/*
 * This handles recursive filename detection with exclude
 * files, index knowledge etc..
 *
 * Copyright (C) Linus Torvalds, 2005-2006
 *               Junio Hamano, 2005-2006
 */
#include "cache.h"
#include "dir.h"
#include "refs.h"

struct path_simplify {
        int len;
        const char *path;
};

static int read_directory_recursive(struct dir_struct *dir, const char *path, int len,
        int check_only, const struct path_simplify *simplify);
static int get_dtype(struct dirent *de, const char *path, int len);

/* helper string functions with support for the ignore_case flag */
int strcmp_icase(const char *a, const char *b)
{
        return ignore_case ? strcasecmp(a, b) : strcmp(a, b);
}

int strncmp_icase(const char *a, const char *b, size_t count)
{
        return ignore_case ? strncasecmp(a, b, count) : strncmp(a, b, count);
}

int fnmatch_icase(const char *pattern, const char *string, int flags)
{
        return fnmatch(pattern, string, flags | (ignore_case ? FNM_CASEFOLD : 0));
}

static int common_prefix(const char **pathspec)
{
        const char *path, *slash, *next;
        int prefix;

        if (!pathspec)
                return 0;

        path = *pathspec;
        slash = strrchr(path, '/');
        if (!slash)
                return 0;

        /*
         * The first 'prefix' characters of 'path' are common leading
         * path components among the pathspecs we have seen so far,
         * including the trailing slash.
         */
        prefix = slash - path + 1;
        while ((next = *++pathspec) != NULL) {
                int len, last_matching_slash = -1;
                for (len = 0; len < prefix && next[len] == path[len]; len++)
                        if (next[len] == '/')
                                last_matching_slash = len;
                if (len == prefix)
                        continue;
                if (last_matching_slash < 0)
                        return 0;
                prefix = last_matching_slash + 1;
        }
        return prefix;
}

int fill_directory(struct dir_struct *dir, const char **pathspec)
{
        const char *path;
        int len;

        /*
         * Calculate common prefix for the pathspec, and
         * use that to optimize the directory walk
         */
        len = common_prefix(pathspec);
        path = "";

        if (len)
                path = xmemdupz(*pathspec, len);

        /* Read the directory and prune it */
        read_directory(dir, path, len, pathspec);
        return len;
}

/*
 * Does 'match' match the given name?
 * A match is found if
 *
 * (1) the 'match' string is leading directory of 'name', or
 * (2) the 'match' string is a wildcard and matches 'name', or
 * (3) the 'match' string is exactly the same as 'name'.
 *
 * and the return value tells which case it was.
 *
 * It returns 0 when there is no match.
 */
static int match_one(const char *match, const char *name, int namelen)
{
        int matchlen;

        /* If the match was just the prefix, we matched */
        if (!*match)
                return MATCHED_RECURSIVELY;

        if (ignore_case) {
                for (;;) {
                        unsigned char c1 = tolower(*match);
                        unsigned char c2 = tolower(*name);
                        if (c1 == '\0' || is_glob_special(c1))
                                break;
                        if (c1 != c2)
                                return 0;
                        match++;
                        name++;
                        namelen--;
                }
        } else {
                for (;;) {
                        unsigned char c1 = *match;
                        unsigned char c2 = *name;
                        if (c1 == '\0' || is_glob_special(c1))
                                break;
                        if (c1 != c2)
                                return 0;
                        match++;
                        name++;
                        namelen--;
                }
        }


        /*
         * If we don't match the matchstring exactly,
         * we need to match by fnmatch
         */
        matchlen = strlen(match);
        if (strncmp_icase(match, name, matchlen))
                return !fnmatch_icase(match, name, 0) ? MATCHED_FNMATCH : 0;

        if (namelen == matchlen)
                return MATCHED_EXACTLY;
        if (match[matchlen-1] == '/' || name[matchlen] == '/')
                return MATCHED_RECURSIVELY;
        return 0;
}

