Fix opam unable to find executables on systems where users belong to …

…more than 32 groups when opam is built using musl libc

Details of the issue in musl described in https://www.openwall.com/lists/musl/2021/07/03/1

.gitignore

@@ -85,8 +85,6 @@ src/client/no-git-version
 src/core/developer
 src/manifest/dune
 src/manifest/install.inc
-src/stubs/libacl/dune
-src/stubs/libacl/c-libraries.sexp
 src/stubs/win32/cc64
 src/stubs/win32/dune
 src/stubs/c-flags.sexp

Makefile

@@ -102,7 +102,7 @@ clean:
 distclean: clean clean-ext
 	rm -rf autom4te.cache bootstrap
 	rm -f Makefile.config config.log config.status aclocal.m4
-	rm -f src/*.META src/*/.merlin src/manifest/dune src/manifest/install.inc src/stubs/libacl/dune src/stubs/win32/dune src/stubs/win32/cc64 src/ocaml-flags-configure.sexp src/stubs/libacl/c-libraries.sexp
+	rm -f src/*.META src/*/.merlin src/manifest/dune src/manifest/install.inc src/stubs/win32/dune src/stubs/win32/cc64 src/ocaml-flags-configure.sexp
 	rm -f src/client/linking.sexp src/stubs/c-flags.sexp src/core/developer src/core/version
 
 OPAMINSTALLER_FLAGS = --prefix "$(call CYGPATH,$(DESTDIR)$(prefix))"

configure.ac

@@ -72,10 +72,6 @@ AS_IF([test "x$with_0install_solver" = xno],
 )
 
 
-AC_ARG_WITH([libacl],
-  AC_HELP_STRING([--with-libacl],
-                 [Compile opam with libacl support]),,[with_libacl=auto])
-
 AC_ARG_WITH([private_runtime],
   AC_HELP_STRING([--with-private-runtime],
                  [For a mingw-w64 build, manifest the runtime DLLs locally in Opam.Runtime.arch]),,[with_private_runtime=no]
@@ -164,23 +160,6 @@ AS_IF([test "x${enable_developer_mode}" = "xyes"],[
 
 AS_IF([test "x${with_mccs}" = "xno"], [AC_SUBST(MCCS_ENABLED,false)], [AC_SUBST(MCCS_ENABLED,true)])
 
-AS_IF([test "x${with_libacl}" != "xno"],[
-  have_libacl=yes
-  AC_CHECK_HEADER([acl/libacl.h],,[have_libacl=no])
-  AC_SEARCH_LIBS([acl_get_perm],[acl],,[have_libacl=no])
-  AS_IF([test "x${SYSTEM}" = "xcygwin"],[
-    AS_IF([test "x${have_libacl}" = "xno"],[AC_MSG_ERROR([opam on Cygwin requires libacl])],[with_libacl=yes])
-  ])
-  AS_IF([test "x${with_libacl}${have_libacl}" = "xyesno"],[AC_MSG_ERROR([libacl not found])])
-])
-AS_IF([test "x${with_libacl}" = "xyes"],[
-  AS_IF([test "x${ac_cv_search_acl_get_perm}" = "xnone required"],[
-    AC_SUBST(CONF_LIBACL_LINK,[])
-  ],[
-    AC_SUBST(CONF_LIBACL_LINK,[${ac_cv_search_acl_get_perm}])
-  ])
-])
-
 CONF_OCAMLFLAGS=''
 
 AS_IF([test "x${CI}" != "x" -o "x${enable_developer_mode}" = "xyes"],[
@@ -427,7 +406,6 @@ AC_CONFIG_FILES(
   Makefile.config
   src/ocaml-flags-configure.sexp
   src/stubs/c-flags.sexp
-  src/stubs/libacl/c-libraries.sexp
 )
 AC_OUTPUT
 
@@ -449,12 +427,6 @@ AS_IF([ test ${WIN32} -eq 1],[
   ${LN_S} -f dune-win32 dune
   cd ../../..
 ])
-rm -f src/stubs/libacl/dune
-AS_IF([ test "x${with_libacl}" = "xyes" ],[
-  cd src/stubs/libacl
-  ${LN_S} -f dune-libacl dune
-  cd ../../..
-])
 
 echo
 

master_changes.md

@@ -584,3 +584,4 @@ users)
   * `OpamStd.Map`: add `filter_map` [#5337 @rjbou]
   * `OpamStd.Set`: Add `to_list_map` [#5308 @kit-ty-kate]
   * `OpamConsole.header_msg`: remove trailing space when there is no left padding [#5363 @rjbou]
+  * Fix opam unable to find executables on systems where users belong to more than 32 groups when opam is built using musl libc [#5381 @kit-ty-kate - fix #5373]

src/core/dune

@@ -3,9 +3,6 @@
   (public_name opam-core)
   (synopsis    "OCaml Package Manager core internal stdlib")
   (libraries   re ocamlgraph unix bigarray sha jsonm
-               (select opamACL.ml from
-                       (opam-core.libacl -> opamACL.libacl.ml)
-                       (                 -> opamACL.dummy.ml))
                (select opamStubs.ml from
                        (opam-core.stubs -> opamStubs.win32.ml)
                        (                -> opamStubs.dummy.ml)))

src/core/opamSystem.ml

@@ -388,32 +388,9 @@ let t_resolve_command =
     let name = forward_to_back name in
     OpamStd.String.contains_char name Filename.dir_sep.[0]
   in
-  let check_perms =
-    if Sys.win32 then fun f ->
-      try (Unix.stat f).Unix.st_kind = Unix.S_REG
-      with e -> OpamStd.Exn.fatal e; false
-    else fun f ->
-      try
-        let open Unix in
-        let uid = geteuid () in
-        let groups = OpamStd.IntSet.of_list (getegid () :: Array.to_list (getgroups ())) in
-        let {st_uid; st_gid; st_perm; _} = stat f in
-        let mask =
-          if uid = st_uid then
-            0o100
-          else if OpamStd.IntSet.mem st_gid groups then
-            0o010
-          else
-            0o001
-        in
-        if (st_perm land mask) <> 0 then
-          true
-        else
-          match OpamACL.get_acl_executable_info f st_uid with
-          | None -> false
-          | Some [] -> true
-          | Some gids -> OpamStd.IntSet.(not (is_empty (inter (of_list gids) groups)))
-      with e -> OpamStd.Exn.fatal e; false
+  let check_perms f =
+    try Unix.access f [if Sys.win32 then Unix.R_OK else Unix.X_OK]; true
+    with Unix.Unix_error _ -> false
   in
   let resolve ?dir env name =
     if not (Filename.is_relative name) then begin