[RTEMS Project] #2757: truncate() is broken for FAT

[RTEMS trac]

#2757: truncate() is broken for FAT
--------------------------+--------------------
 Reporter:  snob-wolpike  |      Owner:
     Type:  defect        |     Status:  new
 Priority:  normal        |  Milestone:  4.11.1
Component:  filesystem    |    Version:  4.11
 Severity:  normal        |   Keywords:
--------------------------+--------------------
 Steps to reproduce:

 - Under RTEMS truncate existing file to zero length.
 - Run chkdsk under any other OS (Linux, MacOSX, Win):

 {{{
 $ sudo fsck_msdos /dev/rdisk3s1
 ** /dev/rdisk3s1
 ** Phase 1 - Preparing FAT
 ** Phase 2 - Checking Directories
 /testwrite starts with free cluster
 Truncate? [yn] n
 /testwrite: Cluster chain starting at 3030 ends with cluster marked free
 Truncate? [yn] n
 /testwrite has too many clusters allocated (logical=0, physical=2048)
 Drop superfluous clusters? [yn] n
 }}}

 Sample test code:

 {{{
 #!c
     FILE* f = fopen(TEST_FILENAME, "wb");
     if(f == 0)
     {
         printk("fopen() failed: %i %s\n", errno, strerror(errno));
         exit(0);
     }
     for(int i = 0; i < 256 * 1024; i += 1)
         fprintf(f, "Test message buffer bum %i\n", i);
     fflush(f);
     fclose(f);
     fflush(NULL);
     if(truncate(TEST_FILENAME, 0) != 0)
     {
         printk("truncate() failed: %i %s\n", errno, strerror(errno));
         exit(0);
     }
 }}}

 Both 4.11 and 4.12 affected

--
Ticket URL: <http://devel.rtems.org/ticket/2757>
RTEMS Project <http://www.rtems.org/>
RTEMS Project