index : cgit

/*
 * The entry point every request passes through. It reads cgitrc and the query
 * string into the global ctx, works out how long the answer may be cached,
 * and then hands over to the cache, which either serves a copy it already has
 * or calls back here to render one. Rendering means authenticating the
 * request, resolving the repository and the branch it names, and dispatching
 * to the page handler cmd.c maps the page name to. Run from a shell rather
 * than from a web server the same binary instead prints what it was built
 * with, or scans a directory tree and writes out the repositories it found in
 * cgitrc form.
 */

#define USE_THE_REPOSITORY_VARIABLE

#include "cache.h"
#include "cgit.h"
#include "cmd.h"
#include "config.h"
#include "filter.h"
#include "html.h"
#include "parsing.h"
#include "scan-tree.h"
#include "shared.h"
#include "ui-blob.h"
#include "ui-diff.h"
#include "ui-empty.h"
#include "ui-shared.h"
#include "ui-snapshot.h"
#include "ui-stats.h"

// Deliberately small. The whole body is read at once and handed to the auth
// filter, so a filter never has to defend itself against a huge or a
// dribbled-out POST.
#define MAX_AUTHENTICATION_POST_BYTES 4096

// The filter bar matches the search against every item a page lists, so this
// bounds both the work one request can ask for and the cache key the query
// lands in.
#define MAX_SEARCH_LEN 512

// Furthest into a listing a request may ask to start. A walk has to step over
// every row it skips, so this bounds the work an offset alone can buy.
#define MAX_QUERY_OFFSET 100000

// cgit knows fewer than eight archive formats, so this stands in for every bit
// a snapshots mask can carry.
#define ALL_SNAPSHOT_FORMATS 0xFF

/*
 * The first branch found is the fallback, so a repository whose default branch
 * does not exist still has something to show.
 */
struct refmatch {
	char *wanted;
	char *first;
	int found;
};

const char *cgit_version = CGIT_VERSION;

/*
 * Isolate git from the calling user's configuration, so a snapshot cannot be
 * broken by something like a core.excludesfile pointing at a "~" path that git
 * can no longer expand once HOME is unset below. Called from cmd_main rather
 * than from a constructor attribute, because git-compat-util.h defines
 * __attribute__ away on a compiler that does not support it, which would leave
 * this silently never running.
 */
static void isolate_git_environment(void)
{
	setenv("GIT_CONFIG_NOSYSTEM", "1", 1);
	setenv("GIT_CONFIG_GLOBAL", "/dev/null", 1);
	setenv("GIT_ATTR_NOSYSTEM", "1", 1);
	unsetenv("HOME");
	unsetenv("XDG_CONFIG_HOME");
}

/*
 * Turn a die from anywhere inside git into a rendered page, since a CGI that
 * produced no output leaves the visitor with whatever the web server makes of
 * it.
 */
static NORETURN void die_routine(const char *msg, va_list params)
{
	// The error page abandons any cache fill in progress, so the message
	// reaches the visitor rather than the cache file stdout points at.
	cgit_vprint_error_page(400, "Bad request", msg, params);
	exit(0);
}

static void prepare_context(void)
{
	memset(&ctx, 0, sizeof(ctx));
	ctx.cfg.agefile = "info/web/last-modified";
	ctx.cfg.cache_size = 0;
	ctx.cfg.cache_root = CGIT_CACHE_ROOT;
	ctx.cfg.cache_about_ttl = 15;
	ctx.cfg.cache_snapshot_ttl = 5;
	ctx.cfg.cache_repo_ttl = 5;
	ctx.cfg.cache_root_ttl = 5;
	ctx.cfg.cache_scanrc_ttl = 15;
	ctx.cfg.cache_dynamic_ttl = 5;
	ctx.cfg.cache_static_ttl = -1;
	ctx.cfg.case_sensitive_sort = 1;
	ctx.cfg.branch_sort = 0;
	ctx.cfg.commit_sort = 0;
	ctx.cfg.logo = "/cgit.png";
	ctx.cfg.favicon = "/favicon.ico";
	ctx.cfg.local_time = 0;
	ctx.cfg.date_mode = date_mode_from_type(DATE_SHORT);
	ctx.cfg.enable_relative_dates = 1;
	ctx.cfg.enable_http_clone = 1;
	ctx.cfg.enable_index_owner = 1;
	ctx.cfg.enable_tree_linenumbers = 1;
	ctx.cfg.enable_git_config = 0;
	ctx.cfg.max_repo_count = 50;
	ctx.cfg.max_commit_count = 50;
	ctx.cfg.max_patch_count = 50;
	ctx.cfg.max_diff_files = 200;
	ctx.cfg.max_diff_lines = 1000;
	ctx.cfg.max_msg_len = 80;
	ctx.cfg.max_ref_count = 200;
	ctx.cfg.max_repodesc_len = 80;
	// Counted in kilobytes, so ten megabytes, which bounds the memory one
	// request can be made to allocate for a blob.
	ctx.cfg.max_blob_size = 10 * 1024;
	ctx.cfg.max_stats = 0;
	ctx.cfg.project_list = NULL;
	ctx.cfg.renamelimit = -1;
	ctx.cfg.remove_suffix = 0;
	ctx.cfg.robots = "index, nofollow";
	ctx.cfg.root_title = "Git repository browser";
	ctx.cfg.root_desc = "a fast webinterface for the git dscm";
	ctx.cfg.scan_hidden_path = 0;
	ctx.cfg.script_name = CGIT_SCRIPT_NAME;
	ctx.cfg.section = "";
	ctx.cfg.repository_sort = "name";
	ctx.cfg.section_sort = 0;
	ctx.cfg.summary_branches = 10;
	ctx.cfg.summary_log = 10;
	ctx.cfg.summary_tags = 10;
	ctx.cfg.max_atom_items = 10;
	ctx.cfg.difftype = DIFF_UNIFIED;
	ctx.env.cgit_config = getenv("CGIT_CONFIG");
	ctx.env.http_host = getenv("HTTP_HOST");
	ctx.env.https = getenv("HTTPS");
	ctx.env.no_http = getenv("NO_HTTP");
	ctx.env.path_info = getenv("PATH_INFO");
	ctx.env.query_string = getenv("QUERY_STRING");
	ctx.env.request_method = getenv("REQUEST_METHOD");
	ctx.env.script_name = getenv("SCRIPT_NAME");
	ctx.env.server_name = getenv("SERVER_NAME");
	ctx.env.server_port = getenv("SERVER_PORT");
	ctx.env.http_cookie = getenv("HTTP_COOKIE");
	ctx.env.http_referer = getenv("HTTP_REFERER");
	ctx.env.content_length = getenv("CONTENT_LENGTH") ?
		strtoul(getenv("CONTENT_LENGTH"), NULL, 10) : 0;
	ctx.env.authenticated = 0;
	ctx.page.mimetype = "text/html";
	ctx.page.charset = PAGE_ENCODING;
	ctx.page.filename = NULL;
	ctx.page.size = 0;
	string_list_init_dup(&ctx.cfg.mimetypes);
	if (ctx.env.script_name)
		ctx.cfg.script_name = xstrdup(ctx.env.script_name);
	if (ctx.env.query_string)
		ctx.qry.raw = xstrdup(ctx.env.query_string);
	if (!ctx.env.cgit_config)
		ctx.env.cgit_config = CGIT_CONFIG;
}

