gdb: allocate symfile_segment_data with new

- Allocate this structure with new instead of XNEW, use a unique pointer
  to manage its lifetime.
- Change a few functions to return a unique   pointer instead of a
  plain pointer.
- Change free_symfile_segment_data to be symfile_segment_data's
  destructor.

gdb/ChangeLog:

	* symfile.h (struct symfile_segment_data): Initialize fields.
	<~symfile_segment_data>: Add.
	(symfile_segment_data_up): New.
	(struct sym_fns) <sym_segments>: Return a
	symfile_segment_data_up.
	(default_symfile_segments): Return a symfile_segment_data_up.
	(free_symfile_segment_data): Remove.
	(get_symfile_segment_data): Return a symfile_segment_data_up.
	* symfile.c (default_symfile_segments): Likewise.
	(get_symfile_segment_data): Likewise.
	(free_symfile_segment_data): Remove.
	(symfile_find_segment_sections): Update.
	* elfread.c (elf_symfile_segments): Return a
	symfile_segment_data_up.
	* remote.c (remote_target::get_offsets): Update.
	* solib-target.c (solib_target_relocate_section_addresses):
	Update.
	* symfile-debug.c (debug_sym_segments): Return a
	symfile_segment_data_up.

gdb/ChangeLog

@@ -1,3 +1,25 @@
+2020-05-19  Simon Marchi  <simon.marchi@efficios.com>
+
+	* symfile.h (struct symfile_segment_data): Initialize fields.
+	<~symfile_segment_data>: Add.
+	(symfile_segment_data_up): New.
+	(struct sym_fns) <sym_segments>: Return a
+	symfile_segment_data_up.
+	(default_symfile_segments): Return a symfile_segment_data_up.
+	(free_symfile_segment_data): Remove.
+	(get_symfile_segment_data): Return a symfile_segment_data_up.
+	* symfile.c (default_symfile_segments): Likewise.
+	(get_symfile_segment_data): Likewise.
+	(free_symfile_segment_data): Remove.
+	(symfile_find_segment_sections): Update.
+	* elfread.c (elf_symfile_segments): Return a
+	symfile_segment_data_up.
+	* remote.c (remote_target::get_offsets): Update.
+	* solib-target.c (solib_target_relocate_section_addresses):
+	Update.
+	* symfile-debug.c (debug_sym_segments): Return a
+	symfile_segment_data_up.
+
 2020-05-18  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	PR build/25981

gdb/elfread.c

@@ -85,14 +85,13 @@ static const struct bfd_key<elfread_data> probe_key;
 
 /* Locate the segments in ABFD.  */
 
-static struct symfile_segment_data *
+static symfile_segment_data_up
 elf_symfile_segments (bfd *abfd)
 {
   Elf_Internal_Phdr *phdrs, **segments;
   long phdrs_size;
   int num_phdrs, num_segments, num_sections, i;
   asection *sect;
-  struct symfile_segment_data *data;
 
   phdrs_size = bfd_get_elf_phdr_upper_bound (abfd);
   if (phdrs_size == -1)
@@ -112,7 +111,7 @@ elf_symfile_segments (bfd *abfd)
   if (num_segments == 0)
     return NULL;
 
-  data = XCNEW (struct symfile_segment_data);
+  symfile_segment_data_up data (new symfile_segment_data);
   data->num_segments = num_segments;
   data->segment_bases = XCNEWVEC (CORE_ADDR, num_segments);
   data->segment_sizes = XCNEWVEC (CORE_ADDR, num_segments);

gdb/remote.c

@@ -4105,7 +4105,6 @@ remote_target::get_offsets ()
   char *ptr;
   int lose, num_segments = 0, do_sections, do_segments;
   CORE_ADDR text_addr, data_addr, bss_addr, segments[2];
-  struct symfile_segment_data *data;
 
   if (symfile_objfile == NULL)
     return;
@@ -4185,7 +4184,8 @@ remote_target::get_offsets ()
 
   section_offsets offs = symfile_objfile->section_offsets;
 
