Re: reading elf section data

Re: reading elf section data

[Glynn Clements]

Gery wrote:

> How to read in human format data from elf section?

Can you be more specific? What kind of data? What format?

objdump and readelf can provide a lot of information about ELF files,
but they can't decode every type of data which could conceivably be
stored in an ELF file.

-- 
Glynn Clements <glynn@gclements.plus.com>

Re: reading elf section data

[Steve Graegert]

On Nov 12, 2007 11:55 AM, Glynn Clements <glynn@gclements.plus.com> wrote:
>
> Gery wrote:
>
> > How to read in human format data from elf section?
>
> Can you be more specific? What kind of data? What format?

I stopped replying to messages like those from the OP.  Demanding help
without providing a minimum of information is just annoying, but
doing so without any etiquette is simply rude.

	\Steve

--

Steve Grägert
DigitalEther.de
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Re: reading elf section data

[Steve Graegert]

On Nov 12, 2007 7:37 PM, Gery <zaphod001@gmail.com> wrote:
>
> Steve Graegert wrote:
> > On Nov 12, 2007 11:55 AM, Glynn Clements <glynn@gclements.plus.com> wrote:
> >> Gery wrote:
> >>
> >>> How to read in human format data from elf section?
> >> Can you be more specific? What kind of data? What format?
> >
> > I stopped replying to messages like those from the OP.  Demanding help
> > without providing a minimum of information is just annoying, but
> > doing so without any etiquette is simply rude.
> >
> >       \Steve
> >
> > --
> >
> > Steve Grägert
> > DigitalEther.de
> > -
> > To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
> > the body of a message to majordomo@vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
> Just for my understanding :)
> What is OP?
> What is it wrong w/ my etiquette?
> PLease, help me to fix my mistakes.
>

Hi Gery,

Let's start with a greeting, you'll be welcome and you're done with
50% of the "etiquette".
The OP stands for "original poster" and refers to the thread starter.
Finally I like to conclude a post with a closing formula or just a
signature including your name.  That's the second part of the
"etiquette".

What I mean by rude is that questions like "How to read ELF data?"
motivates no one to answer as we have to ask for clarification first.
If you'd have asked "How do I read custom ELF sections added by GCC
using C?" everyone knows exactly what you want just by being a bit
more accurate.

Regarding your original question: try readelf first.  It'll probably
do the trick.

	\Steve

--

Steve Grägert
DigitalEther.de
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reading elf section data

[Gery]

How to read in human format data from elf section?

Re: reading elf section data

[Glynn Clements]

Gery wrote:

> i put some structure with gcc attribute to special section named ".my_sec"
> The structure is like
> struct abc {
> char *a;
> char *b;
> };
> and global variable is
> struct abc klm = { "this is 1st string", "this is 2nd string" };

Like this:

struct abc klm __attribute__ ((section (".my_sec"))) = { "this is 1st string", "this is 2nd string" };

?

> Which utility can show me just the data of that section?

	$ objdump -j .my_sec -d foo.o

	foo.o:     file format elf32-i386
	
	Disassembly of section .my_sec:
	
	00000000 <klm>:
	   0:	00 00 00 00 13 00 00 00                             ........

Bear in mind that the structure only contains the pointers, not the
strings themselves. String literals used as values are stored in the
.rodata section. If you want them elsewhere, you'll have to store them
in named variables, e.g.:

	static char s1[] __attribute__ ((section (".my_sec"))) = "this is 1st string";
	static char s2[] __attribute__ ((section (".my_sec"))) = "this is 2nd string";
	struct abc klm __attribute__ ((section (".my_sec"))) = { s1, s2 };

	$ objdump -j .my_sec -d foo.o

	foo.o:     file format elf32-i386
	
	Disassembly of section .my_sec:
	
	00000000 <s1>:
	   0:	74 68 69 73 20 69 73 20 31 73 74 20 73 74 72 69     this is 1st stri
	  10:	6e 67 00                                            ng.
	
	00000013 <s2>:
	  13:	74 68 69 73 20 69 73 20 32 6e 64 20 73 74 72 69     this is 2nd stri
	  23:	6e 67 00 00 00                                      ng...
	
	00000028 <klm>:
	  28:	00 00 00 00 13 00 00 00                             ........

-- 
Glynn Clements <glynn@gclements.plus.com>

Re: reading elf section data

[Gery]

Glynn Clements wrote:
> Gery wrote:
>
>   
>> How to read in human format data from elf section?
>>     
>
> Can you be more specific? What kind of data? What format?
>
> objdump and readelf can provide a lot of information about ELF files,
> but they can't decode every type of data which could conceivably be
> stored in an ELF file.
>
>   
Ok.
i put some structure with gcc attribute to special section named ".my_sec"
The structure is like
struct abc {
char *a;
char *b;
};
and global variable is
struct abc klm = { "this is 1st string", "this is 2nd string" };

Which utility can show me just the data of that section?