static void print_version(void)
{
	printf("CGit %s | https://github.com/brycekwon/cgit\n\nCompiled in features:\n", CGIT_VERSION);
#ifdef NO_LUA
	printf("[-] ");
#else
	printf("[+] ");
#endif
	printf("Lua scripting\n");
#ifndef HAVE_LINUX_SENDFILE
	printf("[-] ");
#else
	printf("[+] ");
#endif
	printf("Linux sendfile() usage\n");
}

static int cmp_repos(const void *a, const void *b)
{
	const struct cgit_repo *repo_a = a, *repo_b = b;
	return strcmp(repo_a->url, repo_b->url);
}

static char *build_snapshot_setting(int mask)
{
	const struct cgit_snapshot_format *format;
	struct strbuf result = STRBUF_INIT;

	for (format = cgit_snapshot_formats; format->suffix; format++) {
		if (cgit_snapshot_format_bit(format) & mask) {
			if (result.len)
				strbuf_addch(&result, ' ');
			strbuf_addstr(&result, format->suffix);
		}
	}
	return strbuf_detach(&result, NULL);
}

static void print_repo(FILE *f, struct cgit_repo *repo)
{
	struct string_list_item *item;

	fprintf(f, "repo.url=%s\n", repo->url);
	fprintf(f, "repo.name=%s\n", repo->name);
	fprintf(f, "repo.path=%s\n", repo->path);
	if (repo->owner)
		fprintf(f, "repo.owner=%s\n", repo->owner);
	if (repo->desc)
		fprintf(f, "repo.desc=%s\n", repo->desc);
	for_each_string_list_item(item, &repo->readme) {
		if (item->util)
			fprintf(f, "repo.readme=%s:%s\n", (char *)item->util, item->string);
		else
			fprintf(f, "repo.readme=%s\n", item->string);
	}
	if (repo->defbranch)
		fprintf(f, "repo.defbranch=%s\n", repo->defbranch);
	if (repo->extra_head_content)
		fprintf(f, "repo.extra-head-content=%s\n", repo->extra_head_content);
	if (repo->module_link)
		fprintf(f, "repo.module-link=%s\n", repo->module_link);
	if (repo->section)
		fprintf(f, "repo.section=%s\n", repo->section);
	if (repo->clone_url)
		fprintf(f, "repo.clone-url=%s\n", repo->clone_url);
	fprintf(f, "repo.enable-blame=%d\n", repo->enable_blame);
	fprintf(f, "repo.enable-commit-graph=%d\n", repo->enable_commit_graph);
	fprintf(f, "repo.enable-follow-links=%d\n", repo->enable_follow_links);
	fprintf(f, "repo.enable-log-filecount=%d\n", repo->enable_log_filecount);
	fprintf(f, "repo.enable-log-linecount=%d\n", repo->enable_log_linecount);
	if (repo->about_filter && repo->about_filter != ctx.cfg.about_filter)
		cgit_fprintf_filter(repo->about_filter, f, "repo.about-filter=");
	if (repo->commit_filter && repo->commit_filter != ctx.cfg.commit_filter)
		cgit_fprintf_filter(repo->commit_filter, f, "repo.commit-filter=");
	if (repo->source_filter && repo->source_filter != ctx.cfg.source_filter)
		cgit_fprintf_filter(repo->source_filter, f, "repo.source-filter=");
	if (repo->email_filter && repo->email_filter != ctx.cfg.email_filter)
		cgit_fprintf_filter(repo->email_filter, f, "repo.email-filter=");
	if (repo->snapshots != ctx.cfg.snapshots) {
		char *formats = build_snapshot_setting(repo->snapshots);
		fprintf(f, "repo.snapshots=%s\n", formats ? formats : "");
		free(formats);
	}
	if (repo->snapshot_prefix)
		fprintf(f, "repo.snapshot-prefix=%s\n", repo->snapshot_prefix);
	if (repo->enable_stats != ctx.cfg.enable_stats)
		fprintf(f, "repo.enable-stats=%d\n", repo->enable_stats);
	if (repo->max_stats != ctx.cfg.max_stats)
		fprintf(f, "repo.max-stats=%s\n",
			cgit_find_stats_periodname(repo->max_stats));
	if (repo->logo)
		fprintf(f, "repo.logo=%s\n", repo->logo);
	if (repo->logo_link)
		fprintf(f, "repo.logo-link=%s\n", repo->logo_link);
	fprintf(f, "repo.enable-remote-branches=%d\n", repo->enable_remote_branches);
	fprintf(f, "repo.enable-subject-links=%d\n", repo->enable_subject_links);
	fprintf(f, "repo.enable-html-serving=%d\n", repo->enable_html_serving);
	if (repo->branch_sort == 1)
		fprintf(f, "repo.branch-sort=age\n");
	if (repo->commit_sort) {
		if (repo->commit_sort == 1)
			fprintf(f, "repo.commit-sort=date\n");
		else if (repo->commit_sort == 2)
			fprintf(f, "repo.commit-sort=topo\n");
	}
	fprintf(f, "repo.hide=%d\n", repo->hide);
	fprintf(f, "repo.ignore=%d\n", repo->ignore);
	fprintf(f, "\n");
}

static void print_repolist(FILE *f, struct cgit_repolist *list, int start)
{
	int i;

