svn commit: r291091 - head/usr.bin/xinstall

[Baptiste Daroussin]

Author: bapt
Date: Fri Nov 20 08:45:59 2015
New Revision: 291091
URL: https://svnweb.freebsd.org/changeset/base/291091

Log:
  install: do not follow symlinks
  
  In case the target of install is a dead symlink, install(1) used to not
  consider it as "existing" because of the usage of stat(2) instead of
  lstat(2).  meaning the old file (the symlink) is not removed before the new
  file is created. The symlink is being followed and the new file becoming the
  target of the symlink instead of the target of install(1)
  
  Reviewed by:	jhb, brooks
  MFC after:	2 weeks
  Differential Revision:	https://reviews.freebsd.org/D4191

Modified:
  head/usr.bin/xinstall/xinstall.c

Modified: head/usr.bin/xinstall/xinstall.c
==============================================================================
--- head/usr.bin/xinstall/xinstall.c	Fri Nov 20 05:15:34 2015	(r291090)
+++ head/usr.bin/xinstall/xinstall.c	Fri Nov 20 08:45:59 2015	(r291091)
@@ -754,10 +754,7 @@ install(const char *from_name, const cha
 		devnull = 1;
 	}
 
-	if (!dolink)
-		target = (stat(to_name, &to_sb) == 0);
-	else
-		target = (lstat(to_name, &to_sb) == 0);
+	target = (lstat(to_name, &to_sb) == 0);
 
 	if (dolink) {
 		if (target && !safecopy) {
@@ -772,8 +769,7 @@ install(const char *from_name, const cha
 		return;
 	}
 
-	/* Only install to regular files. */
-	if (target && !S_ISREG(to_sb.st_mode)) {
+	if (target && !S_ISREG(to_sb.st_mode) && !S_ISLNK(to_sb.st_mode)) {
 		errno = EFTYPE;
 		warn("%s", to_name);
 		return;
@@ -786,7 +782,7 @@ install(const char *from_name, const cha
 		err(EX_OSERR, "%s", from_name);
 
 	/* If we don't strip, we can compare first. */
-	if (docompare && !dostrip && target) {
+	if (docompare && !dostrip && target && S_ISREG(to_sb.st_mode)) {
 		if ((to_fd = open(to_name, O_RDONLY, 0)) < 0)
 			err(EX_OSERR, "%s", to_name);
 		if (devnull)
@@ -838,7 +834,7 @@ install(const char *from_name, const cha
 	/*
 	 * Compare the stripped temp file with the target.
 	 */
-	if (docompare && dostrip && target) {
+	if (docompare && dostrip && target && S_ISREG(to_sb.st_mode)) {
 		temp_fd = to_fd;
 
 		/* Re-open to_fd using the real target name. */
@@ -872,9 +868,7 @@ install(const char *from_name, const cha
 			}
 			(void) close(temp_fd);
 		}
-	}
-
-	if (dostrip && (!docompare || !target))
+	} else if (dostrip)
 		digestresult = digest_file(tempfile);
 
 	/*