stdlib.c

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