	for (i = start; i < list->count; i++)
		print_repo(f, &list->repos[i]);
}

static void parse_args(int argc, const char **argv)
{
	int i;
	const char *arg;
	int scanned = 0;

	for (i = 1; i < argc; i++) {
		if (!strcmp(argv[i], "--version")) {
			print_version();
			exit(0);
		}
		if (skip_prefix(argv[i], "--cache=", &arg)) {
			ctx.cfg.cache_root = xstrdup(arg);
		} else if (!strcmp(argv[i], "--nohttp")) {
			ctx.env.no_http = "1";
		} else if (skip_prefix(argv[i], "--query=", &arg)) {
			ctx.qry.raw = xstrdup(arg);
		} else if (skip_prefix(argv[i], "--repo=", &arg)) {
			ctx.qry.repo = xstrdup(arg);
		} else if (skip_prefix(argv[i], "--page=", &arg)) {
			ctx.qry.page = xstrdup(arg);
		} else if (skip_prefix(argv[i], "--head=", &arg)) {
			ctx.qry.head = xstrdup(arg);
			ctx.qry.has_symref = 1;
		} else if (skip_prefix(argv[i], "--oid=", &arg)) {
			ctx.qry.oid = xstrdup(arg);
			ctx.qry.has_oid = 1;
		} else if (skip_prefix(argv[i], "--ofs=", &arg)) {
			ctx.qry.ofs = atoi(arg);
		} else if (skip_prefix(argv[i], "--scan-tree=", &arg) ||
		           skip_prefix(argv[i], "--scan-path=", &arg)) {
			// A repository's own snapshots setting is masked with
			// the global one, which normally comes from cgitrc.
			// That has not been read yet here, so an empty mask
			// would discard whatever the repository asked for.
			ctx.cfg.snapshots = ALL_SNAPSHOT_FORMATS;
			scanned++;
			scan_tree(arg);
		}
	}
	if (scanned) {
		qsort(cgit_repolist.repos, cgit_repolist.count,
			sizeof(struct cgit_repo), cmp_repos);
		print_repolist(stdout, &cgit_repolist, 0);
		exit(0);
	}
}

static int generate_cached_repolist(const char *path, const char *cached_rc)
{
	struct strbuf locked_rc = STRBUF_INIT;
	int err = 0;
	int first;
	FILE *f;

	strbuf_addf(&locked_rc, "%s.lock", cached_rc);
	f = fopen(locked_rc.buf, "wx");
	if (!f) {
		// An existing lock file only means concurrent requests, which
		// is not worth a line in the server log.
		err = errno;
		if (err != EEXIST)
			fprintf(stderr, "[cgit] Error opening %s: %s (%d)\n",
				locked_rc.buf, strerror(err), err);
		goto out;
	}
	first = cgit_repolist.count;
	if (ctx.cfg.project_list)
		scan_projects(path, ctx.cfg.project_list);
	else
		scan_tree(path);
	print_repolist(f, &cgit_repolist, first);
	// Closed before the rename, because print_repolist writes through stdio
	// and a rename over the live file would otherwise publish a repolist
	// that stops wherever the buffer happened to end.
	if (fclose(f)) {
		err = errno;
		fprintf(stderr, "[cgit] Error writing %s: %s (%d)\n",
			locked_rc.buf, strerror(err), err);
		unlink(locked_rc.buf);
		goto out;
	}
	if (rename(locked_rc.buf, cached_rc)) {
		err = errno;
		fprintf(stderr, "[cgit] Error renaming %s to %s: %s (%d)\n",
			locked_rc.buf, cached_rc, strerror(err), err);
		unlink(locked_rc.buf);
	}
out:
	strbuf_release(&locked_rc);
	return err;
}

// A cached repolist is itself a config file, so these two call each other.
static void apply_config(const char *name, const char *value);

static void process_cached_repolist(const char *path)
{
	struct stat st;
	struct strbuf cached_rc = STRBUF_INIT;
	time_t age;
	unsigned long hash;
	int devnull;

	hash = cache_hash_str(path);
	if (ctx.cfg.project_list)
		hash += cache_hash_str(ctx.cfg.project_list);
	strbuf_addf(&cached_rc, "%s/rc-%8lx", ctx.cfg.cache_root, hash);

	if (stat(cached_rc.buf, &st)) {
		// Nothing is cached yet, so this request scans in its own
		// process, leaving no copy behind when it cannot take the lock.
		if (generate_cached_repolist(path, cached_rc.buf)) {
			if (ctx.cfg.project_list)
				scan_projects(path, ctx.cfg.project_list);
			else
				scan_tree(path);
		}
		goto out;
	}

	config_file_parse(cached_rc.buf, apply_config);

	age = time(NULL) - st.st_mtime;
	if (age <= (ctx.cfg.cache_scanrc_ttl * 60))
		goto out;

	// The list just parsed is stale but usable, so a child rebuilds it
	// while this request answers from what it already has.
	if (fork())
		goto out;

	// The child inherits the descriptors of the request, and the web server
	// reads stdout until every holder of it is gone, so leaving them in
	// place would keep the visitor waiting for the whole scan after their
	// page was written. Anything the scan prints would land on that
	// response as well.
	devnull = open("/dev/null", O_RDWR);
	if (devnull >= 0) {
		dup2(devnull, STDIN_FILENO);
		dup2(devnull, STDOUT_FILENO);
		dup2(devnull, STDERR_FILENO);
		if (devnull > STDERR_FILENO)
			close(devnull);
	}
	// _exit rather than exit, so the handlers the request registered do
	// not run a second time in the child.
	_exit(generate_cached_repolist(path, cached_rc.buf));
out:
	strbuf_release(&cached_rc);
}

static void add_mimetype(const char *name, const char *value)
{
	struct string_list_item *item;

	item = string_list_insert(&ctx.cfg.mimetypes, name);
	item->util = xstrdup(value);
}

static void apply_config(const char *name, const char *value)
{
	const char *arg;

