Commit message: Add support for cloning over http

This patch implements basic support for cloning over http, based on the
work on git-http-backend by Shawn O. Pearce.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>
CVE: None
Vulnerability description: None

Project: cgit

static void blob_fn(struct cgit_context *ctx)
{
	cgit_print_blob(ctx->qry.sha1, ctx->qry.path, ctx->qry.head);
}

Project: cgit

void html_ntxt(int len, char *txt)
{
	char *t = txt;
	while(t && *t && len--){
		int c = *t;
		if (c=='<' || c=='>' || c=='&') {
			write(htmlfd, txt, t - txt);
			if (c=='>')
				html("&gt;");
			else if (c=='<')
				html("&lt;");
			else if (c=='&')
				html("&amp;");
			txt = t+1;
		}
		t++;
	}
	if (t!=txt)
		write(htmlfd, txt, t - txt);
	if (len<0)
		html("...");
}

Project: cgit

int html_include(const char *filename)
{
	FILE *f;
	char buf[4096];
	size_t len;

	if (!(f = fopen(filename, "r"))) {
		fprintf(stderr, "[cgit] Failed to include file %s: %s (%d).\n",
			filename, strerror(errno), errno);
		return -1;
	}
	while((len = fread(buf, 1, 4096, f)) > 0)
		write(htmlfd, buf, len);
	fclose(f);
	return 0;
}

Project: cgit

static void tag_fn(struct cgit_context *ctx)
{
	cgit_print_tag(ctx->qry.sha1);
}

Project: cgit

static void objects_fn(struct cgit_context *ctx)
{
	cgit_clone_objects(ctx);
}

Project: cgit

void html_status(int code, int more_headers)
{
	htmlf("Status: %d\n", code);
	if (!more_headers)
		html("\n");
}

Project: cgit

void html_attr(char *txt)
{
	char *t = txt;
	while(t && *t){
		int c = *t;
		if (c=='<' || c=='>' || c=='\'') {
			write(htmlfd, txt, t - txt);
			if (c=='>')
				html("&gt;");
			else if (c=='<')
				html("&lt;");
			else if (c=='\'')
				html("&quote;");
			txt = t+1;
		}
		t++;
	}
	if (t!=txt)
		html(txt);
}

Project: cgit

static void about_fn(struct cgit_context *ctx)
{
	if (ctx->repo)
		cgit_print_repo_readme();
	else
		cgit_print_site_readme();
}

Project: cgit

static int print_ref_info(const char *refname, const unsigned char *sha1,
                          int flags, void *cb_data)
{
	struct object *obj;

	if (!(obj = parse_object(sha1)))
		return 0;

	if (!strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/"))
		htmlf("%s\t%s\n", sha1_to_hex(sha1), refname);
	else if (!prefixcmp(refname, "refs/tags") && obj->type == OBJ_TAG) {
		if (!(obj = deref_tag(obj, refname, 0)))
			return 0;
		htmlf("%s\t%s\n", sha1_to_hex(sha1), refname);
		htmlf("%s\t%s^{}\n", sha1_to_hex(obj->sha1), refname);
	}
	return 0;
}

Project: cgit

static void summary_fn(struct cgit_context *ctx)
{
	cgit_print_summary();
}

Project: cgit

struct cgit_cmd *cgit_get_cmd(struct cgit_context *ctx)
{
	static struct cgit_cmd cmds[] = {
		def_cmd(HEAD, 1, 0),
		def_cmd(about, 0, 1),
		def_cmd(blob, 1, 0),
		def_cmd(commit, 1, 1),
		def_cmd(diff, 1, 1),
		def_cmd(info, 1, 0),
		def_cmd(log, 1, 1),
		def_cmd(ls_cache, 0, 0),
		def_cmd(objects, 1, 0),
		def_cmd(patch, 1, 0),
		def_cmd(refs, 1, 1),
		def_cmd(repolist, 0, 0),
		def_cmd(snapshot, 1, 0),
		def_cmd(summary, 1, 1),
		def_cmd(tag, 1, 1),
		def_cmd(tree, 1, 1),
	};
	int i;

	if (ctx->qry.page == NULL) {
		if (ctx->repo)
			ctx->qry.page = "summary";
		else
			ctx->qry.page = "repolist";
	}

	for(i = 0; i < sizeof(cmds)/sizeof(*cmds); i++)
		if (!strcmp(ctx->qry.page, cmds[i].name))
			return &cmds[i];
	return NULL;
}

