cronic: run the command with the caller's shell options

cronic

@@ -17,9 +17,27 @@
 # This script runs under bash 3.2, which is /bin/bash on macOS, so it uses a
 # feature of a later bash only after checking the version.
 
-# Exit if a command exits with a non-zero status, and treat unset variables
-# as an error.
-set -eu
+# Save the caller's shell options, as the letters that `$-` uses for them,
+# before this script changes them for itself.  This script changes only
+# allexport, errexit, nounset, verbose, and xtrace, so the command inherits the
+# caller's other `set -o` options, and its `shopt` options, without any
+# restoring; an option that this script changes must be added to the pattern.
+# `$(set +o)` would save every `set -o` option, but bash turns off verbose in a
+# command substitution, so `set +o` there would report verbose as off.
+#
+# Then, exit if a command exits with a non-zero status, and treat unset
+# variables as an error.  Do not export this script's variables to the command,
+# even if the caller's exported SHELLOPTS contains allexport.  Do not trace this
+# script's own commands, even if the caller's exported SHELLOPTS contains
+# verbose or xtrace, so that the report's "TRACE OUTPUT" is the command's.
+# The traces of these two commands are discarded, so that this script produces
+# no output when the command succeeds.  (The lines that verbose prints before
+# this point cannot be discarded.)
+{
+  cronic_caller_flags=${-//[^aeuvx]/}
+  set -eu +a +vx
+} 2> /dev/null
+export -n cronic_caller_flags
 
 # Prints the usage line.
 cronic_usage_line() {
@@ -160,12 +178,31 @@ if ((BASH_VERSINFO[0] > 4 || (BASH_VERSINFO[0] == 4 && BASH_VERSINFO[1] >= 1)));
   export BASH_XTRACEFD=$cronic_xtrace_fd
 fi
 
+# Run the command with the caller's `set -o` shell options rather than this
+# script's.  If the caller exported SHELLOPTS, then the command would otherwise
+# inherit this script's options, and a bash script that reads an unset variable
+# (as `/usr/bin/texi2dvi` does when /bin/sh is bash) would fail.
 # The command runs in a subshell rather than in this shell, so that a builtin
 # such as `exit` or `exec` cannot end this script before it reports.
 # `command` because a function of this script, such as `cronic_usage`, would
-# otherwise run in place of a program of the same name.
+# otherwise run in place of a program of the same name.  The subshell turns off
+# this script's nounset (errexit is off already) in the same command that turns
+# on the caller's options, so that only the `command` line is traced.  The `:+`
+# avoids a bare `-`, which has a special meaning to `set`.  The redirections are
+# on the command rather than on the subshell, so that the trace of the `command`
+# line does not go to the command's standard error; under bash 4.1 or later,
+# it goes to the trace file, and under an older bash, to this script's
+# standard error.
+# The subshell is not the operand of `||` or the like, because then bash would
+# ignore `set -e` in it and would remove "errexit" from the SHELLOPTS that the
+# command inherits.
+# Limitation:  if the command is a builtin that runs code in the subshell, such
+# as `source` or `eval`, that code runs with the caller's options even if the
+# caller does not export SHELLOPTS.  So if the caller does not use `set -u`,
+# that code silently expands an unset variable to the empty string.
 set +e
 (
+  set +u${cronic_caller_flags:+ -$cronic_caller_flags}
   command -- "$@" > "$cronic_out" 2> "$cronic_trace"
 )
 cronic_result=$?