	if (!strcmp(name, "section"))
		ctx.cfg.section = cgit_strdup_first_line(value);
	else if (!strcmp(name, "repo.url"))
		ctx.repo = cgit_add_repo(value);
	else if (ctx.repo && !strcmp(name, "repo.path"))
		ctx.repo->path = cgit_trim_end(value, '/');
	else if (ctx.repo && skip_prefix(name, "repo.", &arg))
		cgit_repo_config(ctx.repo, arg, value);
	else if (!strcmp(name, "readme"))
		string_list_append(&ctx.cfg.readme, cgit_strdup_first_line(value));
	else if (!strcmp(name, "root-title"))
		ctx.cfg.root_title = cgit_strdup_first_line(value);
	else if (!strcmp(name, "root-desc"))
		ctx.cfg.root_desc = cgit_strdup_first_line(value);
	else if (!strcmp(name, "root-readme"))
		ctx.cfg.root_readme = cgit_strdup_first_line(value);
	else if (!strcmp(name, "css"))
		string_list_append(&ctx.cfg.css, cgit_strdup_first_line(value));
	else if (!strcmp(name, "js"))
		string_list_append(&ctx.cfg.js, cgit_strdup_first_line(value));
	else if (!strcmp(name, "favicon"))
		ctx.cfg.favicon = cgit_strdup_first_line(value);
	else if (!strcmp(name, "footer"))
		ctx.cfg.footer = cgit_strdup_first_line(value);
	else if (!strcmp(name, "head-include"))
		ctx.cfg.head_include = cgit_strdup_first_line(value);
	else if (!strcmp(name, "header"))
		ctx.cfg.header = cgit_strdup_first_line(value);
	else if (!strcmp(name, "logo"))
		ctx.cfg.logo = cgit_strdup_first_line(value);
	else if (!strcmp(name, "logo-link"))
		ctx.cfg.logo_link = cgit_strdup_first_line(value);
	else if (!strcmp(name, "module-link"))
		ctx.cfg.module_link = cgit_strdup_first_line(value);
	else if (!strcmp(name, "strict-export"))
		ctx.cfg.strict_export = cgit_strdup_first_line(value);
	else if (!strcmp(name, "virtual-root"))
		ctx.cfg.virtual_root = cgit_ensure_end(value, '/');
	else if (!strcmp(name, "noplainemail"))
		ctx.cfg.noplainemail = atoi(value);
	else if (!strcmp(name, "noheader"))
		ctx.cfg.noheader = atoi(value);
	else if (!strcmp(name, "snapshots"))
		ctx.cfg.snapshots = cgit_parse_snapshots_mask(value);
	else if (!strcmp(name, "enable-filter-overrides"))
		ctx.cfg.enable_filter_overrides = atoi(value);
	else if (!strcmp(name, "enable-follow-links"))
		ctx.cfg.enable_follow_links = atoi(value);
	else if (!strcmp(name, "enable-stats"))
		ctx.cfg.enable_stats = atoi(value);
	else if (!strcmp(name, "enable-http-clone"))
		ctx.cfg.enable_http_clone = atoi(value);
	else if (!strcmp(name, "enable-index-links"))
		ctx.cfg.enable_index_links = atoi(value);
	else if (!strcmp(name, "enable-index-owner"))
		ctx.cfg.enable_index_owner = atoi(value);
	else if (!strcmp(name, "enable-blame"))
		ctx.cfg.enable_blame = atoi(value);
	else if (!strcmp(name, "enable-commit-graph"))
		ctx.cfg.enable_commit_graph = atoi(value);
	else if (!strcmp(name, "enable-log-filecount"))
		ctx.cfg.enable_log_filecount = atoi(value);
	else if (!strcmp(name, "enable-log-linecount"))
		ctx.cfg.enable_log_linecount = atoi(value);
	else if (!strcmp(name, "enable-relative-dates"))
		ctx.cfg.enable_relative_dates = atoi(value);
	else if (!strcmp(name, "enable-remote-branches"))
		ctx.cfg.enable_remote_branches = atoi(value);
	else if (!strcmp(name, "enable-subject-links"))
		ctx.cfg.enable_subject_links = atoi(value);
	else if (!strcmp(name, "enable-html-serving"))
		ctx.cfg.enable_html_serving = atoi(value);
	else if (!strcmp(name, "enable-tree-linenumbers"))
		ctx.cfg.enable_tree_linenumbers = atoi(value);
	else if (!strcmp(name, "enable-tree-group-dirs"))
		ctx.cfg.enable_tree_group_dirs = atoi(value);
	else if (!strcmp(name, "enable-git-config"))
		ctx.cfg.enable_git_config = atoi(value);
	else if (!strcmp(name, "enable-cache-list"))
		ctx.cfg.enable_cache_list = atoi(value);
	else if (!strcmp(name, "max-stats"))
		ctx.cfg.max_stats = cgit_find_stats_period(value, NULL);
	else if (!strcmp(name, "cache-size"))
		ctx.cfg.cache_size = atoi(value);
	else if (!strcmp(name, "cache-root"))
		ctx.cfg.cache_root = cgit_strdup_first_line(cgit_expand_macros(value));
	else if (!strcmp(name, "cache-root-ttl"))
		ctx.cfg.cache_root_ttl = atoi(value);
	else if (!strcmp(name, "cache-repo-ttl"))
		ctx.cfg.cache_repo_ttl = atoi(value);
	else if (!strcmp(name, "cache-scanrc-ttl"))
		ctx.cfg.cache_scanrc_ttl = atoi(value);
	else if (!strcmp(name, "cache-static-ttl"))
