tepoch.c - plan9port - [fork] Plan 9 from user space
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       ---
       tepoch.c (1021B)
       ---
            1 #include "stdinc.h"
            2 #include "dat.h"
            3 #include "fns.h"
            4 
            5 uchar buf[65536];
            6 
            7 void
            8 usage(void)
            9 {
           10         fprint(2, "usage: fossil/epoch fs [new-low-epoch]\n");
           11         threadexitsall("usage");
           12 }
           13 
           14 void
           15 threadmain(int argc, char **argv)
           16 {
           17         int fd;
           18         Header h;
           19         Super s;
           20 
           21         ARGBEGIN{
           22         default:
           23                 usage();
           24         }ARGEND
           25 
           26         if(argc == 0 || argc > 2)
           27                 usage();
           28 
           29         if((fd = open(argv[0], argc==2 ? ORDWR : OREAD)) < 0)
           30                 sysfatal("open %s: %r", argv[0]);
           31 
           32         if(pread(fd, buf, HeaderSize, HeaderOffset) != HeaderSize)
           33                 sysfatal("reading header: %r");
           34         if(!headerUnpack(&h, buf))
           35                 sysfatal("unpacking header: %r");
           36 
           37         if(pread(fd, buf, h.blockSize, (vlong)h.super*h.blockSize) != h.blockSize)
           38                 sysfatal("reading super block: %r");
           39 
           40         if(!superUnpack(&s, buf))
           41                 sysfatal("unpacking super block: %r");
           42 
           43         print("epoch %d\n", s.epochLow);
           44         if(argc == 2){
           45                 s.epochLow = strtoul(argv[1], 0, 0);
           46                 superPack(&s, buf);
           47                 if(pwrite(fd, buf, h.blockSize, (vlong)h.super*h.blockSize) != h.blockSize)
           48                         sysfatal("writing super block: %r");
           49         }
           50         threadexitsall(0);
           51 }