The ninteenth batch

[alt-git.git] / pathspec.c

#include "git-compat-util.h"
#include "abspath.h"
#include "parse.h"
#include "dir.h"
#include "environment.h"
#include "gettext.h"
#include "pathspec.h"
#include "attr.h"
#include "read-cache.h"
#include "repository.h"
#include "setup.h"
#include "strvec.h"
#include "symlinks.h"
#include "quote.h"
#include "wildmatch.h"

/*
 * Finds which of the given pathspecs match items in the index.
 *
 * For each pathspec, sets the corresponding entry in the seen[] array
 * (which should be specs items long, i.e. the same size as pathspec)
 * to the nature of the "closest" (i.e. most specific) match found for
 * that pathspec in the index, if it was a closer type of match than
 * the existing entry.  As an optimization, matching is skipped
 * altogether if seen[] already only contains non-zero entries.
 *
 * If seen[] has not already been written to, it may make sense
 * to use find_pathspecs_matching_against_index() instead.
 */
void add_pathspec_matches_against_index(const struct pathspec *pathspec,
                                        struct index_state *istate,
                                        char *seen,
                                        enum ps_skip_worktree_action sw_action)
{
        int num_unmatched = 0, i;

        /*
         * Since we are walking the index as if we were walking the directory,
         * we have to mark the matched pathspec as seen; otherwise we will
         * mistakenly think that the user gave a pathspec that did not match
         * anything.
         */
        for (i = 0; i < pathspec->nr; i++)
                if (!seen[i])
                        num_unmatched++;
        if (!num_unmatched)
                return;
        for (i = 0; i < istate->cache_nr; i++) {
                const struct cache_entry *ce = istate->cache[i];
                if (sw_action == PS_IGNORE_SKIP_WORKTREE &&
                    (ce_skip_worktree(ce) || !path_in_sparse_checkout(ce->name, istate)))
                        continue;
                ce_path_match(istate, ce, pathspec, seen);
        }
}

/*
 * Finds which of the given pathspecs match items in the index.
 *
 * This is a one-shot wrapper around add_pathspec_matches_against_index()
 * which allocates, populates, and returns a seen[] array indicating the
 * nature of the "closest" (i.e. most specific) matches which each of the
 * given pathspecs achieves against all items in the index.
 */
char *find_pathspecs_matching_against_index(const struct pathspec *pathspec,
                                            struct index_state *istate,
                                            enum ps_skip_worktree_action sw_action)
{
        char *seen = xcalloc(pathspec->nr, 1);
        add_pathspec_matches_against_index(pathspec, istate, seen, sw_action);
        return seen;
}

char *find_pathspecs_matching_skip_worktree(const struct pathspec *pathspec)
{
        struct index_state *istate = the_repository->index;
        char *seen = xcalloc(pathspec->nr, 1);
        int i;

        for (i = 0; i < istate->cache_nr; i++) {
                struct cache_entry *ce = istate->cache[i];
                if (ce_skip_worktree(ce) || !path_in_sparse_checkout(ce->name, istate))
                    ce_path_match(istate, ce, pathspec, seen);
        }

        return seen;
}

/*
 * Magic pathspec
 *
 * Possible future magic semantics include stuff like:
 *
 *      { PATHSPEC_RECURSIVE, '*', "recursive" },
 *      { PATHSPEC_REGEXP, '\0', "regexp" },
 *
 */

static struct pathspec_magic {
        unsigned bit;
        char mnemonic; /* this cannot be ':'! */
        const char *name;
} pathspec_magic[] = {
        { PATHSPEC_FROMTOP,  '/', "top" },
        { PATHSPEC_LITERAL, '\0', "literal" },
        { PATHSPEC_GLOB,    '\0', "glob" },
        { PATHSPEC_ICASE,   '\0', "icase" },
        { PATHSPEC_EXCLUDE,  '!', "exclude" },
        { PATHSPEC_ATTR,    '\0', "attr" },
};

static void prefix_magic(struct strbuf *sb, int prefixlen,
                         unsigned magic, const char *element)
{
        /* No magic was found in element, just add prefix magic */
        if (!magic) {
                strbuf_addf(sb, ":(prefix:%d)", prefixlen);
                return;
        }