		ctx.cfg.cache_static_ttl = atoi(value);
	else if (!strcmp(name, "cache-dynamic-ttl"))
		ctx.cfg.cache_dynamic_ttl = atoi(value);
	else if (!strcmp(name, "cache-about-ttl"))
		ctx.cfg.cache_about_ttl = atoi(value);
	else if (!strcmp(name, "cache-snapshot-ttl"))
		ctx.cfg.cache_snapshot_ttl = atoi(value);
	else if (!strcmp(name, "case-sensitive-sort"))
		ctx.cfg.case_sensitive_sort = atoi(value);
	else if (!strcmp(name, "about-filter"))
		ctx.cfg.about_filter = cgit_new_filter(value, ABOUT);
	else if (!strcmp(name, "commit-filter"))
		ctx.cfg.commit_filter = cgit_new_filter(value, COMMIT);
	else if (!strcmp(name, "email-filter"))
		ctx.cfg.email_filter = cgit_new_filter(value, EMAIL);
	else if (!strcmp(name, "auth-filter"))
		ctx.cfg.auth_filter = cgit_new_filter(value, AUTH);
	else if (!strcmp(name, "embedded"))
		ctx.cfg.embedded = atoi(value);
	else if (!strcmp(name, "max-atom-items"))
		ctx.cfg.max_atom_items = atoi(value);
	else if (!strcmp(name, "max-message-length"))
		ctx.cfg.max_msg_len = atoi(value);
	else if (!strcmp(name, "max-repodesc-length"))
		ctx.cfg.max_repodesc_len = atoi(value);
	else if (!strcmp(name, "max-blob-size"))
		ctx.cfg.max_blob_size = atoi(value);
	else if (!strcmp(name, "max-diff-files"))
		ctx.cfg.max_diff_files = atoi(value);
	else if (!strcmp(name, "max-diff-lines"))
		ctx.cfg.max_diff_lines = atoi(value);
	else if (!strcmp(name, "max-ref-count"))
		ctx.cfg.max_ref_count = atoi(value);
	else if (!strcmp(name, "max-repo-count")) {
		ctx.cfg.max_repo_count = atoi(value);
		if (ctx.cfg.max_repo_count <= 0)
			ctx.cfg.max_repo_count = INT_MAX;
	} else if (!strcmp(name, "max-commit-count"))
		ctx.cfg.max_commit_count = atoi(value);
	else if (!strcmp(name, "max-patch-count"))
		ctx.cfg.max_patch_count = atoi(value);
	else if (!strcmp(name, "project-list"))
		ctx.cfg.project_list = cgit_strdup_first_line(cgit_expand_macros(value));
	else if (!strcmp(name, "scan-path")) {
		if (ctx.cfg.cache_size)
			process_cached_repolist(cgit_expand_macros(value));
		else if (ctx.cfg.project_list)
			scan_projects(cgit_expand_macros(value),
				      ctx.cfg.project_list);
		else
			scan_tree(cgit_expand_macros(value));
	} else if (!strcmp(name, "scan-hidden-path"))
		ctx.cfg.scan_hidden_path = atoi(value);
	else if (!strcmp(name, "section-from-path"))
		ctx.cfg.section_from_path = atoi(value);
	else if (!strcmp(name, "repository-sort"))
		ctx.cfg.repository_sort = cgit_strdup_first_line(value);
	else if (!strcmp(name, "section-sort"))
		ctx.cfg.section_sort = atoi(value);
	else if (!strcmp(name, "source-filter"))
		ctx.cfg.source_filter = cgit_new_filter(value, SOURCE);
	else if (!strcmp(name, "summary-log"))
		ctx.cfg.summary_log = atoi(value);
	else if (!strcmp(name, "summary-branches"))
		ctx.cfg.summary_branches = atoi(value);
	else if (!strcmp(name, "summary-tags"))
		ctx.cfg.summary_tags = atoi(value);
	else if (!strcmp(name, "side-by-side-diffs"))
		ctx.cfg.difftype = atoi(value) ? DIFF_SSDIFF : DIFF_UNIFIED;
	else if (!strcmp(name, "agefile"))
		ctx.cfg.agefile = cgit_strdup_first_line(value);
	else if (!strcmp(name, "mimetype-file"))
		ctx.cfg.mimetype_file = cgit_strdup_first_line(value);
	else if (!strcmp(name, "renamelimit"))
		ctx.cfg.renamelimit = atoi(value);
	else if (!strcmp(name, "remove-suffix"))
		ctx.cfg.remove_suffix = atoi(value);
	else if (!strcmp(name, "robots"))
		ctx.cfg.robots = cgit_strdup_first_line(value);
	else if (!strcmp(name, "clone-prefix"))
		ctx.cfg.clone_prefix = cgit_strdup_first_line(value);
	else if (!strcmp(name, "clone-url"))
		ctx.cfg.clone_url = cgit_strdup_first_line(value);
	else if (!strcmp(name, "local-time"))
		ctx.cfg.local_time = atoi(value);
	else if (!strcmp(name, "date-format"))
		cgit_parse_date_format(value, &ctx.cfg.date_mode);
	else if (!strcmp(name, "commit-sort")) {
		if (!strcmp(value, "date"))
			ctx.cfg.commit_sort = 1;
		if (!strcmp(value, "topo"))
			ctx.cfg.commit_sort = 2;
	} else if (!strcmp(name, "branch-sort")) {
		if (!strcmp(value, "age"))
			ctx.cfg.branch_sort = 1;
		if (!strcmp(value, "name"))
			ctx.cfg.branch_sort = 0;
	} else if (skip_prefix(name, "mimetype.", &arg))
		add_mimetype(arg, value);
	else if (!strcmp(name, "include"))
		config_file_parse(cgit_expand_macros(value), apply_config);
}