tests/cronic-test/cronic-test.sh

@@ -13,6 +13,19 @@
 
 set -eu
 
+# Do not let the user's environment file run in `cronic` or in the bash commands
+# below.  It could write to stderr, especially when an exported SHELLOPTS turns
+# on `-u` for it.
+unset BASH_ENV
+# Do not pass this script's own options, such as `-e` and `-u`, to `cronic` and
+# to the commands below.  If SHELLOPTS is exported, then run this script again
+# without it, because bash makes SHELLOPTS read-only, so it cannot be unset.
+# `printenv` matches the name exactly, unlike a search of the output of `env`,
+# which can match a line within the value of another variable.
+if printenv SHELLOPTS > /dev/null; then
+  exec env -u SHELLOPTS sh "$0" "$@"
+fi
+
 SCRIPT_DIR="$(CDPATH='' cd -- "$(dirname -- "$0")" && pwd -P)"
 CRONIC="$(CDPATH='' cd -- "${SCRIPT_DIR}/../.." && pwd -P)/cronic"
 
@@ -88,6 +101,24 @@ printf '%s\n' "$@" 1>&2
 EOF
 chmod +x "$work/stderr-lines"
 
+# A bash command that reads an unset variable.
+cat > "$work/read-unset" << 'EOF'
+#!/bin/bash
+unset CRONIC_TEST_UNSET_VARIABLE
+echo "value: ${CRONIC_TEST_UNSET_VARIABLE}" > /dev/null
+exit "$1"
+EOF
+chmod +x "$work/read-unset"
+
+# Runs `cronic` with SHELLOPTS set to its first argument and exported.
+cat > "$work/cronic-with-shellopts" << 'EOF2'
+#!/bin/bash
+shellopts="$1"
+shift
+exec env SHELLOPTS="$shellopts" "$REAL_CRONIC" "$@"
+EOF2
+chmod +x "$work/cronic-with-shellopts"
+
 # temp_files: prints `cronic`'s temporary files, in a canonical order.
 temp_files() {
   find "$TMPDIR" -mindepth 1 -maxdepth 1 2> /dev/null | sort
@@ -269,6 +300,38 @@ check "builtin command" 0 silent :
 check "exit builtin" 3 report exit 3
 check "exec builtin" 3 report exec "$work/trace-only" 3
 
+# When SHELLOPTS is exported, `cronic`'s own `-e` and `-u` options do not reach
+# the wrapped command, but the caller's options do.
+REAL_CRONIC="$CRONIC"
+export REAL_CRONIC
+CRONIC="$work/cronic-with-shellopts"
+default_shellopts=braceexpand:hashall:interactive-comments
+check "exported SHELLOPTS, command reads an unset variable" 0 silent \
+  "$default_shellopts" "$work/read-unset" 0
+check "exported SHELLOPTS, command ignores a failure" 0 silent \
+  "$default_shellopts" bash -c 'false; :'
+check "exported SHELLOPTS with nounset, command reads an unset variable" 1 \
+  "report:unbound variable" \
+  "$default_shellopts:nounset" "$work/read-unset" 0
+check "exported SHELLOPTS with errexit, command ignores a failure" 1 report \
+  "$default_shellopts:errexit" bash -c 'false; :'
+# shellcheck disable=SC2016 # The expansion is for the command to do.
+check "exported SHELLOPTS with allexport, command's environment" 0 silent \
+  "$default_shellopts:allexport" bash -c \
+  'case $SHELLOPTS in *allexport*) ;; *) exit 2 ;; esac
+   ! printenv cronic_caller_flags && ! printenv cronic_out'
+check "exported SHELLOPTS with xtrace, trace-only stderr" 0 silent \
+  "$default_shellopts:xtrace" "$work/read-unset" 0
+check "exported SHELLOPTS with xtrace, trace in the report" 3 \
+  "report:^+ exit 3$" "$default_shellopts:xtrace" bash -c 'exit 3'
+# The trace in the report is the command's, not `cronic`'s own.
+if grep -q -e '^+ set ' -e '^+ cronic_' "$work/output"; then
+  echo "FAIL: exported SHELLOPTS with xtrace, cronic's own commands are traced:"
+  cat "$work/output"
+  status=1
+fi
+CRONIC="$REAL_CRONIC"
+
 # The wrapped command sees the caller's exported variables unchanged.  For
 # each variable that `cronic` assigns, the caller exports that name in
 # uppercase, both with and without any "cronic_" prefix (for example,