/*
 * GIT - The information manager from hell
 *
 * Copyright (C) Linus Torvalds, 2005
 */
#include "cache.h"

static void safe_create_dir(const char *dir)
{
        if (mkdir(dir, 0777) < 0) {
                if (errno != EEXIST) {
                        perror(dir);
                        exit(1);
                }
        }
}

static int copy_file(const char *dst, const char *src, int mode)
{
        int fdi, fdo;

        mode = (mode & 0111) ? 0777 : 0666;
        if ((fdi = open(src, O_RDONLY)) < 0)
                return fdi;
        if ((fdo = open(dst, O_WRONLY | O_CREAT | O_EXCL, mode)) < 0) {
                close(fdi);
                return fdo;
        }
        while (1) {
                char buf[BUFSIZ];
                ssize_t leni, leno, ofs;
                leni = read(fdi, buf, sizeof(buf));
                if (leni < 0) {
                error_return:
                        close(fdo);
                        close(fdi);
                        return -1;
                }
                if (!leni)
                        break;
                ofs = 0;
                do {
                        leno = write(fdo, buf+ofs, leni);
                        if (leno < 0)
                                goto error_return;
                        leni -= leno;
                        ofs += leno;
                } while (0 < leni);
        }
        close(fdo);
        close(fdi);
        return 0;
}

static void copy_templates_1(char *path, int baselen,
                             char *template, int template_baselen,
                             DIR *dir)
{
        struct dirent *de;

        /* Note: if ".git/hooks" file exists in the repository being
         * re-initialized, /etc/core-git/templates/hooks/update would
         * cause git-init-db to fail here.  I think this is sane but
         * it means that the set of templates we ship by default, along
         * with the way the namespace under .git/ is organized, should
         * be really carefully chosen.
         */
        safe_create_dir(path);
        while ((de = readdir(dir)) != NULL) {
                struct stat st_git, st_template;
                int namelen;
                int exists = 0;

                if (de->d_name[0] == '.')
                        continue;
                namelen = strlen(de->d_name);
                if ((PATH_MAX <= baselen + namelen) ||
                    (PATH_MAX <= template_baselen + namelen))
                        die("insanely long template name %s", de->d_name);
                memcpy(path + baselen, de->d_name, namelen+1);
                memcpy(template + template_baselen, de->d_name, namelen+1);
                if (lstat(path, &st_git)) {
                        if (errno != ENOENT)
                                die("cannot stat %s", path);
                }
                else
                        exists = 1;

                if (lstat(template, &st_template))
                        die("cannot stat template %s", template);

                if (S_ISDIR(st_template.st_mode)) {
                        DIR *subdir = opendir(template);
                        int baselen_sub = baselen + namelen;
                        int template_baselen_sub = template_baselen + namelen;
                        if (!subdir)
                                die("cannot opendir %s", template);
                        path[baselen_sub++] =
                                template[template_baselen_sub++] = '/';
                        path[baselen_sub] =
                                template[template_baselen_sub] = 0;
                        copy_templates_1(path, baselen_sub,
                                         template, template_baselen_sub,
                                         subdir);
                        closedir(subdir);
                }
                else if (exists)
                        continue;
                else if (S_ISLNK(st_template.st_mode)) {
                        char lnk[256];
                        int len;
                        len = readlink(template, lnk, sizeof(lnk));
                        if (len < 0)
                                die("cannot readlink %s", template);
                        if (sizeof(lnk) <= len)
                                die("insanely long symlink %s", template);
                        lnk[len] = 0;
                        if (symlink(lnk, path))
                                die("cannot symlink %s %s", lnk, path);
                }
                else if (S_ISREG(st_template.st_mode)) {
                        if (copy_file(path, template, st_template.st_mode))
                                die("cannot copy %s to %s", template, path);
                }
                else
                        error("ignoring template %s", template);
        }
}

static void copy_templates(const char *git_dir)
{
        char path[PATH_MAX];
        char template_path[PATH_MAX];
        char *template_dir;
        int len, template_len;
        DIR *dir;

        strcpy(path, git_dir);
        len = strlen(path);
        template_dir = gitenv(TEMPLATE_DIR_ENVIRONMENT);
        if (!template_dir)
                template_dir = DEFAULT_GIT_TEMPLATE_ENVIRONMENT;
        strcpy(template_path, template_dir);
        template_len = strlen(template_path);
        if (template_path[template_len-1] != '/') {
                template_path[template_len++] = '/';
                template_path[template_len] = 0;
        }

        dir = opendir(template_path);
        if (!dir)
                return;
        copy_templates_1(path, len,
                         template_path, template_len,
                         dir);
        closedir(dir);
}

static void create_default_files(const char *git_dir)
{
        unsigned len = strlen(git_dir);
        static char path[PATH_MAX];

        if (len > sizeof(path)-50)
                die("insane git directory %s", git_dir);
        memcpy(path, git_dir, len);

        if (len && path[len-1] != '/')
                path[len++] = '/';

        /*
         * Create .git/refs/{heads,tags}
         */
        strcpy(path + len, "refs");
        safe_create_dir(path);
        strcpy(path + len, "refs/heads");
        safe_create_dir(path);
        strcpy(path + len, "refs/tags");
        safe_create_dir(path);

        /*
         * Create the default symlink from ".git/HEAD" to the "master"
         * branch
         */
        strcpy(path + len, "HEAD");
        if (symlink("refs/heads/master", path) < 0) {
                if (errno != EEXIST) {
                        perror(path);
                        exit(1);
                }
        }
        path[len] = 0;
        copy_templates(path);
}

/*
 * If you want to, you can share the DB area with any number of branches.
 * That has advantages: you can save space by sharing all the SHA1 objects.
 * On the other hand, it might just make lookup slower and messier. You
 * be the judge.  The default case is to have one DB per managed directory.
 */
int main(int argc, char **argv)
{
        const char *git_dir;
        const char *sha1_dir;
        char *path;
        int len, i;

        /*
         * Set up the default .git directory contents
         */
        git_dir = gitenv(GIT_DIR_ENVIRONMENT);
        if (!git_dir) {
                git_dir = DEFAULT_GIT_DIR_ENVIRONMENT;
                fprintf(stderr, "defaulting to local storage area\n");
        }
        safe_create_dir(git_dir);
        create_default_files(git_dir);

        /*
         * And set up the object store.
         */
        sha1_dir = get_object_directory();
        len = strlen(sha1_dir);
        path = xmalloc(len + 40);
        memcpy(path, sha1_dir, len);

        safe_create_dir(sha1_dir);
        for (i = 0; i < 256; i++) {
                sprintf(path+len, "/%02x", i);
                safe_create_dir(path);
        }
        strcpy(path+len, "/pack");
        safe_create_dir(path);
        return 0;
}