[Toybox] [PATCH] fix chown owner:group parsing

[enh]

i found a few problems while manually smoke testing toybox chown
versus toolbox (NetBSD) chown...

new test:

#!/bin/bash

[ -f testing.sh ] && . testing.sh

#if [ "$(id -u)" -ne 0 ]
#then
#  echo "SKIPPED: chown (not root)"
#  continue 2>/dev/null
#  exit
#fi

# We chown between user "root" and the last user in /etc/passwd,
# and group "root" and the last group in /etc/group.

USR="$(sed -n '$s/:.*//p' /etc/passwd)"
GRP="$(sed -n '$s/:.*//p' /etc/group)"

# Set up a little testing hierarchy

rm -rf testdir &&
mkdir testdir &&
touch testdir/file
F=testdir/file

# Wrapper to reset groups and return results

OUT="&& echo \$(ls -l testdir/file | awk '{print \$3,\$4}')"

#testing "name" "command" "result" "infile" "stdin"

# Basic smoketest
testing "chown initial" "chown root:root $F $OUT" "root root\n" "" ""
testing "chown usr:grp" "chown $USR:$GRP $F $OUT" "$USR $GRP\n" "" ""
testing "chown root"    "chown root $F $OUT" "root $GRP\n" "" ""
# TODO: can we test "owner:"?
testing "chown :grp"    "chown root:root $F && chown :$GRP $F $OUT" \
    "root $GRP\n" "" ""
testing "chown :"       "chown $USR:$GRP $F && chown : $F $OUT" \
    "$USR $GRP\n" "" ""

rm -rf testdir




and here's the patch to fix "owner:" ":group" and the ":" special case:




diff --git a/toys/posix/chgrp.c b/toys/posix/chgrp.c
index 3aa2514..3585d28 100644
--- a/toys/posix/chgrp.c
+++ b/toys/posix/chgrp.c
@@ -73,6 +73,8 @@ void chgrp_main(void)
   int ischown = toys.which->name[2] == 'o', hl = toys.optflags&(FLAG_H|FLAG_L);
   char **s, *own;

+  TT.owner = TT.group = -1;
+
   // Distinguish chown from chgrp
   if (ischown) {
     char *grp;
@@ -93,7 +95,7 @@ void chgrp_main(void)
     }
   } else TT.group_name = *toys.optargs;

-  if (TT.group_name) {
+  if (TT.group_name && *TT.group_name) {
     struct group *g;
     g = getgrnam(TT.group_name);
     if (!g) g=getgrgid(atoi(TT.group_name));