Implement a string pool for HTML text, property names, property value…

…s, and

header/footer/heading/chapter strings used when rendering PS or PDF.  This
prevents a whole category of memory management bugs and also will help lower
memory usage.

CHANGES.md

@@ -1,5 +1,7 @@
 # Changes in HTMLDOC v1.9.19
 
+- Updated HTML and header/footer code to use a string pool to simplify memory
+  management and fix potential double-free bugs.
 - Updated configure script to look for zlib with pkg-config (Issue #519)
 - Updated markdown support code to mmd.
 

htmldoc/gui.cxx

@@ -4195,6 +4195,7 @@ GUI::generateBookCB(Fl_Widget *w,	// I - Widget
 
     htmlDeleteTree(document);
     htmlDeleteTree(toc);
+    hd_strfreeall();
 
     file_cleanup();
     image_flush_cache();

htmldoc/hdstring.h

@@ -1,101 +1,97 @@
-/*
- * String definitions for HTMLDOC, a HTML document processing program.
- *
- * Copyright 2011-2014 by Michael R Sweet.
- * Copyright 1997-2010 by Easy Software Products.  All rights reserved.
- *
- * This program is free software.  Distribution and use rights are outlined in
- * the file "COPYING".
- */
+//
+// String definitions for HTMLDOC, a HTML document processing program.
+//
+// Copyright © 2011-2024 by Michael R Sweet.
+// Copyright © 1997-2010 by Easy Software Products.  All rights reserved.
+//
+// This program is free software.  Distribution and use rights are outlined in
+// the file "COPYING".
+//
 
 #ifndef _HDSTRING_H_
 #  define _HDSTRING_H_
-
-/*
- * Include necessary headers...
- */
-
 #  include "config.h"
-
 #  include <stdio.h>
 #  include <stdlib.h>
 #  include <stdarg.h>
 #  include <string.h>
 #  include <ctype.h>
-
 #  ifdef HAVE_STRINGS_H
 #    include <strings.h>
-#  endif /* HAVE_STRINGS_H */
-
+#  endif // HAVE_STRINGS_H
 #  ifdef __cplusplus
 extern "C" {
-#  endif /* __cplusplus */
+#  endif // __cplusplus
 
 
-/*
- * Define some compatibility macros for Microsoft Windows...
- */
+//
+// Define some compatibility macros for Microsoft Windows...
+//
 
 #  ifdef WIN32
 #    define strcasecmp(s,t)	stricmp(s,t)
 #    define strncasecmp(s,t,n)	strnicmp(s,t,n)
 #    define snprintf		_snprintf
 #    define vsnprintf		_vsnprintf
-#  endif /* WIN32 */
+#  endif // WIN32
+
 
-/*
- * Implementation of strcpy() that allows for overlapping buffers.
- */
+//
+// Implementation of strcpy() that allows for overlapping buffers.
+//
 
 extern void	hd_strcpy(char *dst, const char *src);
 
 
-/*
- * Standard string functions that might not be available...
- */
+//
+// Simple string pool functions to replace strdup/free usage in most places...
+//
 
-#  ifndef HAVE_STRDUP
 extern char	*hd_strdup(const char *);
-#    define strdup hd_strdup
-#  endif /* !HAVE_STRDUP */
+extern void	hd_strfreeall(void);
+extern size_t	hd_strgetsize(void);
+
+
+//
+// Standard string functions that might not be available...
+//
+
+#  ifndef HAVE_SNPRINTF
+extern int	hd_snprintf(char *, size_t, const char *, ...)
+#    ifdef __GNUC__
+__attribute__ ((__format__ (__printf__, 3, 4)))
+#    endif // __GNUC__
+;
+#    define snprintf hd_snprintf
+#  endif // !HAVE_SNPRINTF
 
 #  ifndef HAVE_STRCASECMP
 extern int	hd_strcasecmp(const char *, const char *);
 #    define strcasecmp hd_strcasecmp
-#  endif /* !HAVE_STRCASECMP */
+#  endif // !HAVE_STRCASECMP
 
 #  ifndef HAVE_STRNCASECMP
-extern int	hd_strncasecmp(const char *, const char *, size_t n);
-#    define strncasecmp hd_strncasecmp
-#  endif /* !HAVE_STRNCASECMP */
-
 #  ifndef HAVE_STRLCAT
 extern size_t hd_strlcat(char *, const char *, size_t);
 #    define strlcat hd_strlcat
-#  endif /* !HAVE_STRLCAT */
+#  endif // !HAVE_STRLCAT
 
 #  ifndef HAVE_STRLCPY
 extern size_t hd_strlcpy(char *, const char *, size_t);
 #    define strlcpy hd_strlcpy
-#  endif /* !HAVE_STRLCPY */
+#  endif // !HAVE_STRLCPY
 
-#  ifndef HAVE_SNPRINTF
-extern int	hd_snprintf(char *, size_t, const char *, ...)
-#    ifdef __GNUC__
-__attribute__ ((__format__ (__printf__, 3, 4)))
-#    endif /* __GNUC__ */
-;
-#    define snprintf hd_snprintf
-#  endif /* !HAVE_SNPRINTF */
+extern int	hd_strncasecmp(const char *, const char *, size_t n);
+#    define strncasecmp hd_strncasecmp
+#  endif // !HAVE_STRNCASECMP
 
 #  ifndef HAVE_VSNPRINTF
 extern int	hd_vsnprintf(char *, size_t, const char *, va_list);
 #    define vsnprintf hd_vsnprintf
-#  endif /* !HAVE_VSNPRINTF */
+#  endif // !HAVE_VSNPRINTF
 
 
 #  ifdef __cplusplus
 }
-#  endif /* __cplusplus */
-
-#endif /* !_HDSTRING_H_ */
+#  endif // __cplusplus
+#endif // !_HDSTRING_H_