mhbuild implement header folding

[mmh] / sbr / fold.c

diff --git a/sbr/fold.c b/sbr/fold.c
new file mode 100644 (file)
index 0000000..0189382
--- /dev/null
+++ b/sbr/fold.c
@@ -0,0 +1,61 @@
+/* fold.c -- fold a mail header field
+ *
+ * This code is Copyright (c), by the authors of nmh.  See the
+ * COPYRIGHT file in the root directory of the nmh distribution for
+ * complete copyright information. */
+
+#include <h/mh.h>
+#include <stdio.h>
+
+void
+fold(charstring_t dst, size_t namelen, const char *restrict body)
+{
+       const char *restrict body_next;
+       const char *restrict wsp;
+       const char *restrict wsp_next;
+       const int crlf = strchr(body, '\r') != NULL;
+       charstring_clear(dst);
+       namelen++;
+
+       while (*body) {
+               body_next = strchr(body, '\n');
+               if ((unsigned long) (body_next - body) <= MAXTEXTPERLN - namelen) {
+                       charstring_push_back_chars(dst, body, body_next - body + 1);
+                       namelen = 0;
+                       body = body_next + 1;
+                       continue;
+               }
+               wsp = body;
+               while (namelen == 0 && (*wsp == ' ' || *wsp == '\t')) {
+                       wsp++;
+               }
+               wsp = wsp_next = strpbrk(wsp, " \t");
+
+               /* if now whitespace is in the current line just print the curret line as is */
+               if (!wsp_next || wsp_next > body_next) {
+                       charstring_push_back_chars(dst, body, body_next - body + 1);
+                       namelen = 0;
+                       body = body_next + 1;
+                       continue;
+               }
+
+               while ((unsigned long)(wsp_next - body) <= MAXTEXTPERLN - namelen) {
+                       wsp = wsp_next;
+                       wsp_next = strpbrk(wsp+1, " \t");
+                       if (!wsp_next) {
+                               break;
+                       }
+                       if (wsp_next > body_next) {
+                               break;
+                       }
+               }
+
+               charstring_push_back_chars(dst, body, wsp - body);
+               if (crlf) {
+                       charstring_push_back(dst, '\r');
+               }
+               charstring_push_back(dst, '\n');
+               namelen = 0;
+               body = wsp;
+       }
+}