/*
 * Read a whole number a request supplied, clamped into the range the caller
 * accepts. strtol rather than atoi, because atoi has no defined behaviour once
 * the digits overflow and every value here arrives straight from the query
 * string.
 */
static int query_int(const char *value, int min, int max)
{
	long number = strtol(value, NULL, 10);

	if (number < min)
		return min;
	if (number > max)
		return max;
	return number;
}

static void apply_query_param(const char *name, const char *value)
{
	if (!value)
		value = "";

	if (!strcmp(name,"r")) {
		ctx.qry.repo = xstrdup(value);
		ctx.repo = cgit_get_repoinfo(value);
	} else if (!strcmp(name, "p")) {
		ctx.qry.page = xstrdup(value);
	} else if (!strcmp(name, "url")) {
		// Every leading slash goes, not just one. What is left is
		// joined onto the virtual root, so a value like //example.com
		// would otherwise survive as /example.com and make that join a
		// scheme-relative link to another host.
		while (*value == '/')
			value++;
		ctx.qry.url = xstrdup(value);
		cgit_parse_url(value);
	} else if (!strcmp(name, "qt")) {
		ctx.qry.grep = xstrdup(value);
	} else if (!strcmp(name, "q")) {
		if (strlen(value) > MAX_SEARCH_LEN)
			ctx.qry.search = xstrndup(value, MAX_SEARCH_LEN);
		else
			ctx.qry.search = xstrdup(value);
	} else if (!strcmp(name, "h")) {
		ctx.qry.head = xstrdup(value);
		ctx.qry.has_symref = 1;
	} else if (!strcmp(name, "id")) {
		ctx.qry.oid = xstrdup(value);
		ctx.qry.has_oid = 1;
	} else if (!strcmp(name, "id2")) {
		ctx.qry.oid2 = xstrdup(value);
		ctx.qry.has_oid = 1;
	} else if (!strcmp(name, "ofs")) {
		// Bounded above so a crafted value cannot force a walk over the
		// whole history. Negatives stop at -1 rather than at zero,
		// because the offset is overloaded, the stats page submits -1
		// for all authors, and the log skip loop floors a negative
		// itself.
		ctx.qry.ofs = query_int(value, -1, MAX_QUERY_OFFSET);
	} else if (!strcmp(name, "path")) {
		ctx.qry.path = cgit_trim_end(value, '/');
	} else if (!strcmp(name, "s")) {
		ctx.qry.sort = xstrdup(value);
	} else if (!strcmp(name, "showmsg")) {
		ctx.qry.showmsg = query_int(value, INT_MIN, INT_MAX);
	} else if (!strcmp(name, "period")) {
		ctx.qry.period = xstrdup(value);
	} else if (!strcmp(name, "dt")) {
		ctx.qry.difftype = query_int(value, INT_MIN, INT_MAX);
		ctx.qry.has_difftype = 1;
	} else if (!strcmp(name, "ss")) {
		// No longer generated, but old links still carry it.
		ctx.qry.difftype = query_int(value, INT_MIN, INT_MAX) ?
			DIFF_SSDIFF : DIFF_UNIFIED;
		ctx.qry.has_difftype = 1;
	} else if (!strcmp(name, "all")) {
		ctx.qry.show_all = query_int(value, INT_MIN, INT_MAX);
	} else if (!strcmp(name, "context")) {
		// Context lines are not counted against max-diff-lines, so an
		// unbounded width turns a whole blob into context and renders
		// it in full however small the change was.
		ctx.qry.context = query_int(value, 0, MAX_DIFF_CONTEXT_LINES);
	} else if (!strcmp(name, "ignorews")) {
		ctx.qry.ignorews = query_int(value, INT_MIN, INT_MAX);
	} else if (!strcmp(name, "follow")) {
		ctx.qry.follow = query_int(value, INT_MIN, INT_MAX);
	}
}

static void open_auth_filter(const char *action)
{
	cgit_open_filter(ctx.cfg.auth_filter, action,
		ctx.env.http_cookie ? ctx.env.http_cookie : "",
		ctx.env.request_method ? ctx.env.request_method : "",
		ctx.env.query_string ? ctx.env.query_string : "",
		ctx.env.http_referer ? ctx.env.http_referer : "",
		ctx.env.path_info ? ctx.env.path_info : "",
		ctx.env.http_host ? ctx.env.http_host : "",
		ctx.env.https ? ctx.env.https : "",
		ctx.qry.repo ? ctx.qry.repo : "",
		ctx.qry.page ? ctx.qry.page : "",
		cgit_currentfullurl(),
		cgit_loginurl());
}

/*
 * The filter answers the login POST itself, writing the status line and every
 * header, so nothing here prints any and the process ends before this returns.
 */
static void authenticate_post(void)
{
	char buffer[MAX_AUTHENTICATION_POST_BYTES];
	size_t len;
	ssize_t got;

	open_auth_filter("authenticate-post");
	len = ctx.env.content_length;
	if (len > MAX_AUTHENTICATION_POST_BYTES)
		len = MAX_AUTHENTICATION_POST_BYTES;
	if ((got = read(STDIN_FILENO, buffer, len)) < 0)
		die_errno("Could not read POST from stdin");
	if (write(STDOUT_FILENO, buffer, got) < 0)
		die_errno("Could not write POST to stdout");
	cgit_close_filter(ctx.cfg.auth_filter);
	exit(0);
}

static void authenticate_cookie(void)
{
	if (!ctx.cfg.auth_filter) {
		ctx.env.authenticated = 1;
		return;
	}

	if (ctx.env.request_method && ctx.qry.page && !ctx.repo &&
	    !strcmp(ctx.env.request_method, "POST") &&
	    !strcmp(ctx.qry.page, "login")) {
		authenticate_post();
		return;
	}

	open_auth_filter("authenticate-cookie");
	ctx.env.authenticated = cgit_close_filter(ctx.cfg.auth_filter);
}

// Every cache-*-ttl setting is written in minutes, and so is this.
static int calc_ttl(void)
{
	if (!ctx.repo)
		return ctx.cfg.cache_root_ttl;

	if (!ctx.qry.page)
		return ctx.cfg.cache_repo_ttl;

	if (!strcmp(ctx.qry.page, "about"))
		return ctx.cfg.cache_about_ttl;

	if (!strcmp(ctx.qry.page, "snapshot"))
		return ctx.cfg.cache_snapshot_ttl;

	if (ctx.qry.has_oid)
		return ctx.cfg.cache_static_ttl;

	if (ctx.qry.has_symref)
		return ctx.cfg.cache_dynamic_ttl;

	return ctx.cfg.cache_repo_ttl;
}

/*
 * The scheme and the host are folded in because the absolute urls a page
 * carries, its clone urls and atom links, are built from them, so a request
 * arriving with a spoofed Host must not poison the page served to a visitor
 * who came in on the real one.
 */
static void build_cache_key(struct strbuf *key)
{
	char *hosturl = cgit_hosturl();
	const char *parts[] = {
		cgit_httpscheme(),
		hosturl ? hosturl : "",
		ctx.env.path_info ? ctx.env.path_info : "",
		ctx.env.query_string ? ctx.env.query_string : "",
	};
	size_t i;

	// Each part is written behind its own length, so nothing a value
	// contains can make two different requests spell one key. The path and
	// the query come from the environment rather than the query string cgit
	// rebuilds, since that rebuild folds the two together and would let the
	// PATH_INFO and QUERY_STRING forms of one request share a slot.
	for (i = 0; i < ARRAY_SIZE(parts); i++)
		strbuf_addf(key, "%zu|%s", strlen(parts[i]), parts[i]);
	free(hosturl);
}

