Simplify auto_load_expand_dir_vars and remove substitute_path_component

This simplifies auto_load_expand_dir_vars to first split the string,
then do any needed substitutions.  This was suggested by Simon, and is
much simpler than the current approach.

Then this patch also removes substitute_path_component, as it is no
longer called.  This is nice because it helps with the long term goal
of removing utils.h.

Regression tested on x86-64 Fedora 36.

5 files changed, 21 insertions, 121 deletions

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 6af65357243..93f506ee391 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -489,7 +489,6 @@ SELFTESTS_SRCS = \
 	unittests/ui-file-selftests.c \
 	unittests/unique_xmalloc_ptr_char.c \
 	unittests/unpack-selftests.c \
-	unittests/utils-selftests.c \
 	unittests/vec-utils-selftests.c \
 	unittests/xml-utils-selftests.c
 
diff --git a/gdb/auto-load.c b/gdb/auto-load.c
index 5267cb4e64d..9d6fabe6bbc 100644
--- a/gdb/auto-load.c
+++ b/gdb/auto-load.c
@@ -173,24 +173,33 @@ static std::string auto_load_safe_path = AUTO_LOAD_SAFE_PATH;
    counterpart.  */
 static std::vector<gdb::unique_xmalloc_ptr<char>> auto_load_safe_path_vec;
 
-/* Expand $datadir and $debugdir in STRING according to the rules of
-   substitute_path_component.  */
+/* Expand $datadir and $debugdir in STRING.  */
 
 static std::vector<gdb::unique_xmalloc_ptr<char>>
 auto_load_expand_dir_vars (const char *string)
 {
-  char *s = xstrdup (string);
-  substitute_path_component (&s, "$datadir", gdb_datadir.c_str ());
-  substitute_path_component (&s, "$debugdir", debug_file_directory.c_str ());
+  std::vector<gdb::unique_xmalloc_ptr<char>> result
+    = dirnames_to_char_ptr_vec (string);
 
-  if (debug_auto_load && strcmp (s, string) != 0)
-    auto_load_debug_printf ("Expanded $-variables to \"%s\".", s);
-
-  std::vector<gdb::unique_xmalloc_ptr<char>> dir_vec
-    = dirnames_to_char_ptr_vec (s);
-  xfree(s);
+  for (auto &elt : result)
+    {
+      if (strcmp (elt.get (), "$datadir") == 0)
+	{
+	  elt = make_unique_xstrdup (gdb_datadir.c_str ());
+	  if (debug_auto_load)
+	    auto_load_debug_printf ("Expanded $datadir to \"%s\".",
+				    gdb_datadir.c_str ());
+	}
+      else if (strcmp (elt.get (), "$debugdir") == 0)
+	{
+	  elt = make_unique_xstrdup (debug_file_directory.c_str ());
+	  if (debug_auto_load)
+	    auto_load_debug_printf ("Expanded $debugdir to \"%s\".",
+				    debug_file_directory.c_str ());
+	}
+    }
 
-  return dir_vec;
+  return result;
 }
 
 /* Update auto_load_safe_path_vec from current AUTO_LOAD_SAFE_PATH.  */
diff --git a/gdb/unittests/utils-selftests.c b/gdb/unittests/utils-selftests.c
deleted file mode 100644
index 70609aa4294..00000000000
--- a/gdb/unittests/utils-selftests.c
+++ /dev/null
@@ -1,60 +0,0 @@
-/* Unit tests for the utils.c file.
-
-   Copyright (C) 2018-2023 Free Software Foundation, Inc.
-
-   This file is part of GDB.
-
-   This program is free software; you can redistribute it and/or modify
-   it under the terms of the GNU General Public License as published by
-   the Free Software Foundation; either version 3 of the License, or
-   (at your option) any later version.
-
-   This program is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-   GNU General Public License for more details.
-
-   You should have received a copy of the GNU General Public License
-   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
-
-#include "defs.h"
-#include "utils.h"
-#include "gdbsupport/selftest.h"
-
-namespace selftests {
-namespace utils {
-
-static void
-test_substitute_path_component ()
-{
-  auto test = [] (std::string s, const char *from, const char *to,
-		  const char *expected)
-    {
-      char *temp = xstrdup (s.c_str ());
-      substitute_path_component (&temp, from, to);
-      SELF_CHECK (strcmp (temp, expected) == 0);
-      xfree (temp);
-    };
-
-  test ("/abc/$def/g", "abc", "xyz", "/xyz/$def/g");
-  test ("abc/$def/g", "abc", "xyz", "xyz/$def/g");
-  test ("/abc/$def/g", "$def", "xyz", "/abc/xyz/g");
-  test ("/abc/$def/g", "g", "xyz", "/abc/$def/xyz");
-  test ("/abc/$def/g", "ab", "xyz", "/abc/$def/g");
-  test ("/abc/$def/g", "def", "xyz", "/abc/$def/g");
-  test ("/abc/$def/g", "abc", "abc", "/abc/$def/g");
-  test ("/abc/$def/g", "abc", "", "//$def/g");
-  test ("/abc/$def/g", "abc/$def", "xyz", "/xyz/g");
-  test ("/abc/$def/abc", "abc", "xyz", "/xyz/$def/xyz");
-}
-
-}
-}
-
-void _initialize_utils_selftests ();
-void
-_initialize_utils_selftests ()
-{
-  selftests::register_test ("substitute_path_component",
-			    selftests::utils::test_substitute_path_component);
-}
diff --git a/gdb/utils.c b/gdb/utils.c
index 3af54ec5179..0347496e431 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -3346,51 +3346,6 @@ parse_pid_to_attach (const char *args)
   return pid;
 }
 
-/* Substitute all occurrences of string FROM by string TO in *STRINGP.  *STRINGP
-   must come from xrealloc-compatible allocator and it may be updated.  FROM
-   needs to be delimited by IS_DIR_SEPARATOR or DIRNAME_SEPARATOR (or be
-   located at the start or end of *STRINGP.  */
-
-void
-substitute_path_component (char **stringp, const char *from, const char *to)
-{
-  char *string = *stringp, *s;
-  const size_t from_len = strlen (from);
-  const size_t to_len = strlen (to);
-
-  for (s = string;;)
-    {
-      s = strstr (s, from);
-      if (s == NULL)
-	break;
-
-      if ((s == string || IS_DIR_SEPARATOR (s[-1])
-	   || s[-1] == DIRNAME_SEPARATOR)
-	  && (s[from_len] == '\0' || IS_DIR_SEPARATOR (s[from_len])
-	      || s[from_len] == DIRNAME_SEPARATOR))
-	{
-	  char *string_new;
-
-	  string_new
-	    = (char *) xrealloc (string, (strlen (string) + to_len + 1));
-
-	  /* Relocate the current S pointer.  */
-	  s = s - string + string_new;
-	  string = string_new;
-
-	  /* Replace from by to.  */
-	  memmove (&s[to_len], &s[from_len], strlen (&s[from_len]) + 1);
-	  memcpy (s, to, to_len);
-
-	  s += to_len;
-	}
-      else
-	s++;
-    }
-
-  *stringp = string;
-}
-
 #ifdef HAVE_WAITPID
 
 #ifdef SIGALRM
diff --git a/gdb/utils.h b/gdb/utils.h
index 2d831bac184..00b123e6117 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -136,9 +136,6 @@ private:
 extern int gdb_filename_fnmatch (const char *pattern, const char *string,
 				 int flags);
 
-extern void substitute_path_component (char **stringp, const char *from,
-				       const char *to);
-
 std::string ldirname (const char *filename);
 
 extern int count_path_elements (const char *path);