+(defun mm-add-meta-html-tag (handle &optional charset force-charset)
+ "Add meta html tag to specify CHARSET of HANDLE in the current buffer.
+CHARSET defaults to the one HANDLE specifies. Existing meta tag that
+specifies charset will not be modified unless FORCE-CHARSET is non-nil.
+Return t if meta tag is added or replaced."
+ (when (equal (mm-handle-media-type handle) "text/html")
+ (when (or charset
+ (setq charset (mail-content-type-get (mm-handle-type handle)
+ 'charset)))
+ (setq charset (format "\
+<meta http-equiv=\"Content-Type\" content=\"text/html; charset=%s\">" charset))
+ (let ((case-fold-search t))
+ (goto-char (point-min))
+ (if (re-search-forward "\
+<meta\\s-+http-equiv=[\"']?content-type[\"']?\\s-+content=[\"']\
+text/\\(\\sw+\\)\\(?:\;\\s-*charset=\\(.+\\)\\)?[\"'][^>]*>" nil t)
+ (if (and (not force-charset)
+ (match-beginning 2)
+ (string-match "\\`html\\'" (match-string 1)))
+ ;; Don't modify existing meta tag.
+ nil
+ ;; Replace it with the one specifying charset.
+ (replace-match charset)
+ t)
+ (if (re-search-forward "<head>\\s-*" nil t)
+ (insert charset "\n")
+ (re-search-forward "<html\\(?:\\s-+[^>]+\\|\\s-*\\)>\\s-*" nil t)
+ (insert "<head>\n" charset "\n</head>\n"))
+ t)))))
+