Thanks to John Cummings.

src/cmd/upas/alias/aliasmail.c

@@ -0,0 +1,281 @@
+#include "common.h"
+
+/*
+ *  WARNING!  This turns all upper case names into lower case
+ *  local ones.
+ */
+
+/* predeclared */
+static String	*getdbfiles(void);
+static int	translate(char*, char**, String*, String*);
+static int	lookup(String**, String*, String*);
+static int	compare(String*, char*);
+static char*	mklower(char*);
+
+static int debug;
+static int from;
+static char *namefiles = "namefiles";
+#define DEBUG if(debug)
+
+/* loop through the names to be translated */
+void
+main(int argc, char *argv[])
+{
+	String *s;
+	String *alias;		/* the alias for the name */
+	char **names;		/* names of this system */
+	String *files;		/* list of files to search */
+	int i, rv;
+	char *p;
+
+	ARGBEGIN {
+	case 'd':
+		debug = 1;
+		break;
+	case 'f':
+		from = 1;
+		break;
+	case 'n':
+		namefiles = ARGF();
+		break;
+	} ARGEND
+	if (chdir(unsharp(UPASLIB)) < 0) {
+		perror("translate(chdir):");
+		exit9(1);
+	}
+
+	/* get environmental info */
+	names = sysnames_read();
+	files = getdbfiles();
+	alias = s_new();
+
+	/* loop through the names to be translated (from standard input) */
+	for(i=0; i<argc; i++) {
+		s = unescapespecial(s_copy(mklower(argv[i])));
+		if(strchr(s_to_c(s), '!') == 0)
+			rv = translate(s_to_c(s), names, files, alias);
+		else
+			rv = -1;
+		if(from){
+			if (rv >= 0 && *s_to_c(alias) != '\0'){
+				p = strchr(s_to_c(alias), '\n');
+				if(p)
+					*p = 0;
+				p = strchr(s_to_c(alias), '!');
+				if(p) {
+					*p = 0;
+					print("%s", s_to_c(alias));
+				} else {
+					p = strchr(s_to_c(alias), '@');
+					if(p)
+						print("%s", p+1);
+					else
+						print("%s", s_to_c(alias));
+				}
+			}
+		} else {
+			if (rv < 0 || *s_to_c(alias) == '\0')
+				print("local!%s\n", s_to_c(s));
+			else {
+				/* this must be a write, not a print */
+				write(1, s_to_c(alias), strlen(s_to_c(alias)));
+			}
+		}
+		s_free(s);
+	}
+	exits(0);
+}
+
+/* get the list of dbfiles to search */
+static String *
+getdbfiles(void)
+{
+	Sinstack *sp;
+	String *files = s_new();
+	char *nf;
+
+	if(from)
+		nf = "fromfiles";
+	else
+		nf = namefiles;
+
+	/* system wide aliases */
+	if ((sp = s_allocinstack(nf)) != 0){
+		while(s_rdinstack(sp, files))
+			s_append(files, " ");
+		s_freeinstack(sp);
+	}
+
+
+	DEBUG print("files are %s\n", s_to_c(files));
+
+	return files;
+}
+
+/* loop through the translation files */
+static int
+translate(char *name,		/* name to translate */
+	char **namev,		/* names of this system */
+	String *files,		/* names of system alias files */
+	String *alias)		/* where to put the alias */
+{
+	String *file = s_new();
+	String **fullnamev;
+	int n, rv;
+
+	rv = -1;
+
+	DEBUG print("translate(%s, %s, %s)\n", name,
+		s_to_c(files), s_to_c(alias));
+
+	/* create the full name to avoid loops (system!name) */
+	for(n = 0; namev[n]; n++)
+		;
+	fullnamev = (String**)malloc(sizeof(String*)*(n+2));
+	n = 0;
+	fullnamev[n++] = s_copy(name);
+	for(; *namev; namev++){
+		fullnamev[n] = s_copy(*namev);
