Make target_read_alloc & al return vectors

This patch started by changing target_read_alloc_1 to return a
byte_vector, to avoid manual memory management (in target_read_alloc_1
and in the callers).  To communicate failures to the callers, it
actually returns a gdb::optional<gdb::byte_vector>.

Adjusting target_read_stralloc was a bit more tricky, since it wants to
return a buffer of char, and not gdb_byte.  Since you can't just cast a
gdb::byte_vector into a gdb::def_vector<char>, I made
target_read_alloc_1 templated, so both versions (that return vectors of
gdb_byte and char) are generated.  Since target_read_stralloc now
returns a gdb::char_vector instead of a gdb::unique_xmalloc_ptr<char>, a
few callers need to be adjusted.

gdb/ChangeLog:

	* common/byte-vector.h (char_vector): New type.
	* target.h (target_read_alloc): Return
	gdb::optional<byte_vector>.
	(target_read_stralloc): Return gdb::optional<char_vector>.
	(target_get_osdata): Return gdb::optional<char_vector>.
	* target.c (target_read_alloc_1): Templatize.  Replacement
	manual memory management with vector.
	(target_read_alloc): Change return type, adjust.
	(target_read_stralloc): Change return type, adjust.
	(target_get_osdata): Change return type, adjust.
	* auxv.c (struct auxv_info) <length>: Remove.
	<data>: Change type to gdb::optional<byte_vector>.
	(auxv_inferior_data_cleanup): Free auxv_info with delete.
	(get_auxv_inferior_data): Allocate auxv_info with new, adjust.
	(target_auxv_search): Adjust.
	(fprint_target_auxv): Adjust.
	* avr-tdep.c (avr_io_reg_read_command): Adjust.
	* linux-tdep.c (linux_spu_make_corefile_notes): Adjust.
	(linux_make_corefile_notes): Adjust.
	* osdata.c (get_osdata): Adjust.
	* remote.c (remote_get_threads_with_qxfer): Adjust.
	(remote_memory_map): Adjust.
	(remote_traceframe_info): Adjust.
	(btrace_read_config): Adjust.
	(remote_read_btrace): Adjust.
	(remote_pid_to_exec_file): Adjust.
	* solib-aix.c (solib_aix_get_library_list): Adjust.
	* solib-dsbt.c (decode_loadmap): Don't free buf.
	(dsbt_get_initial_loadmaps): Adjust.
	* solib-svr4.c (svr4_current_sos_via_xfer_libraries): Adjust.
	* solib-target.c (solib_target_current_sos): Adjust.
	* tracepoint.c (sdata_make_value): Adjust.
	* xml-support.c (xinclude_start_include): Adjust.
	(xml_fetch_content_from_file): Adjust.
	* xml-support.h (xml_fetch_another): Change return type.
	(xml_fetch_content_from_file): Change return type.
	* xml-syscall.c (xml_init_syscalls_info): Adjust.
	* xml-tdesc.c (file_read_description_xml): Adjust.
	(fetch_available_features_from_target): Change return type.
	(target_fetch_description_xml): Adjust.
	(target_read_description_xml): Adjust.

1 files changed, 15 insertions, 22 deletions

diff --git a/gdb/target.h b/gdb/target.h
index 51ac884..b97f142 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -324,29 +324,26 @@ LONGEST target_write_with_progress (struct target_ops *ops,
 				    void (*progress) (ULONGEST, void *),
 				    void *baton);
 
-/* Wrapper to perform a full read of unknown size.  OBJECT/ANNEX will
-   be read using OPS.  The return value will be -1 if the transfer
-   fails or is not supported; 0 if the object is empty; or the length
-   of the object otherwise.  If a positive value is returned, a
-   sufficiently large buffer will be allocated using xmalloc and
-   returned in *BUF_P containing the contents of the object.
+/* Wrapper to perform a full read of unknown size.  OBJECT/ANNEX will be read
+   using OPS.  The return value will be uninstantiated if the transfer fails or
+   is not supported.
 
    This method should be used for objects sufficiently small to store
    in a single xmalloc'd buffer, when no fixed bound on the object's
    size is known in advance.  Don't try to read TARGET_OBJECT_MEMORY
    through this function.  */
 
-extern LONGEST target_read_alloc (struct target_ops *ops,
-				  enum target_object object,
-				  const char *annex, gdb_byte **buf_p);
+extern gdb::optional<gdb::byte_vector> target_read_alloc
+    (struct target_ops *ops, enum target_object object, const char *annex);
 
-/* Read OBJECT/ANNEX using OPS.  The result is NUL-terminated and
-   returned as a string.  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.  */
+/* Read OBJECT/ANNEX using OPS.  The result is a NUL-terminated character vector
+   (therefore usable as a NUL-terminated string).  If an error occurs or the
+   transfer is unsupported, the return value will be uninstantiated.  Empty
+   objects are returned as allocated but empty strings.  Therefore, on success,
+   the returned vector is guaranteed to have at least one element.  A warning is
+   issued if the result contains any embedded NUL bytes.  */
 
-extern gdb::unique_xmalloc_ptr<char> target_read_stralloc
+extern gdb::optional<gdb::char_vector> target_read_stralloc
     (struct target_ops *ops, enum target_object object, const char *annex);
 
 /* See target_ops->to_xfer_partial.  */
@@ -2384,15 +2381,11 @@ extern struct target_ops *find_target_beneath (struct target_ops *);
 
 struct target_ops *find_target_at (enum strata stratum);
 
-/* Read OS data object of type TYPE from the target, and return it in
-   XML format.  The result is NUL-terminated and returned as a string.
-   If an error occurs or the transfer is unsupported, NULL is
-   returned.  Empty objects are returned as allocated but empty
-   strings.  */
+/* Read OS data object of type TYPE from the target, and return it in XML
+   format.  The return value follows the same rules as target_read_stralloc.  */
 
-extern gdb::unique_xmalloc_ptr<char> target_get_osdata (const char *type);
+extern gdb::optional<gdb::char_vector> target_get_osdata (const char *type);
 
-
 /* Stuff that should be shared among the various remote targets.  */
 
 /* Debugging level.  0 is off, and non-zero values mean to print some debug