        /*
         * At this point, we know that parse_element_magic() was able
         * to extract some pathspec magic from element. So we know
         * element is correctly formatted in either shorthand or
         * longhand form
         */
        if (element[1] != '(') {
                /* Process an element in shorthand form (e.g. ":!/<match>") */
                strbuf_addstr(sb, ":(");
                for (int i = 0; i < ARRAY_SIZE(pathspec_magic); i++) {
                        if ((magic & pathspec_magic[i].bit) &&
                            pathspec_magic[i].mnemonic) {
                                if (sb->buf[sb->len - 1] != '(')
                                        strbuf_addch(sb, ',');
                                strbuf_addstr(sb, pathspec_magic[i].name);
                        }
                }
        } else {
                /* For the longhand form, we copy everything up to the final ')' */
                size_t len = strchr(element, ')') - element;
                strbuf_add(sb, element, len);
        }
        strbuf_addf(sb, ",prefix:%d)", prefixlen);
}

static size_t strcspn_escaped(const char *s, const char *stop)
{
        const char *i;

        for (i = s; *i; i++) {
                /* skip the escaped character */
                if (i[0] == '\\' && i[1]) {
                        i++;
                        continue;
                }

                if (strchr(stop, *i))
                        break;
        }
        return i - s;
}

static inline int invalid_value_char(const char ch)
{
        if (isalnum(ch) || strchr(",-_", ch))
                return 0;
        return -1;
}

static char *attr_value_unescape(const char *value)
{
        const char *src;
        char *dst, *ret;

        ret = xmallocz(strlen(value));
        for (src = value, dst = ret; *src; src++, dst++) {
                if (*src == '\\') {
                        if (!src[1])
                                die(_("Escape character '\\' not allowed as "
                                      "last character in attr value"));
                        src++;
                }
                if (invalid_value_char(*src))
                        die("cannot use '%c' for value matching", *src);
                *dst = *src;
        }
        *dst = '\0';
        return ret;
}

static void parse_pathspec_attr_match(struct pathspec_item *item, const char *value)
{
        struct string_list_item *si;
        struct string_list list = STRING_LIST_INIT_DUP;

        if (item->attr_check || item->attr_match)
                die(_("Only one 'attr:' specification is allowed."));

        if (!value || !*value)
                die(_("attr spec must not be empty"));

        string_list_split(&list, value, ' ', -1);
        string_list_remove_empty_items(&list, 0);

        item->attr_check = attr_check_alloc();
        CALLOC_ARRAY(item->attr_match, list.nr);

        for_each_string_list_item(si, &list) {
                size_t attr_len;
                char *attr_name;
                const struct git_attr *a;

                int j = item->attr_match_nr++;
                const char *attr = si->string;
                struct attr_match *am = &item->attr_match[j];

                switch (*attr) {
                case '!':
                        am->match_mode = MATCH_UNSPECIFIED;
                        attr++;
                        attr_len = strlen(attr);
                        break;
                case '-':
                        am->match_mode = MATCH_UNSET;
                        attr++;
                        attr_len = strlen(attr);
                        break;
                default:
                        attr_len = strcspn(attr, "=");
                        if (attr[attr_len] != '=')
                                am->match_mode = MATCH_SET;
                        else {
                                const char *v = &attr[attr_len + 1];
                                am->match_mode = MATCH_VALUE;
                                am->value = attr_value_unescape(v);
                        }
                        break;
                }

                attr_name = xmemdupz(attr, attr_len);
                a = git_attr(attr_name);
                if (!a)
                        die(_("invalid attribute name %s"), attr_name);

                attr_check_append(item->attr_check, a);

                free(attr_name);
        }

        if (item->attr_check->nr != item->attr_match_nr)
                BUG("should have same number of entries");

        string_list_clear(&list, 0);
}

static inline int get_literal_global(void)
{
        static int literal = -1;

