[thirdparty/git.git] / builtin / diff.c

/*
 * Builtin "git diff"
 *
 * Copyright (c) 2006 Junio C Hamano
 */

#define USE_THE_REPOSITORY_VARIABLE
#define DISABLE_SIGN_COMPARE_WARNINGS

#include "builtin.h"
#include "config.h"
#include "ewah/ewok.h"
#include "lockfile.h"
#include "color.h"
#include "commit.h"
#include "gettext.h"
#include "tag.h"
#include "diff.h"
#include "diff-merges.h"
#include "diffcore.h"
#include "preload-index.h"
#include "read-cache-ll.h"
#include "revision.h"
#include "log-tree.h"
#include "setup.h"
#include "oid-array.h"
#include "tree.h"

#define DIFF_NO_INDEX_EXPLICIT 1
#define DIFF_NO_INDEX_IMPLICIT 2

static const char builtin_diff_usage[] =
"git diff [<options>] [<commit>] [--] [<path>...]\n"
"   or: git diff [<options>] --cached [--merge-base] [<commit>] [--] [<path>...]\n"
"   or: git diff [<options>] [--merge-base] <commit> [<commit>...] <commit> [--] [<path>...]\n"
"   or: git diff [<options>] <commit>...<commit> [--] [<path>...]\n"
"   or: git diff [<options>] <blob> <blob>\n"
"   or: git diff [<options>] --no-index [--] <path> <path> [<pathspec>...]"
"\n"
COMMON_DIFF_OPTIONS_HELP;

static const char *blob_path(struct object_array_entry *entry)
{
        return entry->path ? entry->path : entry->name;
}

static void stuff_change(struct diff_options *opt,
                         unsigned old_mode, unsigned new_mode,
                         const struct object_id *old_oid,
                         const struct object_id *new_oid,
                         int old_oid_valid,
                         int new_oid_valid,
                         const char *old_path,
                         const char *new_path)
{
        struct diff_filespec *one, *two;

        if (!is_null_oid(old_oid) && !is_null_oid(new_oid) &&
            oideq(old_oid, new_oid) && (old_mode == new_mode))
                return;

        if (opt->flags.reverse_diff) {
                SWAP(old_mode, new_mode);
                SWAP(old_oid, new_oid);
                SWAP(old_path, new_path);
        }

        if (opt->prefix &&
            (strncmp(old_path, opt->prefix, opt->prefix_length) ||
             strncmp(new_path, opt->prefix, opt->prefix_length)))
                return;

        one = alloc_filespec(old_path);
        two = alloc_filespec(new_path);
        fill_filespec(one, old_oid, old_oid_valid, old_mode);
        fill_filespec(two, new_oid, new_oid_valid, new_mode);

        diff_queue(&diff_queued_diff, one, two);
}

static void builtin_diff_b_f(struct rev_info *revs,
                             int argc, const char **argv UNUSED,
                             struct object_array_entry **blob)
{
        /* Blob vs file in the working tree*/
        struct stat st;
        const char *path;

        if (argc > 1)
                usage(builtin_diff_usage);

        GUARD_PATHSPEC(&revs->prune_data, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
        path = revs->prune_data.items[0].match;

        if (lstat(path, &st))
                die_errno(_("failed to stat '%s'"), path);
        if (!(S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)))
                die(_("'%s': not a regular file or symlink"), path);

        diff_set_mnemonic_prefix(&revs->diffopt, "o/", "w/");

        if (blob[0]->mode == S_IFINVALID)
                blob[0]->mode = canon_mode(st.st_mode);

        stuff_change(&revs->diffopt,
                     blob[0]->mode, canon_mode(st.st_mode),
                     &blob[0]->item->oid, null_oid(the_hash_algo),
                     1, 0,
                     blob[0]->path ? blob[0]->path : path,
                     path);
        diffcore_std(&revs->diffopt);
        diff_flush(&revs->diffopt);
}

static void builtin_diff_blobs(struct rev_info *revs,
                               int argc, const char **argv UNUSED,
                               struct object_array_entry **blob)
{
        const unsigned mode = canon_mode(S_IFREG | 0644);

        if (argc > 1)
                usage(builtin_diff_usage);

        if (blob[0]->mode == S_IFINVALID)
                blob[0]->mode = mode;

