svn commit: r313107 - head/libexec/getty

[Alexey Dokuchaev]

Author: danfe (ports committer)
Date: Thu Feb  2 20:30:50 2017
New Revision: 313107
URL: https://svnweb.freebsd.org/changeset/base/313107

Log:
  Try to fix the old "he capability is stupid" bug in gettytab(5)/getty(8)
  
  There is one capability explicitly documented in gettytab(5) as stupid: he.
  And it is indeed.  It was meant to facilitate system hostname modification,
  but is hardly usable in practice because it allows very limited editing
  (e.g., it depends on a particular hostname length, making it non-generic).
  
  Replace it with simple implementation that treats ``he'' as POSIX extended
  regular expression which is matched against the hostname.  If there are no
  parenthesized subexpressions in the pattern, entire matched string is used
  as the final hostname.  Otherwise, use the first matched subexpression.
  If the pattern does not match, the original hostname is not modified.
  
  Using regex(3) gives more freedom, does not complicate the code very much,
  and makes a lot more sense, in turn making ``he'' less stupid and actually
  useful (e.g., it is now possible to obtain node or domain names from the
  original hostname string, without knowing it in advance).
  
  Reviewed by:		jilles, manpages (wblock)
  Approved by:		jilles (implied)
  Differential Revision:	https://reviews.freebsd.org/D9244

Modified:
  head/libexec/getty/gettytab.5
  head/libexec/getty/subr.c

Modified: head/libexec/getty/gettytab.5
==============================================================================
--- head/libexec/getty/gettytab.5	Thu Feb  2 20:01:54 2017	(r313106)
+++ head/libexec/getty/gettytab.5	Thu Feb  2 20:30:50 2017	(r313107)
@@ -28,7 +28,7 @@
 .\"     from: @(#)gettytab.5	8.4 (Berkeley) 4/19/94
 .\" $FreeBSD$
 .\" "
-.Dd April 19, 1994
+.Dd February 2, 2017
 .Dt GETTYTAB 5
 .Os
 .Sh NAME
@@ -118,7 +118,7 @@ character
 .Em NOT
 hangup line on last close
 .It "he	str" Ta Dv NULL Ta
-.No "hostname editing string"
+.No "hostname editing regular expression"
 .It "hn	str	hostname	hostname"
 .It "ht	bool	false	terminal has real tabs"
 .It "hw	bool	false	do cts/rts hardware flow control"
@@ -302,18 +302,13 @@ but may also be overridden by the
 table entry.
 In either case it may be edited with the
 .Va \&he
-string.
-A '@' in the
-.Va \&he
-string causes one character from the real hostname to
-be copied to the final hostname.
-A '#' in the
-.Va \&he
-string causes the next character of the real hostname
-to be skipped.
-Each character that
-is neither '@' nor '#' is copied into the final hostname.
-Surplus '@' and '#' characters are ignored.
+POSIX
+.Dq extended
+regular expression, which is matched against the hostname.
+If there are no parenthesized subexpressions in the pattern,
+the entire matched string is used as the final hostname;
+otherwise, the first matched subexpression is used instead.
+If the pattern does not match, the original hostname is not modified.
 .It \&%t
 The tty name.
 .It "\&%m, \&%r, \&%s, \&%v"
@@ -528,10 +523,6 @@ of the delay algorithms are not implemen
 The terminal driver should support sane delay settings.
 .Pp
 The
-.Va \&he
-capability is stupid.
-.Pp
-The
 .Xr termcap 5
 format is horrid, something more rational should
 have been chosen.

Modified: head/libexec/getty/subr.c
==============================================================================
--- head/libexec/getty/subr.c	Thu Feb  2 20:01:54 2017	(r313106)
+++ head/libexec/getty/subr.c	Thu Feb  2 20:30:50 2017	(r313107)
@@ -43,6 +43,7 @@ static const char rcsid[] =
 #include <sys/time.h>
 
 #include <poll.h>
+#include <regex.h>
 #include <stdlib.h>
 #include <string.h>
 #include <syslog.h>
@@ -53,8 +54,6 @@ static const char rcsid[] =
 #include "pathnames.h"
 #include "extern.h"
 
-
-
 /*
  * Get a table entry.
  */
@@ -469,42 +468,48 @@ adelay(int ms, struct delayval *dp)
 char	editedhost[MAXHOSTNAMELEN];
 
 void
-edithost(const char *pat)
+edithost(const char *pattern)
 {
-	const char *host = HN;
-	char *res = editedhost;
-
-	if (!pat)
-		pat = "";
-	while (*pat) {
-		switch (*pat) {
-
-		case '#':
-			if (*host)
-				host++;
-			break;
-
-		case '@':
-			if (*host)
-				*res++ = *host++;
-			break;
-
-		default:
-			*res++ = *pat;
-			break;
+	regex_t regex;
+	regmatch_t *match;
+	int found;
+
+	if (pattern == NULL || *pattern == '\0')
+		goto copyasis;
+	if (regcomp(&regex, pattern, REG_EXTENDED) != 0)
+		goto copyasis;
+
+	match = calloc(regex.re_nsub + 1, sizeof(*match));
+	if (match == NULL) {
+		regfree(&regex);
+		goto copyasis;
+	}
+
+	found = !regexec(&regex, HN, regex.re_nsub + 1, match, 0);
+	if (found) {
+		size_t subex, totalsize;
 
-		}
-		if (res == &editedhost[sizeof editedhost - 1]) {
-			*res = '\0';
-			return;
-		}
-		pat++;
-	}
-	if (*host)
-		strncpy(res, host, sizeof editedhost - (res - editedhost) - 1);
-	else
-		*res = '\0';
-	editedhost[sizeof editedhost - 1] = '\0';
+		/*
+		 * We found a match.  If there were no parenthesized
+		 * subexpressions in the pattern, use entire matched
+		 * string as ``editedhost''; otherwise use the first
+		 * matched subexpression.
+		 */
+		subex = !!regex.re_nsub;
+		totalsize = match[subex].rm_eo - match[subex].rm_so + 1;
+		strlcpy(editedhost, HN + match[subex].rm_so, totalsize >
+		    sizeof(editedhost) ? sizeof(editedhost) : totalsize);
+	}
+	free(match);
+	regfree(&regex);
+	if (found)
+		return;
+	/*
+	 * In case of any errors, or if the pattern did not match, pass
+	 * the original hostname as is.
+	 */
+ copyasis:
+	strlcpy(editedhost, HN, sizeof(editedhost));
 }
 
 static struct speedtab {