wolfsshd: name the large SFTP files per run

sshd_large_sftp_test.sh puts its pid in both the local and the remote
file name, and removes them from an EXIT trap.

- the remote name was fixed in the daemon user's home, one directory
  for the whole host, so two runs uploaded to the same path and each
  compared its own file against the other's upload
- 4.4G apiece, and the transfer runs under "set -e", so a failed run
  left both behind

apps/wolfsshd/test/sshd_large_sftp_test.sh

@@ -38,23 +38,32 @@ if [ -z "$HOME_DIR" ] || [ "$HOME_DIR" = "/" ]; then
     echo "could not resolve a usable home directory for user '$USER'"
     exit 1
 fi
-REMOTE_FILE="$HOME_DIR/large-random-2.txt"
+# Both names carry this test's pid. The remote one has to: it lands in the
+# daemon user's home, which is one directory for the whole host however many
+# checkouts are running, so two runs uploaded to the same path and each then
+# compared its own local file against the other's upload -- "differ: byte 1"
+# on a pair of files that were both transferred correctly. The local name
+# follows for the same reason one checkout down.
+LOCAL_FILE="`pwd`/large-random.$$.txt"
+REMOTE_FILE="$HOME_DIR/large-random-2.$$.txt"
+
+# 4.4G apiece, so do not leave them behind on the paths that do not reach the
+# removals below: the transfer runs under "set -e" and the comparison can fail.
+trap 'rm -f "$LOCAL_FILE" "$REMOTE_FILE"' EXIT
 
 # create a large file with random data (larger than word32 max value)
-head -c 4400000010 < /dev/random > large-random.txt
+head -c 4400000010 < /dev/random > "$LOCAL_FILE"
 
 set -e
-echo "$TEST_SFTP_CLIENT -u $USER -i $PRIVATE_KEY -j $PUBLIC_KEY -g -l large-random.txt -r $REMOTE_FILE -h \"$1\" -p \"$2\""
-$TEST_SFTP_CLIENT -u $USER -i $PRIVATE_KEY -j $PUBLIC_KEY -g -l large-random.txt -r "$REMOTE_FILE" -h "$1" -p "$2"
+echo "$TEST_SFTP_CLIENT -u $USER -i $PRIVATE_KEY -j $PUBLIC_KEY -g -l $LOCAL_FILE -r $REMOTE_FILE -h \"$1\" -p \"$2\""
+$TEST_SFTP_CLIENT -u $USER -i $PRIVATE_KEY -j $PUBLIC_KEY -g -l "$LOCAL_FILE" -r "$REMOTE_FILE" -h "$1" -p "$2"
 
-cmp large-random.txt "$REMOTE_FILE"
+cmp "$LOCAL_FILE" "$REMOTE_FILE"
 RESULT=$?
 if [ "$RESULT" != "0" ]; then
     echo "files did not match when compared"
     exit 1
 fi
-rm -f large-random.txt
-rm -f "$REMOTE_FILE"
 
 set +e