getprotobyname failure

getprotobyname failure

[Yigit Can]

Hello,

I have a problem with getprotobyname() function.

I wrote a simple program that only uses getprotobyname function

I can run this program on my development machine
but when I try to run this program on my basic kernel it gives me the
"memory fault" error.

the "getprotobyname" function returns NULL and i don't know the reason,
becouse i have the /etc/protocols file containing "tcp 6 TCP" line

I'm using Denx embedded linux development kit with libc-2.2.5 with an cross
compiler

my development machine has celeron  type processor
and my target board is TQM850L (powerpc 850)

I've replaced my protocols and nsswitch.conf files with host machines (my
protocols file contians "tcp 6 TCP" line)
and that's made no difference.

Why the getprotobyname function returns NULL?

please help,


 my program :

#include <netdb.h>
#include <stdio.h>

 int main(void){

    struct sockaddr_in addr;
    struct protoent *protocol=NULL;
    protocol=getprotobyname("tcp");
    printf("\n RESULT : %02x \n",protocol->p_proto);

    return 0;
}

Yigit CAN

Re: getprotobyname failure

[Richard B. Johnson]

On Wed, 26 Feb 2003, Yigit Can wrote:

> Hello,
> 
> I have a problem with getprotobyname() function.
> 
> I wrote a simple program that only uses getprotobyname function

[SNIPPED...]
getprotobyname() has nothing to do with linux-kernel so you should
not have sent your inquiry to the linux-kernel list. This is one
of the functions that is provided by your 'C' runtime library.

Here is an example of it working....

Script started on Wed Feb 26 08:46:40 2003

# cat xxx.c

#include <stdio.h>
#include <netdb.h>
#include <netinet/in.h>

 int main(void){

    struct protoent *protocol=NULL;
    protocol=getprotobyname("tcp");
    printf("\n RESULT : %02x \n",protocol->p_proto);

    return 0;
}

# gcc -Wall -o xxx -O2 xxx.c
# xxx

 RESULT : 06 

# # Works. Now you can `strace` it to see why yours doesn't.
# strace xxx
execve("./xxx", ["xxx"], [/* 32 vars */]) = 0
brk(0)                                  = 0x8049680
open("/etc/ld.so.preload", O_RDONLY)    = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=0, ...}) = 0
old_mmap(NULL, 0, PROT_READ|PROT_WRITE, MAP_PRIVATE, 3, 0) = 0
close(3)                                = 0
open("/lib/libc.so.6", O_RDONLY)        = 3
old_mmap(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0) = 0x4000c000
munmap(0x4000c000, 4096)                = 0
old_mmap(NULL, 644232, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x4000c000
mprotect(0x40097000, 74888, PROT_NONE)  = 0
old_mmap(0x40097000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x8b000) = 0x40097000
old_mmap(0x4009d000, 50312, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x4009d000
close(3)                                = 0
mprotect(0x4000c000, 569344, PROT_READ|PROT_WRITE) = 0
mprotect(0x4000c000, 569344, PROT_READ|PROT_EXEC) = 0
personality(PER_LINUX)                  = 0
getpid()                                = 2974
brk(0)                                  = 0x8049680
brk(0x8049a98)                          = 0x8049a98
brk(0x804a000)                          = 0x804a000
open("/etc/nsswitch.conf", O_RDONLY)    = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=1261, ...}) = 0
old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x400aa000
read(3, "#\n# /etc/nsswitch.conf\n#\n# An ex"..., 4096) = 1261
brk(0x804b000)                          = 0x804b000
read(3, "", 4096)                       = 0
close(3)                                = 0
munmap(0x400aa000, 4096)                = 0
open("/lib/libnss_nisplus.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/lib//libnss_nisplus.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/opt/intel/compiler50/ia32/lib/libnss_nisplus.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/X11R6/lib/libnss_nisplus.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/opt/Office50/lib/libnss_nisplus.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/java/lib/i686/libnss_nisplus.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=16707, ...}) = 0
old_mmap(NULL, 16707, PROT_READ, MAP_PRIVATE, 3, 0) = 0x400aa000
close(3)                                = 0
open("/usr/local/lib/libnss_nisplus.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/lib/libnss_files.so.1", O_RDONLY) = 3
old_mmap(NULL, 4096, PROT_READ, MAP_PRIVATE, 3, 0) = 0x400af000
munmap(0x400af000, 4096)                = 0
old_mmap(NULL, 35156, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) = 0x400af000
mprotect(0x400b7000, 2388, PROT_NONE)   = 0
old_mmap(0x400b7000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x7000) = 0x400b7000
close(3)                                = 0
mprotect(0x400af000, 32768, PROT_READ|PROT_WRITE) = 0
mprotect(0x400af000, 32768, PROT_READ|PROT_EXEC) = 0
open("/etc/protocols", O_RDONLY)        = 3
fcntl(3, F_GETFD)                       = 0
fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
fstat(3, {st_mode=S_IFREG|0644, st_size=715, ...}) = 0
old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x400b8000
read(3, "#\n# protocols\tThis file describe"..., 4096) = 715
close(3)                                = 0
munmap(0x400b8000, 4096)                = 0
fstat(1, {st_mode=S_IFCHR|0600, st_rdev=makedev(3, 0), ...}) = 0
old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x400b8000
ioctl(1, TCGETS, {B38400 opost isig icanon echo ...}) = 0
write(1, "\n", 1
)                       = 1
write(1, " RESULT : 06 \n", 14 RESULT : 06 
)         = 14
munmap(0x400b8000, 4096)                = 0
_exit(0)                                = ?
# exit
exit
Script done on Wed Feb 26 08:47:08 2003


