avoid computing zero offsets from NULL pointer

[git.git] / list-objects-filter.c

#include "cache.h"
#include "dir.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
#include "diff.h"
#include "tree-walk.h"
#include "revision.h"
#include "list-objects.h"
#include "list-objects-filter.h"
#include "list-objects-filter-options.h"
#include "oidmap.h"
#include "oidset.h"
#include "object-store.h"

/* Remember to update object flag allocation in object.h */
/*
 * FILTER_SHOWN_BUT_REVISIT -- we set this bit on tree objects
 * that have been shown, but should be revisited if they appear
 * in the traversal (until we mark it SEEN).  This is a way to
 * let us silently de-dup calls to show() in the caller.  This
 * is subtly different from the "revision.h:SHOWN" and the
 * "sha1-name.c:ONELINE_SEEN" bits.  And also different from
 * the non-de-dup usage in pack-bitmap.c
 */
#define FILTER_SHOWN_BUT_REVISIT (1<<21)

struct subfilter {
        struct filter *filter;
        struct oidset seen;
        struct oidset omits;
        struct object_id skip_tree;
        unsigned is_skipping_tree : 1;
};

struct filter {
        enum list_objects_filter_result (*filter_object_fn)(
                struct repository *r,
                enum list_objects_filter_situation filter_situation,
                struct object *obj,
                const char *pathname,
                const char *filename,
                struct oidset *omits,
                void *filter_data);

        /*
         * Optional. If this function is supplied and the filter needs
         * to collect omits, then this function is called once before
         * free_fn is called.
         *
         * This is required because the following two conditions hold:
         *
         *   a. A tree filter can add and remove objects as an object
         *      graph is traversed.
         *   b. A combine filter's omit set is the union of all its
         *      subfilters, which may include tree: filters.
         *
         * As such, the omits sets must be separate sets, and can only
         * be unioned after the traversal is completed.
         */
        void (*finalize_omits_fn)(struct oidset *omits, void *filter_data);

        void (*free_fn)(void *filter_data);

        void *filter_data;

        /* If non-NULL, the filter collects a list of the omitted OIDs here. */
        struct oidset *omits;
};

static enum list_objects_filter_result filter_blobs_none(
        struct repository *r,
        enum list_objects_filter_situation filter_situation,
        struct object *obj,
        const char *pathname,
        const char *filename,
        struct oidset *omits,
        void *filter_data_)
{
        switch (filter_situation) {
        default:
                BUG("unknown filter_situation: %d", filter_situation);

        case LOFS_BEGIN_TREE:
                assert(obj->type == OBJ_TREE);
                /* always include all tree objects */
                return LOFR_MARK_SEEN | LOFR_DO_SHOW;

        case LOFS_END_TREE:
                assert(obj->type == OBJ_TREE);
                return LOFR_ZERO;

        case LOFS_BLOB:
                assert(obj->type == OBJ_BLOB);
                assert((obj->flags & SEEN) == 0);

                if (omits)
                        oidset_insert(omits, &obj->oid);
                return LOFR_MARK_SEEN; /* but not LOFR_DO_SHOW (hard omit) */
        }
}

static void filter_blobs_none__init(
        struct list_objects_filter_options *filter_options,
        struct filter *filter)
{
        filter->filter_object_fn = filter_blobs_none;
        filter->free_fn = free;
}

/*
 * A filter for list-objects to omit ALL trees and blobs from the traversal.
 * Can OPTIONALLY collect a list of the omitted OIDs.
 */
struct filter_trees_depth_data {
        /*
         * Maps trees to the minimum depth at which they were seen. It is not
         * necessary to re-traverse a tree at deeper or equal depths than it has
         * already been traversed.
         *
         * We can't use LOFR_MARK_SEEN for tree objects since this will prevent
         * it from being traversed at shallower depths.
         */
        struct oidmap seen_at_depth;

        unsigned long exclude_depth;
        unsigned long current_depth;
};

struct seen_map_entry {
        struct oidmap_entry base;
        size_t depth;
};

/* Returns 1 if the oid was in the omits set before it was invoked. */
static int filter_trees_update_omits(
        struct object *obj,
        struct oidset *omits,
        int include_it)
{
        if (!omits)
                return 0;

        if (include_it)
                return oidset_remove(omits, &obj->oid);
        else
                return oidset_insert(omits, &obj->oid);
}

static enum list_objects_filter_result filter_trees_depth(
        struct repository *r,
        enum list_objects_filter_situation filter_situation,
        struct object *obj,
        const char *pathname,
        const char *filename,
        struct oidset *omits,
        void *filter_data_)
{
        struct filter_trees_depth_data *filter_data = filter_data_;
        struct seen_map_entry *seen_info;
        int include_it = filter_data->current_depth <
                filter_data->exclude_depth;
        int filter_res;
        int already_seen;