/*
 * Given a name and a list of pathspecs, see if the name matches
 * any of the pathspecs.  The caller is also interested in seeing
 * all pathspec matches some names it calls this function with
 * (otherwise the user could have mistyped the unmatched pathspec),
 * and a mark is left in seen[] array for pathspec element that
 * actually matched anything.
 */
int match_pathspec(const char **pathspec, const char *name, int namelen,
                int prefix, char *seen)
{
        int i, retval = 0;

        if (!pathspec)
                return 1;

        name += prefix;
        namelen -= prefix;

        for (i = 0; pathspec[i] != NULL; i++) {
                int how;
                const char *match = pathspec[i] + prefix;
                if (seen && seen[i] == MATCHED_EXACTLY)
                        continue;
                how = match_one(match, name, namelen);
                if (how) {
                        if (retval < how)
                                retval = how;
                        if (seen && seen[i] < how)
                                seen[i] = how;
                }
        }
        return retval;
}

static int no_wildcard(const char *string)
{
        return string[strcspn(string, "*?[{\\")] == '\0';
}

void add_exclude(const char *string, const char *base,
                 int baselen, struct exclude_list *which)
{
        struct exclude *x;
        size_t len;
        int to_exclude = 1;
        int flags = 0;

        if (*string == '!') {
                to_exclude = 0;
                string++;
        }
        len = strlen(string);
        if (len && string[len - 1] == '/') {
                char *s;
                x = xmalloc(sizeof(*x) + len);
                s = (char *)(x+1);
                memcpy(s, string, len - 1);
                s[len - 1] = '\0';
                string = s;
                x->pattern = s;
                flags = EXC_FLAG_MUSTBEDIR;
        } else {
                x = xmalloc(sizeof(*x));
                x->pattern = string;
        }
        x->to_exclude = to_exclude;
        x->patternlen = strlen(string);
        x->base = base;
        x->baselen = baselen;
        x->flags = flags;
        if (!strchr(string, '/'))
                x->flags |= EXC_FLAG_NODIR;
        if (no_wildcard(string))
                x->flags |= EXC_FLAG_NOWILDCARD;
        if (*string == '*' && no_wildcard(string+1))
                x->flags |= EXC_FLAG_ENDSWITH;
        ALLOC_GROW(which->excludes, which->nr + 1, which->alloc);
        which->excludes[which->nr++] = x;
}

static void *read_skip_worktree_file_from_index(const char *path, size_t *size)
{
        int pos, len;
        unsigned long sz;
        enum object_type type;
        void *data;
        struct index_state *istate = &the_index;

        len = strlen(path);
        pos = index_name_pos(istate, path, len);
        if (pos < 0)
                return NULL;
        if (!ce_skip_worktree(istate->cache[pos]))
                return NULL;
        data = read_sha1_file(istate->cache[pos]->sha1, &type, &sz);
        if (!data || type != OBJ_BLOB) {
                free(data);
                return NULL;
        }
        *size = xsize_t(sz);
        return data;
}

int add_excludes_from_file_to_list(const char *fname,
                                   const char *base,
                                   int baselen,
                                   char **buf_p,
                                   struct exclude_list *which,
                                   int check_index)
{
        struct stat st;
        int fd, i;
        size_t size;
        char *buf, *entry;

        fd = open(fname, O_RDONLY);
        if (fd < 0 || fstat(fd, &st) < 0) {
                if (0 <= fd)
                        close(fd);
                if (!check_index ||
                    (buf = read_skip_worktree_file_from_index(fname, &size)) == NULL)
                        return -1;
                if (size == 0) {
                        free(buf);
                        return 0;
                }
                if (buf[size-1] != '\n') {
                        buf = xrealloc(buf, size+1);
                        buf[size++] = '\n';
                }
        }
        else {
                size = xsize_t(st.st_size);
                if (size == 0) {
                        close(fd);
                        return 0;
                }
                buf = xmalloc(size+1);
                if (read_in_full(fd, buf, size) != size) {
                        free(buf);
                        close(fd);
                        return -1;
                }
                buf[size++] = '\n';
                close(fd);
        }