        if (blob[1]->mode == S_IFINVALID)
                blob[1]->mode = mode;

        stuff_change(&revs->diffopt,
                     blob[0]->mode, blob[1]->mode,
                     &blob[0]->item->oid, &blob[1]->item->oid,
                     1, 1,
                     blob_path(blob[0]), blob_path(blob[1]));
        diffcore_std(&revs->diffopt);
        diff_flush(&revs->diffopt);
}

static void builtin_diff_index(struct rev_info *revs,
                               int argc, const char **argv)
{
        unsigned int option = 0;
        while (1 < argc) {
                const char *arg = argv[1];
                if (!strcmp(arg, "--cached") || !strcmp(arg, "--staged"))
                        option |= DIFF_INDEX_CACHED;
                else if (!strcmp(arg, "--merge-base"))
                        option |= DIFF_INDEX_MERGE_BASE;
                else
                        usage(builtin_diff_usage);
                argv++; argc--;
        }
        /*
         * Make sure there is one revision (i.e. pending object),
         * and there is no revision filtering parameters.
         */
        if (revs->pending.nr != 1 ||
            revs->max_count != -1 || revs->min_age != -1 ||
            revs->max_age != -1)
                usage(builtin_diff_usage);
        if (!(option & DIFF_INDEX_CACHED)) {
                setup_work_tree();
                if (repo_read_index_preload(the_repository,
                                            &revs->diffopt.pathspec, 0) < 0) {
                        die_errno("repo_read_index_preload");
                }
        } else if (repo_read_index(the_repository) < 0) {
                die_errno("repo_read_cache");
        }
        run_diff_index(revs, option);
}

static void builtin_diff_tree(struct rev_info *revs,
                              int argc, const char **argv,
                              struct object_array_entry *ent0,
                              struct object_array_entry *ent1)
{
        const struct object_id *(oid[2]);
        struct object_id mb_oid;
        int merge_base = 0;

        while (1 < argc) {
                const char *arg = argv[1];
                if (!strcmp(arg, "--merge-base"))
                        merge_base = 1;
                else
                        usage(builtin_diff_usage);
                argv++; argc--;
        }

        if (merge_base) {
                diff_get_merge_base(revs, &mb_oid);
                oid[0] = &mb_oid;
                oid[1] = &revs->pending.objects[1].item->oid;
        } else {
                int swap = 0;

                /*
                 * We saw two trees, ent0 and ent1.  If ent1 is uninteresting,
                 * swap them.
                 */
                if (ent1->item->flags & UNINTERESTING)
                        swap = 1;
                oid[swap] = &ent0->item->oid;
                oid[1 - swap] = &ent1->item->oid;
        }
        diff_tree_oid(oid[0], oid[1], "", &revs->diffopt);
        log_tree_diff_flush(revs);
}

static void builtin_diff_combined(struct rev_info *revs,
                                  int argc, const char **argv UNUSED,
                                  struct object_array_entry *ent,
                                  int ents, int first_non_parent)
{
        struct oid_array parents = OID_ARRAY_INIT;
        int i;

        if (argc > 1)
                usage(builtin_diff_usage);

        if (first_non_parent < 0)
                die(_("no merge given, only parents."));
        if (first_non_parent >= ents)
                BUG("first_non_parent out of range: %d", first_non_parent);

        diff_merges_set_dense_combined_if_unset(revs);

        for (i = 0; i < ents; i++) {
                if (i != first_non_parent)
                        oid_array_append(&parents, &ent[i].item->oid);
        }
        diff_tree_combined(&ent[first_non_parent].item->oid, &parents, revs);
        oid_array_clear(&parents);
}

static void refresh_index_quietly(void)
{
        struct lock_file lock_file = LOCK_INIT;
        int fd;

        fd = repo_hold_locked_index(the_repository, &lock_file, 0);
        if (fd < 0)
                return;
        discard_index(the_repository->index);
        repo_read_index(the_repository);
        refresh_index(the_repository->index, REFRESH_QUIET|REFRESH_UNMERGED, NULL, NULL,
                      NULL);
        repo_update_index_if_able(the_repository, &lock_file);
}

static void builtin_diff_files(struct rev_info *revs, int argc, const char **argv)
{
        unsigned int options = 0;

        while (1 < argc && argv[1][0] == '-') {
                if (!strcmp(argv[1], "--base"))
                        revs->max_count = 1;
                else if (!strcmp(argv[1], "--ours"))
                        revs->max_count = 2;
                else if (!strcmp(argv[1], "--theirs"))
                        revs->max_count = 3;
                else if (!strcmp(argv[1], "-q"))
                        options |= DIFF_SILENT_ON_REMOVED;
                else if (!strcmp(argv[1], "-h"))
                        usage(builtin_diff_usage);
                else {
                        error(_("invalid option: %s"), argv[1]);
                        usage(builtin_diff_usage);
                }
                argv++; argc--;
        }

