Make relocate_{path,gdb_directory} return std::string

This simplifies memory management. I've also changed some global variables
to std::string accordingly (which store the result of these functions),
but not all because some are used with add_setshow_optional_filename_cmd
which requires a char*.

gdb/ChangeLog:

2019-09-11  Christian Biesinger  <cbiesinger@google.com>

	* auto-load.c (auto_load_expand_dir_vars): Update.
	* defs.h (gdb_datadir): Change to std::string.
	(python_libdir): Likewise.
	(relocate_gdb_directory): Change return type to std::string.
	* guile/guile.c (gdbscm_data_directory): Update.
	(initialize_scheme_side): Update.
	* jit.c (jit_reader_dir): Change to std::string.
	(jit_reader_load_command): Update.
	* main.c (gdb_datadir): Change to std::string.
	(python_libdir): Likewise.
	(set_gdb_data_directory): Update.
	(relocate_path): Change to return std::string.
	(relocate_gdb_directory): Change to return std::string.
	(relocate_gdbinit_path_maybe_in_datadir): Update.
	(captured_main_1): Update.
	* python/python.c (do_start_initialization): Update.
	* top.c (show_gdb_datadir): Update.
	* xml-syscall.c (xml_init_syscalls_info): Update.
	(init_syscalls_info): Update.

9 files changed, 81 insertions, 60 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 91b860c..4c35470 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,27 @@
 2019-09-11  Christian Biesinger  <cbiesinger@google.com>
 
+	* auto-load.c (auto_load_expand_dir_vars): Update.
+	* defs.h (gdb_datadir): Change to std::string.
+	(python_libdir): Likewise.
+	(relocate_gdb_directory): Change return type to std::string.
+	* guile/guile.c (gdbscm_data_directory): Update.
+	(initialize_scheme_side): Update.
+	* jit.c (jit_reader_dir): Change to std::string.
+	(jit_reader_load_command): Update.
+	* main.c (gdb_datadir): Change to std::string.
+	(python_libdir): Likewise.
+	(set_gdb_data_directory): Update.
+	(relocate_path): Change to return std::string.
+	(relocate_gdb_directory): Change to return std::string.
+	(relocate_gdbinit_path_maybe_in_datadir): Update.
+	(captured_main_1): Update.
+	* python/python.c (do_start_initialization): Update.
+	* top.c (show_gdb_datadir): Update.
+	* xml-syscall.c (xml_init_syscalls_info): Update.
+	(init_syscalls_info): Update.
+
+2019-09-11  Christian Biesinger  <cbiesinger@google.com>
+
 	* main.c (relocate_gdbinit_path_maybe_in_datadir): Factor this code
 	out of get_init_files.
 	(get_init_files): Update.
diff --git a/gdb/auto-load.c b/gdb/auto-load.c
index 616aeb6..115d5c1 100644
--- a/gdb/auto-load.c
+++ b/gdb/auto-load.c
@@ -178,7 +178,7 @@ static std::vector<gdb::unique_xmalloc_ptr<char>>
 auto_load_expand_dir_vars (const char *string)
 {
   char *s = xstrdup (string);
-  substitute_path_component (&s, "$datadir", gdb_datadir);
+  substitute_path_component (&s, "$datadir", gdb_datadir.c_str ());
   substitute_path_component (&s, "$debugdir", debug_file_directory);
 
   if (debug_auto_load && strcmp (s, string) != 0)
diff --git a/gdb/defs.h b/gdb/defs.h
index 14e0a3e..c9a38b6 100644
--- a/gdb/defs.h
+++ b/gdb/defs.h
@@ -115,11 +115,11 @@ extern int dbx_commands;
 extern char *gdb_sysroot;
 
 /* * GDB datadir, used to store data files.  */
-extern char *gdb_datadir;
+extern std::string gdb_datadir;
 
-/* * If non-NULL, the possibly relocated path to python's "lib" directory
+/* * If not empty, the possibly relocated path to python's "lib" directory
    specified with --with-python.  */
-extern char *python_libdir;
+extern std::string python_libdir;
 
