simplest way to get the size of an output section

simplest way to get the size of an output section

[Etienne Lorrain]

  Hello,

  On a Linux ia32 system, I am trying to get the size of an output
 section of an ELF file to use it automatically in a Makefile.

 Ideally I would like to compile a small GCC program like:
gcc -Wl,--defsym,linker_tells_size=SIZEOF(.text16) print_command_line.c
 but that will not work because --defsym cannot get the SIZEOF().

 So I have gone the objcopy way:
objcopy --output-target binary --only-section .text16 vmlinux param.bin
./print_command_line ` cat param.bin | wc -c `
 That does the job, but is there a way to not create the temporary file
 "param.bin" (i.e. objcopy uses standard output) (because it is always
 a problem in Makefiles: it may already exist and be write protected,
 it needs to be cleaned by make clean, an interrupted make command
 may leave the temporary file...) or another way, without using too
 complex awk or sed scripts?

  Thank you,
  Etienne.


	

	
		
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Re: simplest way to get the size of an output section

[Daniel Jacobowitz]

On Mon, Oct 04, 2004 at 11:51:01AM +0200, Etienne Lorrain wrote:
>   Hello,
> 
>   On a Linux ia32 system, I am trying to get the size of an output
>  section of an ELF file to use it automatically in a Makefile.
> 
>  Ideally I would like to compile a small GCC program like:
> gcc -Wl,--defsym,linker_tells_size=SIZEOF(.text16) print_command_line.c
>  but that will not work because --defsym cannot get the SIZEOF().
> 
>  So I have gone the objcopy way:
> objcopy --output-target binary --only-section .text16 vmlinux param.bin
> ./print_command_line ` cat param.bin | wc -c `
>  That does the job, but is there a way to not create the temporary file
>  "param.bin" (i.e. objcopy uses standard output) (because it is always
>  a problem in Makefiles: it may already exist and be write protected,
>  it needs to be cleaned by make clean, an interrupted make command
>  may leave the temporary file...) or another way, without using too
>  complex awk or sed scripts?

Why not use objdump -h or readelf -S?

-- 
Daniel Jacobowitz

Re: simplest way to get the size of an output section

[Etienne Lorrain]

 --- Daniel Jacobowitz <drow@false.org> a écrit : 
> On Mon, Oct 04, 2004 at 11:51:01AM +0200, Etienne Lorrain wrote:
> >   On a Linux ia32 system, I am trying to get the size of an output
> >  section of an ELF file to use it automatically in a Makefile.
> > 
> >  Ideally I would like to compile a small GCC program like:
> > gcc -Wl,--defsym,linker_tells_size=SIZEOF(.text16) print_command_line.c
> >  but that will not work because --defsym cannot get the SIZEOF().
> > 
> >  So I have gone the objcopy way:
> > objcopy --output-target binary --only-section .text16 vmlinux param.bin
> > ./print_command_line ` cat param.bin | wc -c `
> >  That does the job, but is there a way to not create the temporary file
> >  "param.bin" (i.e. objcopy uses standard output) (because it is always
> >  a problem in Makefiles: it may already exist and be write protected,
> >  it needs to be cleaned by make clean, an interrupted make command
> >  may leave the temporary file...) or another way, without using too
> >  complex awk or sed scripts?
> 
> Why not use objdump -h or readelf -S?

  Basically because of the complexity of the sed or awk to get back the 
 hexadecimal number (in a Makefile):
 readelf gives all the sections, so (not tested - not a real awk master)
./print_command_line ` readelf -S vmlinux | awk "/.text16/ {printf $...}" `
 objdump - when I tried yesterday - wanted the number of the input
 section and need quite a complex filtering of the standard output too.

  These tools were not done to be used in a Makefile.
  Etienne.


	

	
		
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Re: simplest way to get the size of an output section

[Paul Brook]

On Monday 04 October 2004 15:06, Etienne Lorrain wrote:
>  --- Daniel Jacobowitz <drow@false.org> a écrit :
> > On Mon, Oct 04, 2004 at 11:51:01AM +0200, Etienne Lorrain wrote:
> > >   On a Linux ia32 system, I am trying to get the size of an output
> > >  section of an ELF file to use it automatically in a Makefile.
> > >
> > >  Ideally I would like to compile a small GCC program like:
> > > gcc -Wl,--defsym,linker_tells_size=SIZEOF(.text16) print_command_line.c
> > >  but that will not work because --defsym cannot get the SIZEOF().
> > >
> > >  So I have gone the objcopy way:
> > > objcopy --output-target binary --only-section .text16 vmlinux param.bin
> > > ./print_command_line ` cat param.bin | wc -c `
> > >  That does the job, but is there a way to not create the temporary file
> > >  "param.bin" (i.e. objcopy uses standard output) (because it is always
> > >  a problem in Makefiles: it may already exist and be write protected,
> > >  it needs to be cleaned by make clean, an interrupted make command
> > >  may leave the temporary file...) or another way, without using too
> > >  complex awk or sed scripts?
> >
> > Why not use objdump -h or readelf -S?
>
>   Basically because of the complexity of the sed or awk to get back the
>  hexadecimal number (in a Makefile):
>  readelf gives all the sections, so (not tested - not a real awk master)
> ./print_command_line ` readelf -S vmlinux | awk "/.text16/ {printf $...}" `
>  objdump - when I tried yesterday - wanted the number of the input
>  section and need quite a complex filtering of the standard output too.

How about "size -A"

Paul

Re: simplest way to get the size of an output section

[Etienne Lorrain]

 --- Paul Brook <paul@codesourcery.com> a écrit : 
> On Monday 04 October 2004 15:06, Etienne Lorrain wrote:
> >  --- Daniel Jacobowitz <drow@false.org> a écrit :
> > > On Mon, Oct 04, 2004 at 11:51:01AM +0200, Etienne Lorrain wrote:
> > > >
> > > >   On a Linux ia32 system, I am trying to get the size of an output
> > > >  section of an ELF file to use it automatically in a Makefile.
> > > >
> > > >  Ideally I would like to compile a small GCC program like:
> > > > gcc -Wl,--defsym,linker_tells_size=SIZEOF(.text16)
print_command_line.c
> > > >  but that will not work because --defsym cannot get the SIZEOF().
> > > >
> > > >  So I have gone the objcopy way:
> > > > objcopy --output-target binary --only-section .text16 vmlinux
> param.bin
> > > > ./print_command_line ` cat param.bin | wc -c `
> > > >  That does the job, but is there a way to not create the temporary
file
> > > >  "param.bin" (i.e. objcopy uses standard output) (because it is
always
> > > >  a problem in Makefiles: it may already exist and be write
protected,
> > > >  it needs to be cleaned by make clean, an interrupted make command
> > > >  may leave the temporary file...) or another way, without using too
> > > >  complex awk or sed scripts?
> > >
> > > Why not use objdump -h or readelf -S?
> >
> >   Basically because of the complexity of the sed or awk to get back the
> >  hexadecimal number (in a Makefile):
> >  readelf gives all the sections, so (not tested - not a real awk master)
> > ./print_command_line ` readelf -S vmlinux | awk "/.text16/ {printf
$...}" `
> >  objdump - when I tried yesterday - wanted the number of the input
> >  section and need quite a complex filtering of the standard output too.
> 
> How about "size -A"

  Thank you, that does the trick (from command line):
./print_command_line ` size -A vmlinux | grep .text16 | awk " { print \$2 }
" `

  Etienne.


	

	
		
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