        if (literal < 0)
                literal = git_env_bool(GIT_LITERAL_PATHSPECS_ENVIRONMENT, 0);

        return literal;
}

static inline int get_glob_global(void)
{
        static int glob = -1;

        if (glob < 0)
                glob = git_env_bool(GIT_GLOB_PATHSPECS_ENVIRONMENT, 0);

        return glob;
}

static inline int get_noglob_global(void)
{
        static int noglob = -1;

        if (noglob < 0)
                noglob = git_env_bool(GIT_NOGLOB_PATHSPECS_ENVIRONMENT, 0);

        return noglob;
}

static inline int get_icase_global(void)
{
        static int icase = -1;

        if (icase < 0)
                icase = git_env_bool(GIT_ICASE_PATHSPECS_ENVIRONMENT, 0);

        return icase;
}

static int get_global_magic(int element_magic)
{
        int global_magic = 0;

        if (get_literal_global())
                global_magic |= PATHSPEC_LITERAL;

        /* --glob-pathspec is overridden by :(literal) */
        if (get_glob_global() && !(element_magic & PATHSPEC_LITERAL))
                global_magic |= PATHSPEC_GLOB;

        if (get_glob_global() && get_noglob_global())
                die(_("global 'glob' and 'noglob' pathspec settings are incompatible"));

        if (get_icase_global())
                global_magic |= PATHSPEC_ICASE;

        if ((global_magic & PATHSPEC_LITERAL) &&
            (global_magic & ~PATHSPEC_LITERAL))
                die(_("global 'literal' pathspec setting is incompatible "
                      "with all other global pathspec settings"));

        /* --noglob-pathspec adds :(literal) _unless_ :(glob) is specified */
        if (get_noglob_global() && !(element_magic & PATHSPEC_GLOB))
                global_magic |= PATHSPEC_LITERAL;

        return global_magic;
}

/*
 * Parse the pathspec element looking for long magic
 *
 * saves all magic in 'magic'
 * if prefix magic is used, save the prefix length in 'prefix_len'
 * returns the position in 'elem' after all magic has been parsed
 */
static const char *parse_long_magic(unsigned *magic, int *prefix_len,
                                    struct pathspec_item *item,
                                    const char *elem)
{
        const char *pos;
        const char *nextat;

        for (pos = elem + 2; *pos && *pos != ')'; pos = nextat) {
                size_t len = strcspn_escaped(pos, ",)");
                int i;

                if (pos[len] == ',')
                        nextat = pos + len + 1; /* handle ',' */
                else
                        nextat = pos + len; /* handle ')' and '\0' */

                if (!len)
                        continue;

                if (starts_with(pos, "prefix:")) {
                        char *endptr;
                        *prefix_len = strtol(pos + 7, &endptr, 10);
                        if (endptr - pos != len)
                                die(_("invalid parameter for pathspec magic 'prefix'"));
                        continue;
                }

                if (starts_with(pos, "attr:")) {
                        char *attr_body = xmemdupz(pos + 5, len - 5);
                        parse_pathspec_attr_match(item, attr_body);
                        *magic |= PATHSPEC_ATTR;
                        free(attr_body);
                        continue;
                }

                for (i = 0; i < ARRAY_SIZE(pathspec_magic); i++) {
                        if (strlen(pathspec_magic[i].name) == len &&
                            !strncmp(pathspec_magic[i].name, pos, len)) {
                                *magic |= pathspec_magic[i].bit;
                                break;
                        }
                }

                if (ARRAY_SIZE(pathspec_magic) <= i)
                        die(_("Invalid pathspec magic '%.*s' in '%s'"),
                            (int) len, pos, elem);
        }

        if (*pos != ')')
                die(_("Missing ')' at the end of pathspec magic in '%s'"),
                    elem);
        pos++;

        return pos;
}

/*
 * Parse the pathspec element looking for short magic
 *
 * saves all magic in 'magic'
 * returns the position in 'elem' after all magic has been parsed
 */
static const char *parse_short_magic(unsigned *magic, const char *elem)
{
        const char *pos;

        for (pos = elem + 1; *pos && *pos != ':'; pos++) {
                char ch = *pos;
                int i;

