[RFA] Use gdb::byte_vector when reading section data

[Tom Tromey]

This changes a couple of spots that read section data to use
gdb::byte_vector rather than a cleanup.

Regression tested by the buildbot.  I am not certain that the buildbot
actually tests the code in question, so I recommend careful review.

gdb/ChangeLog
2018-03-09  Tom Tromey  <tom@tromey.com>

	* rs6000-aix-tdep.c (rs6000_aix_core_xfer_shared_libraries_aix):
	Use gdb::byte_vector.
	* arm-tdep.c (arm_exidx_new_objfile): Use gdb::byte_vector.
---
 gdb/ChangeLog         |  6 ++++++
 gdb/arm-tdep.c        | 39 +++++++++++++++------------------------
 gdb/rs6000-aix-tdep.c | 15 ++++-----------
 3 files changed, 25 insertions(+), 35 deletions(-)

diff --git a/gdb/arm-tdep.c b/gdb/arm-tdep.c
index ef7e66b36a..52d3f41cee 100644
--- a/gdb/arm-tdep.c
+++ b/gdb/arm-tdep.c
@@ -2040,50 +2040,41 @@ arm_obj_section_from_vma (struct objfile *objfile, bfd_vma vma)
 static void
 arm_exidx_new_objfile (struct objfile *objfile)
 {
-  struct cleanup *cleanups;
   struct arm_exidx_data *data;
   asection *exidx, *extab;
   bfd_vma exidx_vma = 0, extab_vma = 0;
   bfd_size_type exidx_size = 0, extab_size = 0;
-  gdb_byte *exidx_data = NULL, *extab_data = NULL;
   LONGEST i;
 
   /* If we've already touched this file, do nothing.  */
   if (!objfile || objfile_data (objfile, arm_exidx_data_key) != NULL)
     return;
-  cleanups = make_cleanup (null_cleanup, NULL);
 
   /* Read contents of exception table and index.  */
   exidx = bfd_get_section_by_name (objfile->obfd, ELF_STRING_ARM_unwind);
+  gdb::byte_vector exidx_data;
   if (exidx)
     {
       exidx_vma = bfd_section_vma (objfile->obfd, exidx);
       exidx_size = bfd_get_section_size (exidx);
-      exidx_data = (gdb_byte *) xmalloc (exidx_size);
-      make_cleanup (xfree, exidx_data);
+      exidx_data.resize (exidx_size);
 
       if (!bfd_get_section_contents (objfile->obfd, exidx,
-				     exidx_data, 0, exidx_size))
-	{
-	  do_cleanups (cleanups);
-	  return;
-	}
+				     exidx_data.data (), 0, exidx_size))
+	return;
     }
 
   extab = bfd_get_section_by_name (objfile->obfd, ".ARM.extab");
+  gdb::byte_vector extab_data;
   if (extab)
     {
       extab_vma = bfd_section_vma (objfile->obfd, extab);
       extab_size = bfd_get_section_size (extab);
-      extab_data = (gdb_byte *) xmalloc (extab_size);
-      make_cleanup (xfree, extab_data);
+      extab_data.resize (extab_size);
 
       if (!bfd_get_section_contents (objfile->obfd, extab,
-				     extab_data, 0, extab_size))
-	{
-	  do_cleanups (cleanups);
-	  return;
-	}
+				     extab_data.data (), 0, extab_size))
+	return;
     }
 
