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blob a458a925f129b5b909b8323aaa55b1f3c7743d6a 1354 bytes (raw)
name: builtin/get-tar-commit-id.c 	 # note: path name is non-authoritative(*)

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/*
 * Copyright (c) 2005, 2006 Rene Scharfe
 */
#include "cache.h"
#include "commit.h"
#include "tar.h"
#include "builtin.h"
#include "quote.h"

static const char builtin_get_tar_commit_id_usage[] =
"git get-tar-commit-id";

/* ustar header + extended global header content */
#define RECORDSIZE	(512)
#define HEADERSIZE (2 * RECORDSIZE)

int cmd_get_tar_commit_id(int argc, const char **argv UNUSED, const char *prefix)
{
	char buffer[HEADERSIZE];
	struct ustar_header *header = (struct ustar_header *)buffer;
	char *content = buffer + RECORDSIZE;
	const char *comment;
	ssize_t n;
	long len;
	char *end;

	BUG_ON_NON_EMPTY_PREFIX(prefix);

	if (argc != 1)
		usage(builtin_get_tar_commit_id_usage);

	n = read_in_full(0, buffer, HEADERSIZE);
	if (n < 0)
		die_errno("git get-tar-commit-id: read error");
	if (n != HEADERSIZE)
		die_errno("git get-tar-commit-id: EOF before reading tar header");
	if (header->typeflag[0] != TYPEFLAG_GLOBAL_HEADER)
		return 1;

	len = strtol(content, &end, 10);
	if (errno == ERANGE || end == content || len < 0)
		return 1;
	if (!skip_prefix(end, " comment=", &comment))
		return 1;
	len -= comment - content;
	if (len < 1 || !(len % 2) ||
	    hash_algo_by_length((len - 1) / 2) == GIT_HASH_UNKNOWN)
		return 1;

	if (write_in_full(1, comment, len) < 0)
		die_errno("git get-tar-commit-id: write error");

	return 0;
}

debug log:

solving a458a925f1 ...
found a458a925f1 in https://80x24.org/lore/git/20230516170932.1358685-6-calvinwan@google.com/
found 564cfcac4f in https://80x24.org/lore/pub/scm/git/git.git/
preparing index
index prepared:
100644 564cfcac4fb0ac4c9de1748b816f395d45665cbb	builtin/get-tar-commit-id.c

applying [1/1] https://80x24.org/lore/git/20230516170932.1358685-6-calvinwan@google.com/
diff --git a/builtin/get-tar-commit-id.c b/builtin/get-tar-commit-id.c
index 564cfcac4f..a458a925f1 100644

Checking patch builtin/get-tar-commit-id.c...
Applied patch builtin/get-tar-commit-id.c cleanly.

index at:
100644 a458a925f129b5b909b8323aaa55b1f3c7743d6a	builtin/get-tar-commit-id.c

(*) Git path names are given by the tree(s) the blob belongs to.
    Blobs themselves have no identifier aside from the hash of its contents.^

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