        if (buf_p)
                *buf_p = buf;
        entry = buf;
        for (i = 0; i < size; i++) {
                if (buf[i] == '\n') {
                        if (entry != buf + i && entry[0] != '#') {
                                buf[i - (i && buf[i-1] == '\r')] = 0;
                                add_exclude(entry, base, baselen, which);
                        }
                        entry = buf + i + 1;
                }
        }
        return 0;
}

void add_excludes_from_file(struct dir_struct *dir, const char *fname)
{
        if (add_excludes_from_file_to_list(fname, "", 0, NULL,
                                           &dir->exclude_list[EXC_FILE], 0) < 0)
                die("cannot use %s as an exclude file", fname);
}

static void prep_exclude(struct dir_struct *dir, const char *base, int baselen)
{
        struct exclude_list *el;
        struct exclude_stack *stk = NULL;
        int current;

        if ((!dir->exclude_per_dir) ||
            (baselen + strlen(dir->exclude_per_dir) >= PATH_MAX))
                return; /* too long a path -- ignore */

        /* Pop the ones that are not the prefix of the path being checked. */
        el = &dir->exclude_list[EXC_DIRS];
        while ((stk = dir->exclude_stack) != NULL) {
                if (stk->baselen <= baselen &&
                    !strncmp(dir->basebuf, base, stk->baselen))
                        break;
                dir->exclude_stack = stk->prev;
                while (stk->exclude_ix < el->nr)
                        free(el->excludes[--el->nr]);
                free(stk->filebuf);
                free(stk);
        }

        /* Read from the parent directories and push them down. */
        current = stk ? stk->baselen : -1;
        while (current < baselen) {
                struct exclude_stack *stk = xcalloc(1, sizeof(*stk));
                const char *cp;

                if (current < 0) {
                        cp = base;
                        current = 0;
                }
                else {
                        cp = strchr(base + current + 1, '/');
                        if (!cp)
                                die("oops in prep_exclude");
                        cp++;
                }
                stk->prev = dir->exclude_stack;
                stk->baselen = cp - base;
                stk->exclude_ix = el->nr;
                memcpy(dir->basebuf + current, base + current,
                       stk->baselen - current);
                strcpy(dir->basebuf + stk->baselen, dir->exclude_per_dir);
                add_excludes_from_file_to_list(dir->basebuf,
                                               dir->basebuf, stk->baselen,
                                               &stk->filebuf, el, 1);
                dir->exclude_stack = stk;
                current = stk->baselen;
        }
        dir->basebuf[baselen] = '\0';
}

/* Scan the list and let the last match determine the fate.
 * Return 1 for exclude, 0 for include and -1 for undecided.
 */
int excluded_from_list(const char *pathname,
                       int pathlen, const char *basename, int *dtype,
                       struct exclude_list *el)
{
        int i;

        if (el->nr) {
                for (i = el->nr - 1; 0 <= i; i--) {
                        struct exclude *x = el->excludes[i];
                        const char *exclude = x->pattern;
                        int to_exclude = x->to_exclude;

                        if (x->flags & EXC_FLAG_MUSTBEDIR) {
                                if (!dtype) {
                                        if (!prefixcmp(pathname, exclude))
                                                return to_exclude;
                                        else
                                                continue;
                                }
                                if (*dtype == DT_UNKNOWN)
                                        *dtype = get_dtype(NULL, pathname, pathlen);
                                if (*dtype != DT_DIR)
                                        continue;
                        }

                        if (x->flags & EXC_FLAG_NODIR) {
                                /* match basename */
                                if (x->flags & EXC_FLAG_NOWILDCARD) {
                                        if (!strcmp_icase(exclude, basename))
                                                return to_exclude;
                                } else if (x->flags & EXC_FLAG_ENDSWITH) {
                                        if (x->patternlen - 1 <= pathlen &&
                                            !strcmp_icase(exclude + 1, pathname + pathlen - x->patternlen + 1))
                                                return to_exclude;
                                } else {
                                        if (fnmatch_icase(exclude, basename, 0) == 0)
                                                return to_exclude;
                                }
                        }
                        else {
                                /* match with FNM_PATHNAME:
                                 * exclude has base (baselen long) implicitly
                                 * in front of it.
                                 */
                                int baselen = x->baselen;
                                if (*exclude == '/')
                                        exclude++;

