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Re-implement "check_file_directory_conflict()"

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This is (imho) more readable, and is also a lot faster.  The expense of
looking up sub-directory beginnings was killing us on things like
"git-diff-cache", even though that one didn't even care at all about the
file vs directory conflicts.

We really only care when somebody tries to add a conflicting name to
stage 0.

We should go through the conflict rules more carefully some day.
This commit is contained in:
Linus Torvalds 2005-06-18 20:21:34 -07:00
parent 3d958064e0
commit 12676608fe
1 changed files with 88 additions and 89 deletions
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177
read-cache.c
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@ -171,6 +171,84 @@ int ce_same_name(struct cache_entry *a, struct cache_entry *b)
return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
}
/*
* Do we have another file that has the beginning components being a
* proper superset of the name we're trying to add?
*/
static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replace)
{
int retval = 0;
int len = ce_namelen(ce);
const char *name = ce->name;
while (pos < active_nr) {
struct cache_entry *p = active_cache[pos++];
if (len >= ce_namelen(p))
break;
if (memcmp(name, p->name, len))
break;
if (p->name[len] != '/')
continue;
fprintf(stderr, "conflict: %s %s\n", ce->name, p->name);
retval = -1;
if (!ok_to_replace)
break;
remove_cache_entry_at(--pos);
}
return retval;
}
/*
* Do we have another file with a pathname that is a proper
* subset of the name we're trying to add?
*/
static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace)
{
int retval = 0;
const char *name = ce->name;
const char *slash = name + ce_namelen(ce);
for (;;) {
int len;
for (;;) {
if (*--slash == '/')
break;
if (slash <= ce->name)
return retval;
}
len = slash - name;
pos = cache_name_pos(name, len);
if (pos >= 0) {
retval = -1;
if (ok_to_replace)
break;
remove_cache_entry_at(pos);
continue;
}
/*
* Trivial optimization: if we find an entry that
* already matches the sub-directory, then we know
* we're ok, and we can exit
*/
pos = -pos-1;
if (pos < active_nr) {
struct cache_entry *p = active_cache[pos];
if (ce_namelen(p) <= len)
continue;
if (p->name[len] != '/')
continue;
if (memcmp(p->name, name, len))
continue;
break;
}
}
return retval;
}
/* We may be in a situation where we already have path/file and path
* is being added, or we already have path and path/file is being
* added. Either one would result in a nonsense tree that has path
@ -180,98 +258,19 @@ int ce_same_name(struct cache_entry *a, struct cache_entry *b)
* from the cache so the caller should recompute the insert position.
* When this happens, we return non-zero.
*/
static int check_file_directory_conflict(const struct cache_entry *ce,
int ok_to_replace)
static int check_file_directory_conflict(const struct cache_entry *ce, int pos, int ok_to_replace)
{
int pos, replaced = 0;
const char *path = ce->name;
int namelen = strlen(path);
int stage = ce_stage(ce);
char *pathbuf = xmalloc(namelen + 1);
char *cp;
memcpy(pathbuf, path, namelen + 1);
/*
* We are inserting path/file. Do they have path registered at
* the same stage? We need to do this for all the levels of our
* subpath.
* We check if the path is a sub-path of a subsequent pathname
* first, since removing those will not change the position
* in the array
*/
cp = pathbuf;
while (1) {
char *ep = strchr(cp, '/');
int len;
if (!ep)
break;
*ep = 0; /* first cut it at slash */
len = ep - pathbuf;
pos = cache_name_pos(pathbuf,
ntohs(create_ce_flags(len, stage)));
if (0 <= pos) {
/* Our leading path component is registered as a file,
* and we are trying to make it a directory. This is
* bad.
*/
if (!ok_to_replace) {
free(pathbuf);
return -1;
}
fprintf(stderr, "removing file '%s' to replace it with a directory to create '%s'.\n", pathbuf, path);
remove_cache_entry_at(pos);
replaced = 1;
}
*ep = '/'; /* then restore it and go downwards */
cp = ep + 1;
}
free(pathbuf);
/* Do we have an entry in the cache that makes our path a prefix
* of it? That is, are we creating a file where they already expect
* a directory there?
int retval = has_file_name(ce, pos, ok_to_replace);
/*
* Then check if the path might have a clashing sub-directory
* before it.
*/
pos = cache_name_pos(path,
ntohs(create_ce_flags(namelen, stage)));
/* (0 <= pos) cannot happen because add_cache_entry()
* should have taken care of that case.
*/
pos = -pos-1;
/* pos would point at an existing entry that would come immediately
* after our path. It could be the same as our path in higher stage,
* or different path but in a lower stage.
*
* E.g. when we are inserting path at stage 2,
*
* 1 path
* pos-> 3 path
* 2 path/file1
* 3 path/file1
* 2 path/file2
* 2 patho
*
* We need to examine pos, ignore it because it is at different
* stage, examine next to find the path/file at stage 2, and
* complain. We need to do this until we are not the leading
* path of an existing entry anymore.
*/
while (pos < active_nr) {
struct cache_entry *other = active_cache[pos];
if (strncmp(other->name, path, namelen))
break; /* it is not our "subdirectory" anymore */
if ((ce_stage(other) == stage) &&
other->name[namelen] == '/') {
if (!ok_to_replace)
return -1;
fprintf(stderr, "removing file '%s' under '%s' to be replaced with a file\n", other->name, path);
remove_cache_entry_at(pos);
replaced = 1;
continue; /* cycle without updating pos */
}
pos++;
}
return replaced;
return retval + has_dir_name(ce, pos, ok_to_replace);
}
int add_cache_entry(struct cache_entry *ce, int option)
@ -304,7 +303,7 @@ int add_cache_entry(struct cache_entry *ce, int option)
if (!ok_to_add)
return -1;
if (check_file_directory_conflict(ce, ok_to_replace)) {
if (!ce_stage(ce) && check_file_directory_conflict(ce, pos, ok_to_replace)) {
if (!ok_to_replace)
return -1;
pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));