git: 24f44a445c48 - main - Remove dependency on files in /usr/bin

[Stefan Eßer]

The branch main has been updated by se:

URL: https://cgit.FreeBSD.org/src/commit/?id=24f44a445c4875a329d3947c50083f3e8b9b37db

commit 24f44a445c4875a329d3947c50083f3e8b9b37db
Author:     Stefan Eßer <se at FreeBSD.org>
AuthorDate: 2021-01-19 11:46:52 +0000
Commit:     Stefan Eßer <se at FreeBSD.org>
CommitDate: 2021-01-19 11:56:23 +0000

    Remove dependency on files in /usr/bin
    
    In order to reduce the pre-requisites of this file, implement the
    pattern matching and creation of a temporary test directory without
    use of grep respectively mktemp.
    
    The new version makes it possible to provide a writable /tmp in any
    case and independently of other local or remote file systems (except /
    and /dev) being mounted.
    
    The use of "dd if=/dev/random" has the same dependency on /dev/random
    being operational as the previous version that used "mktemp". If this
    is found to be an issue on platforms that do not have gathered
    sufficient entropy at the time when this scriot is run, I suggest to
    replace the "dd" command with "ps lauxww" to get a somewhat random
    test directory name.
    
    Approved by:    rgrimes, glebius, cy
    MFC after:      4 weeks
    Differential Revision:  https://reviews.freebsd.org/D28209
---
 libexec/rc/rc.d/tmp | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/libexec/rc/rc.d/tmp b/libexec/rc/rc.d/tmp
index a61321e058ee..7d270335cb27 100755
--- a/libexec/rc/rc.d/tmp
+++ b/libexec/rc/rc.d/tmp
@@ -40,10 +40,16 @@ load_rc_config $name
 
 mount_tmpmfs()
 {
-	if ! /bin/df /tmp | grep -q "^/dev/md[0-9].* /tmp"; then
-		mount_md ${tmpsize} /tmp "${tmpmfs_flags}"
-		chmod 01777 /tmp
-	fi
+	while read line; do
+		case $line in
+		/dev/md[0-9]*\ /tmp)
+			return;;
+		esac
+	done <<*EOF
+$(df /tmp)
+*EOF
+	mount_md ${tmpsize} /tmp "${tmpmfs_flags}"
+	chmod 01777 /tmp
 }
 
 # If we do not have a writable /tmp, create a memory
@@ -52,7 +58,8 @@ mount_tmpmfs()
 #
 case "${tmpmfs}" in
 [Aa][Uu][Tt][Oo])
-	if _tmpdir=$(mktemp -d -q /tmp/.diskless.XXXXXX); then
+	_tmpdir=/tmp/.diskless.$(dd if=/dev/random bs=32 count=1 status=none | sha256)
+	if mkdir -m 0700 ${_tmpdir}; then
 		rmdir ${_tmpdir}
 	else
 		if [ -h /tmp ]; then