                                if (pathlen < baselen ||
                                    (baselen && pathname[baselen-1] != '/') ||
                                    strncmp_icase(pathname, x->base, baselen))
                                    continue;

                                if (x->flags & EXC_FLAG_NOWILDCARD) {
                                        if (!strcmp_icase(exclude, pathname + baselen))
                                                return to_exclude;
                                } else {
                                        if (fnmatch_icase(exclude, pathname+baselen,
                                                    FNM_PATHNAME) == 0)
                                            return to_exclude;
                                }
                        }
                }
        }
        return -1; /* undecided */
}

int excluded(struct dir_struct *dir, const char *pathname, int *dtype_p)
{
        int pathlen = strlen(pathname);
        int st;
        const char *basename = strrchr(pathname, '/');
        basename = (basename) ? basename+1 : pathname;

        prep_exclude(dir, pathname, basename-pathname);
        for (st = EXC_CMDL; st <= EXC_FILE; st++) {
                switch (excluded_from_list(pathname, pathlen, basename,
                                           dtype_p, &dir->exclude_list[st])) {
                case 0:
                        return 0;
                case 1:
                        return 1;
                }
        }
        return 0;
}

static struct dir_entry *dir_entry_new(const char *pathname, int len)
{
        struct dir_entry *ent;

        ent = xmalloc(sizeof(*ent) + len + 1);
        ent->len = len;
        memcpy(ent->name, pathname, len);
        ent->name[len] = 0;
        return ent;
}

static struct dir_entry *dir_add_name(struct dir_struct *dir, const char *pathname, int len)
{
        if (cache_name_exists(pathname, len, ignore_case))
                return NULL;

        ALLOC_GROW(dir->entries, dir->nr+1, dir->alloc);
        return dir->entries[dir->nr++] = dir_entry_new(pathname, len);
}

struct dir_entry *dir_add_ignored(struct dir_struct *dir, const char *pathname, int len)
{
        if (!cache_name_is_other(pathname, len))
                return NULL;

        ALLOC_GROW(dir->ignored, dir->ignored_nr+1, dir->ignored_alloc);
        return dir->ignored[dir->ignored_nr++] = dir_entry_new(pathname, len);
}

enum exist_status {
        index_nonexistent = 0,
        index_directory,
        index_gitdir
};

/*
 * Do not use the alphabetically stored index to look up
 * the directory name; instead, use the case insensitive
 * name hash.
 */
static enum exist_status directory_exists_in_index_icase(const char *dirname, int len)
{
        struct cache_entry *ce = index_name_exists(&the_index, dirname, len + 1, ignore_case);
        unsigned char endchar;

        if (!ce)
                return index_nonexistent;
        endchar = ce->name[len];

        /*
         * The cache_entry structure returned will contain this dirname
         * and possibly additional path components.
         */
        if (endchar == '/')
                return index_directory;

        /*
         * If there are no additional path components, then this cache_entry
         * represents a submodule.  Submodules, despite being directories,
         * are stored in the cache without a closing slash.
         */
        if (!endchar && S_ISGITLINK(ce->ce_mode))
                return index_gitdir;

        /* This should never be hit, but it exists just in case. */
        return index_nonexistent;
}

/*
 * The index sorts alphabetically by entry name, which
 * means that a gitlink sorts as '\0' at the end, while
 * a directory (which is defined not as an entry, but as
 * the files it contains) will sort with the '/' at the
 * end.
 */
static enum exist_status directory_exists_in_index(const char *dirname, int len)
{
        int pos;

        if (ignore_case)
                return directory_exists_in_index_icase(dirname, len);

        pos = cache_name_pos(dirname, len);
        if (pos < 0)
                pos = -pos-1;
        while (pos < active_nr) {
                struct cache_entry *ce = active_cache[pos++];
                unsigned char endchar;

                if (strncmp(ce->name, dirname, len))
                        break;
                endchar = ce->name[len];
                if (endchar > '/')
                        break;
                if (endchar == '/')
                        return index_directory;
                if (!endchar && S_ISGITLINK(ce->ce_mode))
                        return index_gitdir;
        }
        return index_nonexistent;
}

