print_info.c

   1 /* write battery/thermal status to a file ... */
   2
   3 #define _GNU_SOURCE
   4 #include <stdio.h>
   5 #include <sys/types.h>
   6 #include <sys/stat.h>
   7 #include <fcntl.h>
   8 #include <sys/select.h>
   9 #include <unistd.h>
  10
  11 #define BATFILE "/proc/acpi/battery/BAT0/state"
  12
  13 int main(int argc,char **argv) {
  14
  15         int msgfd;
  16         int batfd;
  17         char batfile[64];
  18         struct timeval to;
  19         char buf[512];
  20         char buf_o[512];
  21         int i;
  22
  23         if(argc<2) {
  24                 puts("file to read bat status from not specified,");
  25                 printf("using %s.\n",BATFILE);
  26                 strcpy(batfile,BATFILE);
  27         }
  28         else {
  29                 printf("using %s ...\n",argv[1]);
  30                 strncpy(batfile,argv[1],64-1);
  31         }
  32
  33         if((batfd=open(batfile,O_RDONLY))<0) {
  34                 printf("unable to open file %s\n",batfile);
  35                 return -1;
  36         }
  37
  38         if((msgfd=open("/var/log/battery",O_WRONLY))<0) {
  39                 puts("unable to open file /var/log/battery");
  40                 return -1;
  41         }
  42
  43         to.tv_sec=2;
  44         to.tv_usec=0;
  45
  46         while(1) {
  47                 if(select(1,NULL,NULL,NULL,&to)<0) {
  48                         puts("select call failed");
  49                         return -1;
  50                 }
  51
  52                 i=read(batfd,buf,512);
  53                 lseek(batfd,0,SEEK_SET);
  54                 buf[i]='\0';
  55                 if(strncmp(buf_o,buf,i)) {
  56                         dprintf(msgfd,"%s",buf);
  57                         strcpy(buf_o,buf);
  58                 }
  59         }
  60
  61         return 1;
  62 }