www.nico.schottelius.org/software/cinit/browse_source/cinit-0.0.7/old/run_svc.c04

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

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <fcntl.h>
#include <sys/wait.h>
#include <limits.h>
#include <stdlib.h>
#include <errno.h>
#include <dirent.h>


#include "cinit.h"

/* run a service, gets relative path */
int run_svc_new(char *rpath)
{
   int tmp=0, respawn = 0, status, fd, cnt, sid;
   int p_com[2];
   char pathbuf[PATH_MAX], pathtmp[PATH_MAX]; /* pathtmp = use-it-for-all bitch*/
   char **nargv, *sbuf, *p;   /* the argv for the executed process */ 
   struct stat buf;
   pid_t pid;
   
   /* check if service is already (beeing) started */
   if ( (tmp = chk_svc(rpath) ) != ST_NO) return tmp;

   /* check whether service exists */
   if( stat(rpath,&buf) ) {
      printf("Service does not exist %s\n",rpath);
      return 0;
   } else if( ! S_ISDIR(buf.st_mode) ) {
      printf("Service is not a dir (%s)!\n",rpath);
      return 0;
   }
   
   /* get our own service ID */
   sid = add_mod_svc(rpath,ST_TMP);

   /* check, whether we should respawn */
   strcpy(pathtmp,pathbuf);
   strcat(pathtmp,"/");
   strcat(pathtmp,C_RESPAWN); /* FIXME: check return values */
   if( stat(pathtmp,&buf) == 0) respawn = 1;


   /* if respawn, we have to create a pipe to talk with child */
   if(respawn) {
      if ( pipe(p_com) == -1 )
         cerr("pipe failed",RT_PAR_FAIL);
   }

   /* fork at the beginning and before chdir */
   pid = fork();

   if( pid == -1 ) cerr("fork failed",RT_PAR_FAIL);

   if(pid == -1) {
      cerr("fork failed\n", RT_PAR_FAIL);
   } else if(pid > 0) { /* parent gets child's PID */
      
      if(respawn) {
         /* read the final byte from child */
         read(p_com[0],&tmp,1); /* FIXME: check return */
         if(tmp == ST_RESPAWN) {
            printf("kind sagte, wir respawnenen jetzt\n");
            add_mod_svc(rpath,ST_RESPAWN); /* FIXME: search bei sid! */
            return RT_PAR_OK;
         } else { /* child failed */
            printf("kind sagte, respawn kaputt\n");
            add_mod_svc(rpath,ST_FAIL); /* FIXME: search bei sid! */
         }
      } else { /* execute once */
         waitpid(pid, &status, 0);

         if(WIFEXITED(status)) {
            add_mod_svc(rpath,ST_ONCE); /* FIXME: search bei sid! */
            return RT_PAR_OK;
         } else {
            add_mod_svc(rpath,ST_FAIL); /* FIXME: search bei sid! */
            return RT_PAR_FAIL;
         }
      }
   }

   /* done till here. PARENTS EXECUTION ENDED! */
        
   /*********** CHILD EXECUTION HERE ***********/

   /* change to service dir */
   if( chdir(rpath) == -1) {
      printf("chdir(%s) failed!\n",rpath);
      return 1;
   }

   /* getcwd returns the full service name */
   if(getcwd(pathbuf,PATH_MAX) == NULL) return 0;

   printf("absolut and current %s\n",pathbuf);
 
   
   /* check for needs */

 /* do we need absolute paths anymore? */
 //  strcpy(pathbuf,rpath);
 //  strcat(pathbuf,"/");
   strcat(pathtmp,C_NEEDS);
   if( ! stat(pathbuf,&buf) ) {
      printf("going for %s\n",pathbuf);
      pid = fork();
      if(tmp == -1) {
         cerr("error ...\n", RT_PAR_FAIL);
      } else if(tmp == 0) { 
         printf("child for run_run_svcs()\n");
         run_run_svcs(pathbuf);
         _exit(0);
      }
      else
         printf("parent\n");
   }

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

   if( ! stat(pathbuf,&buf) ) {
      printf("dir gibt es auch: %s\n", pathbuf);
      run_run_svcs(pathbuf);
   }

   /**** RETRIEVE REAL BINARY NAME ****/
   /* .../run */
   strcpy(pathtmp,pathbuf);
   strcat(pathtmp,"/");
   strcat(pathtmp,C_RUN); /* FIXME: check return values */
   
   /* readlink retrieves real name, if run is a symlink */
   if ( (tmp = readlink(C_RUN,pathtmp,PATH_MAX) ) == -1) {
      if (errno != EINVAL) cerr("readlinx failed\n",RT_CHLD_FAIL);

