readmmap.c

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    1 /*
    2  * CDDL HEADER START
    3  *
    4  * The contents of this file are subject to the terms of the
    5  * Common Development and Distribution License (the "License").
    6  * You may not use this file except in compliance with the License.
    7  *
    8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
    9  * or https://opensource.org/licenses/CDDL-1.0.
   10  * See the License for the specific language governing permissions
   11  * and limitations under the License.
   12  *
   13  * When distributing Covered Code, include this CDDL HEADER in each
   14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
   15  * If applicable, add the following below this CDDL HEADER, with the
   16  * fields enclosed by brackets "[]" replaced with your own identifying
   17  * information: Portions Copyright [yyyy] [name of copyright owner]
   18  *
   19  * CDDL HEADER END
   20  */
   21 
   22 /*
   23  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
   24  * Use is subject to license terms.
   25  */
   26 
   27 /*
   28  * --------------------------------------------------------------
   29  *      BugId 5047993 : Getting bad read data.
   30  *
   31  *      Usage: readmmap <filename>
   32  *
   33  *      where:
   34  *              filename is an absolute path to the file name.
   35  *
   36  *      Return values:
   37  *              1 : error
   38  *              0 : no errors
   39  * --------------------------------------------------------------
   40  */
   41 #include <stdio.h>
   42 #include <stdlib.h>
   43 #include <unistd.h>
   44 #include <fcntl.h>
   45 #include <errno.h>
   46 #include <sys/mman.h>
   47 #include <time.h>
   48 
   49 int
   50 main(int argc, char **argv)
   51 {
   52         const char *filename = "badfile";
   53         size_t size = 4395;
   54         size_t idx = 0;
   55         char *buf = NULL;
   56         char *map = NULL;
   57         int fd = -1, bytes, retval = 0;
   58         uint_t seed;
   59 
   60         if (argc < 2 || optind == argc) {
   61                 (void) fprintf(stderr,
   62                     "usage: %s <file name>\n", argv[0]);
   63                 exit(1);
   64         }
   65 
   66         if ((buf = calloc(1, size)) == NULL) {
   67                 perror("calloc");
   68                 exit(1);
   69         }
   70 
   71         filename = argv[optind];
   72 
   73         (void) remove(filename);
   74 
   75         fd = open(filename, O_RDWR|O_CREAT|O_TRUNC, 0666);
   76         if (fd == -1) {
   77                 perror("open to create");
   78                 retval = 1;
   79                 goto end;
   80         }
   81 
   82         bytes = write(fd, buf, size);
   83         if (bytes != size) {
   84                 (void) printf("short write: %d != %zd\n", bytes, size);
   85                 retval = 1;
   86                 goto end;
   87         }
   88 
   89         map = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
   90         if (map == MAP_FAILED) {
   91                 perror("mmap");
   92                 retval = 1;
   93                 goto end;
   94         }
   95         seed = (uint_t)time(NULL);
   96         srandom(seed);
   97 
   98         idx = random() % size;
   99         map[idx] = 1;
  100 
  101         if (msync(map, size, MS_SYNC) != 0) {
  102                 perror("msync");
  103                 retval = 1;
  104                 goto end;
  105         }
  106 
  107         if (munmap(map, size) != 0) {
  108                 perror("munmap");
  109                 retval = 1;
  110                 goto end;
  111         }
  112 
  113         bytes = pread(fd, buf, size, 0);
  114         if (bytes != size) {
  115                 (void) printf("short read: %d != %zd\n", bytes, size);
  116                 retval = 1;
  117                 goto end;
  118         }
  119 
  120         if (buf[idx] != 1) {
  121                 (void) printf(
  122                     "bad data from read!  got buf[%zd]=%d, expected 1\n",
  123                     idx, buf[idx]);
  124                 retval = 1;
  125                 goto end;
  126         }
  127 
  128         (void) printf("good data from read: buf[%zd]=1\n", idx);
  129 end:
  130         if (fd != -1) {
  131                 (void) close(fd);
  132         }
  133         if (buf != NULL) {
  134                 free(buf);
  135         }
  136 
  137         return (retval);
  138 }

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FreeBSD/Linux Kernel Cross Reference sys/contrib/openzfs/tests/zfs-tests/cmd/readmmap.c

FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/tests/zfs-tests/cmd/readmmap.c