From 19a0ff401d8e0f6b0209885b04b21b4c97884f61 Mon Sep 17 00:00:00 2001
From: Marco Fortina <marco_fortina@hotmail.it>
Date: Sat, 16 May 2026 06:09:09 +0000
Subject: [PATCH] libvncserver: read HTTP files in aligned chunks

---
 src/libvncserver/httpd.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/libvncserver/httpd.c b/src/libvncserver/httpd.c
index 7cefadc4..ade3f424 100644
--- a/src/libvncserver/httpd.c
+++ b/src/libvncserver/httpd.c
@@ -295,6 +295,7 @@ httpProcessInput(rfbScreenInfoPtr rfbScreen)
     unsigned int maxFnameLen;
     FILE* fd;
     rfbBool performSubstitutions = FALSE;
+    size_t bytesToRead;
     char str[256+32];
 #ifndef WIN32
     char* user=getenv("USER");
@@ -484,8 +485,12 @@ if(rfbScreen->httpEnableProxyConnect) {
     /* end the header */
     rfbWriteExact(&cl, "\r\n", 2);
 
+    /* .vnc substitutions need one byte for NUL termination. Other
+       HTTP files can use the full, aligned buffer. */
+    bytesToRead = performSubstitutions ? BUF_SIZE - 1 : BUF_SIZE;
+
     while (1) {
-	int n = fread(buf, 1, BUF_SIZE-1, fd);
+	int n = fread(buf, 1, bytesToRead, fd);
 	if (n < 0) {
 	    rfbLogPerror("httpProcessInput: read");
 	    fclose(fd);