-  data = get_symfile_segment_data (symfile_objfile->obfd);
+  symfile_segment_data_up data
+    = get_symfile_segment_data (symfile_objfile->obfd);
   do_segments = (data != NULL);
   do_sections = num_segments == 0;
 
@@ -4220,8 +4220,9 @@ remote_target::get_offsets ()
 
   if (do_segments)
     {
-      int ret = symfile_map_offsets_to_segments (symfile_objfile->obfd, data,
+      int ret = symfile_map_offsets_to_segments (symfile_objfile->obfd,
-						 offs, num_segments, segments);
+						 data.get (), offs,
+						 num_segments, segments);
 
       if (ret == 0 && !do_sections)
 	error (_("Can not handle qOffsets TextSeg "
@@ -4231,9 +4232,6 @@ remote_target::get_offsets ()
 	do_sections = 0;
     }
 
-  if (data)
-    free_symfile_segment_data (data);
-
   if (do_sections)
     {
       offs[SECT_OFF_TEXT (symfile_objfile)] = text_addr;

gdb/solib-target.c

@@ -364,9 +364,9 @@ Could not relocate shared library \"%s\": wrong number of ALLOC sections"),
 	}
       else if (!li->segment_bases.empty ())
 	{
-	  struct symfile_segment_data *data;
+	  symfile_segment_data_up data
+	    = get_symfile_segment_data (so->abfd);
 
-	  data = get_symfile_segment_data (so->abfd);
 	  if (data == NULL)
 	    warning (_("\
 Could not relocate shared library \"%s\": no segments"), so->so_name);
@@ -375,7 +375,7 @@ Could not relocate shared library \"%s\": no segments"), so->so_name);
 	      ULONGEST orig_delta;
 	      int i;
 
-	      if (!symfile_map_offsets_to_segments (so->abfd, data,
+	      if (!symfile_map_offsets_to_segments (so->abfd, data.get (),
 						    li->offsets,
 						    li->segment_bases.size (),
 						    li->segment_bases.data ()))
@@ -407,8 +407,6 @@ Could not relocate shared library \"%s\": bad offsets"), so->so_name);
 			       + data->segment_sizes[i - 1]
 			       + orig_delta);
 	      gdb_assert (so->addr_low <= so->addr_high);
-
-	      free_symfile_segment_data (data);
 	    }
 	}
     }

gdb/symfile-debug.c

@@ -475,7 +475,7 @@ debug_sym_offsets (struct objfile *objfile,
   debug_data->real_sf->sym_offsets (objfile, info);
 }
 
-static struct symfile_segment_data *
+static symfile_segment_data_up
 debug_sym_segments (bfd *abfd)
 {
   /* This API function is annoying, it doesn't take a "this" pointer.

gdb/symfile.c

@@ -717,12 +717,11 @@ default_symfile_offsets (struct objfile *objfile,
    It assumes that object files do not have segments, and fully linked
    files have a single segment.  */
 
-struct symfile_segment_data *
+symfile_segment_data_up
 default_symfile_segments (bfd *abfd)
 {
   int num_sections, i;
   asection *sect;
-  struct symfile_segment_data *data;
   CORE_ADDR low, high;
 
   /* Relocatable files contain enough information to position each
@@ -745,7 +744,7 @@ default_symfile_segments (bfd *abfd)
   low = bfd_section_vma (sect);
   high = low + bfd_section_size (sect);
 
-  data = XCNEW (struct symfile_segment_data);
+  symfile_segment_data_up data (new symfile_segment_data);
   data->num_segments = 1;
   data->segment_bases = XCNEW (CORE_ADDR);
   data->segment_sizes = XCNEW (CORE_ADDR);
@@ -3621,7 +3620,7 @@ symfile_relocate_debug_section (struct objfile *objfile,
   return (*objfile->sf->sym_relocate) (objfile, sectp, buf);
 }
 
-struct symfile_segment_data *
+symfile_segment_data_up
 get_symfile_segment_data (bfd *abfd)
 {
   const struct sym_fns *sf = find_sym_fns (abfd);
@@ -3632,15 +3631,6 @@ get_symfile_segment_data (bfd *abfd)
   return sf->sym_segments (abfd);
 }
 