Project: cgit

static void repolist_fn(struct cgit_context *ctx)
{
	cgit_print_repolist();
}

Project: cgit

void html(const char *txt)
{
	write(htmlfd, txt, strlen(txt));
}

Project: cgit

static void patch_fn(struct cgit_context *ctx)
{
	cgit_print_patch(ctx->qry.sha1);
}

Project: cgit

void html_option(char *value, char *text, char *selected_value)
{
	html("<option value='");
	html_attr(value);
	html("'");
	if (selected_value && !strcmp(selected_value, value))
		html(" selected='selected'");
	html(">");
	html_txt(text);
	html("</option>\n");
}

Project: cgit

void cgit_clone_info(struct cgit_context *ctx)
{
	if (!ctx->qry.path || strcmp(ctx->qry.path, "refs"))
		return;

	ctx->page.mimetype = "text/plain";
	ctx->page.filename = "info/refs";
	cgit_print_http_headers(ctx);
	for_each_ref(print_ref_info, ctx);
}

Project: cgit

static void snapshot_fn(struct cgit_context *ctx)
{
	cgit_print_snapshot(ctx->qry.head, ctx->qry.sha1,
			    cgit_repobasename(ctx->repo->url), ctx->qry.path,
			    ctx->repo->snapshots);
}

Project: cgit

static void refs_fn(struct cgit_context *ctx)
{
	cgit_print_refs();
}

Project: cgit

void cgit_clone_objects(struct cgit_context *ctx)
{
	if (!ctx->qry.path) {
		html_status(400, 0);
		return;
	}

	if (!strcmp(ctx->qry.path, "info/packs")) {
		print_pack_info(ctx);
		return;
	}

	send_file(ctx, git_path("objects/%s", ctx->qry.path));
}

Project: cgit

static void print_pack_info(struct cgit_context *ctx)
{
	struct packed_git *pack;
	int ofs;

	ctx->page.mimetype = "text/plain";
	ctx->page.filename = "objects/info/packs";
	cgit_print_http_headers(ctx);
	ofs = strlen(ctx->repo->path) + strlen("/objects/pack/");
	prepare_packed_git();
	for (pack = packed_git; pack; pack = pack->next)
		if (pack->pack_local)
			htmlf("P %s\n", pack->pack_name + ofs);
}

Project: cgit

void html_link_open(char *url, char *title, char *class)
{
	html("<a href='");
	html_attr(url);
	if (title) {
		html("' title='");
		html_attr(title);
	}
	if (class) {
		html("' class='");
		html_attr(class);
	}
	html("'>");
}

Project: cgit

static void commit_fn(struct cgit_context *ctx)
{
	cgit_print_commit(ctx->qry.sha1);
}

Project: cgit

static void info_fn(struct cgit_context *ctx)
{
	cgit_clone_info(ctx);
}

Project: cgit

void html_txt(char *txt)
{
	char *t = txt;
	while(t && *t){
		int c = *t;
		if (c=='<' || c=='>' || c=='&') {
			write(htmlfd, txt, t - txt);
			if (c=='>')
				html("&gt;");
			else if (c=='<')
				html("&lt;");
			else if (c=='&')
				html("&amp;");
			txt = t+1;
		}
		t++;
	}
	if (t!=txt)
		html(txt);
}

Project: cgit

static void ls_cache_fn(struct cgit_context *ctx)
{
	ctx->page.mimetype = "text/plain";
	ctx->page.filename = "ls-cache.txt";
	cgit_print_http_headers(ctx);
	cache_ls(ctx->cfg.cache_root);
}

