Add strict_env and unstrict_env (direnv#572)

Allows the gradual introduction of `set -euo pipefail` into envrc
processing, as discussed in direnv#566, as well as an escape hatch for
commands that must be run in the envrc context that do not meet `set
-euo pipefail` requirements.

man/direnv-stdlib.1

@@ -483,6 +483,78 @@ Checks that the direnv version is at least old as \fB\fCversion\_at\_least\fR\&.
 be useful when sharing an \fB\fC\&.envrc\fR and to make sure that the users are up to
 date.
 
+.SS \fB\fCstrict\_env [<command> ...]\fR
+.PP
+Turns on shell execution strictness. This will force the .envrc
+evaluation context to exit immediately if:
+.IP \(bu 2
+any command in a pipeline returns a non\-zero exit status that is not
+otherwise handled as part of \fB\fCif\fR, \fB\fCwhile\fR, or \fB\fCuntil\fR tests,
+return value negation (\fB\fC!\fR), or part of a boolean (\fB\fC\&\&\fR or \fB\fC||\fR)
+chain.
+.IP \(bu 2
+any variable that has not explicitly been set or declared (with
+either \fB\fCdeclare\fR or \fB\fClocal\fR) is referenced.
+
+.PP
+If followed by a command\-line, the strictness applies for the duration
+of the command.
+
+.PP
+Example (Whole Script):
+
+.PP
+.RS
+
+.nf
+strict\_env
+has curl
+
+.fi
+.RE
+
+.PP
+Example (Command):
+
+.PP
+.RS
+
+.nf
+strict\_env has curl
+
+.fi
+.RE
+
+.SS \fB\fCunstrict\_env [<command> ...]\fR
+.PP
+Turns off shell execution strictness. If followed by a command\-line, the
+strictness applies for the duration of the command.
+
+.PP
+Example (Whole Script):
+
+.PP
+.RS
+
+.nf
+unstrict\_env
+has curl
+
+.fi
+.RE
+
+.PP
+Example (Command):
+
+.PP
+.RS
+
+.nf
+unstrict\_env has curl
+
+.fi
+.RE
+
 .SH COPYRIGHT
 .PP
 MIT licence \- Copyright (C) 2019 @zimbatm and contributors

man/direnv-stdlib.1.md

@@ -336,6 +336,45 @@ Checks that the direnv version is at least old as `version_at_least`. This can
 be useful when sharing an `.envrc` and to make sure that the users are up to
 date.
 
+### `strict_env [<command> ...]`
+
+Turns on shell execution strictness. This will force the .envrc
+evaluation context to exit immediately if:
+
+- any command in a pipeline returns a non-zero exit status that is not
+  otherwise handled as part of `if`, `while`, or `until` tests,
+  return value negation (`!`), or part of a boolean (`&&` or `||`)
+  chain.
+- any variable that has not explicitly been set or declared (with
+  either `declare` or `local`) is referenced.
+
+If followed by a command-line, the strictness applies for the duration
+of the command.
+
+Example (Whole Script):
+
+    strict_env
+    has curl
+
+Example (Command):
+
+    strict_env has curl
+
+#### `unstrict_env [<command> ...]`
+
+Turns off shell execution strictness. If followed by a command-line, the
+strictness applies for the duration of the command.
+
+Example (Whole Script):
+
+    unstrict_env
+    has curl
+
+Example (Command):
+
+    unstrict_env has curl
+
+
 COPYRIGHT
 ---------
 

