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Copy pathiterator.c
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441 lines (372 loc) · 10.8 KB
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/*
* Generic reference iterator infrastructure. See refs-internal.h for
* documentation about the design and use of reference iterators.
*/
#define DISABLE_SIGN_COMPARE_WARNINGS
#include "git-compat-util.h"
#include "refs.h"
#include "refs/refs-internal.h"
#include "iterator.h"
int ref_iterator_advance(struct ref_iterator *ref_iterator)
{
return ref_iterator->vtable->advance(ref_iterator);
}
int ref_iterator_seek(struct ref_iterator *ref_iterator, const char *refname,
unsigned int flags)
{
return ref_iterator->vtable->seek(ref_iterator, refname, flags);
}
void ref_iterator_free(struct ref_iterator *ref_iterator)
{
if (ref_iterator) {
ref_iterator->vtable->release(ref_iterator);
/* Help make use-after-free bugs fail quickly: */
ref_iterator->vtable = NULL;
free(ref_iterator);
}
}
void base_ref_iterator_init(struct ref_iterator *iter,
struct ref_iterator_vtable *vtable)
{
iter->vtable = vtable;
memset(&iter->ref, 0, sizeof(iter->ref));
}
struct empty_ref_iterator {
struct ref_iterator base;
};
static int empty_ref_iterator_advance(struct ref_iterator *ref_iterator UNUSED)
{
return ITER_DONE;
}
static int empty_ref_iterator_seek(struct ref_iterator *ref_iterator UNUSED,
const char *refname UNUSED,
unsigned int flags UNUSED)
{
return 0;
}
static void empty_ref_iterator_release(struct ref_iterator *ref_iterator UNUSED)
{
}
static struct ref_iterator_vtable empty_ref_iterator_vtable = {
.advance = empty_ref_iterator_advance,
.seek = empty_ref_iterator_seek,
.release = empty_ref_iterator_release,
};
struct ref_iterator *empty_ref_iterator_begin(void)
{
struct empty_ref_iterator *iter = xcalloc(1, sizeof(*iter));
struct ref_iterator *ref_iterator = &iter->base;
base_ref_iterator_init(ref_iterator, &empty_ref_iterator_vtable);
return ref_iterator;
}
int is_empty_ref_iterator(struct ref_iterator *ref_iterator)
{
return ref_iterator->vtable == &empty_ref_iterator_vtable;
}
struct merge_ref_iterator {
struct ref_iterator base;
struct ref_iterator *iter0, *iter0_owned;
struct ref_iterator *iter1, *iter1_owned;
ref_iterator_select_fn *select;
void *cb_data;
/*
* A pointer to iter0 or iter1 (whichever is supplying the
* current value), or NULL if advance has not yet been called.
*/
struct ref_iterator **current;
};
enum iterator_selection ref_iterator_select(struct ref_iterator *iter_worktree,
struct ref_iterator *iter_common,
void *cb_data UNUSED)
{
if (iter_worktree && !iter_common) {
/*
* Return the worktree ref if there are no more common refs.
*/
return ITER_SELECT_0;
} else if (iter_common) {
/*
* In case we have pending worktree and common refs we need to
* yield them based on their lexicographical order. Worktree
* refs that have the same name as common refs shadow the
* latter.
*/
if (iter_worktree) {
int cmp = strcmp(iter_worktree->ref.name,
iter_common->ref.name);
if (cmp < 0)
return ITER_SELECT_0;
else if (!cmp)
return ITER_SELECT_0_SKIP_1;
}
/*
* We now know that the lexicographically-next ref is a common
* ref. When the common ref is a shared one we return it.
*/
if (parse_worktree_ref(iter_common->ref.name, NULL, NULL,
NULL) == REF_WORKTREE_SHARED)
return ITER_SELECT_1;
/*
* Otherwise, if the common ref is a per-worktree ref we skip
* it because it would belong to the main worktree, not ours.
