fix: shell quoting of files

Use $'' to correctly insert literals. This technically loses posix
compatibility, but is supported by all major shells.

Signed-off-by: Rudi Grinberg <me@rgrinberg.com>

Author: rgrinberg

CHANGES.md

@@ -1,6 +1,8 @@
 Unreleased
 ----------
 
+- Allow spaces in cram test paths (#4980, fixes #4162, @rgrinberg)
+
 - Fix `foreign_stubs` inside a `tests` stanza. Previously, dune would crash
   when this field was present (#4942, fix #4946, @rgrinberg)
 

src/dune_rules/cram_exec.ml

@@ -111,10 +111,13 @@ let translate_path_for_sh =
    On Windows, we still generate a [sh] script so we need to quote using Unix
    conventions. *)
 let quote_for_sh fn =
+  (* we lose some portability as [$'] isn't posix. I don't see a better way to
+     do this *)
   let buf = Buffer.create (String.length fn + 2) in
-  Buffer.add_char buf '\'';
+  Buffer.add_string buf "$'";
   String.iter fn ~f:(function
-    | '\'' -> Buffer.add_string buf "'\\''"
+    | '\'' -> Buffer.add_string buf "\'"
+    | '\\' -> Buffer.add_string buf "\\\\"
     | c -> Buffer.add_char buf c);
   Buffer.add_char buf '\'';
   Buffer.contents buf
@@ -353,7 +356,7 @@ let create_sh_script cram_stanzas ~temp_dir : sh_script Fiber.t =
       in
       fprln oc ". %s > %s 2>&1" user_shell_code_file_sh_path
         user_shell_code_output_file_sh_path;
-      fprln oc {|printf "%%d\0%%s\0" $? $%s >> %s|}
+      fprln oc {|printf "%%d\0%%s\0" $? "$%s" >> %s|}
         Action_exec._BUILD_PATH_PREFIX_MAP metadata_file_sh_path;
       Cram_lexer.Command
         { command = lines

test/blackbox-tests/test-cases/gh4162.t

@@ -14,8 +14,6 @@ Cram doesn't like tests in paths
     $ echo foo
 
   $ dune build @foo
-            sh (internal) (exit 1)
-  (cd _build/.sandbox/54ffcedad804d81955c7b33d18d42e68/default && /run/current-system/sw/bin/sh /var/folders/nc/x9_nmmsj0rjbfyzxb_kjk6qr0000gn/T/build_95f84b_dune/dune_cram_01b015_.foo.t/main.sh)
-  /var/folders/nc/x9_nmmsj0rjbfyzxb_kjk6qr0000gn/T/build_95f84b_dune/dune_cram_01b015_.foo.t/main.sh: line 5: printf: bbb/_build/.sandbox/54ffcedad804d81955c7b33d18d42e68/default:$TESTCASE_ROOT=$TESTCASE_ROOT/aaa: invalid number
-  -> required by alias foo
+  File "foo.t", line 1, characters 0-0:
+  Error: Files _build/default/foo.t and _build/default/foo.t.corrected differ.
   [1]