                /* Special case alias for '!' */
                if (ch == '^') {
                        *magic |= PATHSPEC_EXCLUDE;
                        continue;
                }

                if (!is_pathspec_magic(ch))
                        break;

                for (i = 0; i < ARRAY_SIZE(pathspec_magic); i++) {
                        if (pathspec_magic[i].mnemonic == ch) {
                                *magic |= pathspec_magic[i].bit;
                                break;
                        }
                }

                if (ARRAY_SIZE(pathspec_magic) <= i)
                        die(_("Unimplemented pathspec magic '%c' in '%s'"),
                            ch, elem);
        }

        if (*pos == ':')
                pos++;

        return pos;
}

static const char *parse_element_magic(unsigned *magic, int *prefix_len,
                                       struct pathspec_item *item,
                                       const char *elem)
{
        if (elem[0] != ':' || get_literal_global())
                return elem; /* nothing to do */
        else if (elem[1] == '(')
                /* longhand */
                return parse_long_magic(magic, prefix_len, item, elem);
        else
                /* shorthand */
                return parse_short_magic(magic, elem);
}

/*
 * Perform the initialization of a pathspec_item based on a pathspec element.
 */
static void init_pathspec_item(struct pathspec_item *item, unsigned flags,
                               const char *prefix, int prefixlen,
                               const char *elt)
{
        unsigned magic = 0, element_magic = 0;
        const char *copyfrom = elt;
        char *match;
        int pathspec_prefix = -1;

        item->attr_check = NULL;
        item->attr_match = NULL;
        item->attr_match_nr = 0;

        /* PATHSPEC_LITERAL_PATH ignores magic */
        if (flags & PATHSPEC_LITERAL_PATH) {
                magic = PATHSPEC_LITERAL;
        } else {
                copyfrom = parse_element_magic(&element_magic,
                                               &pathspec_prefix,
                                               item,
                                               elt);
                magic |= element_magic;
                magic |= get_global_magic(element_magic);
        }

        item->magic = magic;

        if (pathspec_prefix >= 0 &&
            (prefixlen || (prefix && *prefix)))
                BUG("'prefix' magic is supposed to be used at worktree's root");

        if ((magic & PATHSPEC_LITERAL) && (magic & PATHSPEC_GLOB))
                die(_("%s: 'literal' and 'glob' are incompatible"), elt);

        /* Create match string which will be used for pathspec matching */
        if (pathspec_prefix >= 0) {
                match = xstrdup(copyfrom);
                prefixlen = pathspec_prefix;
        } else if (magic & PATHSPEC_FROMTOP) {
                match = xstrdup(copyfrom);
                prefixlen = 0;
        } else {
                match = prefix_path_gently(prefix, prefixlen,
                                           &prefixlen, copyfrom);
                if (!match) {
                        const char *hint_path;

                        if (!have_git_dir())
                                die(_("'%s' is outside the directory tree"),
                                    copyfrom);
                        hint_path = get_git_work_tree();
                        if (!hint_path)
                                hint_path = get_git_dir();
                        die(_("%s: '%s' is outside repository at '%s'"), elt,
                            copyfrom, absolute_path(hint_path));
                }
        }

        item->match = match;
        item->len = strlen(item->match);
        item->prefix = prefixlen;

        /*
         * Prefix the pathspec (keep all magic) and assign to
         * original. Useful for passing to another command.
         */
        if ((flags & PATHSPEC_PREFIX_ORIGIN) &&
            !get_literal_global()) {
                struct strbuf sb = STRBUF_INIT;