/*
 * When we find a directory when traversing the filesystem, we
 * have three distinct cases:
 *
 *  - ignore it
 *  - see it as a directory
 *  - recurse into it
 *
 * and which one we choose depends on a combination of existing
 * git index contents and the flags passed into the directory
 * traversal routine.
 *
 * Case 1: If we *already* have entries in the index under that
 * directory name, we always recurse into the directory to see
 * all the files.
 *
 * Case 2: If we *already* have that directory name as a gitlink,
 * we always continue to see it as a gitlink, regardless of whether
 * there is an actual git directory there or not (it might not
 * be checked out as a subproject!)
 *
 * Case 3: if we didn't have it in the index previously, we
 * have a few sub-cases:
 *
 *  (a) if "show_other_directories" is true, we show it as
 *      just a directory, unless "hide_empty_directories" is
 *      also true and the directory is empty, in which case
 *      we just ignore it entirely.
 *  (b) if it looks like a git directory, and we don't have
 *      'no_gitlinks' set we treat it as a gitlink, and show it
 *      as a directory.
 *  (c) otherwise, we recurse into it.
 */
enum directory_treatment {
        show_directory,
        ignore_directory,
        recurse_into_directory
};

static enum directory_treatment treat_directory(struct dir_struct *dir,
        const char *dirname, int len,
        const struct path_simplify *simplify)
{
        /* The "len-1" is to strip the final '/' */
        switch (directory_exists_in_index(dirname, len-1)) {
        case index_directory:
                return recurse_into_directory;

        case index_gitdir:
                if (dir->flags & DIR_SHOW_OTHER_DIRECTORIES)
                        return ignore_directory;
                return show_directory;

        case index_nonexistent:
                if (dir->flags & DIR_SHOW_OTHER_DIRECTORIES)
                        break;
                if (!(dir->flags & DIR_NO_GITLINKS)) {
                        unsigned char sha1[20];
                        if (resolve_gitlink_ref(dirname, "HEAD", sha1) == 0)
                                return show_directory;
                }
                return recurse_into_directory;
        }

        /* This is the "show_other_directories" case */
        if (!(dir->flags & DIR_HIDE_EMPTY_DIRECTORIES))
                return show_directory;
        if (!read_directory_recursive(dir, dirname, len, 1, simplify))
                return ignore_directory;
        return show_directory;
}

/*
 * This is an inexact early pruning of any recursive directory
 * reading - if the path cannot possibly be in the pathspec,
 * return true, and we'll skip it early.
 */
static int simplify_away(const char *path, int pathlen, const struct path_simplify *simplify)
{
        if (simplify) {
                for (;;) {
                        const char *match = simplify->path;
                        int len = simplify->len;

                        if (!match)
                                break;
                        if (len > pathlen)
                                len = pathlen;
                        if (!memcmp(path, match, len))
                                return 0;
                        simplify++;
                }
                return 1;
        }
        return 0;
}

/*
 * This function tells us whether an excluded path matches a
 * list of "interesting" pathspecs. That is, whether a path matched
 * by any of the pathspecs could possibly be ignored by excluding
 * the specified path. This can happen if:
 *
 *   1. the path is mentioned explicitly in the pathspec
 *
 *   2. the path is a directory prefix of some element in the
 *      pathspec
 */
static int exclude_matches_pathspec(const char *path, int len,
                const struct path_simplify *simplify)
{
        if (simplify) {
                for (; simplify->path; simplify++) {
                        if (len == simplify->len
                            && !memcmp(path, simplify->path, len))
                                return 1;
                        if (len < simplify->len
                            && simplify->path[len] == '/'
                            && !memcmp(path, simplify->path, len))
                                return 1;
                }
        }
        return 0;
}

static int get_index_dtype(const char *path, int len)
{
        int pos;
        struct cache_entry *ce;

        ce = cache_name_exists(path, len, 0);
        if (ce) {
                if (!ce_uptodate(ce))
                        return DT_UNKNOWN;
                if (S_ISGITLINK(ce->ce_mode))
                        return DT_DIR;
                /*
                 * Nobody actually cares about the
                 * difference between DT_LNK and DT_REG
                 */
                return DT_REG;
        }

