1. /*
2.  * smc_read.c: Written for Mac OS X 10.5. Compile as follows:
3.  *
4.  * gcc -Wall -o smc_read smc_read.c -framework IOKit
5.  */
6.  
7. #include <stdio.h>
8. #include <IOKit/IOKitLib.h>
9.  
10. typedef struct {
11.     uint32_t key;
12.     uint8_t  __d0[22];
13.     uint32_t datasize;
14.     uint8_t  __d1[10];
15.     uint8_t  cmd;
16.     uint32_t __d2;
17.     uint8_t  data[32];
18. } AppleSMCBuffer_t;
19.  
20. int
21. main(void)
22. {
23.     io_service_t service = IOServiceGetMatchingService(kIOMasterPortDefault,
24.                                IOServiceMatching("AppleSMC"));
25.     if (!service)
26.         return -1;
27.  
28.     io_connect_t port = (io_connect_t)0;
29.     kern_return_t kr = IOServiceOpen(service, mach_task_self(), 0, &port);
30.     IOObjectRelease(service);
31.     if (kr != kIOReturnSuccess)
32.         return kr;
33.  
34.     AppleSMCBuffer_t inputStruct = { 'OSK0', {0}, 32, {0}, 5, }, outputStruct;
35.     size_t outputStructCnt = sizeof(outputStruct);
36.  
37.     kr = IOConnectCallStructMethod((mach_port_t)port, (uint32_t)2,
38.              (const void*)&inputStruct, sizeof(inputStruct),
39.              (void*)&outputStruct, &outputStructCnt);
40.     if (kr != kIOReturnSuccess)
41.         return kr;
42.  
43.     int i = 0;
44.     for (i = 0; i < 32; i++)
45.         printf("%c", outputStruct.data[i]);
46.  
47.     inputStruct.key = 'OSK1';
48.     kr = IOConnectCallStructMethod((mach_port_t)port, (uint32_t)2,
49.              (const void*)&inputStruct, sizeof(inputStruct),
50.              (void*)&outputStruct, &outputStructCnt);
51.     if (kr == kIOReturnSuccess)
52.         for (i = 0; i < 32; i++)
53.             printf("%c", outputStruct.data[i]);
54.  
55.     printf("\n");
56.  
57.     return IOServiceClose(port);
58. }