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#include <errno.h>

extern char ** environ;

#ifdef L_execl
int
execl(fname, arg0)
char * fname, *arg0;
{
   return execve(fname, &arg0, environ);
}
#endif

#ifdef L_execv
int
execv(fname, argv)
char * fname, **argv;
{
   return execve(fname, argv, environ);
}
#endif

#ifdef L_execle
int
execle(fname, arg0)
char *fname, *arg0;
{
   char ** envp = &arg0;
   while(*envp) envp++;
   return execve(fname, &arg0, envp+1);
}
#endif

#ifdef L_execve
int
execve(fname, argv, envp)
char * fname;
char ** argv;
char ** envp;
{
	char **p;
	int argv_len=0, argv_count=0;
	int envp_len=0, envp_count=0;
	int stack_bytes;
	unsigned short * pip;
	char * pcp, * stk_ptr, *baseoff;
	int rv;

	/* How much space for argv */
	for(p=argv; p && *p && argv_len >= 0; p++)
	{
	   argv_count++; argv_len += strlen(*p)+1;
	}

	/* How much space for envp */
	for(p=envp; p && *p && envp_len >= 0; p++)
	{
	   envp_count++; envp_len += strlen(*p)+1;
	}

	/* tot it all up */
	stack_bytes = 2				/* argc */
	            + argv_count * 2 + 2	/* argv */
		    + argv_len
		    + envp_count * 2 + 2	/* envp */
		    + envp_len;

	/* Allocate it */
	if( argv_len < 0 || envp_len < 0 || stack_bytes <= 0
	 || (int)(stk_ptr = (char*)sbrk(stack_bytes)) == -1)
	{
	   errno = ENOMEM;
	   return -1;
	}

/* Sanity check 
	printf("Argv = (%d,%d), Envp=(%d,%d), stack=%d\n",
	        argv_count, argv_len, envp_count, envp_len, stack_bytes);
*/

	/* Now copy in the strings */
	pip=(unsigned short *) stk_ptr;
	pcp=stk_ptr+2*(1+argv_count+1+envp_count+1);

	/* baseoff = stk_ptr + stack_bytes; */
	baseoff = stk_ptr;
	*pip++ = argv_count;
	for(p=argv; p && *p; p++)
	{
	   int l;
	   *pip++ = pcp-baseoff;
	   l = strlen(*p)+1;
	   memcpy(pcp, *p, l);
	   pcp += l;
	}
	*pip++ = 0;

	for(p=envp; p && *p; p++)
	{
	   int l;
	   *pip++ = pcp-baseoff;
	   l = strlen(*p)+1;
	   memcpy(pcp, *p, l);
	   pcp += l;
	}
	*pip++ = 0;

	rv = __exec(fname, stk_ptr, stack_bytes);
	/* FIXME: This will probably have to interpret '#!' style exe's */
	sbrk(-stack_bytes);
	return rv;
}
#endif

#ifdef L_execvve
int
execvve(fname, interp, argv, envp)
char * fname;
char ** interp;
char ** argv;
char ** envp;
{
	char **p;
	int argv_len=0, argv_count=0;
	int envp_len=0, envp_count=0;
	int stack_bytes;
	unsigned short * pip;
	char * pcp, * stk_ptr, *baseoff;
	int rv;

	/* How much space for argv */
	for(p=interp; p && *p && argv_len >= 0; p++)
	{
	   argv_count++; argv_len += strlen(*p)+1;
	}
	for(p=argv; p && *p && argv_len >= 0; p++)
	{
	   argv_count++; argv_len += strlen(*p)+1;
	}

	/* How much space for envp */
	for(p=envp; p && *p && envp_len >= 0; p++)
	{
	   envp_count++; envp_len += strlen(*p)+1;
	}

	/* tot it all up */
	stack_bytes = 2				/* argc */
	            + argv_count * 2 + 2	/* argv */
		    + argv_len
		    + envp_count * 2 + 2	/* envp */
		    + envp_len;

	/* Allocate it */
	if( argv_len < 0 || envp_len < 0 || stack_bytes <= 0
	 || (int)(stk_ptr = (char*)sbrk(stack_bytes)) == -1)
	{
	   errno = ENOMEM;
	   return -1;
	}

/* Sanity check 
	printf("Argv = (%d,%d), Envp=(%d,%d), stack=%d\n",
	        argv_count, argv_len, envp_count, envp_len, stack_bytes);
*/

	/* Now copy in the strings */
	pip=(unsigned short *) stk_ptr;
	pcp=stk_ptr+2*(1+argv_count+1+envp_count+1);

	/* baseoff = stk_ptr + stack_bytes; */
	baseoff = stk_ptr;
	*pip++ = argv_count;
	for(p=interp; p && *p; p++)
	{
	   int l;
	   *pip++ = pcp-baseoff;
	   l = strlen(*p)+1;
	   memcpy(pcp, *p, l);
	   pcp += l;
	}
	for(p=argv; p && *p; p++)
	{
	   int l;
	   *pip++ = pcp-baseoff;
	   l = strlen(*p)+1;
	   memcpy(pcp, *p, l);
	   pcp += l;
	}
	*pip++ = 0;

	for(p=envp; p && *p; p++)
	{
	   int l;
	   *pip++ = pcp-baseoff;
	   l = strlen(*p)+1;
	   memcpy(pcp, *p, l);
	   pcp += l;
	}
	*pip++ = 0;

	rv = __exec(fname, stk_ptr, stack_bytes);
	/* FIXME: This will probably have to interpret '#!' style exe's */
	sbrk(-stack_bytes);
	return rv;
}
#endif