        /* Try to look it up as a directory */
        pos = cache_name_pos(path, len);
        if (pos >= 0)
                return DT_UNKNOWN;
        pos = -pos-1;
        while (pos < active_nr) {
                ce = active_cache[pos++];
                if (strncmp(ce->name, path, len))
                        break;
                if (ce->name[len] > '/')
                        break;
                if (ce->name[len] < '/')
                        continue;
                if (!ce_uptodate(ce))
                        break;  /* continue? */
                return DT_DIR;
        }
        return DT_UNKNOWN;
}

static int get_dtype(struct dirent *de, const char *path, int len)
{
        int dtype = de ? DTYPE(de) : DT_UNKNOWN;
        struct stat st;

        if (dtype != DT_UNKNOWN)
                return dtype;
        dtype = get_index_dtype(path, len);
        if (dtype != DT_UNKNOWN)
                return dtype;
        if (lstat(path, &st))
                return dtype;
        if (S_ISREG(st.st_mode))
                return DT_REG;
        if (S_ISDIR(st.st_mode))
                return DT_DIR;
        if (S_ISLNK(st.st_mode))
                return DT_LNK;
        return dtype;
}

enum path_treatment {
        path_ignored,
        path_handled,
        path_recurse
};

static enum path_treatment treat_one_path(struct dir_struct *dir,
                                          char *path, int *len,
                                          const struct path_simplify *simplify,
                                          int dtype, struct dirent *de)
{
        int exclude = excluded(dir, path, &dtype);
        if (exclude && (dir->flags & DIR_COLLECT_IGNORED)
            && exclude_matches_pathspec(path, *len, simplify))
                dir_add_ignored(dir, path, *len);

        /*
         * Excluded? If we don't explicitly want to show
         * ignored files, ignore it
         */
        if (exclude && !(dir->flags & DIR_SHOW_IGNORED))
                return path_ignored;

        if (dtype == DT_UNKNOWN)
                dtype = get_dtype(de, path, *len);

        /*
         * Do we want to see just the ignored files?
         * We still need to recurse into directories,
         * even if we don't ignore them, since the
         * directory may contain files that we do..
         */
        if (!exclude && (dir->flags & DIR_SHOW_IGNORED)) {
                if (dtype != DT_DIR)
                        return path_ignored;
        }

        switch (dtype) {
        default:
                return path_ignored;
        case DT_DIR:
                memcpy(path + *len, "/", 2);
                (*len)++;
                switch (treat_directory(dir, path, *len, simplify)) {
                case show_directory:
                        if (exclude != !!(dir->flags
                                          & DIR_SHOW_IGNORED))
                                return path_ignored;
                        break;
                case recurse_into_directory:
                        return path_recurse;
                case ignore_directory:
                        return path_ignored;
                }
                break;
        case DT_REG:
        case DT_LNK:
                break;
        }
        return path_handled;
}

static enum path_treatment treat_path(struct dir_struct *dir,
                                      struct dirent *de,
                                      char *path, int path_max,
                                      int baselen,
                                      const struct path_simplify *simplify,
                                      int *len)
{
        int dtype;

        if (is_dot_or_dotdot(de->d_name) || !strcmp(de->d_name, ".git"))
                return path_ignored;
        *len = strlen(de->d_name);
        /* Ignore overly long pathnames! */
        if (*len + baselen + 8 > path_max)
                return path_ignored;
        memcpy(path + baselen, de->d_name, *len + 1);
        *len += baselen;
        if (simplify_away(path, *len, simplify))
                return path_ignored;

        dtype = DTYPE(de);
        return treat_one_path(dir, path, len, simplify, dtype, de);
}