   /* Allocate exception table data structure.  */
@@ -2097,8 +2088,9 @@ arm_exidx_new_objfile (struct objfile *objfile)
   for (i = 0; i < exidx_size / 8; i++)
     {
       struct arm_exidx_entry new_exidx_entry;
-      bfd_vma idx = bfd_h_get_32 (objfile->obfd, exidx_data + i * 8);
-      bfd_vma val = bfd_h_get_32 (objfile->obfd, exidx_data + i * 8 + 4);
+      bfd_vma idx = bfd_h_get_32 (objfile->obfd, exidx_data.data () + i * 8);
+      bfd_vma val = bfd_h_get_32 (objfile->obfd,
+				  exidx_data.data () + i * 8 + 4);
       bfd_vma addr = 0, word = 0;
       int n_bytes = 0, n_words = 0;
       struct obj_section *sec;
@@ -2135,7 +2127,7 @@ arm_exidx_new_objfile (struct objfile *objfile)
 	  if (addr >= extab_vma && addr + 4 <= extab_vma + extab_size)
 	    {
 	      word = bfd_h_get_32 (objfile->obfd,
-				   extab_data + addr - extab_vma);
+				   extab_data.data () + addr - extab_vma);
 	      addr += 4;
 
 	      if ((word & 0xff000000) == 0x80000000)
@@ -2193,7 +2185,8 @@ arm_exidx_new_objfile (struct objfile *objfile)
 		      && addr + 4 <= extab_vma + extab_size)
 		    {
 		      word = bfd_h_get_32 (objfile->obfd,
-					   extab_data + addr - extab_vma);
+					   (extab_data.data ()
+					    + addr - extab_vma));
 		      addr += 4;
 		      n_bytes = 3;
 		      n_words = ((word >> 24) & 0xff);
@@ -2222,7 +2215,7 @@ arm_exidx_new_objfile (struct objfile *objfile)
 	  while (n_words--)
 	    {
 	      word = bfd_h_get_32 (objfile->obfd,
-				   extab_data + addr - extab_vma);
+				   extab_data.data () + addr - extab_vma);
 	      addr += 4;
 
 	      *p++ = (gdb_byte) ((word >> 24) & 0xff);
@@ -2243,8 +2236,6 @@ arm_exidx_new_objfile (struct objfile *objfile)
 		     data->section_maps[sec->the_bfd_section->index],
 		     &new_exidx_entry);
     }
-
-  do_cleanups (cleanups);
 }
 
 /* Search for the exception table entry covering MEMADDR.  If one is found,
diff --git a/gdb/rs6000-aix-tdep.c b/gdb/rs6000-aix-tdep.c
index 38c86d4cd8..e3e086c210 100644
--- a/gdb/rs6000-aix-tdep.c
+++ b/gdb/rs6000-aix-tdep.c
@@ -1007,9 +1007,6 @@ rs6000_aix_core_xfer_shared_libraries_aix (struct gdbarch *gdbarch,
 {
   struct bfd_section *ldinfo_sec;
   int ldinfo_size;
-  gdb_byte *ldinfo_buf;
-  struct cleanup *cleanup;
-  LONGEST result;
 
   ldinfo_sec = bfd_get_section_by_name (core_bfd, ".ldinfo");
   if (ldinfo_sec == NULL)
@@ -1017,19 +1014,15 @@ rs6000_aix_core_xfer_shared_libraries_aix (struct gdbarch *gdbarch,
 	   bfd_errmsg (bfd_get_error ()));
   ldinfo_size = bfd_get_section_size (ldinfo_sec);
 
-  ldinfo_buf = (gdb_byte *) xmalloc (ldinfo_size);
-  cleanup = make_cleanup (xfree, ldinfo_buf);
+  gdb::byte_vector ldinfo_buf (ldinfo_size);
 
   if (! bfd_get_section_contents (core_bfd, ldinfo_sec,
-				  ldinfo_buf, 0, ldinfo_size))
+				  ldinfo_buf.data (), 0, ldinfo_size))
     error (_("unable to read .ldinfo section from core file: %s"),
 	  bfd_errmsg (bfd_get_error ()));
 
-  result = rs6000_aix_ld_info_to_xml (gdbarch, ldinfo_buf, readbuf,
-				      offset, len, 0);
-
-  do_cleanups (cleanup);
-  return result;
+  return rs6000_aix_ld_info_to_xml (gdbarch, ldinfo_buf.data (), readbuf,
+				    offset, len, 0);
 }
 
 static void
-- 
2.13.6