libgocryptfs/contrib/maxlen.bash

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#!/bin/bash
#
# Find out the maximum supported filename length and print it.
#
# Part of the gocryptfs test suite
# https://nuetzlich.net/gocryptfs/
set -eu
MYNAME=$(basename "$0")
if [[ $# -ne 1 || $1 == -* ]]; then
echo "Usage: $MYNAME DIRECTORY"
exit 1
fi
# Only show live progress if connected to a termial
# https://stackoverflow.com/a/911213/1380267
INTERACTIVE=0
if [[ -t 1 ]] ; then
INTERACTIVE=1
fi
cd "$1"
echo "Testing $PWD"
echo -n " Maximum filename length: "
# Add one character at a time until we hit an error
NAME=""
while true ; do
NEXT="${NAME}x"
if [[ -e $NEXT ]]; then
echo "error: file $PWD/$NEXT already exists"
exit 1
fi
echo -n 2> /dev/null > $NEXT || break
rm $NEXT
NAME="$NEXT"
done
echo "${#NAME}"
# Set to 0 if undefined
: ${QUICK:=0}
if [[ $QUICK -ne 1 ]]; then
echo -n " Maximum dirname length: "
# Add one character at a time until we hit an error
NAME=""
while true ; do
NEXT="${NAME}x"
mkdir $NEXT 2> /dev/null || break
rmdir $NEXT
NAME="$NEXT"
done
MAX_DIRNAME=${#NAME}
echo "${#NAME}"
fi
if [[ $QUICK -eq 1 ]]; then
CHARS_TODO=100
else
CHARS_TODO="1 10 100 $MAX_DIRNAME"
fi
for CHARS_PER_SUBDIR in $CHARS_TODO ; do
echo -n " Maximum path length with $(printf %3d $CHARS_PER_SUBDIR) chars per subdir: "
if [[ $INTERACTIVE -eq 1 ]] ; then
echo -n " "
fi
# Trick from https://stackoverflow.com/a/5349842/1380267
SUBDIR=$(printf 'x%.0s' $(seq 1 $CHARS_PER_SUBDIR))
mkdir "$SUBDIR"
P=$SUBDIR
# Create a deep path, one $SUBDIR at a time, until we hit an error
while true ; do
NEXT="$P/$SUBDIR"
mkdir "$NEXT" 2> /dev/null || break
P=$NEXT
if [[ $INTERACTIVE -eq 1 ]] ; then
echo -n -e "\b\b\b\b"
printf %4d ${#P}
fi
done
# Then add one character at a time until we hit an error
NAME=""
while true ; do
NEXT="${NAME}x"
touch "$P/$NEXT" 2> /dev/null || break
NAME=$NEXT
done
if [[ $NAME != "" ]] ; then
P=$P/$NAME
fi
if [[ $INTERACTIVE -eq 1 ]] ; then
echo -n -e "\b\b\b\b"
fi
printf %4d ${#P}
echo
rm -R "$SUBDIR"
done