stdstream support (#168)

* stdstream support

* stdstream test (using /dev/std{in,out,err}), and fds directly

test/stdstream.sh

@@ -0,0 +1,51 @@
+#!/bin/sh
+
+TRY_TOP="${TRY_TOP:-$(git rev-parse --show-toplevel --show-superproject-working-tree 2>/dev/null || echo "${0%/*}")}"
+TRY="$TRY_TOP/try"
+
+cmdfile="$(mktemp)"
+
+cat > "$cmdfile" <<'EOF'
+read x < /dev/stdin
+echo $((x * 2)) > /dev/stdout
+echo $((x * 3)) > /dev/stderr
+
+EOF
+
+chmod +x "$cmdfile"
+
+try_stdout=$(mktemp)
+try_stderr=$(mktemp)
+sh_stdout=$(mktemp)
+sh_stderr=$(mktemp)
+
+# test stdout
+echo 5 | "$TRY" "$cmdfile" >"$try_stdout" 2>"$try_stderr"
+echo 5 | sh "$cmdfile" >"$sh_stdout" 2>"$sh_stderr"
+
+diff "$try_stdout" "$sh_stdout" || exit 1
+
+# using grep because there's try errors printed
+grep -q 15 "$try_stderr"
+grep -q 15 "$sh_stderr"
+
+rm "$try_stdout" "$try_stderr" "$sh_stdout" "$sh_stderr"
+
+cat > "$cmdfile" <<'EOF'
+read x <&0
+echo $((x * 2)) >&1
+echo $((x * 3)) >&2
+
+EOF
+
+# test stdout
+echo 5 | "$TRY" "$cmdfile" >"$try_stdout" 2>"$try_stderr"
+echo 5 | sh "$cmdfile" >"$sh_stdout" 2>"$sh_stderr"
+
+diff "$try_stdout" "$sh_stdout" || exit 1
+
+# using grep because there's try errors printed
+grep -q 15 "$try_stderr"
+grep -q 15 "$sh_stderr"
+
+rm "$try_stdout" "$try_stderr" "$sh_stdout" "$sh_stderr"

try

@@ -249,6 +249,10 @@ unshare --root="$SANDBOX_DIR/temproot" /bin/sh "$chroot_executable"
 exitcode="$?"
 
 # unmount the devices
+rm "$sandbox_dir/temproot/dev/stdin"
+rm "$sandbox_dir/temproot/dev/stdout"
+rm "$sandbox_dir/temproot/dev/stderr"
+
 unmount_devices "$SANDBOX_DIR"
 
 exit $exitcode
@@ -262,6 +266,9 @@ unset START_DIR SANDBOX_DIR UNION_HELPER DIRS_AND_MOUNTS TRY_EXIT_STATUS
 unset script_to_execute chroot_executable try_mount_log
 
 mount -t proc proc /proc &&
+ln -s /proc/self/fd/0 /dev/stdin &&
+ln -s /proc/self/fd/1 /dev/stdout &&
+ln -s /proc/self/fd/2 /dev/stderr &&
 cd "$START_DIR" &&
 . "$script_to_execute"
 EOF