        /*
         * Note that we do not use _MARK_SEEN in order to allow re-traversal in
         * case we encounter a tree or blob again at a shallower depth.
         */

        switch (filter_situation) {
        default:
                BUG("unknown filter_situation: %d", filter_situation);

        case LOFS_END_TREE:
                assert(obj->type == OBJ_TREE);
                filter_data->current_depth--;
                return LOFR_ZERO;

        case LOFS_BLOB:
                filter_trees_update_omits(obj, omits, include_it);
                return include_it ? LOFR_MARK_SEEN | LOFR_DO_SHOW : LOFR_ZERO;

        case LOFS_BEGIN_TREE:
                seen_info = oidmap_get(
                        &filter_data->seen_at_depth, &obj->oid);
                if (!seen_info) {
                        seen_info = xcalloc(1, sizeof(*seen_info));
                        oidcpy(&seen_info->base.oid, &obj->oid);
                        seen_info->depth = filter_data->current_depth;
                        oidmap_put(&filter_data->seen_at_depth, seen_info);
                        already_seen = 0;
                } else {
                        already_seen =
                                filter_data->current_depth >= seen_info->depth;
                }

                if (already_seen) {
                        filter_res = LOFR_SKIP_TREE;
                } else {
                        int been_omitted = filter_trees_update_omits(
                                obj, omits, include_it);
                        seen_info->depth = filter_data->current_depth;

                        if (include_it)
                                filter_res = LOFR_DO_SHOW;
                        else if (omits && !been_omitted)
                                /*
                                 * Must update omit information of children
                                 * recursively; they have not been omitted yet.
                                 */
                                filter_res = LOFR_ZERO;
                        else
                                filter_res = LOFR_SKIP_TREE;
                }

                filter_data->current_depth++;
                return filter_res;
        }
}

static void filter_trees_free(void *filter_data) {
        struct filter_trees_depth_data *d = filter_data;
        if (!d)
                return;
        oidmap_free(&d->seen_at_depth, 1);
        free(d);
}

static void filter_trees_depth__init(
        struct list_objects_filter_options *filter_options,
        struct filter *filter)
{
        struct filter_trees_depth_data *d = xcalloc(1, sizeof(*d));
        oidmap_init(&d->seen_at_depth, 0);
        d->exclude_depth = filter_options->tree_exclude_depth;
        d->current_depth = 0;

        filter->filter_data = d;
        filter->filter_object_fn = filter_trees_depth;
        filter->free_fn = filter_trees_free;
}

/*
 * A filter for list-objects to omit large blobs.
 * And to OPTIONALLY collect a list of the omitted OIDs.
 */
struct filter_blobs_limit_data {
        unsigned long max_bytes;
};

static enum list_objects_filter_result filter_blobs_limit(
        struct repository *r,
        enum list_objects_filter_situation filter_situation,
        struct object *obj,
        const char *pathname,
        const char *filename,
        struct oidset *omits,
        void *filter_data_)
{
        struct filter_blobs_limit_data *filter_data = filter_data_;
        unsigned long object_length;
        enum object_type t;

        switch (filter_situation) {
        default:
                BUG("unknown filter_situation: %d", filter_situation);

        case LOFS_BEGIN_TREE:
                assert(obj->type == OBJ_TREE);
                /* always include all tree objects */
                return LOFR_MARK_SEEN | LOFR_DO_SHOW;

        case LOFS_END_TREE:
                assert(obj->type == OBJ_TREE);
                return LOFR_ZERO;

        case LOFS_BLOB:
                assert(obj->type == OBJ_BLOB);
                assert((obj->flags & SEEN) == 0);

                t = oid_object_info(r, &obj->oid, &object_length);
                if (t != OBJ_BLOB) { /* probably OBJ_NONE */
                        /*
                         * We DO NOT have the blob locally, so we cannot
                         * apply the size filter criteria.  Be conservative
                         * and force show it (and let the caller deal with
                         * the ambiguity).
                         */
                        goto include_it;
                }

                if (object_length < filter_data->max_bytes)
                        goto include_it;

                if (omits)
                        oidset_insert(omits, &obj->oid);
                return LOFR_MARK_SEEN; /* but not LOFR_DO_SHOW (hard omit) */
        }

include_it:
        if (omits)
                oidset_remove(omits, &obj->oid);
        return LOFR_MARK_SEEN | LOFR_DO_SHOW;
}

static void filter_blobs_limit__init(
        struct list_objects_filter_options *filter_options,
        struct filter *filter)
{
        struct filter_blobs_limit_data *d = xcalloc(1, sizeof(*d));
        d->max_bytes = filter_options->blob_limit_value;

        filter->filter_data = d;
        filter->filter_object_fn = filter_blobs_limit;
        filter->free_fn = free;
}