*/
return ITER_SKIP_1;
} else {
return ITER_DONE;
}
}
static int merge_ref_iterator_advance(struct ref_iterator *ref_iterator)
{
struct merge_ref_iterator *iter =
(struct merge_ref_iterator *)ref_iterator;
int ok;
if (!iter->current) {
/* Initialize: advance both iterators to their first entries */
if ((ok = ref_iterator_advance(iter->iter0)) != ITER_OK) {
iter->iter0 = NULL;
if (ok == ITER_ERROR)
goto error;
}
if ((ok = ref_iterator_advance(iter->iter1)) != ITER_OK) {
iter->iter1 = NULL;
if (ok == ITER_ERROR)
goto error;
}
} else {
/*
* Advance the current iterator past the just-used
* entry:
*/
if ((ok = ref_iterator_advance(*iter->current)) != ITER_OK) {
*iter->current = NULL;
if (ok == ITER_ERROR)
goto error;
}
}
/* Loop until we find an entry that we can yield. */
while (1) {
struct ref_iterator **secondary;
enum iterator_selection selection =
iter->select(iter->iter0, iter->iter1, iter->cb_data);
if (selection == ITER_SELECT_DONE) {
return ITER_DONE;
} else if (selection == ITER_SELECT_ERROR) {
return ITER_ERROR;
}
if ((selection & ITER_CURRENT_SELECTION_MASK) == 0) {
iter->current = &iter->iter0;
secondary = &iter->iter1;
} else {
iter->current = &iter->iter1;
secondary = &iter->iter0;
}
if (selection & ITER_SKIP_SECONDARY) {
if ((ok = ref_iterator_advance(*secondary)) != ITER_OK) {
*secondary = NULL;
if (ok == ITER_ERROR)
goto error;
}
}
if (selection & ITER_YIELD_CURRENT) {
iter->base.ref = (*iter->current)->ref;
return ITER_OK;
}
}
error:
return ITER_ERROR;
}
static int merge_ref_iterator_seek(struct ref_iterator *ref_iterator,
const char *refname, unsigned int flags)
{
struct merge_ref_iterator *iter =
(struct merge_ref_iterator *)ref_iterator;
int ret;
iter->current = NULL;
iter->iter0 = iter->iter0_owned;
iter->iter1 = iter->iter1_owned;
ret = ref_iterator_seek(iter->iter0, refname, flags);
if (ret < 0)
return ret;
ret = ref_iterator_seek(iter->iter1, refname, flags);
if (ret < 0)
return ret;
return 0;
}
static void merge_ref_iterator_release(struct ref_iterator *ref_iterator)
{
struct merge_ref_iterator *iter =
(struct merge_ref_iterator *)ref_iterator;
ref_iterator_free(iter->iter0_owned);
ref_iterator_free(iter->iter1_owned);
}
static struct ref_iterator_vtable merge_ref_iterator_vtable = {
.advance = merge_ref_iterator_advance,
.seek = merge_ref_iterator_seek,
.release = merge_ref_iterator_release,
};
struct ref_iterator *merge_ref_iterator_begin(
struct ref_iterator *iter0, struct ref_iterator *iter1,
ref_iterator_select_fn *select, void *cb_data)
{
struct merge_ref_iterator *iter = xcalloc(1, sizeof(*iter));
struct ref_iterator *ref_iterator = &iter->base;
/*
* We can't do the same kind of is_empty_ref_iterator()-style
* optimization here as overlay_ref_iterator_begin() does,
* because we don't know the semantics of the select function.
* It might, for example, implement "intersect" by passing
* references through only if they exist in both iterators.
*/
base_ref_iterator_init(ref_iterator, &merge_ref_iterator_vtable);
iter->iter0 = iter->iter0_owned = iter0;
iter->iter1 = iter->iter1_owned = iter1;
iter->select = select;
iter->cb_data = cb_data;
iter->current = NULL;
return ref_iterator;
}
/*
* A ref_iterator_select_fn that overlays the items from front on top
* of those from back (like loose refs over packed refs). See
* overlay_ref_iterator_begin().
