stdlib.c

   1 #include <stdlib.h>
   2 #include <string.h>
   3 #include <sys/types.h>
   4 #include <sys/wait.h>
   5
   6 char **environ;
   7
   8 void exit(int status)
   9 {
  10         _exit(status);
  11 }
  12
  13 int abs(int n)
  14 {
  15         return n >= 0 ? n : -n;
  16 }
  17
  18 long labs(long n)
  19 {
  20         return n >= 0 ? n : -n;
  21 }
  22
  23 char *getenv(char *name)
  24 {
  25         char **p = environ;
  26         int len = strlen(name);
  27         for (; *p; p++)
  28                 if (!memcmp(name, *p, len) && (*p)[len] == '=')
  29                         return *p + len + 1;
  30         return NULL;
  31 }
  32
  33 int system(char *cmd)
  34 {
  35         char *argv[] = {"/bin/sh", "-c", cmd, NULL};
  36         pid_t pid;
  37         int ret;
  38         pid = fork();
  39         if (pid < 0)
  40                 return -1;
  41         if (!pid) {
  42                 execv(argv[0], argv);
  43                 exit(1);
  44         }
  45         if (waitpid(pid, &ret, 0) != pid)
  46                 return -1;
  47         return ret;
  48 }