Return unique_xmalloc_ptr from target_read_stralloc

This changes target_read_stralloc to return a unique_xmalloc_ptr, and
then fixes all the callers.  unique_xmalloc_ptr is used, rather than
std::string, because target_read_stralloc gives a special meaning to a
NULL return.

ChangeLog
2017-10-16  Tom Tromey  <tom@tromey.com>

	* xml-syscall.c (xml_init_syscalls_info): Update.
	* xml-support.c (xinclude_start_include): Update.
	(xml_fetch_content_from_file): Return unique_xmalloc_ptr.
	* xml-support.h (xml_fetch_another): Return unique_xmalloc_ptr.
	(xml_fetch_content_from_file): Likewise.
	* osdata.c (get_osdata): Update.
	* target.h (target_read_stralloc, target_get_osdata): Return
	unique_xmalloc_ptr.
	* solib-aix.c (solib_aix_get_library_list): Update.
	* solib-target.c (solib_target_current_sos): Update.
	* solib-svr4.c (svr4_current_sos_via_xfer_libraries): Update.
	* xml-tdesc.c (fetch_available_features_from_target): Update.
	(target_fetch_description_xml): Update.
	(file_read_description_xml): Update.
	* remote.c (remote_get_threads_with_qxfer, remote_memory_map)
	(remote_traceframe_info, btrace_read_config, remote_read_btrace)
	(remote_pid_to_exec_file): Update.
	* target.c (target_read_stralloc): Return unique_xmalloc_ptr.
	(target_get_osdata): Likewise.

1 files changed, 7 insertions, 9 deletions

diff --git a/gdb/target.c b/gdb/target.c
index 4a7589d..94307cb 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -1924,13 +1924,9 @@ target_read_alloc (struct target_ops *ops, enum target_object object,
   return target_read_alloc_1 (ops, object, annex, buf_p, 0);
 }
 
-/* Read OBJECT/ANNEX using OPS.  The result is NUL-terminated and
-   returned as a string, allocated using xmalloc.  If an error occurs
-   or the transfer is unsupported, NULL is returned.  Empty objects
-   are returned as allocated but empty strings.  A warning is issued
-   if the result contains any embedded NUL bytes.  */
+/* See target.h.  */
 
-char *
+gdb::unique_xmalloc_ptr<char>
 target_read_stralloc (struct target_ops *ops, enum target_object object,
 		      const char *annex)
 {
@@ -1945,7 +1941,7 @@ target_read_stralloc (struct target_ops *ops, enum target_object object,
     return NULL;
 
   if (transferred == 0)
-    return xstrdup ("");
+    return gdb::unique_xmalloc_ptr<char> (xstrdup (""));
 
   bufstr[transferred] = 0;
 
@@ -1959,7 +1955,7 @@ target_read_stralloc (struct target_ops *ops, enum target_object object,
 	break;
       }
 
-  return bufstr;
+  return gdb::unique_xmalloc_ptr<char> (bufstr);
 }
 
 /* Memory transfer methods.  */
@@ -2654,7 +2650,9 @@ target_supports_multi_process (void)
   return (*current_target.to_supports_multi_process) (&current_target);
 }
 
-char *
+/* See target.h.  */
+
+gdb::unique_xmalloc_ptr<char>
 target_get_osdata (const char *type)
 {
   struct target_ops *t;