toybox: tar: Fix support for long names

Pathnames may be longer than the name field in the header, so use
strncpy() instead of xstrncpy() to avoid bailing out.

Also add unit tests to ensure proper handling of short and long
pathnames.

Change-Id: Id025891993746889564b479e5185cf9721b54a55

tests/tar.test

@@ -71,3 +71,20 @@ rm -rf temp_dir
 mkdir dir/dir1 -p 
 echo "Inside dir/dir1" > dir/dir1/file ; echo "Hello Inside dir" > dir/file
 testing "Extraction on STDOUT : -O" " tar -czf dir.tgz dir/ ; rm -rf dir ; tar -xf dir.tgz -O ; [ -e 'Inside dir/dir1/\nHello Inside dir\n' ] && echo 'yes'; rm -rf dir.tgz " "" "" ""
+
+#Creating short filename
+f="filename_with_100_chars_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
+echo "This is testdata" > $f
+testing "tar shortname filename" "tar -cf testFile.tar $f && [ -e testFile.tar ] && echo 'yes'; rm -f $f; tar -xf testFile.tar && [ -f $f ] && cat $f && strings testFile.tar | grep -o LongLink; rm -f testFile.tar; rm -f $f" "yes\nThis is testdata\n" "" ""
+
+#Creating long filename
+f="filename_with_101_chars_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
+echo "This is testdata" > $f
+testing "tar longname filename" "tar -cf testFile.tar $f && [ -e testFile.tar ] && echo 'yes'; rm -f $f; tar -xf testFile.tar && [ -f $f ] && cat $f && strings testFile.tar | grep -o LongLink; rm -f testFile.tar; rm -f $f" "yes\nThis is testdata\nLongLink\n" "" ""
+
+#Creating long pathname
+d="dirname_with_50_chars_xxxxxxxxxxxxxxxxxxxxxxxxxxxx"
+f="filename_with_50_chars_xxxxxxxxxxxxxxxxxxxxxxxxxxx"
+mkdir $d
+echo "This is testdata" > $d/$f
+testing "tar longname pathname" "tar -cf testFile.tar $d/$f && [ -e testFile.tar ] && echo 'yes'; rm -rf $d; tar -xf testFile.tar && [ -f $d/$f ] && cat $d/$f && strings testFile.tar | grep -o LongLink; rm -f testFile.tar; rm -rf $d" "yes\nThis is testdata\nLongLink\n" "" ""

toys/pending/tar.c

@@ -190,7 +190,7 @@ static void add_file(struct archive_handler *tar, char **nam, struct stat *st)
  }
 
  memset(&hdr, 0, sizeof(hdr));
- xstrncpy(hdr.name, hname, sizeof(hdr.name));
+ strncpy(hdr.name, hname, sizeof(hdr.name));
  itoo(hdr.mode, sizeof(hdr.mode), st->st_mode &07777);
  itoo(hdr.uid, sizeof(hdr.uid), st->st_uid);
  itoo(hdr.gid, sizeof(hdr.gid), st->st_gid);