+		s_append(fullnamev[n], "!");
+		s_append(fullnamev[n], name);
+		n++;
+	}
+	fullnamev[n] = 0;
+
+	/* look at system-wide names */
+	s_restart(files);
+	while (s_parse(files, s_restart(file)) != 0) {
+		if (lookup(fullnamev, file, alias)==0) {
+			rv = 0;
+			goto out;
+		}
+	}
+
+out:
+	for(n = 0; fullnamev[n]; n++)
+		s_free(fullnamev[n]);
+	s_free(file);
+	free(fullnamev);
+	return rv;
+}
+
+/*
+ *  very dumb conversion to bang format
+ */
+static String*
+attobang(String *token)
+{
+	char *p;
+	String *tok;
+
+	p = strchr(s_to_c(token), '@');
+	if(p == 0)
+		return token;
+
+	p++;
+	tok = s_copy(p);
+	s_append(tok, "!");
+	s_nappend(tok, s_to_c(token), p - s_to_c(token) - 1);
+
+	return tok;
+}
+
+/*  Loop through the entries in a translation file looking for a match.
+ *  Return 0 if found, -1 otherwise.
+ */
+static int
+lookup(
+	String **namev,
+	String *file,
+	String *alias)	/* returned String */
+{
+	String *line = s_new();
+	String *token = s_new();
+	String *bangtoken;
+	int i, rv = -1;
+	char *name =  s_to_c(namev[0]);
+	Sinstack *sp;
+
+	DEBUG print("lookup(%s, %s, %s, %s)\n", s_to_c(namev[0]), s_to_c(namev[1]),
+		s_to_c(file), s_to_c(alias));
+
+	s_reset(alias);
+	if ((sp = s_allocinstack(s_to_c(file))) == 0)
+		return -1;
+
+	/* look for a match */
+	while (s_rdinstack(sp, s_restart(line))!=0) {
+		DEBUG print("line is %s\n", s_to_c(line));
+		s_restart(token);
+		if (s_parse(s_restart(line), token)==0)
+			continue;
+		if (compare(token, "#include")==0){
+			if(s_parse(line, s_restart(token))!=0) {
+				if(lookup(namev, line, alias) == 0)
+					break;
+			}
+			continue;
+		}
+		if (compare(token, name)!=0)
+			continue;
+		/* match found, get the alias */
+		while(s_parse(line, s_restart(token))!=0) {
+			bangtoken = attobang(token);
+
+			/* avoid definition loops */
+			for(i = 0; namev[i]; i++)
+				if(compare(bangtoken, s_to_c(namev[i]))==0) {
+					s_append(alias, "local");
+					s_append(alias, "!");
+					s_append(alias, name);
+					break;
+				}
+
+			if(namev[i] == 0)
+				s_append(alias, s_to_c(token));
+			s_append(alias, "\n");
+
+			if(bangtoken != token)
+				s_free(bangtoken);
+		}
+		rv = 0;
+		break;
+	}
+	s_free(line);
+	s_free(token);
+	s_freeinstack(sp);
+	return rv;
+}
+
+#define lower(c) ((c)>='A' && (c)<='Z' ? (c)-('A'-'a'):(c))
+
+/* compare two Strings (case insensitive) */
+static int
+compare(String *s1,
+	char *p2)
+{
+	char *p1 = s_to_c(s1);
+	int rv;
+
+	DEBUG print("comparing %s to %s\n", p1, p2);
+	while((rv = lower(*p1) - lower(*p2)) == 0) {
+		if (*p1 == '\0')
+			break;
+		p1++;
+		p2++;
+	}
+	return rv;
+}
+
+static char*
+mklower(char *name)
+{
+	char *p;
+	char c;
+
+	for(p = name; *p; p++){
+		c = *p;
+		*p = lower(c);
+	}
+	return name;
+}

src/cmd/upas/alias/mkfile

@@ -0,0 +1,21 @@
+<$PLAN9/src/mkhdr
+
+TARG=aliasmail
+
+OFILES=aliasmail.$O\
+
+LIB=../common/libcommon.a\
+
+HFILES=../common/common.h\
+	 ../common/sys.h\
+
+
+BIN=$PLAN9/bin/upas
+
+UPDATE=\
+	mkfile\
+	$HFILES\
+	${OFILES:%.$O=%.c}\
+
+<$PLAN9/src/mkone
+CFLAGS=$CFLAGS -I../common