Re: [RFA 2/2] Remove some clanups from solib-svr4.c

[Tom Tromey <tom@tromey.com>]

>> -  newobj = XCNEW (struct so_list);
>> -  old_chain = make_cleanup (xfree, newobj);
>> -  lm_info_svr4 *li = lm_info_read (ldsomap);
>> -  newobj->lm_info = li;
>> -  make_cleanup (xfree, newobj->lm_info);
>> +  gdb::unique_xmalloc_ptr<lm_info_svr4> li (lm_info_read (ldsomap));

Simon> This is not an error because lm_info_svr4 is trivially destructible,
Simon> but since we allocate it with "new", we might as well use a
Simon> unique_ptr, it's more future-proof.

Good catch, thanks.

Simon> How about making lm_info_read return an std::unique_ptr<lm_info_svr4>?

Simon> The patch LGTM with or without those changes.

How's this?

I re-ran it through the buildbot.

Tom

commit 0662ad7b81c11c4b23e74c1d2fcf847ca63e3a8d
Author: Tom Tromey <tom@tromey.com>
Date:   Tue Mar 27 14:42:55 2018 -0600

    Remove some cleanups from solib-svr4.c
    
    This removes a few cleanups from solib-svr4.c in a straightforward
    way.
    
    gdb/ChangeLog
    2018-03-30  Tom Tromey  <tom@tromey.com>
    
            * solib-svr4.c (lm_info_read): Use gdb::byte_vector.  Return
            std::unique_ptr.
            (svr4_keep_data_in_core): Update.
            (svr4_read_so_list): Update.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index d2fe40d0a7..7add93ed63 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2018-03-30  Tom Tromey  <tom@tromey.com>
+
+	* solib-svr4.c (lm_info_read): Use gdb::byte_vector.  Return
+	std::unique_ptr.
+	(svr4_keep_data_in_core): Update.
+	(svr4_read_so_list): Update.
+
 2018-03-27  Tom Tromey  <tom@tromey.com>
 
 	* windows-nat.c (handle_output_debug_string, handle_exception):
diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index d8d047d394..7644c9f4a9 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -168,28 +168,24 @@ svr4_same (struct so_list *gdb, struct so_list *inferior)
   return (svr4_same_1 (gdb->so_original_name, inferior->so_original_name));
 }
 
-static lm_info_svr4 *
+static std::unique_ptr<lm_info_svr4>
 lm_info_read (CORE_ADDR lm_addr)
 {
   struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
-  gdb_byte *lm;
-  lm_info_svr4 *lm_info;
-  struct cleanup *back_to;
+  std::unique_ptr<lm_info_svr4> lm_info;
 
-  lm = (gdb_byte *) xmalloc (lmo->link_map_size);
-  back_to = make_cleanup (xfree, lm);
+  gdb::byte_vector lm (lmo->link_map_size);
 
-  if (target_read_memory (lm_addr, lm, lmo->link_map_size) != 0)
+  if (target_read_memory (lm_addr, lm.data (), lmo->link_map_size) != 0)
     {
       warning (_("Error reading shared library list entry at %s"),
-	       paddress (target_gdbarch (), lm_addr)),
-      lm_info = NULL;
+	       paddress (target_gdbarch (), lm_addr));
     }
   else
     {
       struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
 
-      lm_info = new lm_info_svr4;
+      lm_info.reset (new lm_info_svr4);
       lm_info->lm_addr = lm_addr;
 
       lm_info->l_addr_inferior = extract_typed_address (&lm[lmo->l_addr_offset],
@@ -203,8 +199,6 @@ lm_info_read (CORE_ADDR lm_addr)
 					       ptr_type);
     }
 
-  do_cleanups (back_to);
-
   return lm_info;
 }
 
@@ -958,8 +952,6 @@ svr4_keep_data_in_core (CORE_ADDR vaddr, unsigned long size)
 {
   struct svr4_info *info;
   CORE_ADDR ldsomap;
-  struct so_list *newobj;
-  struct cleanup *old_chain;
   CORE_ADDR name_lm;
 
   info = get_svr4_info ();
@@ -973,13 +965,8 @@ svr4_keep_data_in_core (CORE_ADDR vaddr, unsigned long size)
   if (!ldsomap)
     return 0;
 
-  newobj = XCNEW (struct so_list);
-  old_chain = make_cleanup (xfree, newobj);
-  lm_info_svr4 *li = lm_info_read (ldsomap);
-  newobj->lm_info = li;
-  make_cleanup (xfree, newobj->lm_info);
+  std::unique_ptr<lm_info_svr4> li (lm_info_read (ldsomap));
   name_lm = li != NULL ? li->l_name : 0;
-  do_cleanups (old_chain);
 
   return (name_lm >= vaddr && name_lm < vaddr + size);
 }
@@ -995,8 +982,7 @@ open_symbol_file_object (int from_tty)
   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);
-  gdb_byte *l_name_buf = (gdb_byte *) xmalloc (l_name_size);
-  struct cleanup *cleanups = make_cleanup (xfree, l_name_buf);
+  gdb::byte_vector l_name_buf (l_name_size);
   struct svr4_info *info = get_svr4_info ();
   symfile_add_flags add_flags = 0;
 
@@ -1005,38 +991,26 @@ open_symbol_file_object (int from_tty)
 
   if (symfile_objfile)
     if (!query (_("Attempt to reload symbols from process? ")))
-      {
-	do_cleanups (cleanups);
-	return 0;
-      }
+      return 0;
 
   /* Always locate the debug struct, in case it has moved.  */
   info->debug_base = 0;
   if (locate_base (info) == 0)
-    {
-      do_cleanups (cleanups);
-      return 0;	/* failed somehow...  */
-    }
+    return 0;	/* failed somehow...  */
 
   /* First link map member should be the executable.  */
   lm = solib_svr4_r_map (info);
   if (lm == 0)
-    {
-      do_cleanups (cleanups);
-      return 0;	/* failed somehow...  */
-    }
+    return 0;	/* failed somehow...  */
 
   /* Read address of name from target memory to GDB.  */
-  read_memory (lm + lmo->l_name_offset, l_name_buf, l_name_size);
+  read_memory (lm + lmo->l_name_offset, l_name_buf.data (), l_name_size);
 
   /* Convert the address to host format.  */
-  l_name = extract_typed_address (l_name_buf, ptr_type);
+  l_name = extract_typed_address (l_name_buf.data (), ptr_type);
 
   if (l_name == 0)
-    {
-      do_cleanups (cleanups);
-      return 0;		/* No filename.  */
-    }
+    return 0;		/* No filename.  */
 
   /* Now fetch the filename from target memory.  */
   target_read_string (l_name, &filename, SO_NAME_MAX_PATH_SIZE - 1, &errcode);
@@ -1045,14 +1019,12 @@ open_symbol_file_object (int from_tty)
     {
       warning (_("failed to read exec filename from attached file: %s"),
 	       safe_strerror (errcode));
-      do_cleanups (cleanups);
       return 0;
     }
 
   /* Have a pathname: read the symbol file.  */
   symbol_file_add_main (filename.get (), add_flags);
 
-  do_cleanups (cleanups);
   return 1;
 }
 
@@ -1342,7 +1314,7 @@ svr4_read_so_list (CORE_ADDR lm, CORE_ADDR prev_lm,
 
       so_list_up newobj (XCNEW (struct so_list));
 
-      lm_info_svr4 *li = lm_info_read (lm);
+      lm_info_svr4 *li = lm_info_read (lm).release ();
       newobj->lm_info = li;
       if (li == NULL)
 	return 0;