// Returning non-zero ends git's walk, so the search stops at the first hit.
static int find_current_ref(const struct reference *ref, void *data)
{
	struct refmatch *match = data;

	if (!strcmp(ref->name, match->wanted))
		match->found = 1;
	if (!match->first)
		match->first = xstrdup(ref->name);
	return match->found;
}

static char *find_default_branch(struct cgit_repo *repo)
{
	struct refmatch match;
	char *ref;

	match.wanted = repo->defbranch;
	match.first = NULL;
	match.found = 0;
	refs_for_each_branch_ref(get_main_ref_store(the_repository),
				 find_current_ref, &match);
	if (match.found)
		ref = match.wanted;
	else
		ref = match.first;
	if (ref)
		ref = xstrdup(ref);
	free(match.first);

	return ref;
}

static char *guess_defbranch(void)
{
	const char *ref, *refname;
	struct object_id oid;

	ref = refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
				     "HEAD", 0, &oid, NULL);
	if (!ref || !skip_prefix(ref, "refs/heads/", &refname))
		return "master";
	return xstrdup(refname);
}

/*
 * Split one readme setting into the file it names and the ref that file is
 * read from, leaving the ref NULL for a file on disk. The caller frees both.
 */
static void parse_readme(const char *readme, char **filename, char **ref,
			 struct cgit_repo *repo)
{
	const char *colon;

	*filename = NULL;
	*ref = NULL;

	if (!readme || !readme[0])
		return;

	// A colon separates a ref from a path, so a setting carrying one names
	// a file tracked in the repository rather than one on disk.
	colon = strchr(readme, ':');
	if (colon && strlen(colon) > 1) {
		if (colon == readme && ctx.qry.head)
			*ref = xstrdup(ctx.qry.head);
		else if (colon == readme && repo->defbranch)
			*ref = xstrdup(repo->defbranch);
		else
			*ref = xstrndup(readme, colon - readme);
		readme = colon + 1;
	}

	if (!(*ref) && readme[0] != '/')
		*filename = cgit_fmtalloc("%s/%s", repo->path, readme);
	else
		*filename = xstrdup(readme);
}

static void choose_readme(struct cgit_repo *repo)
{
	int found;
	char *filename, *ref;
	struct string_list_item *entry;

	if (!repo->readme.nr)
		return;

	found = 0;
	for_each_string_list_item(entry, &repo->readme) {
		parse_readme(entry->string, &filename, &ref, repo);
		if (!filename) {
			free(filename);
			free(ref);
			continue;
		}
		if (ref) {
			if (cgit_ref_path_exists(filename, ref, 1)) {
				found = 1;
				break;
			}
		}
		else if (!access(filename, R_OK)) {
			found = 1;
			break;
		}
		free(filename);
		free(ref);
	}
	repo->readme.strdup_strings = 1;
	string_list_clear(&repo->readme, 0);
	repo->readme.strdup_strings = 0;
	if (found)
		string_list_append(&repo->readme, filename)->util = ref;
}

static void prepare_repo_env(int *nongit)
{
	setenv("GIT_DIR", ctx.repo->path, 1);

	// Both read configuration out of the repository, with the user's own
	// git configuration already stripped by isolate_git_environment.
	setup_git_directory_gently(the_repository, nongit);
	load_display_notes(NULL);
}

/*
 * Returns non-zero once it has written a complete response of its own, in
 * which case the caller must not render a page over the top of it.
 */
static int prepare_repo_cmd(int nongit)
{
	struct object_id oid;
	int err;

	if (nongit) {
		const char *name = ctx.repo->name;
		err = errno;
		ctx.page.title = cgit_fmtalloc("%s - %s", ctx.cfg.root_title,
						"config error");
		ctx.repo = NULL;
		cgit_print_http_headers();
		cgit_print_docstart();
		cgit_print_pageheader();
		cgit_print_error("Failed to open %s: %s", name,
				 err ? strerror(err) : "Not a valid git repository");
		cgit_print_docend();
		return 1;
	}
	ctx.page.title = cgit_fmtalloc("%s - %s", ctx.repo->name, ctx.repo->desc);

	if (!ctx.repo->defbranch)
		ctx.repo->defbranch = guess_defbranch();

	if (!ctx.qry.head) {
		ctx.qry.nohead = 1;
		ctx.qry.head = find_default_branch(ctx.repo);
	}

	if (!ctx.qry.head) {
		ctx.empty_repo = 1;
		// Before the document starts, since the <head> carries
		// <link rel='vcs-git'> and those clone urls expand macros such
		// as $CGIT_REPO_URL out of this environment.
		cgit_prepare_repo_env(ctx.repo);
		cgit_print_http_headers();
		cgit_print_docstart();
		cgit_print_pageheader();
		cgit_print_empty_repo();
		cgit_print_docend();
		return 1;
	}

	if (repo_get_oid(the_repository, ctx.qry.head, &oid)) {
		char *old_head = ctx.qry.head;
		ctx.qry.head = xstrdup(ctx.repo->defbranch);
		cgit_print_error_page(404, "Not found",
				"Invalid branch: %s", old_head);
		free(old_head);
		return 1;
	}
	string_list_sort(&ctx.repo->submodules);
	cgit_prepare_repo_env(ctx.repo);
	choose_readme(ctx.repo);
	return 0;
}

static void process_request(void)
{
	const struct cgit_cmd *cmd;
	int nongit = 0;

	// An unauthenticated request is answered with the filter's own body
	// whatever page it asked for.
	if (!ctx.env.authenticated) {
		ctx.page.title = "Authentication Required";
		cgit_print_http_headers();
		cgit_print_docstart();
		cgit_print_pageheader();
		open_auth_filter("body");
		cgit_close_filter(ctx.cfg.auth_filter);
		cgit_print_docend();
		return;
	}

	if (ctx.repo)
		prepare_repo_env(&nongit);

	cmd = cgit_get_cmd();
	if (!cmd) {
		ctx.page.title = "cgit error";
		cgit_print_error_page(404, "Not found", "Invalid request");
		return;
	}

	if (!ctx.cfg.enable_http_clone && cmd->is_clone) {
		ctx.page.title = "cgit error";
		cgit_print_error_page(404, "Not found", "Invalid request");
		return;
	}

	if (cmd->want_repo && !ctx.repo) {
		cgit_print_error_page(400, "Bad request",
				"No repository selected");
		return;
	}

	ctx.qry.vpath = cmd->want_vpath ? ctx.qry.path : NULL;

	if (ctx.repo && prepare_repo_cmd(nongit))
		return;

	cmd->fn();
}

void cgit_repo_config(struct cgit_repo *repo, const char *name, const char *value)
{
	const char *path;
	struct string_list_item *item;