        /*
         * "diff --base" should not combine merges because it was not
         * asked to.  "diff -c" should not densify (if the user wants
         * dense one, --cc can be explicitly asked for, or just rely
         * on the default).
         */
        if (revs->max_count == -1 &&
            (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
                diff_merges_set_dense_combined_if_unset(revs);

        setup_work_tree();
        if (repo_read_index_preload(the_repository, &revs->diffopt.pathspec,
                                    0) < 0) {
                die_errno("repo_read_index_preload");
        }
        run_diff_files(revs, options);
}

struct symdiff {
        struct bitmap *skip;
        int warn;
        const char *base, *left, *right;
};

/*
 * Check for symmetric-difference arguments, and if present, arrange
 * everything we need to know to handle them correctly.  As a bonus,
 * weed out all bogus range-based revision specifications, e.g.,
 * "git diff A..B C..D" or "git diff A..B C" get rejected.
 *
 * For an actual symmetric diff, *symdiff is set this way:
 *
 *  - its skip is non-NULL and marks *all* rev->pending.objects[i]
 *    indices that the caller should ignore (extra merge bases, of
 *    which there might be many, and A in A...B).  Note that the
 *    chosen merge base and right side are NOT marked.
 *  - warn is set if there are multiple merge bases.
 *  - base, left, and right point to the names to use in a
 *    warning about multiple merge bases.
 *
 * If there is no symmetric diff argument, sym->skip is NULL and
 * sym->warn is cleared.  The remaining fields are not set.
 */
static void symdiff_prepare(struct rev_info *rev, struct symdiff *sym)
{
        int i, is_symdiff = 0, basecount = 0, othercount = 0;
        int lpos = -1, rpos = -1, basepos = -1;
        struct bitmap *map = NULL;

        /*
         * Use the whence fields to find merge bases and left and
         * right parts of symmetric difference, so that we do not
         * depend on the order that revisions are parsed.  If there
         * are any revs that aren't from these sources, we have a
         * "git diff C A...B" or "git diff A...B C" case.  Or we
         * could even get "git diff A...B C...E", for instance.
         *
         * If we don't have just one merge base, we pick one
         * at random.
         *
         * NB: REV_CMD_LEFT, REV_CMD_RIGHT are also used for A..B,
         * so we must check for SYMMETRIC_LEFT too.  The two arrays
         * rev->pending.objects and rev->cmdline.rev are parallel.
         */
        for (i = 0; i < rev->cmdline.nr; i++) {
                struct object *obj = rev->pending.objects[i].item;
                switch (rev->cmdline.rev[i].whence) {
                case REV_CMD_MERGE_BASE:
                        if (basepos < 0)
                                basepos = i;
                        basecount++;
                        break;          /* do mark all bases */
                case REV_CMD_LEFT:
                        if (lpos >= 0)
                                usage(builtin_diff_usage);
                        lpos = i;
                        if (obj->flags & SYMMETRIC_LEFT) {
                                is_symdiff = 1;
                                break;  /* do mark A */
                        }
                        continue;
                case REV_CMD_RIGHT:
                        if (rpos >= 0)
                                usage(builtin_diff_usage);
                        rpos = i;
                        continue;       /* don't mark B */
                case REV_CMD_PARENTS_ONLY:
                case REV_CMD_REF:
                case REV_CMD_REV:
                        othercount++;
                        continue;
                }
                if (!map)
                        map = bitmap_new();
                bitmap_set(map, i);
        }

