Re: libc6 bug? or C programming error?

[viro@parcelfarce.linux.theplanet.co.uk]

>   /* map the file and load an extra page in case the new line expands the
>      file across the page boundary; adding 2 allows for the truncating
>      effect of integer division.  Forcing an extra page ensures
>      that we can identify the end of the buffer by finding a NUL */

No, it does not.  Access past the EOF will give you page fault, not zero-filled
page.

>   if ((int)(buf = (char *) mmap(buf, ((c / getpagesize()) + 2) * getpagesize(),
>                   PROT_NONE, MAP_SHARED, fileno(ucf), 0)) == -1) {
>     perror("Could not map user_clusters");
>     exit(LOC_ERR_READ_FAIL);
>   }