	if (!strcmp(name, "name"))
		repo->name = cgit_strdup_first_line(value);
	else if (!strcmp(name, "clone-url"))
		repo->clone_url = cgit_strdup_first_line(value);
	else if (!strcmp(name, "desc"))
		repo->desc = cgit_strdup_first_line(value);
	else if (!strcmp(name, "owner"))
		repo->owner = cgit_strdup_first_line(value);
	else if (!strcmp(name, "defbranch"))
		repo->defbranch = cgit_strdup_first_line(value);
	else if (!strcmp(name, "extra-head-content"))
		repo->extra_head_content = cgit_strdup_first_line(value);
	else if (!strcmp(name, "snapshots"))
		repo->snapshots = ctx.cfg.snapshots & cgit_parse_snapshots_mask(value);
	else if (!strcmp(name, "enable-blame"))
		repo->enable_blame = atoi(value);
	else if (!strcmp(name, "enable-commit-graph"))
		repo->enable_commit_graph = atoi(value);
	else if (!strcmp(name, "enable-follow-links"))
		repo->enable_follow_links = atoi(value);
	else if (!strcmp(name, "enable-log-filecount"))
		repo->enable_log_filecount = atoi(value);
	else if (!strcmp(name, "enable-log-linecount"))
		repo->enable_log_linecount = atoi(value);
	else if (!strcmp(name, "enable-remote-branches"))
		repo->enable_remote_branches = atoi(value);
	else if (!strcmp(name, "enable-subject-links"))
		repo->enable_subject_links = atoi(value);
	else if (!strcmp(name, "enable-html-serving"))
		repo->enable_html_serving = atoi(value);
	else if (!strcmp(name, "enable-stats"))
		repo->enable_stats = atoi(value);
	else if (!strcmp(name, "branch-sort")) {
		if (!strcmp(value, "age"))
			repo->branch_sort = 1;
		if (!strcmp(value, "name"))
			repo->branch_sort = 0;
	} else if (!strcmp(name, "commit-sort")) {
		if (!strcmp(value, "date"))
			repo->commit_sort = 1;
		if (!strcmp(value, "topo"))
			repo->commit_sort = 2;
	} else if (!strcmp(name, "max-stats"))
		repo->max_stats = cgit_find_stats_period(value, NULL);
	else if (!strcmp(name, "module-link"))
		repo->module_link = cgit_strdup_first_line(value);
	else if (skip_prefix(name, "module-link.", &path)) {
		item = string_list_append(&repo->submodules,
					  cgit_strdup_first_line(path));
		item->util = cgit_strdup_first_line(value);
	} else if (!strcmp(name, "section"))
		repo->section = cgit_strdup_first_line(value);
	else if (!strcmp(name, "snapshot-prefix"))
		repo->snapshot_prefix = cgit_strdup_first_line(value);
	else if (!strcmp(name, "readme") && value != NULL) {
		if (repo->readme.items == ctx.cfg.readme.items)
			memset(&repo->readme, 0, sizeof(repo->readme));
		string_list_append(&repo->readme, cgit_strdup_first_line(value));
	} else if (!strcmp(name, "logo") && value != NULL)
		repo->logo = cgit_strdup_first_line(value);
	else if (!strcmp(name, "logo-link") && value != NULL)
		repo->logo_link = cgit_strdup_first_line(value);
	else if (!strcmp(name, "hide"))
		repo->hide = atoi(value);
	else if (!strcmp(name, "ignore"))
		repo->ignore = atoi(value);
	else if (ctx.cfg.enable_filter_overrides) {
		if (!strcmp(name, "about-filter"))
			repo->about_filter = cgit_new_filter(value, ABOUT);
		else if (!strcmp(name, "commit-filter"))
			repo->commit_filter = cgit_new_filter(value, COMMIT);
		else if (!strcmp(name, "source-filter"))
			repo->source_filter = cgit_new_filter(value, SOURCE);
		else if (!strcmp(name, "email-filter"))
			repo->email_filter = cgit_new_filter(value, EMAIL);
	}
}

int cmd_main(int argc, const char **argv)
{
	struct strbuf cache_key = STRBUF_INIT;
	const char *path;
	int err, ttl;

	isolate_git_environment();
	cgit_init_filters();
	atexit(cgit_cleanup_filters);
	// Registered second so it runs first, since exit is reached from error
	// paths and from the HEAD shortcut with a page still buffered.
	atexit(html_flush);
	set_die_routine(die_routine);

	prepare_context();
	cgit_repolist.length = 0;
	cgit_repolist.count = 0;
	cgit_repolist.repos = NULL;

	parse_args(argc, argv);
	config_file_parse(cgit_expand_macros(ctx.env.cgit_config), apply_config);
	ctx.repo = NULL;
	http_parse_querystring(ctx.qry.raw, apply_query_param);

	if (!ctx.cfg.virtual_root && ctx.cfg.script_name)
		ctx.cfg.virtual_root = cgit_ensure_end(ctx.cfg.script_name, '/');

	// Falling back to PATH_INFO lets cgit serve virtual urls without a
	// rewrite rule in the web server, and folding it into the raw query
	// string keeps it part of the cache key.
	path = ctx.env.path_info;
	if (!ctx.qry.url && path) {
		// Stripped like the url parameter and for the same reason, so
		// a request for //example.com cannot turn into a link off site.
		while (*path == '/')
			path++;
		ctx.qry.url = xstrdup(path);
		if (ctx.qry.raw) {
			char *path_and_query = cgit_fmtalloc("%s?%s", path, ctx.qry.raw);
			free(ctx.qry.raw);
			ctx.qry.raw = path_and_query;
		} else
			ctx.qry.raw = xstrdup(ctx.qry.url);
		cgit_parse_url(ctx.qry.url);
	}

	authenticate_cookie();

	ttl = calc_ttl();
	// An unauthenticated request gets a body meant for one visitor, and a
	// HEAD request stops after the headers.
	if (!ctx.env.authenticated ||
	    (ctx.env.request_method && !strcmp(ctx.env.request_method, "HEAD")))
		ctx.cfg.cache_size = 0;

	build_cache_key(&cache_key);
	err = cache_process(ctx.cfg.cache_size, ctx.cfg.cache_root,
			    cache_key.buf, ttl, process_request);
	strbuf_release(&cache_key);

	cgit_cleanup_filters();
	if (err)
		cgit_print_error("Error processing page: %s (%d)",
				 strerror(err), err);
	return err;
}