 /* * Search path for separate debug files.  */
 extern char *debug_file_directory;
@@ -282,7 +282,7 @@ struct value;
 
 /* This really belong in utils.c (path-utils.c?), but it references some
    globals that are currently only available to main.c.  */
-extern char *relocate_gdb_directory (const char *initial, bool relocatable);
+extern std::string relocate_gdb_directory (const char *initial, bool relocatable);
 
 
 /* Annotation stuff.  */
diff --git a/gdb/guile/guile.c b/gdb/guile/guile.c
index 39bec87..defe554 100644
--- a/gdb/guile/guile.c
+++ b/gdb/guile/guile.c
@@ -325,7 +325,7 @@ gdbscm_execute_gdb_command (SCM command_scm, SCM rest)
 static SCM
 gdbscm_data_directory (void)
 {
-  return gdbscm_scm_from_c_string (gdb_datadir);
+  return gdbscm_scm_from_c_string (gdb_datadir.c_str ());
 }
 
 /* (guile-data-directory) -> string */
@@ -582,7 +582,8 @@ initialize_scheme_side (void)
 {
   char *boot_scm_path;
 
-  guile_datadir = concat (gdb_datadir, SLASH_STRING, "guile", (char *) NULL);
+  guile_datadir = concat (gdb_datadir.c_str (), SLASH_STRING, "guile",
+			  (char *) NULL);
   boot_scm_path = concat (guile_datadir, SLASH_STRING, "gdb",
 			  SLASH_STRING, boot_scm_filename, (char *) NULL);
 
diff --git a/gdb/jit.c b/gdb/jit.c
index 5fef037..4722d6c 100644
--- a/gdb/jit.c
+++ b/gdb/jit.c
@@ -42,7 +42,7 @@
 #include "readline/tilde.h"
 #include "completer.h"
 
-static const char *jit_reader_dir = NULL;
+static std::string jit_reader_dir;
 
 static const struct objfile_data *jit_objfile_data;
 
@@ -216,7 +216,7 @@ jit_reader_load_command (const char *args, int from_tty)
     error (_("JIT reader already loaded.  Run jit-reader-unload first."));
 
   if (!IS_ABSOLUTE_PATH (file.get ()))
-    file.reset (xstrprintf ("%s%s%s", jit_reader_dir, SLASH_STRING,
+    file.reset (xstrprintf ("%s%s%s", jit_reader_dir.c_str (), SLASH_STRING,
 			    file.get ()));
 
   loaded_jit_reader = jit_reader_load (file.get ());
diff --git a/gdb/main.c b/gdb/main.c
index 9e22889..6b75fce 100644
--- a/gdb/main.c
+++ b/gdb/main.c
@@ -61,7 +61,7 @@ int dbx_commands = 0;
 char *gdb_sysroot = 0;
 
 /* GDB datadir, used to store data files.  */
-char *gdb_datadir = 0;
+std::string gdb_datadir;
 
 /* Non-zero if GDB_DATADIR was provided on the command line.
    This doesn't track whether data-directory is set later from the
@@ -70,7 +70,7 @@ static int gdb_datadir_provided = 0;
 
 /* If gdb was configured with --with-python=/path,
    the possibly relocated path to python's lib directory.  */
-char *python_libdir = 0;
+std::string python_libdir;
 
 /* Target IO streams.  */
 struct ui_file *gdb_stdtargin;
@@ -121,71 +121,70 @@ set_gdb_data_directory (const char *new_datadir)
   else if (!S_ISDIR (st.st_mode))
     warning (_("%s is not a directory."), new_datadir);
 
-  xfree (gdb_datadir);
-  gdb_datadir = gdb_realpath (new_datadir).release ();
+  gdb_datadir = gdb_realpath (new_datadir).get ();
 
