www.nico.schottelius.org/software/cinit/browse_source/cinit-0.0.5/old/cinit.c03

/* 
 * (c) 2005 Nico Schottelius (nico-linux at schottelius.org)
 * cinit.c
 * part of cLinux
 */

#define CINIT_DIR "/etc/cinit"

#define C_INIT    "init"
#define C_SHD     "shutdown"
#define C_REBOOT  "reboot"

#define C_NEEDS   "needs"
#define C_WANTS   "wants"
#define C_RUN     "run"

/* opendir() */
#include <sys/types.h>
#include <dirent.h>

/* *stat() */
#include <sys/stat.h>
#include <unistd.h>

/* wait() */
#include <sys/wait.h>

/* strlen */
#include <string.h>

#include <stdio.h>

#include "cinit.h"

#define EKEL "/etc/cinit/init/wants"

/* status of a service */
#define ST_TMP       1        /* currently working on it */
#define ST_ONCE      2        /* executed once */
#define ST_RESPAWN   3        /* running and respawning */

/* array of svc */
/* linked list of services */
/* balanced trees */
struct svc {
   char *abs_path;
//   struct svc *next;
   int status; /* tmp, respawn, ran once */
   /* evtl: */
};

struct svcl {
   struct svc svc_list[1000];
   int process;
} svc_list;

void cerr(char *msg)
{
   printf("%s\n", msg);
}

/*********************************************************************** 
 * parallel run forked() run_svc()
 */
#define MAX_PAR 32

int run_run_svcs(char *rpath)
{
   DIR *d_tmp = NULL;
   struct dirent *tdirent;
   char *p, pathbuf[1024];
   pid_t pids[MAX_PAR];
   int tmp,i=0;

   printf("run_run_svcs on: %s\n",rpath);
  
   d_tmp = opendir(rpath);

   if(d_tmp == NULL) {
      printf("Failed to open dir: %s", rpath);
      return 0;
   }

   while( (tdirent = readdir(d_tmp) ) != NULL) {
      if (strcmp(tdirent->d_name, ".") == 0
       || strcmp(tdirent->d_name, "..") == 0)
         continue;
      
      if(i < MAX_PAR) {
         pids[i] = fork();
         i++;
      } else {
         cerr("to many dependencies");
         return 1;
      }

      if(pids[i-1] == -1) { /* err */
         cerr("fork failed\n");
         return 0;
      } else if(pids[i-1] == 0) { /* child */
         printf("Service zu starten nun: %s\n", tdirent->d_name);
         run_svc(tdirent->d_name);
         _exit(0);
      } else /* the parent simply goes the loop again */
         printf("run_svcs_PARENT\n");
   }

   closedir(d_tmp);
   
   /* wait for pids */
   while(i >= 0) {
//      printf("waiting for %d ... \n",i);
      waitpid(pids[i], &tmp, 0);
      i--;
   }
}

/*********************************************************************** 
 * run_svc: gets a wants/needs directory
 * returns whether _one_ service failed or not
 */
int run_svc(char *path)
{
   DIR *d_tmp = NULL;
   struct dirent *tdirent;
   char *p, pathbuf[1024];
   struct stat buf;
   int tmp;

   /* check if already running  / ran / currently starting */

   /* debug */
   getcwd(pathbuf,1024);

   printf("dir: %s\n",pathbuf);

   /* check for service dir */
   if( stat(path,&buf) ) {
      printf("no such service: %s\n", path);
      return 1;
   }

   /* check for needs  -> forked() */
   strcpy(pathbuf,path);
   strcat(pathbuf,"/");
   strcat(pathbuf,C_NEEDS);
   if( ! stat(pathbuf,&buf) ) {
      printf("going for %s\n",pathbuf);
      tmp = fork();
      if(tmp == -1) {
         printf("error ...\n");
         exit(1);
      } else if(tmp == 0) { /* child */
         printf("child for run_run_svcs()\n");
         run_run_svcs(pathbuf);
         _exit(0);
         printf("ZOOOMBIE\n");
      }
      else
         printf("parent\n");
   }

   /* check for wants  -> forked() ? */
   strcpy(pathbuf,path);
   strcat(pathbuf,"/");
   strcat(pathbuf,C_WANTS);

   if( ! stat(pathbuf,&buf) ) {
      printf("dir gibt es auch: %s\n", pathbuf);
      run_run_svcs(pathbuf);
   }
   
   /* check for service/run */
   strcpy(pathbuf,path);
   strcat(pathbuf,"/");
   strcat(pathbuf,C_RUN);

   d_tmp = opendir(pathbuf);

   if(d_tmp == NULL) {
      cerr("failed to open dir...");
      return 0;
   }

   while( (tdirent = readdir(d_tmp) ) != NULL) {
      if (strcmp(tdirent->d_name, ".") == 0  || strcmp(tdirent->d_name, "..") == 0)
         continue;

      p=tdirent->d_name;
      while(*p != '\0') {
         write(1,p,1);
         p++;
      }
      write(1,"\n",1);
   }

   closedir(d_tmp);

   return 1;
}

/***********************************************************************
 * the main procedure
 */

int main()
{
   char pathbuf[MAXPATH];
   struct stat buf;

   strcpy(pathbuf,CINIT_DIR);
   strcat(pathbuf,"/");
   strcat(pathbuf,C_INIT);

   printf("path: %s\n",pathbuf);

   svc_list.process = 0; 
   
   /* stat, checkdir */
   if( stat(pathbuf,&buf) ) {
      printf("PANIC ACTION: init dir missing\n");
      return 1;
   } else if( ! S_ISDIR(buf.st_mode) ) {
      printf("PANIC ACTION: init is not a dir\n");
      return 1;
   }

   if( chdir(pathbuf) == -1) {
      printf("PANIC ACTION: chdir(%s) failed!\n",pathbuf);
      return 1;
   }
   run_svc("/etc/cinit/init");
//   run_svc("");

//   run_svc("/NOT_THERE");

//   execl("/bin/zsh","zsh", "-l");

   return 0;

}