1 files changed, 129 insertions, 0 deletions
diff --git a/libio/dbz/case.c b/libio/dbz/case.c
new file mode 100644
index 00000000000..87b741ff54a
--- /dev/null
+++ b/libio/dbz/case.c
@@ -0,0 +1,129 @@
+/*
+ * case-mapping stuff
+ *
+ * We exploit the fact that we are dealing only with headers here, and
+ * headers are limited to the ASCII characters by RFC822.  It is barely
+ * possible that we might be dealing with a translation into another
+ * character set, but in particular it's very unlikely for a header
+ * character to be outside -128..255.
+ *
+ * Life would be a whole lot simpler if tolower() could safely and portably
+ * be applied to any char.
+ */
+#include <stdio.h>
+#include "string.h"
+#include "case.h"
+
+/* note that case.h knows the value of OFFSET */
+#define	OFFSET	128		/* avoid trouble with negative chars */
+#define	MAPSIZE	(256+OFFSET)
+char casemap[MAPSIZE];		/* relies on init to '\0' */
+static int primed = 0;		/* has casemap been set up? */
+
+/*
+ - prime - set up case-mapping stuff
+ */
+static void
+prime()
+{
+	register char *lp;
+	register char *up;
+	register int c;
+	register int i;
+	static char lower[] = "abcdefghijklmnopqrstuvwxyz";
+	static char upper[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+
+	for (lp = lower, up = upper; *lp != '\0'; lp++, up++) {
+		c = *lp;
+		casemap[c+OFFSET] = c;
+		casemap[*up+OFFSET] = c;
+	}
+	for (i = 0; i < MAPSIZE; i++)
+		if (casemap[i] == '\0')
+			casemap[i] = (char)(i-OFFSET);
+	primed = 1;
+}
+
+/*
+ - cistrncmp - case-independent strncmp
+ */
+int				/* < == > 0 */
+cistrncmp(s1, s2, len)
+char *s1;
+char *s2;
+int len;
+{
+	register char *p1;
+	register char *p2;
+	register int n;
+
+	if (!primed)
+		prime();
+
+	p1 = s1;
+	p2 = s2;
+	n = len;
+	while (--n >= 0 && *p1 != '\0' && TOLOW(*p1) == TOLOW(*p2)) {
+		p1++;
+		p2++;
+	}
+	if (n < 0)
+		return(0);
+
+	/*
+	 * The following case analysis is necessary so that characters
+	 * which look negative collate low against normal characters but
+	 * high against the end-of-string NUL.
+	 */
+	if (*p1 == '\0' && *p2 == '\0')
+		return(0);
+	else if (*p1 == '\0')
+		return(-1);
+	else if (*p2 == '\0')
+		return(1);
+	else
+		return(TOLOW(*p1) - TOLOW(*p2));
+}
+
+/*
+ - rfc822ize - do the bizarre case conversion needed for rfc822 message-ids
+ *
+ * Actually, this is not quite complete.  Absolute, total, full RFC822
+ * compliance requires a horrible parsing job, because of the arcane
+ * quoting conventions -- abc"def"ghi is not equivalent to abc"DEF"ghi,
+ * for example.  There are three or four things that might occur in the
+ * domain part of a message-id that are case-sensitive.  They don't seem
+ * to ever occur in real news, thank Cthulhu.  (What?  You were expecting
+ * a merciful and forgiving deity to be invoked in connection with RFC822?
+ * Forget it; none of them would come near it.)
+ */
+char *				/* returns the argument */
+rfc822ize(s)
+char *s;
+{
+	register char *p;
+	static char post[] = "postmaster";
+	static int postlen = sizeof(post)-1;
+
+	if (!primed)
+		prime();
+
+	p = strrchr(s, '@');
+	if (p == NULL)			/* no local/domain split */
+		p = "";			/* assume all local */
+	else if	(p - (s+1) == postlen && CISTREQN(s+1, post, postlen)) {
+		/* crazy special case -- "postmaster" is case-insensitive */
+		p = s;
+	}
+#ifdef NONSTANDARD
+#ifdef RFCVIOLATION
+#ifdef B_2_11_MISTAKE
+	p = s;				/* all case-insensitive */
+#endif
+#endif
+#endif
+	for (; *p != '\0'; p++)
+		*p = TOLOW(*p);
+
+	return(s);
+}