chkdwfile.c

这是一个针对大数据的反复多线程读写文件系统的测试代码。

/* Companion to some test programs... Verify that a file contains a certain
   progression: the file it expected to contain a sequence of 8byte values,
   each 8byte having the current file offset encoded in its 48LSbs. */

#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>

int main(int argc, char *argv[])
{
  int fd, i, r, err;
  unsigned long long buf[2048];
  unsigned long long pos;

  if(argc != 2) {
    fprintf(stderr, "Usage: %s <filename>\n", argv[0]);
    exit(1);
  }

  if((fd = open(argv[1], O_RDONLY)) <0) {
    perror("open"); exit(1);
  }

  err = 0;
  pos = 0LL;
  while(1) {
    int rem;
    if((r = read(fd, buf, sizeof(buf))) <0) {
      perror("read"); exit(1);
    }else if(r==0)
      break;
    rem = (r % sizeof(unsigned long long));
    r /= sizeof(unsigned long long);
    for(i=0; i<r; i++) {
      if((buf[i] & 0x0000FFFFFFFFFFFF) != pos) {
	printf("Error: offset %12llu, "
		"data 0x%.16llx expected 0x%.16llx\n",
		pos, buf[i], pos);
	err = 1;
	goto out;
      }		
      pos += sizeof(unsigned long long);
    }
    if(rem) {
      fprintf(stderr,"Extra %d martian bytes\n", rem);
      err = 1;
      pos += rem;
      if((r = read(fd, buf, sizeof(buf))) <0) {
	perror("read"); exit(1);
      }else if(r!=0)
	fprintf(stderr,"And file wasn't finished???\n");
      break;
    }
  }
  printf("File size %llu\n", pos);
 out:
  close(fd);
  if(err) {
    fprintf(stderr, "Error!!\n");
    return 99;
  }else fprintf(stderr, "OK\n");
  return 0;
}