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Revision b2732e609785dbaa8f13e6c8d80f8e1eb0baae8f authored by Johannes Schindelin on 17 December 2019, 12:16:34 UTC, committed by Johannes Schindelin on 09 January 2020, 11:54:30 UTC 
mingw: safeguard better against backslashes in file names
 
In 224c7d70fa1 (mingw: only test index entries for backslashes, not tree
entries, 2019-12-31), we relaxed the check for backslashes in tree
entries to check only index entries.

However, the code change was incorrect: it was added to
`add_index_entry_with_check()`, not to `add_index_entry()`, so under
certain circumstances it was possible to side-step the protection.

Besides, the description of that commit purported that all index entries
would be checked when in fact they were only checked when being added to
the index (there are code paths that do not do that, constructing
"transient" index entries).

In any case, it was pointed out in one insightful review at
https://github.com/git-for-windows/git/pull/2437#issuecomment-566771835
that it would be a much better idea to teach `verify_path()` to perform
the check for a backslash. This is safer, even if it comes with two
notable drawbacks:

- `verify_path()` cannot say _what_ is wrong with the path, therefore
  the user will no longer be told that there was a backslash in the
  path, only that the path was invalid.

- The `git apply` command also calls the `verify_path()` function, and
  might have been able to handle Windows-style paths (i.e. with
  backslashes instead of forward slashes). This will no longer be
  possible unless the user (temporarily) sets `core.protectNTFS=false`.

Note that `git add <windows-path>` will _still_ work because
`normalize_path_copy_len()` will convert the backslashes to forward
slashes before hitting the code path that creates an index entry.

The clear advantage is that `verify_path()`'s purpose is to check the
validity of the file name, therefore we naturally tap into all the code
paths that need safeguarding, also implicitly into future code paths.

The benefits of that approach outweigh the downsides, so let's move the
check from `add_index_entry_with_check()` to `verify_path()`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
1 parent 7a6a90c
Raw File
notes-cache.c 
#include "cache.h"
#include "notes-cache.h"
#include "object-store.h"
#include "repository.h"
#include "commit.h"
#include "refs.h"

static int notes_cache_match_validity(struct repository *r,
				      const char *ref,
				      const char *validity)
{
	struct object_id oid;
	struct commit *commit;
	struct pretty_print_context pretty_ctx;
	struct strbuf msg = STRBUF_INIT;
	int ret;

	if (read_ref(ref, &oid) < 0)
		return 0;

	commit = lookup_commit_reference_gently(r, &oid, 1);
	if (!commit)
		return 0;

	memset(&pretty_ctx, 0, sizeof(pretty_ctx));
	format_commit_message(commit, "%s", &msg, &pretty_ctx);
	strbuf_trim(&msg);

	ret = !strcmp(msg.buf, validity);
	strbuf_release(&msg);

	return ret;
}

void notes_cache_init(struct repository *r, struct notes_cache *c,
		      const char *name, const char *validity)
{
	struct strbuf ref = STRBUF_INIT;
	int flags = NOTES_INIT_WRITABLE;

	memset(c, 0, sizeof(*c));
	c->validity = xstrdup(validity);

	strbuf_addf(&ref, "refs/notes/%s", name);
	if (!notes_cache_match_validity(r, ref.buf, validity))
		flags |= NOTES_INIT_EMPTY;
	init_notes(&c->tree, ref.buf, combine_notes_overwrite, flags);
	strbuf_release(&ref);
}

int notes_cache_write(struct notes_cache *c)
{
	struct object_id tree_oid, commit_oid;

	if (!c || !c->tree.initialized || !c->tree.update_ref ||
	    !*c->tree.update_ref)
		return -1;
	if (!c->tree.dirty)
		return 0;

	if (write_notes_tree(&c->tree, &tree_oid))
		return -1;
	if (commit_tree(c->validity, strlen(c->validity), &tree_oid, NULL,
			&commit_oid, NULL, NULL) < 0)
		return -1;
	if (update_ref("update notes cache", c->tree.update_ref, &commit_oid,
		       NULL, 0, UPDATE_REFS_QUIET_ON_ERR) < 0)
		return -1;

	return 0;
}

char *notes_cache_get(struct notes_cache *c, struct object_id *key_oid,
		      size_t *outsize)
{
	const struct object_id *value_oid;
	enum object_type type;
	char *value;
	unsigned long size;

	value_oid = get_note(&c->tree, key_oid);
	if (!value_oid)
		return NULL;
	value = read_object_file(value_oid, &type, &size);

	*outsize = size;
	return value;
}

int notes_cache_put(struct notes_cache *c, struct object_id *key_oid,
		    const char *data, size_t size)
{
	struct object_id value_oid;

	if (write_object_file(data, size, "blob", &value_oid) < 0)
		return -1;
	return add_note(&c->tree, key_oid, &value_oid, NULL);
}
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