/*
 * A filter driven by a sparse-checkout specification to only
 * include blobs that a sparse checkout would populate.
 *
 * The sparse-checkout spec can be loaded from a blob with the
 * given OID or from a local pathname.  We allow an OID because
 * the repo may be bare or we may be doing the filtering on the
 * server.
 */
struct frame {
        /*
         * default_match is the usual default include/exclude value that
         * should be inherited as we recurse into directories based
         * upon pattern matching of the directory itself or of a
         * containing directory.
         */
        enum pattern_match_result default_match;

        /*
         * 1 if the directory (recursively) contains any provisionally
         * omitted objects.
         *
         * 0 if everything (recursively) contained in this directory
         * has been explicitly included (SHOWN) in the result and
         * the directory may be short-cut later in the traversal.
         */
        unsigned child_prov_omit : 1;
};

struct filter_sparse_data {
        struct pattern_list pl;

        size_t nr, alloc;
        struct frame *array_frame;
};

static enum list_objects_filter_result filter_sparse(
        struct repository *r,
        enum list_objects_filter_situation filter_situation,
        struct object *obj,
        const char *pathname,
        const char *filename,
        struct oidset *omits,
        void *filter_data_)
{
        struct filter_sparse_data *filter_data = filter_data_;
        int dtype;
        struct frame *frame;
        enum pattern_match_result match;

        switch (filter_situation) {
        default:
                BUG("unknown filter_situation: %d", filter_situation);

        case LOFS_BEGIN_TREE:
                assert(obj->type == OBJ_TREE);
                dtype = DT_DIR;
                match = path_matches_pattern_list(pathname, strlen(pathname),
                                                  filename, &dtype, &filter_data->pl,
                                                  r->index);
                if (match == UNDECIDED)
                        match = filter_data->array_frame[filter_data->nr - 1].default_match;

                ALLOC_GROW(filter_data->array_frame, filter_data->nr + 1,
                           filter_data->alloc);
                filter_data->array_frame[filter_data->nr].default_match = match;
                filter_data->array_frame[filter_data->nr].child_prov_omit = 0;
                filter_data->nr++;

                /*
                 * A directory with this tree OID may appear in multiple
                 * places in the tree. (Think of a directory move or copy,
                 * with no other changes, so the OID is the same, but the
                 * full pathnames of objects within this directory are new
                 * and may match is_excluded() patterns differently.)
                 * So we cannot mark this directory as SEEN (yet), since
                 * that will prevent process_tree() from revisiting this
                 * tree object with other pathname prefixes.
                 *
                 * Only _DO_SHOW the tree object the first time we visit
                 * this tree object.
                 *
                 * We always show all tree objects.  A future optimization
                 * may want to attempt to narrow this.
                 */
                if (obj->flags & FILTER_SHOWN_BUT_REVISIT)
                        return LOFR_ZERO;
                obj->flags |= FILTER_SHOWN_BUT_REVISIT;
                return LOFR_DO_SHOW;

        case LOFS_END_TREE:
                assert(obj->type == OBJ_TREE);
                assert(filter_data->nr > 1);

                frame = &filter_data->array_frame[--filter_data->nr];

                /*
                 * Tell our parent directory if any of our children were
                 * provisionally omitted.
                 */
                filter_data->array_frame[filter_data->nr - 1].child_prov_omit |=
                        frame->child_prov_omit;

                /*
                 * If there are NO provisionally omitted child objects (ALL child
                 * objects in this folder were INCLUDED), then we can mark the
                 * folder as SEEN (so we will not have to revisit it again).
                 */
                if (!frame->child_prov_omit)
                        return LOFR_MARK_SEEN;
                return LOFR_ZERO;

        case LOFS_BLOB:
                assert(obj->type == OBJ_BLOB);
                assert((obj->flags & SEEN) == 0);

                frame = &filter_data->array_frame[filter_data->nr - 1];

                dtype = DT_REG;
                match = path_matches_pattern_list(pathname, strlen(pathname),
                                            filename, &dtype, &filter_data->pl,
                                            r->index);
                if (match == UNDECIDED)
                        match = frame->default_match;
                if (match == MATCHED) {
                        if (omits)
                                oidset_remove(omits, &obj->oid);
                        return LOFR_MARK_SEEN | LOFR_DO_SHOW;
                }