Project: cgit

static void log_fn(struct cgit_context *ctx)
{
	cgit_print_log(ctx->qry.sha1, ctx->qry.ofs, ctx->cfg.max_commit_count,
		       ctx->qry.grep, ctx->qry.search, ctx->qry.path, 1);
}

Project: cgit

static void diff_fn(struct cgit_context *ctx)
{
	cgit_print_diff(ctx->qry.sha1, ctx->qry.sha2, ctx->qry.path);
}

Project: cgit

void htmlf(const char *format, ...)
{
	static char buf[65536];
	va_list args;

	va_start(args, format);
	vsnprintf(buf, sizeof(buf), format, args);
	va_end(args);
	html(buf);
}

Project: cgit

int hextoint(char c)
{
	if (c >= 'a' && c <= 'f')
		return 10 + c - 'a';
	else if (c >= 'A' && c <= 'F')
		return 10 + c - 'A';
	else if (c >= '0' && c <= '9')
		return c - '0';
	else
		return -1;
}

Project: cgit

void cgit_clone_head(struct cgit_context *ctx)
{
	send_file(ctx, git_path("%s", "HEAD"));
}

Project: cgit

void html_hidden(char *name, char *value)
{
	html("<input type='hidden' name='");
	html_attr(name);
	html("' value='");
	html_attr(value);
	html("'/>");
}

Project: cgit

static void send_file(struct cgit_context *ctx, char *path)
{
	struct stat st;
	int err;

	if (stat(path, &st)) {
		switch (errno) {
		case ENOENT:
			err = 404;
			break;
		case EACCES:
			err = 403;
			break;
		default:
			err = 400;
		}
		html_status(err, 0);
		return;
	}
	ctx->page.mimetype = "application/octet-stream";
	ctx->page.filename = path;
	if (prefixcmp(ctx->repo->path, path))
		ctx->page.filename += strlen(ctx->repo->path) + 1;
	cgit_print_http_headers(ctx);
	html_include(path);
}

Project: cgit

static void tree_fn(struct cgit_context *ctx)
{
	cgit_print_tree(ctx->qry.sha1, ctx->qry.path);
}

Project: cgit

char *convert_query_hexchar(char *txt)
{
	int d1, d2;
	if (strlen(txt) < 3) {
		*txt = '\0';
		return txt-1;
	}
	d1 = hextoint(*(txt+1));
	d2 = hextoint(*(txt+2));
	if (d1<0 || d2<0) {
		strcpy(txt, txt+3);
		return txt-1;
	} else {
		*txt = d1 * 16 + d2;
		strcpy(txt+1, txt+3);
		return txt;
	}
}

Project: cgit

char *fmt(const char *format, ...)
{
	static char buf[8][1024];
	static int bufidx;
	int len;
	va_list args;

	bufidx++;
	bufidx &= 7;

	va_start(args, format);
	len = vsnprintf(buf[bufidx], sizeof(buf[bufidx]), format, args);
	va_end(args);
	if (len>sizeof(buf[bufidx])) {
		fprintf(stderr, "[html.c] string truncated: %s\n", format);
		exit(1);
	}
	return buf[bufidx];
}

Project: cgit

int http_parse_querystring(char *txt, void (*fn)(const char *name, const char *value))
{
	char *t, *value = NULL, c;

	if (!txt)
		return 0;

	t = txt = strdup(txt);
	if (t == NULL) {
		printf("Out of memory\n");
		exit(1);
	}
	while((c=*t) != '\0') {
		if (c=='=') {
			*t = '\0';
			value = t+1;
		} else if (c=='+') {
			*t = ' ';
		} else if (c=='%') {
			t = convert_query_hexchar(t);
		} else if (c=='&') {
			*t = '\0';
			(*fn)(txt, value);
			txt = t+1;
			value = NULL;
		}
		t++;
	}
	if (t!=txt)
		(*fn)(txt, value);
	return 0;
}

Project: cgit

static void HEAD_fn(struct cgit_context *ctx)
{
	cgit_clone_head(ctx);
}