src/main.cpp

   1 /**
   2  * shuber, 2008-04-24
   3  *
   4  * Little hack to let a process run only a specific amount of time. If process
   5  * has not finished until that amount of time it is killed.
   6  *
   7  */
   8
   9
  10 #include <stdlib.h>
  11 #include <stdio.h>
  12 #include <string.h>
  13 #include <time.h>
  14 #include <unistd.h>
  15
  16 #include <sys/wait.h>
  17 #include <sys/types.h>
  18
  19
  20
  21 #define ERR_WRONGARGS   -1
  22 #define ERR_EXECVE      -2
  23 #define ERR_FORK        -3
  24 #define ERR_WAITPID     -4
  25 #define ERR_KILL        -5
  26
  27
  28
  29 void printUsage(FILE* out, int argc, char** argv)
  30 {
  31         fprintf(out, "Run command <command> for at least a specific time. Kill\n");
  32         fprintf(out, "process executing <command> if time is over. \n");
  33         fprintf(out, "\n");
  34         fprintf(out, "Usage: %s [options] <command>\n", argv[0]);
  35         fprintf(out, "\n");
  36         fprintf(out, "Options:\n");
  37         fprintf(out, "  -h        Print this help.\n");
  38         fprintf(out, "  -t <sec>  Number of seconds.\n");
  39         fprintf(out, "  -v        Be verbose.\n");
  40 }
  41
  42
  43 int main(int argc, char** argv)
  44 {
  45         bool argHelp=false;
  46         bool argTime=false;
  47         bool argVerbose=false;
  48         float maxtime=0;
  49
  50         //Wrong arguments
  51         if( argc<=1 )
  52         {
  53                 printUsage(stderr, argc, argv);
  54                 return ERR_WRONGARGS;
  55         }
  56
  57
  58         //Get the argument index of the head of <command>
  59         int fiarg=1;
  60
  61         //Aha, argument -- skip it
  62         while( fiarg<argc && strncmp(argv[fiarg], "-", 1)==0 )
  63         {
  64                 //Help option
  65                 if( strncmp(argv[fiarg], "-h", 2) == 0 )
  66                 {
  67                         argHelp = true;
  68                 }
  69
  70                 //Parse time
  71                 else if( strncmp(argv[fiarg], "-t", 2) == 0 )
  72                 {
  73                         //Time is given -- goto next argument
  74                         argTime=true;
  75                         fiarg++;
  76                         if( fiarg >= argc)
  77                         {
  78                                 fprintf(stderr, "Missing time.\n");
  79                                 fprintf(stderr, "\n");
  80                                 printUsage(stderr, argc, argv);
  81                                 return ERR_WRONGARGS;
  82                         }
  83
  84                         //Convert the time given in seconds to float
  85                         char* endptr;
  86                         maxtime = strtof( argv[fiarg], &endptr);
  87                         if( endptr != argv[fiarg] + strlen(argv[fiarg]) ||
  88                                 maxtime<0.0)
  89                         {
  90                                 fprintf(stderr, "Invalid time.\n");
  91                                 fprintf(stderr, "\n");
  92                                 printUsage(stderr, argc, argv);
  93                                 return ERR_WRONGARGS;
  94                         }
  95                 }
  96
  97                 //Help option
  98                 else if( strncmp(argv[fiarg], "-v", 2) == 0 )
  99                 {
 100                         argVerbose = true;
 101                 }
 102
 103
 104                 //Unknown option
 105                 else
 106                 {
 107                         fprintf(stderr, "Invalid argument: %s\n", argv[fiarg]);
 108                         fprintf(stderr, "\n");
 109                         printUsage(stderr, argc, argv);
 110                         return ERR_WRONGARGS;
 111                 }
 112
 113                 //Goto next argument
 114                 fiarg++;
 115         }
 116
 117
 118         //Print help
 119         if( argHelp )
 120         {
 121                 printUsage(stdout, argc, argv);
 122                 return 0;
 123         }
 124
 125
 126         //No time given...
 127         if( !argTime )
 128         {
 129                 fprintf(stderr, "No time given!\n");
 130                 fprintf(stderr, "\n");
 131                 printUsage(stderr, argc, argv);
 132                 return ERR_WRONGARGS;
 133         }
 134
 135         //No command left
 136         if( fiarg>=argc )
 137         {
 138                 fprintf(stderr, "No command given!\n");
 139                 fprintf(stderr, "\n");
 140                 printUsage(stderr, argc, argv);
 141                 return ERR_WRONGARGS;
 142         }
 143
 144
 145
 146         //Fork process
 147         pid_t pid = fork();
 148
 149
 150         //Childrens code...
 151         if( pid == 0)
 152         {
 153                 char** newargv = (char**) malloc( sizeof(char*)*(argc-fiarg+1) );
 154                 char* newenv[] = {NULL};
 155
 156                 //Copy arguments
 157                 for( int i=fiarg; i<argc; i++)
 158                 {
 159                         newargv[i-fiarg] = (char*)malloc(strlen(argv[i])+1);
 160                         strcpy(newargv[i-fiarg], argv[i]);
 161                 }
 162                 newargv[argc-fiarg] = NULL;
 163
 164
 165                 //Execute child process
 166                 execve(newargv[0], newargv, newenv);
 167                 perror("execve");
 168                 return ERR_EXECVE;
 169         }
 170         //Parents code...
 171         else
 172         {
 173                 //Failure
 174                 if(pid==-1)
 175                 {
 176                         perror("fork");
 177                         return ERR_FORK;
 178                 }
 179
 180
 181                 //Nmb of loops=seconds
 182                 float loops=0;
 183                 //Status flags of child process
 184                 int status;
 185                 //granularity
 186                 const int ussleep=25000;
 187
 188                 while(true)
 189                 {
 190                         //Kill the child
 191                         if( loops*ussleep/1e6 >= maxtime )
 192                         {
 193                                 if( argVerbose )
 194                                         printf("Kill child...\n");
 195
 196                                 if( kill(pid, SIGTERM ) < 0)
 197                                         break;
 198                         }
 199
 200                         //Test for child
 201                         if( waitpid(-1, &status, WNOHANG | WUNTRACED | WCONTINUED) < 0 )
 202                                 break;
 203
 204                         if( WIFEXITED(status) )
 205                                 break;
 206
 207                         //Sleep a round
 208                         usleep(ussleep);
 209                         loops++;
 210
 211                 }
 212         }
 213
 214
 215         if( argVerbose)
 216                 printf("Finished\n");
 217
 218         return 0;
 219 }
 220
 221