                /*
                 * Provisionally omit it.  We've already established that
                 * this pathname is not in the sparse-checkout specification
                 * with the CURRENT pathname, so we *WANT* to omit this blob.
                 *
                 * However, a pathname elsewhere in the tree may also
                 * reference this same blob, so we cannot reject it yet.
                 * Leave the LOFR_ bits unset so that if the blob appears
                 * again in the traversal, we will be asked again.
                 */
                if (omits)
                        oidset_insert(omits, &obj->oid);

                /*
                 * Remember that at least 1 blob in this tree was
                 * provisionally omitted.  This prevents us from short
                 * cutting the tree in future iterations.
                 */
                frame->child_prov_omit = 1;
                return LOFR_ZERO;
        }
}


static void filter_sparse_free(void *filter_data)
{
        struct filter_sparse_data *d = filter_data;
        free(d->array_frame);
        free(d);
}

static void filter_sparse_oid__init(
        struct list_objects_filter_options *filter_options,
        struct filter *filter)
{
        struct filter_sparse_data *d = xcalloc(1, sizeof(*d));
        struct object_context oc;
        struct object_id sparse_oid;

        if (get_oid_with_context(the_repository,
                                 filter_options->sparse_oid_name,
                                 GET_OID_BLOB, &sparse_oid, &oc))
                die(_("unable to access sparse blob in '%s'"),
                    filter_options->sparse_oid_name);
        if (add_patterns_from_blob_to_list(&sparse_oid, "", 0, &d->pl) < 0)
                die(_("unable to parse sparse filter data in %s"),
                    oid_to_hex(&sparse_oid));

        ALLOC_GROW(d->array_frame, d->nr + 1, d->alloc);
        d->array_frame[d->nr].default_match = 0; /* default to include */
        d->array_frame[d->nr].child_prov_omit = 0;
        d->nr++;

        filter->filter_data = d;
        filter->filter_object_fn = filter_sparse;
        filter->free_fn = filter_sparse_free;
}

/* A filter which only shows objects shown by all sub-filters. */
struct combine_filter_data {
        struct subfilter *sub;
        size_t nr;
};

static enum list_objects_filter_result process_subfilter(
        struct repository *r,
        enum list_objects_filter_situation filter_situation,
        struct object *obj,
        const char *pathname,
        const char *filename,
        struct subfilter *sub)
{
        enum list_objects_filter_result result;

        /*
         * Check and update is_skipping_tree before oidset_contains so
         * that is_skipping_tree gets unset even when the object is
         * marked as seen.  As of this writing, no filter uses
         * LOFR_MARK_SEEN on trees that also uses LOFR_SKIP_TREE, so the
         * ordering is only theoretically important. Be cautious if you
         * change the order of the below checks and more filters have
         * been added!
         */
        if (sub->is_skipping_tree) {
                if (filter_situation == LOFS_END_TREE &&
                    oideq(&obj->oid, &sub->skip_tree))
                        sub->is_skipping_tree = 0;
                else
                        return LOFR_ZERO;
        }
        if (oidset_contains(&sub->seen, &obj->oid))
                return LOFR_ZERO;

        result = list_objects_filter__filter_object(
                r, filter_situation, obj, pathname, filename, sub->filter);

        if (result & LOFR_MARK_SEEN)
                oidset_insert(&sub->seen, &obj->oid);

        if (result & LOFR_SKIP_TREE) {
                sub->is_skipping_tree = 1;
                sub->skip_tree = obj->oid;
        }

        return result;
}

static enum list_objects_filter_result filter_combine(
        struct repository *r,
        enum list_objects_filter_situation filter_situation,
        struct object *obj,
        const char *pathname,
        const char *filename,
        struct oidset *omits,
        void *filter_data)
{
        struct combine_filter_data *d = filter_data;
        enum list_objects_filter_result combined_result =
                LOFR_DO_SHOW | LOFR_MARK_SEEN | LOFR_SKIP_TREE;
        size_t sub;

