/* 
 * hack for acpi userspace battery for QEMU
 * Michael John Wensley
 * gcc -Wall -Wextra -o ioacpi ioacpi.c $(pkg-config --cflags --libs libsystemd)
 *
 * This deals with the simplest case that guest reads variable data from a file stored on the host
 * and discard any writes, although leave open the possibility in the ioport to ioacpi protocol
 * to react to writes for subaddressing, or settings changes.
 *
 * lowlevel test, boot guest, hexedit /dev/port, goto 0xff00 and read/write
 * highlevel test, goto /sys/bus/acpi/devices/PNP0C0A:00/power_supply/BAT1
 *
 * test unsolicted writing back to ioport for interrupt injection:
 *
 *  echo -e "call lseek(4,0,0)\ncall (int)sendfile(3,4,0,1)" | gdb -p "$(pidof ioacpi)"
 *
 * When linux is the guest, code of interest:
 * linux/drivers/acpi/battery.c - search for "_B", get _BIF _BIX _BST (set interrupts at guest)
 */

#define BUFFER_SIZE 12

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <unistd.h>
#include <sys/select.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/select.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <systemd/sd-daemon.h>

void connection(int data_socket, int file_socket) {
 int ret;
 int sofar;
 int request;
 unsigned char buffer[BUFFER_SIZE];
 for (;;) {
              printf("wait data\n");
//			block(data_socket);
			ret = read(data_socket, buffer, 1);
                   	if (ret == -1) {
                       		perror("read");
                       		exit(EXIT_FAILURE);
			}
			if (ret > 0) {
				sofar = ret;
				//printf("aquire address length = %d\n", buffer[0]);
				while (sofar < (1 + buffer[0])) {
			               //printf("incomplete read, so far = %ld\n", sofar);
					ret = read(data_socket, buffer + sofar, 1 + buffer[0] - sofar);
			               //printf("read = %d\n", ret);
			                if (ret == -1) {
                        		        perror("read");
                                		exit(EXIT_FAILURE);
		                        }
					sofar += ret;
					if (ret == 0) {
						return;
					}
				}
				if (0) {
	 	                printf("have data %d %02x %02x %02x %02x %02x %02x %02x %02x %02x\n", ret,
					buffer[0],buffer[1],buffer[2],buffer[3],
					buffer[4],buffer[5],buffer[6],buffer[7],
					buffer[8]);
				}

				//printf("read data octet\n");
				ret = read(data_socket, buffer, 1);
				if (ret == 0) {
					return;
				}
				if (buffer[0] & 0x80) {
					if ((buffer[0] & 0x7f) > 0) {
						request = buffer[0] & 0x7f;
						u_int64_t addr = *((uint64_t*)&buffer[1]);
						printf("request for %d octets from address %ld\n", request, addr);
						buffer[0] = 0xEA;
						buffer[1] = 0xEA;
						buffer[2] = 0xEA;
						buffer[3] = 0xEA;
						buffer[4] = 0xEA;
						buffer[5] = 0xEA;
						buffer[6] = 0xEA;
						buffer[7] = 0xEA;
						pread(file_socket, buffer, request, addr );
						write(data_socket, buffer, request );
					} 
				} else {
					if ((buffer[0] & 0x7f) > 0) {
						request = buffer[0] & 0x7f;
						u_int64_t addr = *((uint64_t*)&buffer[1]);
						printf("offer for %d octets from address %ld\n", request, addr);
						buffer[0] = 0xEA;
						buffer[1] = 0xEA;
						buffer[2] = 0xEA;
						buffer[3] = 0xEA;
						buffer[4] = 0xEA;
						buffer[5] = 0xEA;
						buffer[6] = 0xEA;
						buffer[7] = 0xEA;
						read(data_socket, buffer, request );
						/* currently discard writes, could be enabled to test this: pwrite(file_socket, buffer, request, addr ); */
					}
				}
				fflush(stdout);
			} else {
				return;
			}
               }
}


     int
       main(int argc, char *argv[])
       {
           int connection_socket;
           int data_socket;
	   int file_socket;
		if (argc < 2) return EXIT_FAILURE;

           /* Create local socket. */
	   file_socket = open(argv[1], 0);
           if (file_socket == -1) {
               perror("cannot find acpi template file");
               exit(EXIT_FAILURE);
           }

          int n;
          for (n = SD_LISTEN_FDS_START; n < (SD_LISTEN_FDS_START + sd_listen_fds(0)); n++ ) {
                if (sd_is_socket_unix(n, SOCK_STREAM, 0, NULL, 0)) {
			printf("have connected socket\n");
                        connection(n, file_socket);
                }
                if (sd_is_socket_unix(n, SOCK_STREAM, 1, NULL, 0)) {
			printf("have listening socket\n");
                        connection_socket = n;
			break;
                }
          }
	 
	  if (n == (SD_LISTEN_FDS_START + sd_listen_fds(0))) {
		perror("Not passed fd for local socket");
		exit(EXIT_FAILURE);
	  }

	   printf("wait connection\n");
           for (;;) {

               /* Wait for incoming connection. */
               data_socket = accept(connection_socket, NULL, NULL);
               if (data_socket == -1) {
                   perror("accept");
                   exit(EXIT_FAILURE);
               }

               printf("have connection\n");
	       connection(data_socket, file_socket);

           }

           close(connection_socket);

           exit(EXIT_SUCCESS);
       }