[committed] Handle .bss at same offset as .debug_pubnames

[committed] Handle .bss at same offset as .debug_pubnames

[Tom de Vries]

Hi,

when running make CC=clang check on ubuntu 18.04, we get:
...
$ make CC=clang check
  ...
dwz: Allocatable section in 1.debug after non-allocatable ones
FAIL: /home/vries/dwz/dwz.git/testsuite/dwz.tests/eu-strip-unstrip.sh
...

The trigger is that the 1.debug file (generated using eu-strip -f) contains
a .bss section with the same offset as the .debug_pubnames section.
...
  [Nr] Name              Type             Address           Offset
       Size              EntSize          Flags  Link  Info  Align
  ...
  [23] .bss              NOBITS           0000000000601030  00000260
       0000000000000008  0000000000000000  WA       0     0     1
  [24] .comment          NOBITS           0000000000000000  00000260
       0000000000000061  0000000000000001  MS       0     0     1
  [25] .debug_pubnames   PROGBITS         0000000000000000  00000260
       000000000000001b  0000000000000000           0     0     1
...

The problem is here in write_dso:
...
              else if (!last_shoff
                       && (dso->shdr[j].sh_offset < min_shoff
                           || (dso->shdr[j].sh_offset == min_shoff
                               && dso->shdr[j].sh_size == 0)))
                continue;
              else if ((dso->shdr[j].sh_flags & SHF_ALLOC) != 0)
                {
                  error (0, 0, "Allocatable section in %s after "
                         "non-allocatable ones", dso->filename);
                  return 1;
                }
...
For the .bss section, "dso->shdr[j].sh_offset == min_shoff" holds, but
"dso->shdr[j].sh_size == 0" doesn't hold, so it won't get skipped.

Fix this by testing for sh_type == SHT_NOBITS in addition to sh_size == 0.


Committed to trunk.

Thanks,
- Tom

Handle .bss at same offset as .debug_pubnames

2019-07-05  Tom de Vries  <tdevries@suse.de>

	* dwz.c (write_dso): Handle NOBITS allocatable section.

---
 dwz.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/dwz.c b/dwz.c
index f959ffb..98f6f53 100644
--- a/dwz.c
+++ b/dwz.c
@@ -10683,7 +10683,8 @@ write_dso (DSO *dso, const char *file, struct stat *st)
 	      else if (!last_shoff
 		       && (dso->shdr[j].sh_offset < min_shoff
 			   || (dso->shdr[j].sh_offset == min_shoff
-			       && dso->shdr[j].sh_size == 0)))
+			       && (dso->shdr[j].sh_size == 0
+				   || dso->shdr[j].sh_type & SHT_NOBITS))))
 		continue;
 	      else if ((dso->shdr[j].sh_flags & SHF_ALLOC) != 0)
 		{