Re: reading elf section data

[Gery]

Steve Graegert wrote:
> On Nov 12, 2007 11:55 AM, Glynn Clements <glynn@gclements.plus.com> wrote:
>> Gery wrote:
>>
>>> How to read in human format data from elf section?
>> Can you be more specific? What kind of data? What format?
> 
> I stopped replying to messages like those from the OP.  Demanding help
> without providing a minimum of information is just annoying, but
> doing so without any etiquette is simply rude.
> 
> 	\Steve
> 
> --
> 
> Steve Grägert
> DigitalEther.de
> -
> To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 
Just for my understanding :)
What is OP?
What is it wrong w/ my etiquette?
PLease, help me to fix my mistakes.
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Re: reading elf section data

[Gery]

Steve Graegert wrote:
> On Nov 12, 2007 7:37 PM, Gery <zaphod001@gmail.com> wrote:
>   
>> Steve Graegert wrote:
>>     
>>> On Nov 12, 2007 11:55 AM, Glynn Clements <glynn@gclements.plus.com> wrote:
>>>       
>>>> Gery wrote:
>>>>
>>>>         
>>>>> How to read in human format data from elf section?
>>>>>           
>>>> Can you be more specific? What kind of data? What format?
>>>>         
>>> I stopped replying to messages like those from the OP.  Demanding help
>>> without providing a minimum of information is just annoying, but
>>> doing so without any etiquette is simply rude.
>>>
>>>       \Steve
>>>
>>> --
>>>
>>> Steve Grägert
>>> DigitalEther.de
>>> -
>>> To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
>>> the body of a message to majordomo@vger.kernel.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>>
>>>       
>> Just for my understanding :)
>> What is OP?
>> What is it wrong w/ my etiquette?
>> PLease, help me to fix my mistakes.
>>
>>     
>
> Hi Gery,
>
> Let's start with a greeting, you'll be welcome and you're done with
> 50% of the "etiquette".
> The OP stands for "original poster" and refers to the thread starter.
> Finally I like to conclude a post with a closing formula or just a
> signature including your name.  That's the second part of the
> "etiquette".
>
> What I mean by rude is that questions like "How to read ELF data?"
> motivates no one to answer as we have to ask for clarification first.
> If you'd have asked "How do I read custom ELF sections added by GCC
> using C?" everyone knows exactly what you want just by being a bit
> more accurate.
>
> Regarding your original question: try readelf first.  It'll probably
> do the trick.
>
> 	\Steve
>
> --
>
> Steve Grägert
> DigitalEther.de
>
>   
Thank you, Steve.

I already tried readelf and even sectiondump utility from 
elfutils-0.130/tests/
I hope there is a solution w/o coding, but may be not :(

Gery
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Re: reading elf section data

[Kristof Provost]

[-- Attachment #1: Type: text/plain, Size: 175 bytes --]

On 2007-11-12 08:36:34 (-0500), Gery <zaphod001@gmail.com> wrote:
> How to read in human format data from elf section?
The readelf and objdump tools should help you.

Kristof

[-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --]

Re: reading elf section data

[Gery]

Glynn Clements wrote:
> Gery wrote:
>
>   
>> i put some structure with gcc attribute to special section named ".my_sec"
>> The structure is like
>> struct abc {
>> char *a;
>> char *b;
>> };
>> and global variable is
>> struct abc klm = { "this is 1st string", "this is 2nd string" };
>>     
>
> Like this:
>
> struct abc klm __attribute__ ((section (".my_sec"))) = { "this is 1st string", "this is 2nd string" };
>
> ?
>
>   
>> Which utility can show me just the data of that section?
>>     
>
> 	$ objdump -j .my_sec -d foo.o
>
> 	foo.o:     file format elf32-i386
> 	
> 	Disassembly of section .my_sec:
> 	
> 	00000000 <klm>:
> 	   0:	00 00 00 00 13 00 00 00                             ........
>
> Bear in mind that the structure only contains the pointers, not the
> strings themselves. String literals used as values are stored in the
> .rodata section. If you want them elsewhere, you'll have to store them
> in named variables, e.g.:
>
> 	static char s1[] __attribute__ ((section (".my_sec"))) = "this is 1st string";
> 	static char s2[] __attribute__ ((section (".my_sec"))) = "this is 2nd string";
> 	struct abc klm __attribute__ ((section (".my_sec"))) = { s1, s2 };
>
> 	$ objdump -j .my_sec -d foo.o
>
> 	foo.o:     file format elf32-i386
> 	
> 	Disassembly of section .my_sec:
> 	
> 	00000000 <s1>:
> 	   0:	74 68 69 73 20 69 73 20 31 73 74 20 73 74 72 69     this is 1st stri
> 	  10:	6e 67 00                                            ng.
> 	
> 	00000013 <s2>:
> 	  13:	74 68 69 73 20 69 73 20 32 6e 64 20 73 74 72 69     this is 2nd stri
> 	  23:	6e 67 00 00 00                                      ng...
> 	
> 	00000028 <klm>:
> 	  28:	00 00 00 00 13 00 00 00                             ........
>
>   
Thank you very much :))

Re: reading elf section data

[Gery]

Kristof Provost wrote:
> On 2007-11-12 08:36:34 (-0500), Gery <zaphod001@gmail.com> wrote:
>   
>> How to read in human format data from elf section?
>>     
> The readelf and objdump tools should help you.
>
> Kristof
>   
thank you.