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/* html.c: helper functions for html output
 *
 * Copyright (C) 2006-2014 cgit Development Team <cgit@lists.zx2c4.com>
 *
 * Licensed under GNU General Public License v2
 *   (see LICENSE.txt for full license text)
 */

#include "cgit.h"
#include "html.h"
#include "url.h"
#define HTML_WRITE_BUFSIZE (64 * 1024)
static char html_buf[HTML_WRITE_BUFSIZE];
static size_t html_buflen;

/* Percent-encoding of each character, except: a-zA-Z0-9!$()*,./:;@- */
static const char* url_escape_table[256] = {
	"%00", "%01", "%02", "%03", "%04", "%05", "%06", "%07",
	"%08", "%09", "%0a", "%0b", "%0c", "%0d", "%0e", "%0f",
	"%10", "%11", "%12", "%13", "%14", "%15", "%16", "%17",
	"%18", "%19", "%1a", "%1b", "%1c", "%1d", "%1e", "%1f",
	"%20", NULL,  "%22", "%23", NULL,  "%25", "%26", "%27",
	NULL,  NULL,  NULL,  "%2b", NULL,  NULL,  NULL,  NULL,
	NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,
	NULL,  NULL,  NULL,  NULL,  "%3c", "%3d", "%3e", "%3f",
	NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,
	NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,
	NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,
	NULL,  NULL,  NULL,  NULL,  "%5c", NULL,  "%5e", NULL,
	"%60", NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,
	NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,
	NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,  NULL,
	NULL,  NULL,  NULL,  "%7b", "%7c", "%7d", NULL,  "%7f",
	"%80", "%81", "%82", "%83", "%84", "%85", "%86", "%87",
	"%88", "%89", "%8a", "%8b", "%8c", "%8d", "%8e", "%8f",
	"%90", "%91", "%92", "%93", "%94", "%95", "%96", "%97",
	"%98", "%99", "%9a", "%9b", "%9c", "%9d", "%9e", "%9f",
	"%a0", "%a1", "%a2", "%a3", "%a4", "%a5", "%a6", "%a7",
	"%a8", "%a9", "%aa", "%ab", "%ac", "%ad", "%ae", "%af",
	"%b0", "%b1", "%b2", "%b3", "%b4", "%b5", "%b6", "%b7",
	"%b8", "%b9", "%ba", "%bb", "%bc", "%bd", "%be", "%bf",
	"%c0", "%c1", "%c2", "%c3", "%c4", "%c5", "%c6", "%c7",
	"%c8", "%c9", "%ca", "%cb", "%cc", "%cd", "%ce", "%cf",
	"%d0", "%d1", "%d2", "%d3", "%d4", "%d5", "%d6", "%d7",
	"%d8", "%d9", "%da", "%db", "%dc", "%dd", "%de", "%df",
	"%e0", "%e1", "%e2", "%e3", "%e4", "%e5", "%e6", "%e7",
	"%e8", "%e9", "%ea", "%eb", "%ec", "%ed", "%ee", "%ef",
	"%f0", "%f1", "%f2", "%f3", "%f4", "%f5", "%f6", "%f7",
	"%f8", "%f9", "%fa", "%fb", "%fc", "%fd", "%fe", "%ff"
};

char *cgit_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 < 0 || (size_t)len >= sizeof(buf[bufidx])) {
		fprintf(stderr, "[html.c] string truncated: %s\n", format);
		exit(1);
	}
	return buf[bufidx];
}

char *cgit_fmtalloc(const char *format, ...)
{
	struct strbuf sb = STRBUF_INIT;
	va_list args;

	va_start(args, format);
	strbuf_vaddf(&sb, format, args);
	va_end(args);

	return strbuf_detach(&sb, NULL);
}

/*
 * Page output is collected here and written out in whole buffers. A page is
 * built from a great many small fragments, and writing each one cost a syscall
 * apiece: a tree listing spent more time entering the kernel than generating
 * anything.
 *
 * cgit does not own stdout by itself, so the buffer has to be emptied before
 * anything else writes there. Those points are a filter taking over stdout,
 * the header block that precedes output produced by git itself, the cache
 * slot being measured, and process exit.
 */
static void html_write(const char *data, size_t size)
{
	// A blob, snapshot or patch reaches this with a size well past what one
	// write can move onto a pipe, so a short write is ordinary rather than
	// an error and has to be resumed instead of reported.
	if (write_in_full(STDOUT_FILENO, data, size) < 0)
		die_errno("write error on html output");
}

void html_flush(void)
{
	size_t len = html_buflen;

	if (!len)
		return;
	// Clear the length first: html_write can die, and the error page it
	// produces would otherwise try to flush the same bytes again.
	html_buflen = 0;
	html_write(html_buf, len);
}

