#include <limits.h>
#include "ourhdr.h"
#ifdef PATH_MAX
static int pathmax=PATH_MAX;
#else
static int pathmax=0;
#endif
#define PATH_MAX_GUESS 1024
char * path_alloc(int *size)
{
char *ptr;
if(pathmax==0){
errno=0;
if((pathmax=pathconf("/",_PC_PATH_MAX))<0)
{
if(errno==0) pathmax=PATH_MAX_GUESS;
else printf("pathconf error for _PC_PATH_MAX");
}else pathmax++;
}
if((ptr=malloc(pathmax+1))==NULL)
printf("malloc error for pathname");
if(size!=NULL)
*size=pathmax+1;
return (ptr);
}
#ifdef OPEN_MAX
static int openmax=OPEN_MAX;
#else
static int openmax=0;
#endif
#define OPEN_MAX_GUESS 256
int open_max(void)
{
if(openmax==0)
{
errno=0;
if((openmax=sysconf(_SC_OPEN_MAX))<0)
{
if(errno==0) openmax=OPEN_MAX_GUESS;
else printf("sysconf error for _SC_OPEN_MAX");
}
}
return (openmax);
}
int main()
{
int a=3;
printf("open_max=%d\n",open_max());
printf("address=%d\n",(void*)path_alloc(&a));
printf("%d\n",a);
return 0;
}
resut
[matcha-vanilla@localhost test]$ cc j.c
[matcha-vanilla@localhost test]$ ./a.out
open_max=1024
address=139612168
4097
[matcha-vanilla@localhost test]$
