				if ((off & 0x7fffffff) != off64_nr)
					die("inconsistent 64b offset index");
				if (fread(off64, 8, 1, stdin) != 1)
					die("unable to read 64b offset %u", off64_nr);
				offset = (((uint64_t)ntohl(off64[0])) << 32) |
						     ntohl(off64[1]);
				off64_nr++;
			}
			printf("%llu %s (%08x)\n", (unsigned long long) offset,
			       sha1_to_hex(entries[i].sha1),
			       ntohl(entries[i].crc));
		}
		free(entries);
	}
	return 0;
}
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