execve errno setting on MIPS

execve errno setting on MIPS

[Sadashiiv, Halesh]

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Hi all,
 
Please find the below testcase..
 
#include <stdio.h>
#include <limits.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
 
#define EXE_NAME "./exe"
 
char e2BIG[ARG_MAX+1][10];
char *envList[]={NULL};
 
int main(void)
{
  int ret,ind;
 
  for(ind = 0; ind < ARG_MAX+1; ind++)
    strcpy(e2BIG[ind], "helloword");
 
  if ((ret = chmod(EXE_NAME,0744)) != 0){
    printf("chmod failed\n");
    exit(1);
  }
 
  /* whne arg list is too long */
  if ((ret = execve(EXE_NAME,e2BIG,envList)) == -1) {
    if ( errno == E2BIG)
      printf("Test Pass\n");
    else
      printf("Test Fail : Got Errno %d\n", errno);
    exit(0);
  }
  else
    printf("execve worked out of limit\n");
  exit(1);
}
 
On MIPS E2BIG is not getting set as errno instead EFAULT is set, while
on 
other archs like ARM, PowerPC and i686 I am able to get E2BIG.
 
Please let me know about the issue...
 
Let EXE_NAME be any executable....
 
Thanks,
Halesh

 



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execve errno setting on MIPS

[Sadashiiv, Halesh]

[-- Attachment #1: Type: text/plain, Size: 1690 bytes --]

Hi all,
 
Please find the below testcase..
 
#include <stdio.h>
#include <limits.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
 
#define EXE_NAME "./exe"
 
char e2BIG[ARG_MAX+1][10];
char *envList[]={NULL};
 
int main(void)
{
  int ret,ind;
 
  for(ind = 0; ind < ARG_MAX+1; ind++)
    strcpy(e2BIG[ind], "helloword");
 
  if ((ret = chmod(EXE_NAME,0744)) != 0){
    printf("chmod failed\n");
    exit(1);
  }
 
  /* whne arg list is too long */
  if ((ret = execve(EXE_NAME,e2BIG,envList)) == -1) {
    if ( errno == E2BIG)
      printf("Test Pass\n");
    else
      printf("Test Fail : Got Errno %d\n", errno);
    exit(0);
  }
  else
    printf("execve worked out of limit\n");
  exit(1);
}
 
On MIPS E2BIG is not getting set as errno instead EFAULT is set, while
on 
other archs like ARM, PowerPC and i686 I am able to get E2BIG.
 
Please let me know about the issue...
 
Let EXE_NAME be any executable....
 
Thanks,
Halesh

 



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Re: execve errno setting on MIPS

[Ralf Baechle]

On Thu, Sep 18, 2008 at 05:09:35PM +0530, Sadashiiv, Halesh wrote:
> From: "Sadashiiv, Halesh" <halesh.sadashiv@ap.sony.com>
> Date: Thu, 18 Sep 2008 17:09:35 +0530
> To: linux-mips@linux-mips.org
> Subject: execve errno setting on MIPS
> Content-Type: multipart/alternative;
> 	boundary="----_=_NextPart_001_01C91983.39F24AAB"
> 
> Hi all,
>  
> Please find the below testcase..
>  
> #include <stdio.h>
> #include <limits.h>
> #include <errno.h>
> #include <unistd.h>
> #include <stdlib.h>
> #include <string.h>
> #include <sys/types.h>
> #include <sys/stat.h>
>  
> #define EXE_NAME "./exe"
>  
> char e2BIG[ARG_MAX+1][10];
> char *envList[]={NULL};
>  
> int main(void)
> {
>   int ret,ind;
>  
>   for(ind = 0; ind < ARG_MAX+1; ind++)
>     strcpy(e2BIG[ind], "helloword");
>  
>   if ((ret = chmod(EXE_NAME,0744)) != 0){
>     printf("chmod failed\n");
>     exit(1);
>   }
>  
>   /* whne arg list is too long */
>   if ((ret = execve(EXE_NAME,e2BIG,envList)) == -1) {
>     if ( errno == E2BIG)
>       printf("Test Pass\n");
>     else
>       printf("Test Fail : Got Errno %d\n", errno);
>     exit(0);
>   }
>   else
>     printf("execve worked out of limit\n");
>   exit(1);
> }
>  
> On MIPS E2BIG is not getting set as errno instead EFAULT is set, while
> on 
> other archs like ARM, PowerPC and i686 I am able to get E2BIG.
>  
> Please let me know about the issue...
>  
> Let EXE_NAME be any executable....

Let there be light:

  char *foo[] != char foo[][]

char *e2BIG[ARG_MAX + 1] = {
        [0 ... ARG_MAX] = "helloword"
};

        for (ind = 0; ind < ARG_MAX + 1; ind++)
                strcpy(e2BIG[ind], "helloword");

is different from

char *e2BIG[ARG_MAX + 1] = {
        [0 ... ARG_MAX] = "helloword"
};

The one is two dimensional array, the other an array of pointers to char.