stdlib.go

@@ -15,7 +15,6 @@ const StdLib = "#!/usr/bin/env bash\n" +
 	"shopt -s nullglob\n" +
 	"shopt -s extglob\n" +
 	"\n" +
-	"\n" +
 	"# NOTE: don't touch the RHS, it gets replaced at runtime\n" +
 	"direnv=\"$(command -v direnv)\"\n" +
 	"\n" +
@@ -30,6 +29,90 @@ const StdLib = "#!/usr/bin/env bash\n" +
 	"# algorithm and so it won't be re-exported.\n" +
 	"export DIRENV_IN_ENVRC=1\n" +
 	"\n" +
+	"__env_strictness() {\n" +
+	"  local mode tmpfile old_shell_options\n" +
+	"  local -i res\n" +
+	"\n" +
+	"  tmpfile=$(mktemp)\n" +
+	"  res=0\n" +
+	"  mode=\"$1\"\n" +
+	"  shift\n" +
+	"\n" +
+	"  set +o | grep 'pipefail\\|nounset\\|errexit' > \"$tmpfile\"\n" +
+	"  old_shell_options=$(< \"$tmpfile\")\n" +
+	"  rm -f tmpfile\n" +
+	"\n" +
+	"  case \"$mode\" in\n" +
+	"  strict)\n" +
+	"    set -o errexit -o nounset -o pipefail\n" +
+	"    ;;\n" +
+	"  unstrict)\n" +
+	"    set +o errexit +o nounset +o pipefail\n" +
+	"    ;;\n" +
+	"  *)\n" +
+	"    log_error \"Unknown strictness mode '${mode}'.\"\n" +
+	"    exit 1\n" +
+	"    ;;\n" +
+	"  esac\n" +
+	"\n" +
+	"  if (($#)); then\n" +
+	"    \"${@}\"\n" +
+	"    res=$?\n" +
+	"    eval \"$old_shell_options\"\n" +
+	"  fi\n" +
+	"\n" +
+	"  # Force failure if the inner script has failed and the mode is strict\n" +
+	"  if [[ $mode = strict && $res -gt 0 ]]; then\n" +
+	"    exit 1\n" +
+	"  fi\n" +
+	"\n" +
+	"  return $res\n" +
+	"}\n" +
+	"\n" +
+	"# Usage: strict_env [<command> ...]\n" +
+	"#\n" +
+	"# Turns on shell execution strictness. This will force the .envrc\n" +
+	"# evaluation context to exit immediately if:\n" +
+	"#\n" +
+	"# - any command in a pipeline returns a non-zero exit status that is\n" +
+	"#   not otherwise handled as part of `if`, `while`, or `until` tests,\n" +
+	"#   return value negation (`!`), or part of a boolean (`&&` or `||`)\n" +
+	"#   chain.\n" +
+	"# - any variable that has not explicitly been set or declared (with\n" +
+	"#   either `declare` or `local`) is referenced.\n" +
+	"#\n" +
+	"# If followed by a command-line, the strictness applies for the duration\n" +
+	"# of the command.\n" +
+	"#\n" +
+	"# Example:\n" +
+	"#\n" +
+	"#    strict_env\n" +
+	"#    has curl\n" +
+	"#\n" +
+	"#    strict_env has curl\n" +
+	"strict_env() {\n" +
+	"  __env_strictness strict \"$@\"\n" +
+	"}\n" +
+	"\n" +
+	"# Usage: unstrict_env [<command> ...]\n" +
+	"#\n" +
+	"# Turns off shell execution strictness. If followed by a command-line, the\n" +
+	"# strictness applies for the duration of the command.\n" +
+	"#\n" +
+	"# Example:\n" +
+	"#\n" +
+	"#    unstrict_env\n" +
+	"#    has curl\n" +
+	"#\n" +
+	"#    unstrict_env has curl\n" +
+	"unstrict_env() {\n" +
+	"  if (($#)); then\n" +
+	"    __env_strictness unstrict \"$@\"\n" +
+	"  else\n" +
+	"    set +o errexit +o nounset +o pipefail\n" +
+	"  fi\n" +
+	"}\n" +
+	"\n" +
 	"# Usage: direnv_layout_dir\n" +
 	"#\n" +
 	"# Prints the folder path that direnv should use to store layout content.\n" +

stdlib.sh

@@ -12,7 +12,6 @@ shopt -s gnu_errfmt
 shopt -s nullglob
 shopt -s extglob
 
-
 # NOTE: don't touch the RHS, it gets replaced at runtime
 direnv="$(command -v direnv)"
 
@@ -27,6 +26,90 @@ direnv_config_dir="${DIRENV_CONFIG:-${XDG_CONFIG_HOME:-$HOME/.config}/direnv}"
 # algorithm and so it won't be re-exported.
 export DIRENV_IN_ENVRC=1
 