   /* gdb_realpath won't return an absolute path if the path doesn't exist,
      but we still want to record an absolute path here.  If the user entered
      "../foo" and "../foo" doesn't exist then we'll record $(pwd)/../foo which
      isn't canonical, but that's ok.  */
-  if (!IS_ABSOLUTE_PATH (gdb_datadir))
+  if (!IS_ABSOLUTE_PATH (gdb_datadir.c_str ()))
     {
-      gdb::unique_xmalloc_ptr<char> abs_datadir = gdb_abspath (gdb_datadir);
+      gdb::unique_xmalloc_ptr<char> abs_datadir
+        = gdb_abspath (gdb_datadir.c_str ());
 
-      xfree (gdb_datadir);
-      gdb_datadir = abs_datadir.release ();
+      gdb_datadir = abs_datadir.get ();
     }
 }
 
 /* Relocate a file or directory.  PROGNAME is the name by which gdb
    was invoked (i.e., argv[0]).  INITIAL is the default value for the
    file or directory.  RELOCATABLE is true if the value is relocatable,
-   false otherwise.  Returns a newly allocated string; this may return
-   NULL under the same conditions as make_relative_prefix.  */
+   false otherwise.  This may return an empty string under the same
+   conditions as make_relative_prefix returning NULL.  */
 
-static char *
+static std::string
 relocate_path (const char *progname, const char *initial, bool relocatable)
 {
   if (relocatable)
-    return make_relative_prefix (progname, BINDIR, initial);
-  return xstrdup (initial);
+    {
+      gdb::unique_xmalloc_ptr<char> str (make_relative_prefix (progname,
+							       BINDIR,
+							       initial));
+      if (str != nullptr)
+	return str.get ();
+      return std::string ();
+    }
+  return initial;
 }
 
 /* Like relocate_path, but specifically checks for a directory.
    INITIAL is relocated according to the rules of relocate_path.  If
    the result is a directory, it is used; otherwise, INITIAL is used.
-   The chosen directory is then canonicalized using lrealpath.  This
-   function always returns a newly-allocated string.  */
+   The chosen directory is then canonicalized using lrealpath.  */
 
-char *
+std::string
 relocate_gdb_directory (const char *initial, bool relocatable)
 {
-  char *dir;
-
-  dir = relocate_path (gdb_program_name, initial, relocatable);
-  if (dir)
+  std::string dir = relocate_path (gdb_program_name, initial, relocatable);
+  if (!dir.empty ())
     {
       struct stat s;
 
-      if (*dir == '\0' || stat (dir, &s) != 0 || !S_ISDIR (s.st_mode))
+      if (stat (dir.c_str (), &s) != 0 || !S_ISDIR (s.st_mode))
 	{
-	  xfree (dir);
-	  dir = NULL;
+	  dir.clear ();
 	}
     }
-  if (!dir)
-    dir = xstrdup (initial);
+  if (dir.empty ())
+    dir = initial;
 
   /* Canonicalize the directory.  */
-  if (*dir)
+  if (!dir.empty ())
     {
-      char *canon_sysroot = lrealpath (dir);
+      gdb::unique_xmalloc_ptr<char> canon_sysroot (lrealpath (dir.c_str ()));
 
       if (canon_sysroot)
-	{
-	  xfree (dir);
-	  dir = canon_sysroot;
-	}
+	dir = canon_sysroot.get ();
     }
 
   return dir;
@@ -220,14 +219,9 @@ relocate_gdbinit_path_maybe_in_datadir (const std::string& file)
     }
   else
     {
-      char *relocated = relocate_path (gdb_program_name,
-				       file.c_str (),
-				       SYSTEM_GDBINIT_RELOCATABLE);
-      if (relocated != nullptr)
-	{
-	  relocated_path = relocated;
-	  xfree (relocated);
-	}
+      relocated_path = relocate_path (gdb_program_name,
+				      file.c_str (),
+				      SYSTEM_GDBINIT_RELOCATABLE);
     }
     return relocated_path;
 }
@@ -541,20 +535,23 @@ captured_main_1 (struct captured_main_args *context)
     perror_warning_with_name (_("error finding working directory"));
 
