stdlib.c

   1 #include <stdlib.h>
   2 #include <string.h>
   3 #include <sys/types.h>
   4 #include <sys/wait.h>
   5 #include <unistd.h>
   6
   7 #define ATEXIT_MAX              32
   8
   9 char **environ;
  10
  11 int abs(int n)
  12 {
  13         return n >= 0 ? n : -n;
  14 }
  15
  16 long labs(long n)
  17 {
  18         return n >= 0 ? n : -n;
  19 }
  20
  21 char *getenv(char *name)
  22 {
  23         char **p = environ;
  24         int len = strlen(name);
  25         for (; *p; p++)
  26                 if (!memcmp(name, *p, len) && (*p)[len] == '=')
  27                         return *p + len + 1;
  28         return NULL;
  29 }
  30
  31 int system(char *cmd)
  32 {
  33         char *argv[] = {"/bin/sh", "-c", cmd, NULL};
  34         pid_t pid;
  35         int ret;
  36         pid = fork();
  37         if (pid < 0)
  38                 return -1;
  39         if (!pid) {
  40                 execv(argv[0], argv);
  41                 exit(1);
  42         }
  43         if (waitpid(pid, &ret, 0) != pid)
  44                 return -1;
  45         return ret;
  46 }
  47
  48 static void (*atexit_func[ATEXIT_MAX])(void);
  49 static int atexit_cnt;
  50
  51 int atexit(void (*func)(void))
  52 {
  53         if (atexit_cnt >= ATEXIT_MAX)
  54                 return -1;
  55         atexit_func[atexit_cnt++] = func;
  56         return 0;
  57 }
  58
  59 void __neatlibc_exit(void)
  60 {
  61         int i;
  62         for (i = 0; i < atexit_cnt; i++)
  63                 atexit_func[i]();
  64 }
  65
  66 void exit(int status)
  67 {
  68         __neatlibc_exit();
  69         _exit(status);
  70 }