Change target_read_string API

This simplifies the target_read_string API a bit.

Note that some code was using safe_strerror on the error codes
returned by target_read_string.  It seems to me that this is incorrect
(if it was ever correct, it must have been quite a long time ago).

gdb/ChangeLog
2020-06-15  Tom Tromey  <tromey@adacore.com>

	* windows-nat.c (windows_nat::handle_output_debug_string):
	Update.
	(windows_nat::handle_ms_vc_exception): Update.
	* target.h (target_read_string): Change API.
	* target.c (target_read_string): Change API.
	* solib-svr4.c (open_symbol_file_object, svr4_read_so_list):
	Update.
	* solib-frv.c (frv_current_sos): Update.
	* solib-dsbt.c (dsbt_current_sos): Update.
	* solib-darwin.c (darwin_current_sos): Update.
	* linux-thread-db.c (inferior_has_bug): Update.
	* expprint.c (print_subexp_standard): Update.
	* ada-lang.c (ada_main_name, ada_tag_name_from_tsd)
	(ada_exception_message_1): Update.

1 files changed, 8 insertions, 14 deletions

diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index 19d1105..570450c 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -957,8 +957,6 @@ static int
 open_symbol_file_object (int from_tty)
 {
   CORE_ADDR lm, l_name;
-  gdb::unique_xmalloc_ptr<char> filename;
-  int errcode;
   struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
   struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
   int l_name_size = TYPE_LENGTH (ptr_type);
@@ -993,12 +991,12 @@ open_symbol_file_object (int from_tty)
     return 0;		/* No filename.  */
 
   /* Now fetch the filename from target memory.  */
-  target_read_string (l_name, &filename, SO_NAME_MAX_PATH_SIZE - 1, &errcode);
+  gdb::unique_xmalloc_ptr<char> filename
+    = target_read_string (l_name, SO_NAME_MAX_PATH_SIZE - 1);
 
-  if (errcode)
+  if (filename == nullptr)
     {
-      warning (_("failed to read exec filename from attached file: %s"),
-	       safe_strerror (errcode));
+      warning (_("failed to read exec filename from attached file"));
       return 0;
     }
 
@@ -1297,9 +1295,6 @@ svr4_read_so_list (svr4_info *info, CORE_ADDR lm, CORE_ADDR prev_lm,
 
   for (; lm != 0; prev_lm = lm, lm = next_lm)
     {
-      int errcode;
-      gdb::unique_xmalloc_ptr<char> buffer;
-
       so_list_up newobj (XCNEW (struct so_list));
 
       lm_info_svr4 *li = lm_info_read (lm).release ();
@@ -1330,17 +1325,16 @@ svr4_read_so_list (svr4_info *info, CORE_ADDR lm, CORE_ADDR prev_lm,
 	}
 
       /* Extract this shared object's name.  */
-      target_read_string (li->l_name, &buffer, SO_NAME_MAX_PATH_SIZE - 1,
-			  &errcode);
-      if (errcode != 0)
+      gdb::unique_xmalloc_ptr<char> buffer
+	= target_read_string (li->l_name, SO_NAME_MAX_PATH_SIZE - 1);
+      if (buffer == nullptr)
 	{
 	  /* If this entry's l_name address matches that of the
 	     inferior executable, then this is not a normal shared
 	     object, but (most likely) a vDSO.  In this case, silently
 	     skip it; otherwise emit a warning. */
 	  if (first_l_name == 0 || li->l_name != first_l_name)
-	    warning (_("Can't read pathname for load map: %s."),
-		     safe_strerror (errcode));
+	    warning (_("Can't read pathname for load map."));
 	  continue;
 	}