   /* Set the sysroot path.  */
-  gdb_sysroot = relocate_gdb_directory (TARGET_SYSTEM_ROOT,
-					TARGET_SYSTEM_ROOT_RELOCATABLE);
+  gdb_sysroot
+    = xstrdup (relocate_gdb_directory (TARGET_SYSTEM_ROOT,
+				     TARGET_SYSTEM_ROOT_RELOCATABLE).c_str ());
 
-  if (gdb_sysroot == NULL || *gdb_sysroot == '\0')
+  if (*gdb_sysroot == '\0')
     {
       xfree (gdb_sysroot);
       gdb_sysroot = xstrdup (TARGET_SYSROOT_PREFIX);
     }
 
-  debug_file_directory = relocate_gdb_directory (DEBUGDIR,
-						 DEBUGDIR_RELOCATABLE);
+  debug_file_directory
+    = xstrdup (relocate_gdb_directory (DEBUGDIR,
+				     DEBUGDIR_RELOCATABLE).c_str ());
 
-  gdb_datadir = relocate_gdb_directory (GDB_DATADIR,
-					GDB_DATADIR_RELOCATABLE);
+  gdb_datadir
+    = xstrdup (relocate_gdb_directory (GDB_DATADIR,
+				     GDB_DATADIR_RELOCATABLE).c_str ());
 
 #ifdef WITH_PYTHON_PATH
   {
diff --git a/gdb/python/python.c b/gdb/python/python.c
index 9c49151..9c8c635 100644
--- a/gdb/python/python.c
+++ b/gdb/python/python.c
@@ -1608,7 +1608,7 @@ do_start_initialization ()
      /foo/lib/pythonX.Y/...
      This must be done before calling Py_Initialize.  */
   gdb::unique_xmalloc_ptr<char> progname
-    (concat (ldirname (python_libdir).c_str (), SLASH_STRING, "bin",
+    (concat (ldirname (python_libdir.c_str ()).c_str (), SLASH_STRING, "bin",
 	      SLASH_STRING, "python", (char *) NULL));
 #ifdef IS_PY3K
   std::string oldloc = setlocale (LC_ALL, NULL);
diff --git a/gdb/top.c b/gdb/top.c
index 9d4ce1f..2b53640 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -2038,7 +2038,7 @@ show_gdb_datadir (struct ui_file *file, int from_tty,
 		  struct cmd_list_element *c, const char *value)
 {
   fprintf_filtered (file, _("GDB's data directory is \"%s\".\n"),
-		    gdb_datadir);
+		    gdb_datadir.c_str ());
 }
 
 static void
diff --git a/gdb/xml-syscall.c b/gdb/xml-syscall.c
index d144f82..dc988df 100644
--- a/gdb/xml-syscall.c
+++ b/gdb/xml-syscall.c
@@ -316,7 +316,8 @@ static struct syscalls_info *
 xml_init_syscalls_info (const char *filename)
 {
   gdb::optional<gdb::char_vector> full_file
-    = xml_fetch_content_from_file (filename, gdb_datadir);
+    = xml_fetch_content_from_file (filename,
+				   const_cast<char *>(gdb_datadir.c_str ()));
   if (!full_file)
     return NULL;
 
@@ -336,7 +337,7 @@ init_syscalls_info (struct gdbarch *gdbarch)
   /* Should we re-read the XML info for this target?  */
   if (syscalls_info != NULL && !syscalls_info->my_gdb_datadir.empty ()
       && filename_cmp (syscalls_info->my_gdb_datadir.c_str (),
-		       gdb_datadir) != 0)
+		       gdb_datadir.c_str ()) != 0)
     {
       /* The data-directory changed from the last time we used it.
 	 It means that we have to re-read the XML info.  */
@@ -361,7 +362,7 @@ init_syscalls_info (struct gdbarch *gdbarch)
     {
       if (xml_syscall_file != NULL)
 	warning (_("Could not load the syscall XML file `%s/%s'."),
-		 gdb_datadir, xml_syscall_file);
+		 gdb_datadir.c_str (), xml_syscall_file);
       else
 	warning (_("There is no XML file to open."));