                /* Preserve the actual prefix length of each pattern */
                prefix_magic(&sb, prefixlen, element_magic, elt);

                strbuf_addstr(&sb, match);
                item->original = strbuf_detach(&sb, NULL);
        } else {
                item->original = xstrdup(elt);
        }

        if (magic & PATHSPEC_LITERAL) {
                item->nowildcard_len = item->len;
        } else {
                item->nowildcard_len = simple_length(item->match);
                if (item->nowildcard_len < prefixlen)
                        item->nowildcard_len = prefixlen;
        }

        item->flags = 0;
        if (magic & PATHSPEC_GLOB) {
                /*
                 * FIXME: should we enable ONESTAR in _GLOB for
                 * pattern "* * / * . c"?
                 */
        } else {
                if (item->nowildcard_len < item->len &&
                    item->match[item->nowildcard_len] == '*' &&
                    no_wildcard(item->match + item->nowildcard_len + 1))
                        item->flags |= PATHSPEC_ONESTAR;
        }

        /* sanity checks, pathspec matchers assume these are sane */
        if (item->nowildcard_len > item->len ||
            item->prefix         > item->len) {
                BUG("error initializing pathspec_item");
        }
}

static int pathspec_item_cmp(const void *a_, const void *b_)
{
        struct pathspec_item *a, *b;

        a = (struct pathspec_item *)a_;
        b = (struct pathspec_item *)b_;
        return strcmp(a->match, b->match);
}

void pathspec_magic_names(unsigned magic, struct strbuf *out)
{
        int i;
        for (i = 0; i < ARRAY_SIZE(pathspec_magic); i++) {
                const struct pathspec_magic *m = pathspec_magic + i;
                if (!(magic & m->bit))
                        continue;
                if (out->len)
                        strbuf_addstr(out, ", ");

                if (m->mnemonic)
                        strbuf_addf(out, _("'%s' (mnemonic: '%c')"),
                                    m->name, m->mnemonic);
                else
                        strbuf_addf(out, "'%s'", m->name);
        }
}

static void NORETURN unsupported_magic(const char *pattern,
                                       unsigned magic)
{
        struct strbuf sb = STRBUF_INIT;
        pathspec_magic_names(magic, &sb);
        /*
         * We may want to substitute "this command" with a command
         * name. E.g. when "git add -p" or "git add -i" dies when running
         * "checkout -p"
         */
        die(_("%s: pathspec magic not supported by this command: %s"),
            pattern, sb.buf);
}

void parse_pathspec(struct pathspec *pathspec,
                    unsigned magic_mask, unsigned flags,
                    const char *prefix, const char **argv)
{
        struct pathspec_item *item;
        const char *entry = argv ? *argv : NULL;
        int i, n, prefixlen, nr_exclude = 0;

        memset(pathspec, 0, sizeof(*pathspec));

        if (flags & PATHSPEC_MAXDEPTH_VALID)
                pathspec->magic |= PATHSPEC_MAXDEPTH;

        /* No arguments, no prefix -> no pathspec */
        if (!entry && !prefix)
                return;

        if ((flags & PATHSPEC_PREFER_CWD) &&
            (flags & PATHSPEC_PREFER_FULL))
                BUG("PATHSPEC_PREFER_CWD and PATHSPEC_PREFER_FULL are incompatible");

        /* No arguments with prefix -> prefix pathspec */
        if (!entry) {
                if (flags & PATHSPEC_PREFER_FULL)
                        return;

                if (!(flags & PATHSPEC_PREFER_CWD))
                        BUG("PATHSPEC_PREFER_CWD requires arguments");

                pathspec->items = CALLOC_ARRAY(item, 1);
                item->match = xstrdup(prefix);
                item->original = xstrdup(prefix);
                item->nowildcard_len = item->len = strlen(prefix);
                item->prefix = item->len;
                pathspec->nr = 1;
                return;
        }

        n = 0;
        while (argv[n]) {
                if (*argv[n] == '\0')
                        die("empty string is not a valid pathspec. "
                                  "please use . instead if you meant to match all paths");
                n++;
        }

        pathspec->nr = n;
        ALLOC_ARRAY(pathspec->items, n + 1);
        item = pathspec->items;
        prefixlen = prefix ? strlen(prefix) : 0;

        for (i = 0; i < n; i++) {
                entry = argv[i];