        /*
         * Forbid any additional revs for both A...B and A..B.
         */
        if (lpos >= 0 && othercount > 0)
                usage(builtin_diff_usage);

        if (!is_symdiff) {
                bitmap_free(map);
                sym->warn = 0;
                sym->skip = NULL;
                return;
        }

        sym->left = rev->pending.objects[lpos].name;
        sym->right = rev->pending.objects[rpos].name;
        if (basecount == 0)
                die(_("%s...%s: no merge base"), sym->left, sym->right);
        sym->base = rev->pending.objects[basepos].name;
        bitmap_unset(map, basepos);     /* unmark the base we want */
        sym->warn = basecount > 1;
        sym->skip = map;
}

static void symdiff_release(struct symdiff *sdiff)
{
        bitmap_free(sdiff->skip);
}

int cmd_diff(int argc,
             const char **argv,
             const char *prefix,
             struct repository *repo UNUSED)
{
        int i;
        struct rev_info rev;
        struct object_array ent = OBJECT_ARRAY_INIT;
        int first_non_parent = -1;
        int blobs = 0, paths = 0;
        struct object_array_entry *blob[2];
        int nongit = 0, no_index = 0;
        int result;
        struct symdiff sdiff;

        /*
         * We could get N tree-ish in the rev.pending_objects list.
         * Also there could be M blobs there, and P pathspecs. --cached may
         * also be present.
         *
         * N=0, M=0:
         *      cache vs files (diff-files)
         *
         * N=0, M=0, --cached:
         *      HEAD vs cache (diff-index --cached)
         *
         * N=0, M=2:
         *      compare two random blobs.  P must be zero.
         *
         * N=0, M=1, P=1:
         *      compare a blob with a working tree file.
         *
         * N=1, M=0:
         *      tree vs files (diff-index)
         *
         * N=1, M=0, --cached:
         *      tree vs cache (diff-index --cached)
         *
         * N=2, M=0:
         *      tree vs tree (diff-tree)
         *
         * N=0, M=0, P=2:
         *      compare two filesystem entities (aka --no-index).
         *
         * Other cases are errors.
         */

        /* Were we asked to do --no-index explicitly? */
        for (i = 1; i < argc; i++) {
                if (!strcmp(argv[i], "--")) {
                        i++;
                        break;
                }
                if (!strcmp(argv[i], "--no-index"))
                        no_index = DIFF_NO_INDEX_EXPLICIT;
                if (argv[i][0] != '-')
                        break;
        }

        prefix = setup_git_directory_gently(&nongit);

        if (!nongit) {
                prepare_repo_settings(the_repository);
                the_repository->settings.command_requires_full_index = 0;
        }

        if (!no_index) {
                /*
                 * Treat git diff with at least one path outside of the
                 * repo the same as if the command would have been executed
                 * outside of a git repository.  In this case it behaves
                 * the same way as "git diff --no-index <a> <b>", which acts
                 * as a colourful "diff" replacement.
                 */
                if (nongit || ((argc == i + 2) &&
                               (!path_inside_repo(prefix, argv[i]) ||
                                !path_inside_repo(prefix, argv[i + 1]))))
                        no_index = DIFF_NO_INDEX_IMPLICIT;
        }

        /*
         * When operating outside of a Git repository we need to have a hash
         * algorithm at hand so that we can generate the blob hashes. We
         * default to SHA1 here, but may eventually want to change this to be
         * configurable via a command line option.
         */
        if (nongit)
                repo_set_hash_algo(the_repository, GIT_HASH_SHA1);

        init_diff_ui_defaults();
        git_config(git_diff_ui_config, NULL);
        prefix = precompose_argv_prefix(argc, argv, prefix);

        repo_init_revisions(the_repository, &rev, prefix);

        /* Set up defaults that will apply to both no-index and regular diffs. */
        init_diffstat_widths(&rev.diffopt);
        rev.diffopt.flags.allow_external = 1;
        rev.diffopt.flags.allow_textconv = 1;

        /* If this is a no-index diff, just run it and exit there. */
        if (no_index)
                exit(diff_no_index(&rev, the_repository->hash_algo,
                                   no_index == DIFF_NO_INDEX_IMPLICIT,
                                   argc, argv));


        /*
         * Otherwise, we are doing the usual "git" diff; set up any
         * further defaults that apply to regular diffs.
         */
        rev.diffopt.skip_stat_unmatch = !!diff_auto_refresh_index;