+__env_strictness() {
+  local mode tmpfile old_shell_options
+  local -i res
+
+  tmpfile=$(mktemp)
+  res=0
+  mode="$1"
+  shift
+
+  set +o | grep 'pipefail\|nounset\|errexit' > "$tmpfile"
+  old_shell_options=$(< "$tmpfile")
+  rm -f tmpfile
+
+  case "$mode" in
+  strict)
+    set -o errexit -o nounset -o pipefail
+    ;;
+  unstrict)
+    set +o errexit +o nounset +o pipefail
+    ;;
+  *)
+    log_error "Unknown strictness mode '${mode}'."
+    exit 1
+    ;;
+  esac
+
+  if (($#)); then
+    "${@}"
+    res=$?
+    eval "$old_shell_options"
+  fi
+
+  # Force failure if the inner script has failed and the mode is strict
+  if [[ $mode = strict && $res -gt 0 ]]; then
+    exit 1
+  fi
+
+  return $res
+}
+
+# Usage: strict_env [<command> ...]
+#
+# Turns on shell execution strictness. This will force the .envrc
+# evaluation context to exit immediately if:
+#
+# - any command in a pipeline returns a non-zero exit status that is
+#   not otherwise handled as part of `if`, `while`, or `until` tests,
+#   return value negation (`!`), or part of a boolean (`&&` or `||`)
+#   chain.
+# - any variable that has not explicitly been set or declared (with
+#   either `declare` or `local`) is referenced.
+#
+# If followed by a command-line, the strictness applies for the duration
+# of the command.
+#
+# Example:
+#
+#    strict_env
+#    has curl
+#
+#    strict_env has curl
+strict_env() {
+  __env_strictness strict "$@"
+}
+
+# Usage: unstrict_env [<command> ...]
+#
+# Turns off shell execution strictness. If followed by a command-line, the
+# strictness applies for the duration of the command.
+#
+# Example:
+#
+#    unstrict_env
+#    has curl
+#
+#    unstrict_env has curl
+unstrict_env() {
+  if (($#)); then
+    __env_strictness unstrict "$@"
+  else
+    set +o errexit +o nounset +o pipefail
+  fi
+}
+
 # Usage: direnv_layout_dir
 #
 # Prints the folder path that direnv should use to store layout content.

test/stdlib.bash

@@ -155,4 +155,7 @@ test_name source_env_if_exists
   [[ $FOO = bar ]]
 )
 
+# test strict_env and unstrict_env
+./strict_env_test.bash
+
 echo OK

test/strict_env_test.bash

@@ -0,0 +1,67 @@
+#! /usr/bin/env bash
+
+# Note: this is _explicitly_ not setting `set -euo pipefail`
+# because we are testing functions that configure that.
+
+declare base expected actual
+base="${TMPDIR:-/tmp}/$(basename "$0").$$"
+expected="$base".expected
+actual="$base".actual
+
+declare -i success
+success=0
+
+# always execute relative to here
+cd "$(dirname "$0")" || exit 1
+
+# add the built direnv to the path
+root=$(cd .. && pwd -P)
+export PATH=$root:$PATH
+
+load_stdlib() {
+  # shellcheck disable=SC1090
+  source "$root/stdlib.sh"
+}
+
+test_fail() {
+  echo "FAILED $*: expected is not actual"
+  exit 1
+}
+
+test_strictness() {
+  local step
+  step="$1"
+  echo "$2" > "$expected"
+
+  set -o | grep 'errexit\|nounset\|pipefail' > "$actual"
+  diff -u "$expected" "$actual" || test_fail "$step"
+  (( success += 1 ))
+}
+
+load_stdlib
+
+test_strictness 'after source' $'errexit        	off
+nounset        	off
+pipefail       	off'
+
+strict_env
+test_strictness 'after strict_env' $'errexit        	on
+nounset        	on
+pipefail       	on'
+
+unstrict_env echo HELLO > /dev/null
+test_strictness "after unstrict_env with command" $'errexit        	on
+nounset        	on
+pipefail       	on'
+
+strict_env echo HELLO > /dev/null
+test_strictness "after strict_env with command" $'errexit        	on
+nounset        	on
+pipefail       	on'
+
+unstrict_env
+test_strictness 'after unstrict_env' $'errexit        	off
+nounset        	off
+pipefail       	off'
+
+echo "OK ($success tests)"