/*
 * While a capture is in effect, page output is collected into the caller's
 * buffer instead of being written. The diff view uses this to render a file's
 * body at the point it already has the file open, rather than walking the whole
 * tree a second time to produce what the diffstat above it has to be printed
 * before.
 *
 * A capture must not span anything that writes to stdout by another route, a
 * filter in particular, since that output would escape the capture.
 */
static struct strbuf *html_capture;

void html_capture_begin(struct strbuf *sb)
{
	html_flush();
	html_capture = sb;
}

void html_capture_end(void)
{
	html_capture = NULL;
}

void html_raw(const char *data, size_t size)
{
	if (html_capture) {
		strbuf_add(html_capture, data, size);
		return;
	}
	if (size >= HTML_WRITE_BUFSIZE) {
		// Nothing is gained by copying a blob through the buffer.
		html_flush();
		html_write(data, size);
		return;
	}
	if (html_buflen + size > HTML_WRITE_BUFSIZE)
		html_flush();
	memcpy(html_buf + html_buflen, data, size);
	html_buflen += size;
}

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

void htmlf(const char *format, ...)
{
	va_list args;
	struct strbuf buf = STRBUF_INIT;

	va_start(args, format);
	strbuf_vaddf(&buf, format, args);
	va_end(args);
	html(buf.buf);
	strbuf_release(&buf);
}

void html_txtf(const char *format, ...)
{
	va_list args;

	va_start(args, format);
	html_vtxtf(format, args);
	va_end(args);
}

void html_vtxtf(const char *format, va_list ap)
{
	va_list cp;
	struct strbuf buf = STRBUF_INIT;

	va_copy(cp, ap);
	strbuf_vaddf(&buf, format, cp);
	va_end(cp);
	html_txt(buf.buf);
	strbuf_release(&buf);
}

void html_txt(const char *txt)
{
	if (txt)
		html_ntxt(txt, strlen(txt));
}

ssize_t html_ntxt(const char *txt, size_t len)
{
	const char *t = txt;
	ssize_t slen;

	if (len > SSIZE_MAX)
		return -1;

	slen = (ssize_t) len;
	while (t && *t && slen--) {
		int c = *t;
		if (c == '<' || c == '>' || c == '&') {
			html_raw(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_raw(txt, t - txt);
	return slen;
}

void html_attrf(const char *fmt, ...)
{
	va_list ap;
	struct strbuf sb = STRBUF_INIT;

	va_start(ap, fmt);
	strbuf_vaddf(&sb, fmt, ap);
	va_end(ap);

	html_attr(sb.buf);
	strbuf_release(&sb);
}

void html_attr(const char *txt)
{
	const char *t = txt;
	while (t && *t) {
		int c = *t;
		if (c == '<' || c == '>' || c == '\'' || c == '\"' || c == '&') {
			html_raw(txt, t - txt);
			if (c == '>')
				html("&gt;");
			else if (c == '<')
				html("&lt;");
			else if (c == '\'')
				html("&#x27;");
			else if (c == '"')
				html("&quot;");
			else if (c == '&')
				html("&amp;");
			txt = t + 1;
		}
		t++;
	}
	if (t != txt)
		html(txt);
}

void html_url_path(const char *txt)
{
	const char *t = txt;
	while (t && *t) {
		unsigned char c = *t;
		const char *e = url_escape_table[c];
		if (e && c != '+' && c != '&') {
			html_raw(txt, t - txt);
			html(e);
			txt = t + 1;
		}
		t++;
	}
	if (t != txt)
		html(txt);
}

void html_url_arg(const char *txt)
{
	const char *t = txt;
	while (t && *t) {
		unsigned char c = *t;
		const char *e = url_escape_table[c];
		if (c == ' ')
			e = "+";
		if (e) {
			html_raw(txt, t - txt);
			html(e);
			txt = t + 1;
		}
		t++;
	}
	if (t != txt)
		html(txt);
}

void html_header_arg_in_quotes(const char *txt)
{
	const char *t = txt;
	while (t && *t) {
		unsigned char c = *t;
		const char *e = NULL;
		if (c == '\\')
			e = "\\\\";
		else if (c == '\r')
			e = "\\r";
		else if (c == '\n')
			e = "\\n";
		else if (c == '"')
			e = "\\\"";
		if (e) {
			html_raw(txt, t - txt);
			html(e);
			txt = t + 1;
		}
		t++;
	}
	if (t != txt)
		html(txt);

}

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

void html_option(const char *value, const char *text, const 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");
}

void html_intoption(int value, const char *text, int selected_value)
{
	htmlf("<option value='%d'%s>", value,
	      value == selected_value ? " selected='selected'" : "");
	html_txt(text);
	html("</option>");
}

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

void html_link_close(void)
{
	html("</a>");
}

void html_fileperm(unsigned short mode)
{
	htmlf("%c%c%c", (mode & 4 ? 'r' : '-'),
	      (mode & 2 ? 'w' : '-'), (mode & 1 ? 'x' : '-'));
}

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)
		html_raw(buf, len);
	fclose(f);
	return 0;
}

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

	while (t && *t) {
		char *name = url_decode_parameter_name(&t);
		if (*name) {
			char *value = url_decode_parameter_value(&t);
			fn(name, value);
			free(value);
		}
		free(name);
	}
}