*/
static enum iterator_selection overlay_iterator_select(
struct ref_iterator *front, struct ref_iterator *back,
void *cb_data UNUSED)
{
int cmp;
if (!back)
return front ? ITER_SELECT_0 : ITER_SELECT_DONE;
else if (!front)
return ITER_SELECT_1;
cmp = strcmp(front->ref.name, back->ref.name);
if (cmp < 0)
return ITER_SELECT_0;
else if (cmp > 0)
return ITER_SELECT_1;
else
return ITER_SELECT_0_SKIP_1;
}
struct ref_iterator *overlay_ref_iterator_begin(
struct ref_iterator *front, struct ref_iterator *back)
{
/*
* Optimization: if one of the iterators is empty, return the
* other one rather than incurring the overhead of wrapping
* them.
*/
if (is_empty_ref_iterator(front)) {
ref_iterator_free(front);
return back;
} else if (is_empty_ref_iterator(back)) {
ref_iterator_free(back);
return front;
}
return merge_ref_iterator_begin(front, back, overlay_iterator_select, NULL);
}
struct prefix_ref_iterator {
struct ref_iterator base;
struct ref_iterator *iter0;
char *prefix;
int trim;
};
/* Return -1, 0, 1 if refname is before, inside, or after the prefix. */
static int compare_prefix(const char *refname, const char *prefix)
{
while (*prefix) {
if (*refname != *prefix)
return ((unsigned char)*refname < (unsigned char)*prefix) ? -1 : +1;
refname++;
prefix++;
}
return 0;
}
static int prefix_ref_iterator_advance(struct ref_iterator *ref_iterator)
{
struct prefix_ref_iterator *iter =
(struct prefix_ref_iterator *)ref_iterator;
int ok;
while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
int cmp = compare_prefix(iter->iter0->ref.name, iter->prefix);
if (cmp < 0)
continue;
/*
* As the source iterator is ordered, we
* can stop the iteration as soon as we see a
* refname that comes after the prefix:
*/
if (cmp > 0)
return ITER_DONE;
iter->base.ref = iter->iter0->ref;
if (iter->trim) {
/*
* It is nonsense to trim off characters that
* you haven't already checked for via a
* prefix check, whether via this
* `prefix_ref_iterator` or upstream in
* `iter0`). So if there wouldn't be at least
* one character left in the refname after
* trimming, report it as a bug:
*/
if (strlen(iter->base.ref.name) <= iter->trim)
BUG("attempt to trim too many characters");
iter->base.ref.name += iter->trim;
}
return ITER_OK;
}
return ok;
}
static int prefix_ref_iterator_seek(struct ref_iterator *ref_iterator,
const char *refname, unsigned int flags)
{
struct prefix_ref_iterator *iter =
(struct prefix_ref_iterator *)ref_iterator;
if (flags & REF_ITERATOR_SEEK_SET_PREFIX) {
free(iter->prefix);
iter->prefix = xstrdup_or_null(refname);
}
return ref_iterator_seek(iter->iter0, refname, flags);
}
static void prefix_ref_iterator_release(struct ref_iterator *ref_iterator)
{
struct prefix_ref_iterator *iter =
(struct prefix_ref_iterator *)ref_iterator;
ref_iterator_free(iter->iter0);
free(iter->prefix);
}
static struct ref_iterator_vtable prefix_ref_iterator_vtable = {
.advance = prefix_ref_iterator_advance,
.seek = prefix_ref_iterator_seek,
.release = prefix_ref_iterator_release,
};
struct ref_iterator *prefix_ref_iterator_begin(struct ref_iterator *iter0,
const char *prefix,
int trim)
{
struct prefix_ref_iterator *iter;
struct ref_iterator *ref_iterator;
if (!*prefix && !trim)
return iter0; /* optimization: no need to wrap iterator */
CALLOC_ARRAY(iter, 1);
ref_iterator = &iter->base;
base_ref_iterator_init(ref_iterator, &prefix_ref_iterator_vtable);
iter->iter0 = iter0;
iter->prefix = xstrdup(prefix);
iter->trim = trim;
return ref_iterator;
}
int do_for_each_ref_iterator(struct ref_iterator *iter,
refs_for_each_cb fn, void *cb_data)
{
int retval = 0, ok;
while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
retval = fn(&iter->ref, cb_data);
if (retval)
goto out;
}
out:
if (ok == ITER_ERROR)
retval = -1;
ref_iterator_free(iter);
return retval;
}
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