        for (sub = 0; sub < d->nr; sub++) {
                enum list_objects_filter_result sub_result = process_subfilter(
                        r, filter_situation, obj, pathname, filename,
                        &d->sub[sub]);
                if (!(sub_result & LOFR_DO_SHOW))
                        combined_result &= ~LOFR_DO_SHOW;
                if (!(sub_result & LOFR_MARK_SEEN))
                        combined_result &= ~LOFR_MARK_SEEN;
                if (!d->sub[sub].is_skipping_tree)
                        combined_result &= ~LOFR_SKIP_TREE;
        }

        return combined_result;
}

static void filter_combine__free(void *filter_data)
{
        struct combine_filter_data *d = filter_data;
        size_t sub;
        for (sub = 0; sub < d->nr; sub++) {
                list_objects_filter__free(d->sub[sub].filter);
                oidset_clear(&d->sub[sub].seen);
                if (d->sub[sub].omits.set.size)
                        BUG("expected oidset to be cleared already");
        }
        free(d->sub);
}

static void add_all(struct oidset *dest, struct oidset *src) {
        struct oidset_iter iter;
        struct object_id *src_oid;

        oidset_iter_init(src, &iter);
        while ((src_oid = oidset_iter_next(&iter)) != NULL)
                oidset_insert(dest, src_oid);
}

static void filter_combine__finalize_omits(
        struct oidset *omits,
        void *filter_data)
{
        struct combine_filter_data *d = filter_data;
        size_t sub;

        for (sub = 0; sub < d->nr; sub++) {
                add_all(omits, &d->sub[sub].omits);
                oidset_clear(&d->sub[sub].omits);
        }
}

static void filter_combine__init(
        struct list_objects_filter_options *filter_options,
        struct filter* filter)
{
        struct combine_filter_data *d = xcalloc(1, sizeof(*d));
        size_t sub;

        d->nr = filter_options->sub_nr;
        d->sub = xcalloc(d->nr, sizeof(*d->sub));
        for (sub = 0; sub < d->nr; sub++)
                d->sub[sub].filter = list_objects_filter__init(
                        filter->omits ? &d->sub[sub].omits : NULL,
                        &filter_options->sub[sub]);

        filter->filter_data = d;
        filter->filter_object_fn = filter_combine;
        filter->free_fn = filter_combine__free;
        filter->finalize_omits_fn = filter_combine__finalize_omits;
}

typedef void (*filter_init_fn)(
        struct list_objects_filter_options *filter_options,
        struct filter *filter);

/*
 * Must match "enum list_objects_filter_choice".
 */
static filter_init_fn s_filters[] = {
        NULL,
        filter_blobs_none__init,
        filter_blobs_limit__init,
        filter_trees_depth__init,
        filter_sparse_oid__init,
        filter_combine__init,
};

struct filter *list_objects_filter__init(
        struct oidset *omitted,
        struct list_objects_filter_options *filter_options)
{
        struct filter *filter;
        filter_init_fn init_fn;

        assert((sizeof(s_filters) / sizeof(s_filters[0])) == LOFC__COUNT);

        if (filter_options->choice >= LOFC__COUNT)
                BUG("invalid list-objects filter choice: %d",
                    filter_options->choice);

        init_fn = s_filters[filter_options->choice];
        if (!init_fn)
                return NULL;

        filter = xcalloc(1, sizeof(*filter));
        filter->omits = omitted;
        init_fn(filter_options, filter);
        return filter;
}

enum list_objects_filter_result list_objects_filter__filter_object(
        struct repository *r,
        enum list_objects_filter_situation filter_situation,
        struct object *obj,
        const char *pathname,
        const char *filename,
        struct filter *filter)
{
        if (filter && (obj->flags & NOT_USER_GIVEN))
                return filter->filter_object_fn(r, filter_situation, obj,
                                                pathname, filename,
                                                filter->omits,
                                                filter->filter_data);
        /*
         * No filter is active or user gave object explicitly. In this case,
         * always show the object (except when LOFS_END_TREE, since this tree
         * had already been shown when LOFS_BEGIN_TREE).
         */
        if (filter_situation == LOFS_END_TREE)
                return 0;
        return LOFR_MARK_SEEN | LOFR_DO_SHOW;
}

void list_objects_filter__free(struct filter *filter)
{
        if (!filter)
                return;
        if (filter->finalize_omits_fn && filter->omits)
                filter->finalize_omits_fn(filter->omits, filter->filter_data);
        filter->free_fn(filter->filter_data);
        free(filter);
}