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* Don't attempt to compress bss sections
@ 2022-09-23  2:26 Alan Modra
  2022-09-23  6:33 ` Jan Beulich
  0 siblings, 1 reply; 3+ messages in thread
From: Alan Modra @ 2022-09-23  2:26 UTC (permalink / raw)
  To: binutils

It doesn't make sense to try to compress a section without contents
since those sections take no space on disk.  Compression can only
increase the disk image size.

	* coffgen.c (make_a_section_from_file): Exclude !SEC_HAS_CONTENTS
	sections from compression and decompression.
	* elf.c (_bfd_elf_make_section_from_shdr): Likewise.

diff --git a/bfd/coffgen.c b/bfd/coffgen.c
index 90fba3b8554..8eb69af2ce2 100644
--- a/bfd/coffgen.c
+++ b/bfd/coffgen.c
@@ -146,7 +146,8 @@ make_a_section_from_file (bfd *abfd,
 
   /* Compress/decompress DWARF debug sections with names: .debug_* and
      .zdebug_*, after the section flags is set.  */
-  if ((flags & SEC_DEBUGGING)
+  if ((flags & SEC_DEBUGGING) != 0
+      && (flags & SEC_HAS_CONTENTS) != 0
       && strlen (name) > 7
       && ((name[1] == 'd' && name[6] == '_')
 	  || (strlen (name) > 8 && name[1] == 'z' && name[7] == '_')))
diff --git a/bfd/elf.c b/bfd/elf.c
index bc433cf516c..16cea4f8aeb 100644
--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -1201,7 +1201,8 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
 
   /* Compress/decompress DWARF debug sections with names: .debug_* and
      .zdebug_*, after the section flags is set.  */
-  if ((newsect->flags & SEC_DEBUGGING)
+  if ((newsect->flags & SEC_DEBUGGING) != 0
+      && (newsect->flags & SEC_HAS_CONTENTS) != 0
       && ((name[1] == 'd' && name[6] == '_')
 	  || (name[1] == 'z' && name[7] == '_')))
     {

-- 
Alan Modra
Australia Development Lab, IBM

^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: Don't attempt to compress bss sections
  2022-09-23  2:26 Don't attempt to compress bss sections Alan Modra
@ 2022-09-23  6:33 ` Jan Beulich
  2022-09-23  6:49   ` Alan Modra
  0 siblings, 1 reply; 3+ messages in thread
From: Jan Beulich @ 2022-09-23  6:33 UTC (permalink / raw)
  To: Alan Modra; +Cc: binutils

On 23.09.2022 04:26, Alan Modra via Binutils wrote:
> It doesn't make sense to try to compress a section without contents
> since those sections take no space on disk.  Compression can only
> increase the disk image size.
> 
> 	* coffgen.c (make_a_section_from_file): Exclude !SEC_HAS_CONTENTS
> 	sections from compression and decompression.
> 	* elf.c (_bfd_elf_make_section_from_shdr): Likewise.

So I'm curious - are there debugging sections without contents? Or
is the change more for the sake of documentation?

Jan

> --- a/bfd/coffgen.c
> +++ b/bfd/coffgen.c
> @@ -146,7 +146,8 @@ make_a_section_from_file (bfd *abfd,
>  
>    /* Compress/decompress DWARF debug sections with names: .debug_* and
>       .zdebug_*, after the section flags is set.  */
> -  if ((flags & SEC_DEBUGGING)
> +  if ((flags & SEC_DEBUGGING) != 0
> +      && (flags & SEC_HAS_CONTENTS) != 0
>        && strlen (name) > 7
>        && ((name[1] == 'd' && name[6] == '_')
>  	  || (strlen (name) > 8 && name[1] == 'z' && name[7] == '_')))
> diff --git a/bfd/elf.c b/bfd/elf.c
> index bc433cf516c..16cea4f8aeb 100644
> --- a/bfd/elf.c
> +++ b/bfd/elf.c
> @@ -1201,7 +1201,8 @@ _bfd_elf_make_section_from_shdr (bfd *abfd,
>  
>    /* Compress/decompress DWARF debug sections with names: .debug_* and
>       .zdebug_*, after the section flags is set.  */
> -  if ((newsect->flags & SEC_DEBUGGING)
> +  if ((newsect->flags & SEC_DEBUGGING) != 0
> +      && (newsect->flags & SEC_HAS_CONTENTS) != 0
>        && ((name[1] == 'd' && name[6] == '_')
>  	  || (name[1] == 'z' && name[7] == '_')))
>      {
> 


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: Don't attempt to compress bss sections
  2022-09-23  6:33 ` Jan Beulich
@ 2022-09-23  6:49   ` Alan Modra
  0 siblings, 0 replies; 3+ messages in thread
From: Alan Modra @ 2022-09-23  6:49 UTC (permalink / raw)
  To: Jan Beulich; +Cc: binutils

On Fri, Sep 23, 2022 at 08:33:05AM +0200, Jan Beulich wrote:
> On 23.09.2022 04:26, Alan Modra via Binutils wrote:
> > It doesn't make sense to try to compress a section without contents
> > since those sections take no space on disk.  Compression can only
> > increase the disk image size.
> > 
> > 	* coffgen.c (make_a_section_from_file): Exclude !SEC_HAS_CONTENTS
> > 	sections from compression and decompression.
> > 	* elf.c (_bfd_elf_make_section_from_shdr): Likewise.
> 
> So I'm curious - are there debugging sections without contents? Or
> is the change more for the sake of documentation?

There are fuzzers that try any mad thing.

-- 
Alan Modra
Australia Development Lab, IBM

^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2022-09-23  6:50 UTC | newest]

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2022-09-23  2:26 Don't attempt to compress bss sections Alan Modra
2022-09-23  6:33 ` Jan Beulich
2022-09-23  6:49   ` Alan Modra

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