Move executable-check to C++

This was already apparently supposed to work, but didn't because we
just overrode errno again.

This now means that, if a correctly named candidate exists, we don't
start the command-not-found handler.

See #8804

share/config.fish

@@ -13,12 +13,6 @@ or set -g __fish_added_user_paths
 #
 function __fish_default_command_not_found_handler
     printf (_ "fish: Unknown command: %s\n") (string escape -- $argv[1]) >&2
-    for file in $PATH/$argv[1]
-        if test -e $file -a ! -x $file
-            printf (_ "fish: %s exists but isn't executable\n") (string escape -- $file) >&2
-            break
-        end
-    end
 end
 
 

share/functions/fish_command_not_found.fish

@@ -13,12 +13,6 @@ end
 
 function __fish_default_command_not_found_handler
     printf (_ "fish: Unknown command: %s\n") (string escape -- $argv[1]) >&2
-    for file in $PATH/$argv[1]
-        if test -e $file -a ! -x $file
-            printf (_ "fish: %s exists but isn't executable\n") (string escape -- $file) >&2
-            break
-        end
-    end
 end
 
 # If an old handler already exists, defer to that.

src/parse_execution.cpp

@@ -731,8 +731,12 @@ end_execution_reason_t parse_execution_context_t::handle_command_not_found(
 
     const wchar_t *const cmd = cmd_str.c_str();
     if (err_code != ENOENT) {
+        // TODO: We currently handle all errors here the same,
+        // but this mainly applies to EACCES. We could also feasibly get:
+        // ELOOP
+        // ENAMETOOLONG
         return this->report_error(STATUS_NOT_EXECUTABLE, statement,
-                                  _(L"The file '%ls' is not executable by this user"), cmd);
+                                  _(L"Unknown command. '%ls' exists but is not an executable file."), cmd);
     }
 
     // Handle unrecognized commands with standard command not found handler that can make better
@@ -872,7 +876,7 @@ end_execution_reason_t parse_execution_context_t::populate_plain_process(
         if (!has_command && !use_implicit_cd) {
             // No command. If we're --no-execute return okay - it might be a function.
             if (no_exec()) return end_execution_reason_t::ok;
-            return this->handle_command_not_found(cmd, statement, no_cmd_err_code);
+            return this->handle_command_not_found(path_to_external_command.empty() ? cmd : path_to_external_command, statement, no_cmd_err_code);
         }
     }
 

src/path.cpp

@@ -87,6 +87,15 @@ static bool path_get_path_core(const wcstring &cmd, wcstring *out_path,
                 return true;
             }
             err = EACCES;
+            if (out_path) *out_path = std::move(next_path);
+        } else if (errno != ENOENT && err == ENOENT) {
+            // Keep the first *interesting* error and path around.
+            // ENOENT isn't interesting because not having a file is the normal case.
+            auto tmperr = errno;
+            // Ignore if the parent directory is already inaccessible.
+            if (access(wcs2string(wdirname(next_path)).c_str(), X_OK) != 0) continue;
+            err = tmperr;
+            if (out_path) *out_path = std::move(next_path);
         }
     }
 

tests/checks/command-not-found.fish

@@ -35,9 +35,7 @@ echo $status
 set -g PATH .
 echo banana > foobar
 foobar --banana
-# CHECKERR: fish: Unknown command: foobar
+# CHECKERR: checks/command-not-found.fish (line {{\d+}}): Unknown command. './foobar' exists but is not an executable file.
-# CHECKERR: fish: ./foobar exists but isn't executable
-# CHECKERR: checks/command-not-found.fish (line 37):
 # CHECKERR: foobar --banana
 # CHECKERR: ^