Teach git-describe --exact-match to avoid expensive tag searches

[alt-git.git] / dir.c

/*
 * 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, const char *base, int baselen,
        int check_only, const struct path_simplify *simplify);
static int get_dtype(struct dirent *de, const char *path);

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;

        prefix = slash - path + 1;
        while ((next = *++pathspec) != NULL) {
                int len = strlen(next);
                if (len >= prefix && !memcmp(path, next, prefix))
                        continue;
                len = prefix - 1;
                for (;;) {
                        if (!len)
                                return 0;
                        if (next[--len] != '/')
                                continue;
                        if (memcmp(path, next, len+1))
                                continue;
                        prefix = len + 1;
                        break;
                }
        }
        return prefix;
}

/*
 * Does 'match' matches 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 */
        matchlen = strlen(match);
        if (!matchlen)
                return MATCHED_RECURSIVELY;

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

        if (!name[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 retval;
        const char *match;

        name += prefix;
        namelen -= prefix;

        for (retval = 0; (match = *pathspec++) != NULL; seen++) {
                int how;
                if (retval && *seen == MATCHED_EXACTLY)
                        continue;
                match += prefix;
                how = match_one(match, name, namelen);
                if (how) {
                        if (retval < how)
                                retval = how;
                        if (*seen < how)
                                *seen = 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 int add_excludes_from_file_1(const char *fname,
                                    const char *base,
                                    int baselen,
                                    char **buf_p,
                                    struct exclude_list *which)
{
        struct stat st;
        int fd, i;
        size_t size;
        char *buf, *entry;

        fd = open(fname, O_RDONLY);
        if (fd < 0 || fstat(fd, &st) < 0)
                goto err;
        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);
                goto err;
        }
        close(fd);

        if (buf_p)
                *buf_p = buf;
        buf[size++] = '\n';
        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;

 err:
        if (0 <= fd)
                close(fd);
        return -1;
}

void add_excludes_from_file(struct dir_struct *dir, const char *fname)
{
        if (add_excludes_from_file_1(fname, "", 0, NULL,
                                     &dir->exclude_list[EXC_FILE]) < 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_1(dir->basebuf,
                                         dir->basebuf, stk->baselen,
                                         &stk->filebuf, el);
                dir->exclude_stack = stk;
                current = stk->baselen;
        }
        dir->basebuf[baselen] = '\0';
}

/* Scan the list and let the last match determines the fate.
 * Return 1 for exclude, 0 for include and -1 for undecided.
 */
static int excluded_1(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 == DT_UNKNOWN)
                                        *dtype = get_dtype(NULL, pathname);
                                if (*dtype != DT_DIR)
                                        continue;
                        }

                        if (x->flags & EXC_FLAG_NODIR) {
                                /* match basename */
                                if (x->flags & EXC_FLAG_NOWILDCARD) {
                                        if (!strcmp(exclude, basename))
                                                return to_exclude;
                                } else if (x->flags & EXC_FLAG_ENDSWITH) {
                                        if (x->patternlen - 1 <= pathlen &&
                                            !strcmp(exclude + 1, pathname + pathlen - x->patternlen + 1))
                                                return to_exclude;
                                } else {
                                        if (fnmatch(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(pathname, x->base, baselen))
                                    continue;

                                if (x->flags & EXC_FLAG_NOWILDCARD) {
                                        if (!strcmp(exclude, pathname + baselen))
                                                return to_exclude;
                                } else {
                                        if (fnmatch(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_1(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;
}

struct dir_entry *dir_add_name(struct dir_struct *dir, const char *pathname, int len)
{
        if (cache_name_exists(pathname, len))
                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_pos(pathname, len) >= 0)
                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,
};

/*
 * 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 = 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->show_other_directories)
                        return ignore_directory;
                return show_directory;

        case index_nonexistent:
                if (dir->show_other_directories)
                        break;
                if (!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->hide_empty_directories)
                return show_directory;
        if (!read_directory_recursive(dir, dirname, 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;
}

static int in_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;
                }
        }
        return 0;
}

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

        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;
}

/*
 * 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 *path, const char *base, int baselen, int check_only, const struct path_simplify *simplify)
{
        DIR *fdir = opendir(path);
        int contents = 0;

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

                while ((de = readdir(fdir)) != NULL) {
                        int len, dtype;
                        int exclude;

                        if ((de->d_name[0] == '.') &&
                            (de->d_name[1] == 0 ||
                             !strcmp(de->d_name + 1, ".") ||
                             !strcmp(de->d_name + 1, "git")))
                                continue;
                        len = strlen(de->d_name);
                        /* Ignore overly long pathnames! */
                        if (len + baselen + 8 > sizeof(fullname))
                                continue;
                        memcpy(fullname + baselen, de->d_name, len+1);
                        if (simplify_away(fullname, baselen + len, simplify))
                                continue;

                        dtype = DTYPE(de);
                        exclude = excluded(dir, fullname, &dtype);
                        if (exclude && dir->collect_ignored
                            && in_pathspec(fullname, baselen + len, simplify))
                                dir_add_ignored(dir, fullname, baselen + len);

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

                        if (dtype == DT_UNKNOWN)
                                dtype = get_dtype(de, fullname);

                        /*
                         * 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->show_ignored) {
                                if (dtype != DT_DIR)
                                        continue;
                        }

                        switch (dtype) {
                        default:
                                continue;
                        case DT_DIR:
                                memcpy(fullname + baselen + len, "/", 2);
                                len++;
                                switch (treat_directory(dir, fullname, baselen + len, simplify)) {
                                case show_directory:
                                        if (exclude != dir->show_ignored)
                                                continue;
                                        break;
                                case recurse_into_directory:
                                        contents += read_directory_recursive(dir,
                                                fullname, fullname, baselen + len, 0, simplify);
                                        continue;
                                case ignore_directory:
                                        continue;
                                }
                                break;
                        case DT_REG:
                        case DT_LNK:
                                break;
                        }
                        contents++;
                        if (check_only)
                                goto exit_early;
                        else
                                dir_add_name(dir, fullname, baselen + 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)
{
        const char special[256] = {
                [0] = 1, ['?'] = 1,
                ['\\'] = 1, ['*'] = 1,
                ['['] = 1
        };
        int len = -1;

        for (;;) {
                unsigned char c = *match++;
                len++;
                if (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)
{
        if (simplify)
                free(simplify);
}

int read_directory(struct dir_struct *dir, const char *path, const char *base, int baselen, const char **pathspec)
{
        struct path_simplify *simplify = create_simplify(pathspec);

        read_directory_recursive(dir, path, base, baselen, 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("can't find the current directory: %s", strerror(errno));

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

        while (*dir && *dir == *cwd) {
                dir++;
                cwd++;
        }
        if (*dir)
                return NULL;
        if (*cwd == '/')
                return cwd + 1;
        return cwd;
}

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

int remove_dir_recursively(struct strbuf *path, int only_empty)
{
        DIR *dir = opendir(path->buf);
        struct dirent *e;
        int ret = 0, original_len = path->len, len;

        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 ((e->d_name[0] == '.') &&
                    ((e->d_name[1] == 0) ||
                     ((e->d_name[1] == '.') && e->d_name[2] == 0)))
                        continue; /* "." and ".." */

                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);
}