Use mktemp to create workspace directory

mktemp is a better idea for security, as well as enabling users to
specify a different directory using the TMPDIR environment variable,
which is useful if /tmp is a small tmpfs.

Also fix a bug where the first few log messages were failing as the
workspace directory wasn't been created early enough.

training/tesstrain.sh

@@ -49,11 +49,8 @@ source `dirname $0`/tesstrain_utils.sh
 ARGV=("$@")
 parse_flags
 
-tlog "\n=== Starting training for language '${LANG_CODE}'"
-
-tlog "Cleaning workspace directory ${TRAINING_DIR}..."
 mkdir -p ${TRAINING_DIR}
-rm -fr ${TRAINING_DIR}/*
+tlog "\n=== Starting training for language '${LANG_CODE}'"
 
 source `dirname $0`/language-specific.sh
 set_lang_specific_parameters ${LANG_CODE}

training/tesstrain_utils.sh

@@ -25,7 +25,7 @@ OUTPUT_DIR="/tmp/tesstrain/tessdata"
 OVERWRITE=0
 RUN_SHAPE_CLUSTERING=0
 EXTRACT_FONT_PROPERTIES=1
-WORKSPACE_DIR="/tmp/tesstrain"
+WORKSPACE_DIR=`mktemp -d`
 EXPOSURES=0
 
 # Logging helper functions.