                init_pathspec_item(item + i, flags, prefix, prefixlen, entry);

                if (item[i].magic & PATHSPEC_EXCLUDE)
                        nr_exclude++;
                if (item[i].magic & magic_mask)
                        unsupported_magic(entry, item[i].magic & magic_mask);

                if ((flags & PATHSPEC_SYMLINK_LEADING_PATH) &&
                    has_symlink_leading_path(item[i].match, item[i].len)) {
                        die(_("pathspec '%s' is beyond a symbolic link"), entry);
                }

                if (item[i].nowildcard_len < item[i].len)
                        pathspec->has_wildcard = 1;
                pathspec->magic |= item[i].magic;
        }

        /*
         * If everything is an exclude pattern, add one positive pattern
         * that matches everything. We allocated an extra one for this.
         */
        if (nr_exclude == n) {
                int plen = (!(flags & PATHSPEC_PREFER_CWD)) ? 0 : prefixlen;
                init_pathspec_item(item + n, 0, prefix, plen, ".");
                pathspec->nr++;
        }

        if (pathspec->magic & PATHSPEC_MAXDEPTH) {
                if (flags & PATHSPEC_KEEP_ORDER)
                        BUG("PATHSPEC_MAXDEPTH_VALID and PATHSPEC_KEEP_ORDER are incompatible");
                QSORT(pathspec->items, pathspec->nr, pathspec_item_cmp);
        }
}

void parse_pathspec_file(struct pathspec *pathspec, unsigned magic_mask,
                         unsigned flags, const char *prefix,
                         const char *file, int nul_term_line)
{
        struct strvec parsed_file = STRVEC_INIT;
        strbuf_getline_fn getline_fn = nul_term_line ? strbuf_getline_nul :
                                                       strbuf_getline;
        struct strbuf buf = STRBUF_INIT;
        struct strbuf unquoted = STRBUF_INIT;
        FILE *in;

        if (!strcmp(file, "-"))
                in = stdin;
        else
                in = xfopen(file, "r");

        while (getline_fn(&buf, in) != EOF) {
                if (!nul_term_line && buf.buf[0] == '"') {
                        strbuf_reset(&unquoted);
                        if (unquote_c_style(&unquoted, buf.buf, NULL))
                                die(_("line is badly quoted: %s"), buf.buf);
                        strbuf_swap(&buf, &unquoted);
                }
                strvec_push(&parsed_file, buf.buf);
                strbuf_reset(&buf);
        }

        strbuf_release(&unquoted);
        strbuf_release(&buf);
        if (in != stdin)
                fclose(in);

        parse_pathspec(pathspec, magic_mask, flags, prefix, parsed_file.v);
        strvec_clear(&parsed_file);
}

void copy_pathspec(struct pathspec *dst, const struct pathspec *src)
{
        int i, j;

        *dst = *src;
        DUP_ARRAY(dst->items, src->items, dst->nr);

        for (i = 0; i < dst->nr; i++) {
                struct pathspec_item *d = &dst->items[i];
                struct pathspec_item *s = &src->items[i];

                d->match = xstrdup(s->match);
                d->original = xstrdup(s->original);

                DUP_ARRAY(d->attr_match, s->attr_match, d->attr_match_nr);
                for (j = 0; j < d->attr_match_nr; j++) {
                        const char *value = s->attr_match[j].value;
                        d->attr_match[j].value = xstrdup_or_null(value);
                }

                d->attr_check = attr_check_dup(s->attr_check);
        }
}

void clear_pathspec(struct pathspec *pathspec)
{
        int i, j;

        for (i = 0; i < pathspec->nr; i++) {
                free(pathspec->items[i].match);
                free(pathspec->items[i].original);

                for (j = 0; j < pathspec->items[i].attr_match_nr; j++)
                        free(pathspec->items[i].attr_match[j].value);
                free(pathspec->items[i].attr_match);

                if (pathspec->items[i].attr_check)
                        attr_check_free(pathspec->items[i].attr_check);
        }

