warn unused result for bfd IO functions

This patch fixes all the warnings I found in bfd, binutils and ld,
plus some bitrotted COFF_GO32 code that tried to allocate -168ul
bytes.  When the malloc fail was reported these testsuite fails
resulted:

i386-go32  +FAIL: go32 stub
i386-go32  +ERROR: tcl error sourcing /home/alan/src/binutils-gdb/ld/testsuite/ld-i386/i386.exp.
i386-go32  +ERROR: couldn't open "tmpdir/go32stub": no such file or directory
i386-go32  +FAIL: ld-scripts/sane1
i386-go32  +FAIL: ld-scripts/assign-loc
i386-go32  +FAIL: ld-scripts/pr18963

This does result in some warnings in gdb which are fixed in a followup
patch.

bfd/
	* bfdio.c (bfd_read, bfd_write): Add ATTRIBUTE_WARN_UNUSED_RESULT.
	(bfd_tell, bfd_stat, bfd_seek, bfd_mmap): Likewise.
	* bfd-in2.h: Regenerate.
	* coff-rs6000.c (xcoff_write_armap_big) Don't ignore bfd_write
	return value.
	(xcoff_generate_rtinit): Likewise.  Also free data_buffer and
	string_table before returning.
	* coff64-rs6000.c (xcoff64_generate_rtinit): Likewise.
	* coff-stgo32.c (go32exe_check_format): Don't ignore bfd_seek
	return value.
	* coffcode.h (coff_apply_checksum): Don't ignore bfd_write return.
	(coff_write_object_contents <COFF_GO32>): Likewise, and bfd_malloc.
	Fix bitrotted code to look for first section with non-zero filepos.
	* elf64-ia64-vms.c (elf64_vms_write_shdrs_and_ehdr): Don't ignore
	bfd_seek or bfd_write return values.
	* pef.c (bfd_pef_scan_section): Likewise.
	(bfd_pef_read_header, bfd_pef_xlib_read_header): Likewise.
	* vms-misc.c (_bfd_vms_output_end): Likewise.  Return status.
	* vms.h (_bfd_vms_output_end): Update prototype.
	* vms-alpha.c: Pass _bfd_vms_output_end status up call chains.
	* wasm-module.c (wasm_compute_custom_section_file_position): Don't
	ignore bfd_seek or bfd_write return values.
	(wasm_compute_section_file_positions): Likewise.
	* xsym.c (bfd_sym_scan): Don't ignore bfd_seek return value.
	(bfd_sym_read_name_table): Likewise.
binutils/
	* ar.c (print_contents, extract_file): Don't ignore bfd_seek
	return value.
ld/
	* pdb.c (create_section_contrib_substream): Don't ignore bfd_seek
	return value.
	(create_section_header_stream): Likewise.
	* pe-dll.c (pe_get16, pe_get32): Add fail param to return results
	from bfd_seek and bfd_read.
	(pe_implied_import_dll): Handle these fails, and other bfd_seek
	and bfd_read return values.

1 files changed, 23 insertions, 12 deletions

diff --git a/bfd/coffcode.h b/bfd/coffcode.h
index 99d9a56..6789f7f 100644
--- a/bfd/coffcode.h
+++ b/bfd/coffcode.h
@@ -3411,7 +3411,8 @@ coff_apply_checksum (bfd *abfd)
     return false;
 
   checksum = 0;
-  bfd_write (&checksum, 4, abfd);
+  if (bfd_write (&checksum, 4, abfd) != 4)
+    return false;
 
   if (bfd_seek (abfd, peheader, SEEK_SET) != 0)
     return false;
@@ -3423,9 +3424,7 @@ coff_apply_checksum (bfd *abfd)
   if (bfd_seek (abfd, peheader + 0x58, SEEK_SET) != 0)
     return false;
 
-  bfd_write (&checksum, 4, abfd);
-
-  return true;
+  return bfd_write (&checksum, 4, abfd) == 4;
 }
 
 #endif /* COFF_IMAGE_WITH_PE */
@@ -3885,16 +3884,28 @@ coff_write_object_contents (bfd * abfd)
 
 #if defined (COFF_GO32_EXE) || defined (COFF_GO32)
   /* Pad section headers.  */
-  if ((abfd->flags & EXEC_P) && abfd->sections != NULL)
+  if ((abfd->flags & EXEC_P) != 0)
     {
-      file_ptr cur_ptr = scn_base
-			 + abfd->section_count * bfd_coff_scnhsz (abfd);
-      long fill_size = (abfd->sections->filepos - cur_ptr);
-      bfd_byte *b = bfd_zmalloc (fill_size);
-      if (b)
+      asection *s = abfd->sections;
+      while (s != NULL && s->filepos == 0)
+	s = s->next;
+      if (s != NULL)
 	{
-	  bfd_write (b, fill_size, abfd);
-	  free (b);
+	  file_ptr cur_ptr
+	    = scn_base + abfd->section_count * bfd_coff_scnhsz (abfd);
+	  file_ptr fill_size = s->filepos - cur_ptr;
+	  if (fill_size > 0)
+	    {
+	      bfd_byte *b = bfd_zmalloc (fill_size);
+	      if (!b)
+		return false;
+	      if (bfd_write (b, fill_size, abfd) != (ufile_ptr) fill_size)
+		{
+		  free (b);
+		  return false;
+		}
+	      free (b);
+	    }
 	}
     }
 #endif