If you are not running from an ix86 PC, you may need to
link in another library when you compile the code. For instance,
on my Sun workstation, I have to do...


gcc -Wall -O2 -o xxx xxx.c -lsocket -lnsl

... to load all the libraries I need for networking. It's just
the same as when you do floating-point math, you need to load
the math libraries with '-lm'



Cheers,
Dick Johnson
Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).
Why is the government concerned about the lunatic fringe? Think about it.

getprotobyname failure

[Yigit Can]

Hello,

I have a problem with getprotobyname() function.

I wrote a simple program that only uses getprotobyname function

I can run this program on my development machine=20
but when I try to run this program on my basic kernel it gives me the =
"memory fault" error.

I'm using libc-2.2.5 on a powerpc 8xx development kit
so, i'm using the same library on the host and target machine.

my development machine has celeron  type processor
and my target board is TQM850L (has ppc_850 processor).

I've replaced my protocols and nsswitch.conf files with host machines (my
protocols file contians "tcp 6 TCP" line)
and that's made no difference.

what can I do?
 
please help,
 

 my program :
 
#include <netdb.h>
#include <stdio.h>
 
 int main(void){
 
    struct sockaddr_in addr;
    struct protoent *protocol=3DNULL;
    protocol=3Dgetprotobyname("tcp");
    printf("\n RESULT : %02x \n",protocol->p_proto);
 
    return 0;
}

Yigit CAN
Karel Electronics Corp.
yigit.can@karel.com.tr

Re: getprotobyname failure

[Glynn Clements]

Yigit Can wrote:

> I have a problem with getprotobyname() function.
> 
> I wrote a simple program that only uses getprotobyname function
> 
> I can run this program on my development machine 
> but when I try to run this program on my basic kernel it gives me
> the "memory fault" error.
> 
> I'm using libc-2.2.5 on a powerpc 8xx development kit
> so, i'm using the same library on the host and target machine.
> 
> my development machine has celeron  type processor
> and my target board is TQM850L (has ppc_850 processor).

I presume that you have managed to get other programs to work by
cross-compiling, right?

> I've replaced my protocols and nsswitch.conf files with host machines (my
> protocols file contians "tcp 6 TCP" line)
> and that's made no difference.
> 
> what can I do?
> 
> please help,
> 
> 
>  my program :
> 
> #include <netdb.h>
> #include <stdio.h>
> 
>  int main(void){
> 
>     struct sockaddr_in addr;
>     struct protoent *protocol=NULL;
>     protocol=getprotobyname("tcp");
>     printf("\n RESULT : %02x \n",protocol->p_proto);

You should check that the pointer which getprotobyname() returns is
non-NULL before trying to dereference it.

-- 
Glynn Clements <glynn.clements@virgin.net>

getprotobyname failure

[Yigit Can]

Hello,

I have a problem with getprotobyname() function.

I wrote a simple program that only uses getprotobyname function

I can run this program on my development machine=20
but when I try to run this program on my basic kernel it gives me the =
"memory fault" error.

I'm using libc-2.2.5 on a powerpc 8xx development kit
so, i'm using the same library on the host and target machine.

my development machine has celeron  type processor
and my target board is TQM850L (has ppc_850 processor).

I've replaced my protocols and nsswitch.conf files with host machines (my
protocols file contians "tcp 6 TCP" line)
and that's made no difference.

what can I do?
 
please help,
 

 my program :
 
 #include <netdb.h>
#include <stdio.h>
 
 int main(void){
 
    struct sockaddr_in addr;
    struct protoent *protocol=3DNULL;
    protocol=3Dgetprotobyname("tcp");
    printf("\n RESULT : %02x \n",protocol->p_proto);
 
    return 0;
}

Yigit CAN
Karel Electronics Corp.
yigit.can@karel.com.tr
 

Re: getprotobyname failure

[Jason Cooper]

Yigit Can (yigit.can@karel.com.tr) wrote:
> 
> I can run this program on my development machine=20
> but when I try to run this program on my basic kernel it gives me the =
> "memory fault" error.
> 
> I'm using libc-2.2.5 on a powerpc 8xx development kit
> so, i'm using the same library on the host and target machine.
> 
> my development machine has celeron  type processor
> and my target board is TQM850L (has ppc_850 processor).
> 
> I've replaced my protocols and nsswitch.conf files with host machines (my
> protocols file contians "tcp 6 TCP" line)
> and that's made no difference.

Yigit, 

My first guess would be byte order because of the different processors.  Try
this page out:

http://www.ecst.csuchico.edu/~beej/guide/net/bgnet.pdf

It is a beginners guide, however, it does talk a bit about byte order, etc.

Cooper.