cqfd: add shell command

This adds the shell command to run a $CQFD_SHELL (or /bin/sh) command
from within the container.

It is a convenient frontend to "cqfd run bash", which also respects the
arguments:

	$ cqfd shell -c 'printf "0=$0,*=$*,#=$#\n"' zero one two three
	0=zero,*=one two three,#=3

While the run command does not:

	$ cqfd run /bin/bash -c 'printf "0=$0,*=$*,#=$#\n"' zero one two three
	printf: usage: printf [-v var] format [arguments]

	$ cqfd run /bin/sh -c 'printf "0=$0,*=$*,#=$#\n"' zero one two three
	0=bash,*=,#=0\n: 1: printf: usage: printf format [arg ...]

Note: The command shell does not run the command= set in the file
.cqfdrc.

README.md

@@ -48,6 +48,14 @@ executed from inside the build container.
     $ cqfd run make clean
     $ cqfd run "make linux-dirclean && make foobar-dirclean"
 
+Additionally, you may want to open an interactive shell:
+
+    $ cqfd shell
+
+Or run a shell script with arguments:
+
+    $ cqfd shell ./build.sh debug
+
 When ``cqfd`` is running, the current directory is mounted by Docker
 as a volume. As a result, all the build artefacts generated inside the
 container are still accessible in this directory after the container
@@ -190,6 +198,8 @@ The following environment variables are supported by cqfd to provide
 the user with extra flexibility during his day-to-day development
 tasks:
 
+``CQFD_SHELL``: A string specifying the shell to run with `cqfd shell`.
+
 ``CQFD_EXTRA_RUN_ARGS``: A space-separated list of additional
 docker-run options to be append to the starting container.
 Format is the same as (and passed to) docker-run’s options.

bash-completion

@@ -63,6 +63,19 @@ _cqfd() {
 
 		COMPREPLY=( $(compgen -c -W "-c" -- "$cur") )
 		return
+	elif [[ "$arg" == shell ]]; then
+		for (( i=1; i <= cword; i++ )); do
+			if [[ ${words[i]} == shell ]]; then
+				((i++))
+				break
+			fi
+		done
+
+		COMP_WORDS=("${SHELL:-/bin/sh}" "${COMP_WORDS[@]:$i}" "$cur")
+		COMP_LINE="${COMP_WORDS[*]}"
+		COMP_POINT="${#COMP_LINE}"
+		_command_offset 0
+		return
 	fi
 
 	local opts="-C -d -f -b -q -V --version -h --help"
@@ -71,7 +84,7 @@ _cqfd() {
 		return
 	fi
 
-	local cmds="init flavors run release version help"
+	local cmds="init flavors run release shell version help"
 	COMPREPLY=( $(compgen -W "$cmds $opts" -- "$cur") )
 } &&
 complete -F _cqfd cqfd

cqfd

@@ -46,6 +46,7 @@ Commands:
     flavors              List flavors from config file to stdout.
     run [cmdstring]      Run argument(s) inside build container.
     release [cmdstring]  Run argument(s) and release software.
+    shell [shargs]       Run shell command inside build container.
     help                 Show this help text.
 
     By default, the 'run' command is assumed, with the default
@@ -136,7 +137,7 @@ docker_build() {
 # arg$1: the command string to execute as $cqfd_user
 #
 docker_run() {
-	local args=(--privileged)
+	local args=(--privileged -i)
 
 	if ! docker image inspect $docker_img_name &> /dev/null; then
 		die "The docker image doesn't exist, launch 'cqfd init' to create it"
@@ -160,7 +161,7 @@ docker_run() {
 
 	# Set the interactive options if standard input is connected to a tty
 	if tty -s; then
-		args+=(-ti)
+		args+=(-t)
 	fi
 
 	# If possible, map cqfd_user from the calling user's
@@ -542,6 +543,16 @@ while [ $# -gt 0 ]; do
 		has_alternate_command=true
 		break
 		;;
+	shell)
+		shift
+		config_load $flavor
+		command_string="${CQFD_SHELL:-/bin/sh}"
+		if [ "$#" -ne 0 ]; then
+			command_string+=" ${@@Q}"
+		fi
+		docker_run "$command_string"
+		exit
+		;;
 	?*)
 		echo "Unknown command: $1" >&2
 		usage

tests/05-cqfd_run_do_not_preserve_arguments

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+#
+# validate the behavior of run command that do not preserve arguments
+
+set -o pipefail
+
+. "$(dirname "$0")"/jtest.inc "$1"
+cqfd="$TDIR/.cqfd/cqfd"
+
+cd $TDIR/
+
+jtest_prepare "cqfd run do not preserve the arguments"
+if ( ! $cqfd run /bin/sh -c 'printf "0=$0,*=$*,#=$#"' zero one two three ) \
+           | grep "0=sh,\*=,#=0"; then
+	jtest_result pass
+else
+	jtest_result fail
+fi

tests/08-cqfd_shell

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+#
+# validate the behavior of shell command
+
+set -o pipefail
+
+unset CQFD_SHELL
+
+. "$(dirname "$0")"/jtest.inc "$1"
+cqfd="$TDIR/.cqfd/cqfd"
+
+cd $TDIR/
+
+jtest_prepare "cqfd shell should succeed with no stdin"
+if $cqfd shell </dev/null; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
+
+jtest_prepare "cqfd shell should read commands from stdin"
+if ( ! $cqfd shell <<<"tty" ) | grep "not a tty"; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
+
+jtest_prepare "cqfd shell should preserve the arguments"
+if $cqfd shell -c 'printf "0=$0,*=$*,#=$#"' zero one two three \
+       | grep "0=zero,\*=one two three,#=3$"; then
+	jtest_result pass
+else
+	jtest_result fail
+fi
+
+jtest_prepare "cqfd shell should fail with 127 if \$CQFD_SHELL is not found"
+if CQFD_SHELL=/bin/non-existant-shell $cqfd shell <<<"tty";
+                                      test "$?" -eq 127; then
+	jtest_result pass
+else
+	jtest_result fail
+fi