-void
-free_symfile_segment_data (struct symfile_segment_data *data)
-{
-  xfree (data->segment_bases);
-  xfree (data->segment_sizes);
-  xfree (data->segment_info);
-  xfree (data);
-}
-
 /* Given:
    - DATA, containing segment addresses from the object file ABFD, and
      the mapping from ABFD's sections onto the segments that own them,
@@ -3703,17 +3693,14 @@ symfile_find_segment_sections (struct objfile *objfile)
   bfd *abfd = objfile->obfd;
   int i;
   asection *sect;
-  struct symfile_segment_data *data;
 
-  data = get_symfile_segment_data (objfile->obfd);
+  symfile_segment_data_up data
+    = get_symfile_segment_data (objfile->obfd);
   if (data == NULL)
     return;
 
   if (data->num_segments != 1 && data->num_segments != 2)
-    {
-      free_symfile_segment_data (data);
     return;
-    }
 
   for (i = 0, sect = abfd->sections; sect != NULL; i++, sect = sect->next)
     {
@@ -3736,8 +3723,6 @@ symfile_find_segment_sections (struct objfile *objfile)
 	    objfile->sect_index_bss = sect->index;
 	}
     }
-
-  free_symfile_segment_data (data);
 }
 
 /* Listen for free_objfile events.  */

gdb/symfile.h

@@ -80,26 +80,35 @@ typedef std::vector<other_sections> section_addr_info;
    each BFD section belongs to.  */
 struct symfile_segment_data
 {
+  ~symfile_segment_data ()
+  {
+    xfree (this->segment_bases);
+    xfree (this->segment_sizes);
+    xfree (this->segment_info);
+  }
+
   /* How many segments are present in this file.  If there are
      two, the text segment is the first one and the data segment
      is the second one.  */
-  int num_segments;
+  int num_segments = 0;
 
   /* If NUM_SEGMENTS is greater than zero, the original base address
      of each segment.  */
-  CORE_ADDR *segment_bases;
+  CORE_ADDR *segment_bases = nullptr;
 
   /* If NUM_SEGMENTS is greater than zero, the memory size of each
      segment.  */
-  CORE_ADDR *segment_sizes;
+  CORE_ADDR *segment_sizes = nullptr;
 
   /* If NUM_SEGMENTS is greater than zero, this is an array of entries
      recording which segment contains each BFD section.
      SEGMENT_INFO[I] is S+1 if the I'th BFD section belongs to segment
      S, or zero if it is not in any segment.  */
-  int *segment_info;
+  int *segment_info = nullptr;
 };
 
+using symfile_segment_data_up = std::unique_ptr<symfile_segment_data>;
+
 /* Callback for quick_symbol_functions->map_symbol_filenames.  */
 
 typedef void (symbol_filename_ftype) (const char *filename,
@@ -360,7 +369,7 @@ struct sym_fns
      the segments of ABFD.  Each segment is a unit of the file
      which may be relocated independently.  */
 
-  struct symfile_segment_data *(*sym_segments) (bfd *abfd);
+  symfile_segment_data_up (*sym_segments) (bfd *abfd);
 
   /* This function should read the linetable from the objfile when
      the line table cannot be read while processing the debugging
@@ -401,7 +410,7 @@ extern void default_symfile_offsets (struct objfile *objfile,
 /* The default version of sym_fns.sym_segments for readers that don't
    do anything special.  */
 
-extern struct symfile_segment_data *default_symfile_segments (bfd *abfd);
+extern symfile_segment_data_up default_symfile_segments (bfd *abfd);
 
 /* The default version of sym_fns.sym_relocate for readers that don't
    do anything special.  */
@@ -530,8 +539,7 @@ extern int symfile_map_offsets_to_segments (bfd *,
 					    const struct symfile_segment_data *,
 					    section_offsets &,
 					    int, const CORE_ADDR *);
-struct symfile_segment_data *get_symfile_segment_data (bfd *abfd);
+symfile_segment_data_up get_symfile_segment_data (bfd *abfd);
-void free_symfile_segment_data (struct symfile_segment_data *data);
 
 extern scoped_restore_tmpl<int> increment_reading_symtab (void);