  Ralf

Re: execve errno setting on MIPS

[Thomas Bogendoerfer]

On Thu, Sep 18, 2008 at 05:09:35PM +0530, Sadashiiv, Halesh wrote:
> char e2BIG[ARG_MAX+1][10];
> char *envList[]={NULL};
>  
> int main(void)
> {
>   int ret,ind;
>  
>   for(ind = 0; ind < ARG_MAX+1; ind++)
>     strcpy(e2BIG[ind], "helloword");

this is broken and does cause an EFAULT on x86 as well (you should
take the warning from gcc about the second argument of execve serious).

Try:

char *e2BIG[ARG_MAX+1];
char *envList[]={NULL};

int main(void)
{
  int ret,ind;

    for(ind = 0; ind < ARG_MAX+1; ind++)
    	e2BIG[ind] = strdup("helloword");


And it looks like the ARG_MAX limit is bigger than my installed glibc
thinks, because it works at least on x86. When I increase the array two
2 * ARG_MAX I'll get the wanted E2BIG.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessary a
good idea.                                                [ RFC1925, 2.3 ]

Re: execve errno setting on MIPS

[Sadashiiv, Halesh]

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>this is broken and does cause an EFAULT on x86 as well (you should
>take the warning from gcc about the second argument of execve serious).
 
 Thanks, you are right.
 
>Try:
 
>char *e2BIG[ARG_MAX+1];
>char *envList[]={NULL};
> 
>int main(void)
>{
>  int ret,ind;
> 
>   for(ind = 0; ind < ARG_MAX+1; ind++)
>        e2BIG[ind] = strdup("helloword");
> 
> 
 It wroks on X86 and other Archs.
> 
> 
>And it looks like the ARG_MAX limit is bigger than my installed glibc
>thinks, because it works at least on x86. When I increase the array two
>2 * ARG_MAX I'll get the wanted E2BIG.
 
 Yes, on MIPS we need to increase the ARM_MAX to 2*ARG_MAX to get E2BIG.
 
Thanks,
Halesh

 



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Re: execve errno setting on MIPS

[Sadashiiv, Halesh]

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>this is broken and does cause an EFAULT on x86 as well (you should
>take the warning from gcc about the second argument of execve serious).
 
 Thanks, you are right.
 
>Try:
 
>char *e2BIG[ARG_MAX+1];
>char *envList[]={NULL};
> 
>int main(void)
>{
>  int ret,ind;
> 
>   for(ind = 0; ind < ARG_MAX+1; ind++)
>        e2BIG[ind] = strdup("helloword");
> 
> 
 It wroks on X86 and other Archs.
> 
> 
>And it looks like the ARG_MAX limit is bigger than my installed glibc
>thinks, because it works at least on x86. When I increase the array two
>2 * ARG_MAX I'll get the wanted E2BIG.
 
 Yes, on MIPS we need to increase the ARM_MAX to 2*ARG_MAX to get E2BIG.
 
Thanks,
Halesh

 



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Re: execve errno setting on MIPS

[Sadashiiv, Halesh]

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>> The one is two dimensional array, the other an array of pointers to
char.
 
Yes, Fixed the problem, 
But on MIPS, ARG_MAX is not considered, I was able to get the E2BIG on
2*ARG_MAX.
 
Check
http://www.linux-mips.org/archives/linux-mips/2008-09/msg00136.html  
 

Thanks,

Halesh



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Re: execve errno setting on MIPS

[Sadashiiv, Halesh]

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>> The one is two dimensional array, the other an array of pointers to
char.
 
Yes, Fixed the problem, 
But on MIPS, ARG_MAX is not considered, I was able to get the E2BIG on
2*ARG_MAX.
 
Check
http://www.linux-mips.org/archives/linux-mips/2008-09/msg00136.html  
 

Thanks,

Halesh



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Re: execve errno setting on MIPS

[Thomas Bogendoerfer]

On Fri, Sep 19, 2008 at 08:57:17AM +0530, Sadashiiv, Halesh wrote:
> >And it looks like the ARG_MAX limit is bigger than my installed glibc
> >thinks, because it works at least on x86. When I increase the array two
> >2 * ARG_MAX I'll get the wanted E2BIG.
>  
>  Yes, on MIPS we need to increase the ARM_MAX to 2*ARG_MAX to get E2BIG.

I've tested only on x86 and I also needed to use 2 * ARG_MAX. This all
depends on the installed glibc, which provides ARG_MAX and the installed
kernel, which sets the rules independand from glibc. If you look at
fs/exec.c in the kernel source, you see these rules. Current kernels
for example have a limit of 

#define MAX_ARG_STRINGS 0x7FFFFFFF

for the number of strings. Looks like E2BIG is triggered by the space
needed for the strings (I only had a quick look at exec.c).

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessary a
good idea.                                                [ RFC1925, 2.3 ]