/*
 * Read a directory tree. We currently ignore anything but
 * directories, regular files and symlinks. That's because git
 * doesn't handle them at all yet. Maybe that will change some
 * day.
 *
 * Also, we ignore the name ".git" (even if it is not a directory).
 * That likely will not change.
 */
static int read_directory_recursive(struct dir_struct *dir,
                                    const char *base, int baselen,
                                    int check_only,
                                    const struct path_simplify *simplify)
{
        DIR *fdir = opendir(*base ? base : ".");
        int contents = 0;

        if (fdir) {
                struct dirent *de;
                char path[PATH_MAX + 1];
                memcpy(path, base, baselen);

                while ((de = readdir(fdir)) != NULL) {
                        int len;
                        switch (treat_path(dir, de, path, sizeof(path),
                                           baselen, simplify, &len)) {
                        case path_recurse:
                                contents += read_directory_recursive
                                        (dir, path, len, 0, simplify);
                                continue;
                        case path_ignored:
                                continue;
                        case path_handled:
                                break;
                        }
                        contents++;
                        if (check_only)
                                goto exit_early;
                        else
                                dir_add_name(dir, path, len);
                }
exit_early:
                closedir(fdir);
        }

        return contents;
}

static int cmp_name(const void *p1, const void *p2)
{
        const struct dir_entry *e1 = *(const struct dir_entry **)p1;
        const struct dir_entry *e2 = *(const struct dir_entry **)p2;

        return cache_name_compare(e1->name, e1->len,
                                  e2->name, e2->len);
}

/*
 * Return the length of the "simple" part of a path match limiter.
 */
static int simple_length(const char *match)
{
        int len = -1;

        for (;;) {
                unsigned char c = *match++;
                len++;
                if (c == '\0' || is_glob_special(c))
                        return len;
        }
}

static struct path_simplify *create_simplify(const char **pathspec)
{
        int nr, alloc = 0;
        struct path_simplify *simplify = NULL;

        if (!pathspec)
                return NULL;

        for (nr = 0 ; ; nr++) {
                const char *match;
                if (nr >= alloc) {
                        alloc = alloc_nr(alloc);
                        simplify = xrealloc(simplify, alloc * sizeof(*simplify));
                }
                match = *pathspec++;
                if (!match)
                        break;
                simplify[nr].path = match;
                simplify[nr].len = simple_length(match);
        }
        simplify[nr].path = NULL;
        simplify[nr].len = 0;
        return simplify;
}

static void free_simplify(struct path_simplify *simplify)
{
        free(simplify);
}

static int treat_leading_path(struct dir_struct *dir,
                              const char *path, int len,
                              const struct path_simplify *simplify)
{
        char pathbuf[PATH_MAX];
        int baselen, blen;
        const char *cp;

        while (len && path[len - 1] == '/')
                len--;
        if (!len)
                return 1;
        baselen = 0;
        while (1) {
                cp = path + baselen + !!baselen;
                cp = memchr(cp, '/', path + len - cp);
                if (!cp)
                        baselen = len;
                else
                        baselen = cp - path;
                memcpy(pathbuf, path, baselen);
                pathbuf[baselen] = '\0';
                if (!is_directory(pathbuf))
                        return 0;
                if (simplify_away(pathbuf, baselen, simplify))
                        return 0;
                blen = baselen;
                if (treat_one_path(dir, pathbuf, &blen, simplify,
                                   DT_DIR, NULL) == path_ignored)
                        return 0; /* do not recurse into it */
                if (len <= baselen)
                        return 1; /* finished checking */
        }
}

int read_directory(struct dir_struct *dir, const char *path, int len, const char **pathspec)
{
        struct path_simplify *simplify;

        if (has_symlink_leading_path(path, len))
                return dir->nr;

        simplify = create_simplify(pathspec);
        if (!len || treat_leading_path(dir, path, len, simplify))
                read_directory_recursive(dir, path, len, 0, simplify);
        free_simplify(simplify);
        qsort(dir->entries, dir->nr, sizeof(struct dir_entry *), cmp_name);
        qsort(dir->ignored, dir->ignored_nr, sizeof(struct dir_entry *), cmp_name);
        return dir->nr;
}

int file_exists(const char *f)
{
        struct stat sb;
        return lstat(f, &sb) == 0;
}

