Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!usc!elroy.jpl.nasa.gov!jpl-devvax!lwall
From: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Newsgroups: comp.lang.perl
Subject: Re: perl will not open block-special files
Message-ID: <7070@jpl-devvax.JPL.NASA.GOV>
Date: 14 Feb 90 01:42:15 GMT
References: <1108@etnibsd.UUCP>
Reply-To: lwall@jpl-devvax.JPL.NASA.GOV (Larry Wall)
Organization: Jet Propulsion Laboratory, Pasadena, CA
Lines: 57

In article <1108@etnibsd.UUCP> vsh@etnibsd.UUCP (Steve Harris) writes:
: I wrote a little script to read disk blocks.  It starts with
: the following two lines:
: 
: 	$DEV = "<" . $ARGV[0];		# make sure DEV is opened for reading
: 	open DEV || die "cannot open $DEV";
: 
: The open works fine when I open a character device, but fails when I
: try to open a block device:
: 
: 	perl test.pl /dev/xy0c		# fails; xy0c is block-special
: 	perl test.pl /dev/rxy0c		# okay; rxy0c is character-special
: 
: If I open stdin and use shell redirection to associate stdin with the
: file, the open succeeds:
: 
: 	perl test.pl - < /dev/rxy0c	# okay; open stdin
: 
: So I dug into the source, and found, in "doio.c", the following code:
: 
: /**********************************************************/
:     if (stio->type &&
:       stio->type != '|' && stio->type != '-') {
: 	if (fstat(fileno(fp),&statbuf) < 0) {
: 	    (void)fclose(fp);
: 	    return FALSE;
: 	}
: 	if ((statbuf.st_mode & S_IFMT) != S_IFREG &&
: #ifdef S_IFSOCK
: 	    (statbuf.st_mode & S_IFMT) != S_IFSOCK &&
: #endif
: #ifdef S_IFFIFO
: 	    (statbuf.st_mode & S_IFMT) != S_IFFIFO &&
: #endif
: 	    (statbuf.st_mode & S_IFMT) != S_IFCHR) {
: 	    (void)fclose(fp);
: 	    return FALSE;
: 	}
:     }
: /**********************************************************/
: 
: I'm not sure what's going on here, but it sure looks like perl wants
: the device to be either regular, character-special, socket, or fifo.
: 
: Why is this?  Is it necessary?  Is this "fixed" with a patch I haven't
: had time to obtain and install?  (I'm running 3.0, patch level 1; I
: know I should get up to date but it works well enough that I have not
: done so, yet.)

This was a holdover from when perl only processed text files.  Now that
binary files won't blow things sky high, the paranoia check is unnecessary.

>>patch9  as usual

[For once, a change that deletes code rather than adding it...]

Larry