[SOLVED] Where to find Linux constants values?

Blue-Knight · 01-29-2014, 10:41 AM

In the "Linux Programmer's Manual" I find many names that represents a simple value, some of them are: O_RDWRCLONE_FILES, CLONE_FILES, O_RDWR, SIGCHLD, SIGSEGV...

But where to find which values they actually represent? How to find where they can be found (i.e. where they're defined)?

Thank you!

smallpond · 01-29-2014, 11:02 AM

The header files that define these constants live under the /usr/include directory. They will be installed as part of the developer packages for the libraries which implement the code. For example, glibc-headers has the header files for the standard Linux libraries.

Blue-Knight · 01-29-2014, 11:22 AM

Quote:

Originally Posted by smallpond

The header files that define these constants live under the /usr/include directory. They will be installed as part of the developer packages for the libraries which implement the code. For example, glibc-headers has the header files for the standard Linux libraries.

Ah, there's no easy way then. I will have to search and then copy them one by one...

The good thing is that I will have to do this one time only.

Thank you!

sag47 · 01-29-2014, 11:24 AM

If you know what you're looking for using grep on the source code will be a quick and dirty way to find it.

Code:

grep -irl 'O_RDWRCLONE_FILES' /path/to/source/

See grep man page for a description of -i -r and -l options.

NevemTeve · 01-29-2014, 11:25 AM

Note: Specially O_RDWR comes from /usr/include/asm-generic/fcntl.h (But you are not supposed to include this file into your program -- 'man 2 open' tells you which headers you should include)

Blue-Knight · 01-29-2014, 11:32 AM

Quote:

Originally Posted by NevemTeve

Note: Specially O_RDWR comes from /usr/include/asm-generic/fcntl.h (But you are not supposed to include this file into your program -- 'man 2 open' tells you which headers you should include)

I know, the problem is that I cannot simply include any of those files because I'm not using C. I have to know the value of all of them...

NevemTeve · 01-29-2014, 11:49 AM

Please don't tell you are trying to write code in Assembly...

Blue-Knight · 01-29-2014, 11:59 AM

Quote:

Originally Posted by NevemTeve

Please don't tell you are trying to write code in Assembly...

But I am. =X

mina86 · 01-29-2014, 05:28 PM

You can use preprocessor to get the values:

Code:

[/tmp]$ cat a.c
#define _GNU_SOURCE
#include <fcntl.h>
#include <sched.h>
#include <signal.h>

"CLONE_FILES"=CLONE_FILES
"O_RDWR"=O_RDWR
"SIGCHLD"=SIGCHLD
"SIGSEGV"=SIGSEGV
[/tmp]$ gcc -E a.c | tail -n 4
"CLONE_FILES"=0x00000400
"O_RDWR"=02
"SIGCHLD"=17
"SIGSEGV"=11
[/tmp]$

I'm not aware of a portable way of getting those constants included in assembly source code though.