Fix a crash bug with malformed URIs (Issue #418)

michaelrsweet · Jan 26, 2021 · 19c582f · 19c582f
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diff --git a/CHANGES.md b/CHANGES.md
@@ -1,6 +1,7 @@
 # Changes in HTMLDOC v1.9.12
 
 - Fixed a crash bug with "data:" URIs and EPUB output (Issue #410)
+- Fixed a crash bug with malformed URIs (Issue #418)
 - Fixed some issues reported by Coverity.
 
 

diff --git a/htmldoc/file.c b/htmldoc/file.c
@@ -304,6 +304,7 @@ const char *			/* O - File extension */
 file_extension(const char *s)	/* I - Filename or URL */
 {
   const char	*extension;	/* Pointer to directory separator */
+  char		*bufptr;	/* Pointer into buffer */
   static char	buf[1024];	/* Buffer for files with targets */
 
 
@@ -334,7 +335,8 @@ file_extension(const char *s)	/* I - Filename or URL */
 
   strlcpy(buf, extension, sizeof(buf));
 
-  *(char *)strchr(buf, '#') = '\0';
+  if ((bufptr = strchr(buf, '#')) != NULL)
+    *bufptr = '\0';
 
   return (buf);
 }