        /*
         * Default to intent-to-add entries invisible in the
         * index. This makes them show up as new files in diff-files
         * and not at all in diff-cached.
         */
        rev.diffopt.ita_invisible_in_index = 1;

        if (nongit)
                die(_("Not a git repository"));
        argc = setup_revisions(argc, argv, &rev, NULL);
        if (!rev.diffopt.output_format) {
                rev.diffopt.output_format = DIFF_FORMAT_PATCH;
                diff_setup_done(&rev.diffopt);
        }

        rev.diffopt.flags.recursive = 1;
        rev.diffopt.rotate_to_strict = 1;

        setup_diff_pager(&rev.diffopt);

        /*
         * Do we have --cached and not have a pending object, then
         * default to HEAD by hand.  Eek.
         */
        if (!rev.pending.nr) {
                int i;
                for (i = 1; i < argc; i++) {
                        const char *arg = argv[i];
                        if (!strcmp(arg, "--"))
                                break;
                        else if (!strcmp(arg, "--cached") ||
                                 !strcmp(arg, "--staged")) {
                                add_head_to_pending(&rev);
                                if (!rev.pending.nr) {
                                        struct tree *tree;
                                        tree = lookup_tree(the_repository,
                                                           the_repository->hash_algo->empty_tree);
                                        add_pending_object(&rev, &tree->object, "HEAD");
                                }
                                break;
                        }
                }
        }

        symdiff_prepare(&rev, &sdiff);
        for (i = 0; i < rev.pending.nr; i++) {
                struct object_array_entry *entry = &rev.pending.objects[i];
                struct object *obj = entry->item;
                const char *name = entry->name;
                int flags = (obj->flags & UNINTERESTING);
                if (!obj->parsed)
                        obj = parse_object(the_repository, &obj->oid);
                obj = deref_tag(the_repository, obj, NULL, 0);
                if (!obj)
                        die(_("invalid object '%s' given."), name);
                if (obj->type == OBJ_COMMIT)
                        obj = &repo_get_commit_tree(the_repository,
                                                    ((struct commit *)obj))->object;

                if (obj->type == OBJ_TREE) {
                        if (sdiff.skip && bitmap_get(sdiff.skip, i))
                                continue;
                        obj->flags |= flags;
                        add_object_array(obj, name, &ent);
                        if (first_non_parent < 0 &&
                            (i >= rev.cmdline.nr || /* HEAD by hand. */
                             rev.cmdline.rev[i].whence != REV_CMD_PARENTS_ONLY))
                                first_non_parent = ent.nr - 1;
                } else if (obj->type == OBJ_BLOB) {
                        if (2 <= blobs)
                                die(_("more than two blobs given: '%s'"), name);
                        blob[blobs] = entry;
                        blobs++;

                } else {
                        die(_("unhandled object '%s' given."), name);
                }
        }
        if (rev.prune_data.nr)
                paths += rev.prune_data.nr;

        /*
         * Now, do the arguments look reasonable?
         */
        if (!ent.nr) {
                switch (blobs) {
                case 0:
                        builtin_diff_files(&rev, argc, argv);
                        break;
                case 1:
                        if (paths != 1)
                                usage(builtin_diff_usage);
                        builtin_diff_b_f(&rev, argc, argv, blob);
                        break;
                case 2:
                        if (paths)
                                usage(builtin_diff_usage);
                        builtin_diff_blobs(&rev, argc, argv, blob);
                        break;
                default:
                        usage(builtin_diff_usage);
                }
        }
        else if (blobs)
                usage(builtin_diff_usage);
        else if (ent.nr == 1)
                builtin_diff_index(&rev, argc, argv);
        else if (ent.nr == 2) {
                if (sdiff.warn)
                        warning(_("%s...%s: multiple merge bases, using %s"),
                                sdiff.left, sdiff.right, sdiff.base);
                builtin_diff_tree(&rev, argc, argv,
                                  &ent.objects[0], &ent.objects[1]);
        } else
                builtin_diff_combined(&rev, argc, argv,
                                      ent.objects, ent.nr,
                                      first_non_parent);
        result = diff_result_code(&rev);
        if (1 < rev.diffopt.skip_stat_unmatch)
                refresh_index_quietly();
        release_revisions(&rev);
        object_array_clear(&ent);
        symdiff_release(&sdiff);
        return result;
}