      /* binary is not a link, copy that to argv0 */
      sbuf = (char *) malloc( strlen(pathbuf) + strlen(C_RUN) + 1 );
      if(sbuf == NULL) cerr("malloc failed\n",RT_CHLD_FAIL);

      strcpy(sbuf,pathbuf);
      strcat(pathtmp,"/");
      strcat(pathtmp,C_RUN); /* FIXME: check return values */

   } else { /* it's a link, copy to sbuf */
      sbuf = (char *) malloc( tmp + 1 );
      if(sbuf == NULL) cerr("malloc failed\n",RT_CHLD_FAIL);

      strncpy(sbuf,pathtmp,tmp);
      sbuf[tmp] = '\0';
   }
   printf("argv0: %s\n",sbuf);

   /**** BUILD ARGV ****/
   nargv = malloc( sizeof(char *) );
   if(nargv == NULL) cerr("malloc failed\n",RT_CHLD_FAIL);
   
   nargv[0] = sbuf;

   /**** read params ****/
   strcpy(pathtmp,pathbuf);
   strcat(pathtmp,"/");
   strcat(pathtmp,C_PARAMS);
   if( !stat(pathtmp,&buf) ) {
      fd = open(pathtmp,O_RDONLY);
      if(fd == -1) cerr("open params failed\n",RT_CHLD_FAIL);
   
      sbuf  = NULL;
      cnt   = 0;
      /* most likely one round */
      while ( (tmp = read(fd,pathtmp,PATH_MAX-1) ) != 0 ) {
         if(tmp == -1) cerr("read params failed\n",RT_CHLD_FAIL);
         
         /* STRCHR >> tmp ???? */
         /* terminate for strchr - do we really need that? */
         pathtmp[PATH_MAX-1] = '\0';

         sbuf = realloc(sbuf,cnt + tmp + 1);
         if(sbuf == NULL) cerr("realloc failed\n",RT_CHLD_FAIL);
         
         /* copy to temporary buffer */
         strncpy(&sbuf[cnt],pathtmp,tmp);

         cnt += tmp;
         printf("Groesse: %d (%d)\n",tmp,cnt+1);
      }
      close(fd);
   } /* if params */
   sbuf[cnt] = '\0';

   /* build argv, now really */
   /* use the allocated buffer and replace \n with \0 ;-) */
   
   cnt = 1;
//   p = sbuf;
   while ( *sbuf != '\0' ) {
      p = strchr(sbuf,'\n'); /* set p to next \n */

      nargv = realloc(nargv,(cnt+1) * sizeof(char *) );
      if(nargv == NULL) cerr("malloc failed\n",RT_CHLD_FAIL);
//      nargv[cnt] = malloc( sizeof(char *) );
//      if(nargv[cnt] == NULL) cerr("malloc failed\n",RT_CHLD_FAIL);

      nargv[cnt] = sbuf;   /* beginning of argv[cnt] */
      *p = '\0';           /* end argv[cnt] */

      tmp  = p - sbuf;
      printf("argv[%d]: %s (%d)\n",cnt,nargv[cnt],tmp);
      sbuf = p+1;
      cnt++;
   }
   /* GNAAAAAAAAAA: correct???? */
   /* close argv list */
   nargv[cnt] = malloc( sizeof(char *) );
   if(nargv[cnt] == NULL) cerr("malloc failed\n",RT_CHLD_FAIL);

   nargv[cnt] = NULL;

  //    char *strchr(const char *s, int c);
   /* end buffer */

         /* get size of argv[n] */

   /* run the fscking service */
   strcpy(pathtmp,pathbuf);
   strcat(pathtmp,"/");
   strcat(pathtmp,C_RUN);
   printf("Service starten: %s \n", pathtmp);

   /* nothing to run, so it's finished */
   if( stat(pathtmp,&buf) ) _exit(0);

   //execl(pathtmp,pathtmp,"/bin/ls","-l", "/bin/echo");
   execv(pathtmp,nargv);
   
//   _exit(1);

/* 
   if(respawn)
      tmp = 0;
   execl();
   return 1;
*/
}


/*********************************************************************** 
 * run_svc: gets a wants/needs directory
 * returns whether the 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 for service/run */
   strcpy(pathbuf,path);
   strcat(pathbuf,"/");
   strcat(pathbuf,C_RUN);

   d_tmp = opendir(pathbuf);

   if(d_tmp == NULL) {
      printf("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;
}