/*
 * get_relative_cwd() gets the prefix of the current working directory
 * relative to 'dir'.  If we are not inside 'dir', it returns NULL.
 *
 * As a convenience, it also returns NULL if 'dir' is already NULL.  The
 * reason for this behaviour is that it is natural for functions returning
 * directory names to return NULL to say "this directory does not exist"
 * or "this directory is invalid".  These cases are usually handled the
 * same as if the cwd is not inside 'dir' at all, so get_relative_cwd()
 * returns NULL for both of them.
 *
 * Most notably, get_relative_cwd(buffer, size, get_git_work_tree())
 * unifies the handling of "outside work tree" with "no work tree at all".
 */
char *get_relative_cwd(char *buffer, int size, const char *dir)
{
        char *cwd = buffer;

        if (!dir)
                return NULL;
        if (!getcwd(buffer, size))
                die_errno("can't find the current directory");

        if (!is_absolute_path(dir))
                dir = make_absolute_path(dir);

        while (*dir && *dir == *cwd) {
                dir++;
                cwd++;
        }
        if (*dir)
                return NULL;
        switch (*cwd) {
        case '\0':
                return cwd;
        case '/':
                return cwd + 1;
        default:
                return NULL;
        }
}

int is_inside_dir(const char *dir)
{
        char buffer[PATH_MAX];
        return get_relative_cwd(buffer, sizeof(buffer), dir) != NULL;
}

int is_empty_dir(const char *path)
{
        DIR *dir = opendir(path);
        struct dirent *e;
        int ret = 1;

        if (!dir)
                return 0;

        while ((e = readdir(dir)) != NULL)
                if (!is_dot_or_dotdot(e->d_name)) {
                        ret = 0;
                        break;
                }

        closedir(dir);
        return ret;
}

int remove_dir_recursively(struct strbuf *path, int flag)
{
        DIR *dir;
        struct dirent *e;
        int ret = 0, original_len = path->len, len;
        int only_empty = (flag & REMOVE_DIR_EMPTY_ONLY);
        unsigned char submodule_head[20];

        if ((flag & REMOVE_DIR_KEEP_NESTED_GIT) &&
            !resolve_gitlink_ref(path->buf, "HEAD", submodule_head))
                /* Do not descend and nuke a nested git work tree. */
                return 0;

        dir = opendir(path->buf);
        if (!dir)
                return -1;
        if (path->buf[original_len - 1] != '/')
                strbuf_addch(path, '/');

        len = path->len;
        while ((e = readdir(dir)) != NULL) {
                struct stat st;
                if (is_dot_or_dotdot(e->d_name))
                        continue;

                strbuf_setlen(path, len);
                strbuf_addstr(path, e->d_name);
                if (lstat(path->buf, &st))
                        ; /* fall thru */
                else if (S_ISDIR(st.st_mode)) {
                        if (!remove_dir_recursively(path, only_empty))
                                continue; /* happy */
                } else if (!only_empty && !unlink(path->buf))
                        continue; /* happy, too */

                /* path too long, stat fails, or non-directory still exists */
                ret = -1;
                break;
        }
        closedir(dir);

        strbuf_setlen(path, original_len);
        if (!ret)
                ret = rmdir(path->buf);
        return ret;
}

void setup_standard_excludes(struct dir_struct *dir)
{
        const char *path;

        dir->exclude_per_dir = ".gitignore";
        path = git_path("info/exclude");
        if (!access(path, R_OK))
                add_excludes_from_file(dir, path);
        if (excludes_file && !access(excludes_file, R_OK))
                add_excludes_from_file(dir, excludes_file);
}

int remove_path(const char *name)
{
        char *slash;

        if (unlink(name) && errno != ENOENT)
                return -1;

        slash = strrchr(name, '/');
        if (slash) {
                char *dirs = xstrdup(name);
                slash = dirs + (slash - name);
                do {
                        *slash = '\0';
                } while (rmdir(dirs) == 0 && (slash = strrchr(dirs, '/')));
                free(dirs);
        }
        return 0;
}