mbedtls/programs/demo_common.sh
Gilles Peskine 911081efd2 Explain why $root_dir needs a complicated calculation
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
2023-07-25 19:40:14 +02:00

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## Common shell functions used by demo scripts programs/*/*.sh.
## How to write a demo script
## ==========================
##
## Include this file near the top of each demo script:
## . "${0%/*}/../demo_common.sh"
##
## Start with a "msg" call that explains the purpose of the script.
## Then call the "depends_on" function to ensure that all config
## dependencies are met.
##
## As the last thing in the script, call the cleanup function.
##
## You can use the functions and variables described below.
set -e -u
## $root_dir is the root directory of the Mbed TLS source tree.
root_dir="${0%/*}"
# Find a nice path to the root directory, avoiding unnecessary "../".
# The code supports demo scripts nested up to 4 levels deep.
# The code works no matter where the demo script is relative to the current
# directory, even if it is called with a relative path.
n=4 # limit the search depth
while ! [ -d "$root_dir/programs" ] || ! [ -d "$root_dir/library" ]; do
if [ $n -eq 0 ]; then
echo >&2 "This doesn't seem to be an Mbed TLS source tree."
exit 125
fi
n=$((n - 1))
case $root_dir in
.) root_dir="..";;
..|?*/..) root_dir="$root_dir/..";;
?*/*) root_dir="${root_dir%/*}";;
/*) root_dir="/";;
*) root_dir=".";;
esac
done
## $programs_dir is the directory containing the sample programs.
# Assume an in-tree build.
programs_dir="$root_dir/programs"
## msg LINE...
## msg <TEXT_ORIGIN
## Display an informational message.
msg () {
if [ $# -eq 0 ]; then
sed 's/^/# /'
else
for x in "$@"; do
echo "# $x"
done
fi
}
## run "Message" COMMAND ARGUMENT...
## Display the message, then run COMMAND with the specified arguments.
run () {
echo
echo "# $1"
shift
echo "+ $*"
"$@"
}
## Like '!', but stop on failure with 'set -e'
not () {
if "$@"; then false; fi
}
## run_bad "Message" COMMAND ARGUMENT...
## Like run, but the command is expected to fail.
run_bad () {
echo
echo "$1 This must fail."
shift
echo "+ ! $*"
not "$@"
}
## config_has SYMBOL...
## Succeeds if the library configuration has all SYMBOLs set.
config_has () {
for x in "$@"; do
"$programs_dir/test/query_compile_time_config" "$x"
done
}
## depends_on SYMBOL...
## Exit if the library configuration does not have all SYMBOLs set.
depends_on () {
m=
for x in "$@"; do
if ! config_has "$x"; then
m="$m $x"
fi
done
if [ -n "$m" ]; then
cat >&2 <<EOF
$0: this demo requires the following
configuration options to be enabled at compile time:
$m
EOF
# Exit with a success status so that this counts as a pass for run_demos.py.
exit
fi
}
## Add the names of files to clean up to this whitespace-separated variable.
## The file names must not contain whitespace characters.
files_to_clean=
## Call this function at the end of each script.
## It is called automatically if the script is killed by a signal.
cleanup () {
rm -f -- $files_to_clean
}
################################################################
## End of the public interfaces. Code beyond this point is not
## meant to be called directly from a demo script.
trap 'cleanup; trap - HUP; kill -HUP $$' HUP
trap 'cleanup; trap - INT; kill -INT $$' INT
trap 'cleanup; trap - TERM; kill -TERM $$' TERM
if config_has MBEDTLS_ENTROPY_NV_SEED; then
# Create a seedfile that's sufficiently long in all library configurations.
# This is necessary for programs that use randomness.
# Assume that the name of the seedfile is the default name.
files_to_clean="$files_to_clean seedfile"
dd if=/dev/urandom of=seedfile ibs=64 obs=64 count=1
fi