        FREE_AND_NULL(pathspec->items);
        pathspec->nr = 0;
}

int match_pathspec_attrs(struct index_state *istate,
                         const char *name, int namelen,
                         const struct pathspec_item *item)
{
        int i;
        char *to_free = NULL;

        if (name[namelen])
                name = to_free = xmemdupz(name, namelen);

        git_check_attr(istate, name, item->attr_check);

        free(to_free);

        for (i = 0; i < item->attr_match_nr; i++) {
                const char *value;
                int matched;
                enum attr_match_mode match_mode;

                value = item->attr_check->items[i].value;
                match_mode = item->attr_match[i].match_mode;

                if (ATTR_TRUE(value))
                        matched = (match_mode == MATCH_SET);
                else if (ATTR_FALSE(value))
                        matched = (match_mode == MATCH_UNSET);
                else if (ATTR_UNSET(value))
                        matched = (match_mode == MATCH_UNSPECIFIED);
                else
                        matched = (match_mode == MATCH_VALUE &&
                                   !strcmp(item->attr_match[i].value, value));
                if (!matched)
                        return 0;
        }

        return 1;
}

int pathspec_needs_expanded_index(struct index_state *istate,
                                  const struct pathspec *pathspec)
{
        unsigned int i, pos;
        int res = 0;
        char *skip_worktree_seen = NULL;

        /*
         * If index is not sparse, no index expansion is needed.
         */
        if (!istate->sparse_index)
                return 0;

        /*
         * When using a magic pathspec, assume for the sake of simplicity that
         * the index needs to be expanded to match all matchable files.
         */
        if (pathspec->magic)
                return 1;

        for (i = 0; i < pathspec->nr; i++) {
                struct pathspec_item item = pathspec->items[i];

                /*
                 * If the pathspec item has a wildcard, the index should be expanded
                 * if the pathspec has the possibility of matching a subset of entries inside
                 * of a sparse directory (but not the entire directory).
                 *
                 * If the pathspec item is a literal path, the index only needs to be expanded
                 * if a) the pathspec isn't in the sparse checkout cone (to make sure we don't
                 * expand for in-cone files) and b) it doesn't match any sparse directories
                 * (since we can reset whole sparse directories without expanding them).
                 */
                if (item.nowildcard_len < item.len) {
                        /*
                         * Special case: if the pattern is a path inside the cone
                         * followed by only wildcards, the pattern cannot match
                         * partial sparse directories, so we know we don't need to
                         * expand the index.
                         *
                         * Examples:
                         * - in-cone/foo***: doesn't need expanded index
                         * - not-in-cone/bar*: may need expanded index
                         * - **.c: may need expanded index
                         */
                        if (strspn(item.original + item.nowildcard_len, "*") == item.len - item.nowildcard_len &&
                            path_in_cone_mode_sparse_checkout(item.original, istate))
                                continue;

                        for (pos = 0; pos < istate->cache_nr; pos++) {
                                struct cache_entry *ce = istate->cache[pos];

                                if (!S_ISSPARSEDIR(ce->ce_mode))
                                        continue;

                                /*
                                 * If the pre-wildcard length is longer than the sparse
                                 * directory name and the sparse directory is the first
                                 * component of the pathspec, need to expand the index.
                                 */
                                if (item.nowildcard_len > ce_namelen(ce) &&
                                    !strncmp(item.original, ce->name, ce_namelen(ce))) {
                                        res = 1;
                                        break;
                                }

                                /*
                                 * If the pre-wildcard length is shorter than the sparse
                                 * directory and the pathspec does not match the whole
                                 * directory, need to expand the index.
                                 */
                                if (!strncmp(item.original, ce->name, item.nowildcard_len) &&
                                    wildmatch(item.original, ce->name, 0)) {
                                        res = 1;
                                        break;
                                }
                        }
                } else if (!path_in_cone_mode_sparse_checkout(item.original, istate) &&
                           !matches_skip_worktree(pathspec, i, &skip_worktree_seen))
                        res = 1;

                if (res > 0)
                        break;
        }

        free(skip_worktree_seen);
        return res;
}