tlast.c - plan9port - [fork] Plan 9 from user space
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       ---
       tlast.c (812B)
       ---
            1 #include <u.h>
            2 #include <libc.h>
            3 
            4 void
            5 usage(void)
            6 {
            7         fprint(2, "usage: fossil/last disk\n");
            8         exits("usage");
            9 }
           10 
           11 void
           12 main(int argc, char **argv)
           13 {
           14         int fd, bs, addr;
           15         char buf[20];
           16 
           17         ARGBEGIN{
           18         default:
           19                 usage();
           20         }ARGEND
           21 
           22         if(argc != 1)
           23                 usage();
           24 
           25         if((fd = open(argv[0], OREAD)) < 0)
           26                 sysfatal("open %s: %r", argv[0]);
           27 
           28         werrstr("end of file");
           29         if(seek(fd, 131072, 0) < 0 || readn(fd, buf, 20) != 20)
           30                 sysfatal("error reading %s: %r", argv[0]);
           31         fmtinstall('H', encodefmt);
           32         if(memcmp(buf, "\x37\x76\xAE\x89", 4) != 0)
           33                 sysfatal("bad magic %.4H != 3776AE89", buf);
           34         bs = buf[7]|(buf[6]<<8);
           35         addr = (buf[8]<<24)|(buf[9]<<16)|(buf[10]<<8)|buf[11];
           36         if(seek(fd, (vlong)bs*addr+34, 0) < 0 || readn(fd, buf, 20) != 20)
           37                 sysfatal("error reading %s: %r", argv[0]);
           38         print("vac:%.20lH\n", buf);
           39         exits(0);
           40 }