Harden the request path, scan and error recovery

1 file changed, 28 insertions, 4 deletions

diff --git a/source/html.c b/source/html.c
index 5972d97..a1d244b 100644
--- a/source/html.c
+++ b/source/html.c
@@ -9,6 +9,7 @@
  */
 
 #include "cgit.h"
+#include "cache.h"
 #include "html.h"
 
 #define HTML_WRITE_BUFSIZE (64 * 1024)
@@ -58,8 +59,22 @@ static void write_out(const char *data, size_t size)
 {
 	// A blob or snapshot is well past what one write can move onto a
 	// pipe, so short writes are resumed rather than reported.
-	if (write_in_full(STDOUT_FILENO, data, size) < 0)
-		die_errno("write error on html output");
+	while (size) {
+		ssize_t written = xwrite(STDOUT_FILENO, data, size);
+
+		if (written < 0)
+			break;
+		data += written;
+		size -= written;
+	}
+	if (!size)
+		return;
+	// While a cache slot is being filled stdout is a file, and a full disk
+	// must not cost the visitor the page. Abandoning the fill puts stdout
+	// back on the client along with what the file already holds, so only
+	// the rest is written again.
+	if (!cache_abandon_fill() || write_in_full(STDOUT_FILENO, data, size) < 0)
+		die_errno("Unable to write the page");
 }
 
 /*
@@ -111,6 +126,11 @@ void html_flush(void)
 	write_out(out_buf, len);
 }
 
+void html_discard(void)
+{
+	out_len = 0;
+}
+
 void html_capture_begin(struct strbuf *sb)
 {
 	html_flush();
@@ -191,7 +211,7 @@ ssize_t html_ntxt(const char *txt, size_t len)
 	if (len > SSIZE_MAX)
 		return -1;
 
-	left = (ssize_t) len;
+	left = (ssize_t)len;
 	while (p && *p && left--) {
 		int c = *p;
 		if (c == '<' || c == '>' || c == '&') {
@@ -227,6 +247,7 @@ void html_attrf(const char *format, ...)
 void html_attr(const char *txt)
 {
 	const char *p = txt;
+
 	while (p && *p) {
 		int c = *p;
 		if (c == '<' || c == '>' || c == '\'' || c == '\"' || c == '&') {
@@ -252,6 +273,7 @@ void html_attr(const char *txt)
 void html_url_path(const char *txt)
 {
 	const char *p = txt;
+
 	while (p && *p) {
 		unsigned char c = *p;
 		// A raw ampersand or plus is legal in a URL path, but this
@@ -274,6 +296,7 @@ void html_url_path(const char *txt)
 void html_url_arg(const char *txt)
 {
 	const char *p = txt;
+
 	while (p && *p) {
 		unsigned char c = *p;
 		const char *esc = url_escape_table[c];
@@ -293,6 +316,7 @@ void html_url_arg(const char *txt)
 void html_header_arg_in_quotes(const char *txt)
 {
 	const char *p = txt;
+
 	while (p && *p) {
 		unsigned char c = *p;
 		const char *esc = NULL;
@@ -379,7 +403,7 @@ int html_include(const char *filename)
 	size_t len;
 
 	if (!(f = fopen(filename, "r"))) {
-		fprintf(stderr, "[cgit] Error including file %s: %s (%d)\n", filename, strerror(errno), errno);
+		fprintf(stderr, "[cgit] Unable to include %s: %s (%d)\n", filename, strerror(errno), errno);
 		return -1;
 	}
 	while ((len = fread(buf, 1, sizeof(buf), f)) > 0)