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diff --git a/sys/mtio/mtgtyopen.x b/sys/mtio/mtgtyopen.x
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+# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
+
+include <syserr.h>
+include "mtio.h"
+
+# MT_GTYOPEN -- Given a logical device name, open the tapecap file and extract
+# the entry for the named device into an open GTY descriptor.  The descriptor
+# pointer is returned as the function value.  The last entry accessed is
+# cached indefinitely so that repeated references cause the tapecap file to
+# be scanned only once.
+#
+# The tapecap file may be defined in the user environment, otherwise it
+# defaults to the compiled in default TAPECAP (dev$tapecap).  The format
+# of the "tapecap" environment variable is "filename[:devcap]", e.g.
+#
+#	home$tapecap:so
+#
+#
+# would cause the file home$tapecap to be used as the tapecap file, adding the
+# device capabilities :so to each tapecap device access (any devcap fields
+# given on the command line will override these).  Either the filename or
+# devcap field may be omitted.  For example,  reset tapecap = ":so"  causes
+# the default tapecap file dev$tapecap to be used, but enables status output
+# logging in each magtape access.
+
+pointer procedure mt_gtyopen (device, ufields)
+
+char	device[ARB]			#I local device name (incl node)
+char	ufields[ARB]			#I optional user tapecap fields
+
+int	len_ufields, junk
+char	c_device[SZ_DEVICE]
+char	c_ufields[SZ_DEVCAP]
+bool	first_time, capseen, remote
+pointer	c_gty, gty, sp, tapecap, devcap, ip, op
+pointer	fname, dname, nname, tname
+
+bool	streq()
+pointer	gtyopen()
+int	envfind(), stridxs(), strlen(), gstrcpy(), ki_gnode()
+errchk	gtyopen, syserrs
+data	first_time /true/
+
+begin
+	# First time initialization.
+	if (first_time) {
+	    c_gty = NULL
+	    first_time = false
+	}
+
+	# Check the cache.
+	if (c_gty != NULL && streq(device,c_device) && streq(ufields,c_ufields))
+	    return (c_gty)
+
+	# Cache miss.  Free the old descriptor.
+	if (c_gty != NULL)
+	    call gtyclose (c_gty)
+
+	call smark (sp)
+	call salloc (tapecap, SZ_DEVCAP, TY_CHAR)
+	call salloc (devcap, SZ_DEVCAP, TY_CHAR)
+	call salloc (fname, SZ_PATHNAME, TY_CHAR)
+	call salloc (tname, SZ_PATHNAME, TY_CHAR)
+	call salloc (dname, SZ_FNAME, TY_CHAR)
+	call salloc (nname, SZ_FNAME, TY_CHAR)
+
+	# Get tapecap definition.
+	if (envfind ("tapecap", Memc[tapecap], SZ_DEVCAP) <= 0)
+	    call strcpy (TAPECAP, Memc[tapecap], SZ_DEVCAP)
+
+	# Parse into filename and devcap fields.
+	op = fname
+	capseen = false
+	len_ufields = gstrcpy (ufields, Memc[devcap], SZ_DEVCAP)
+	for (ip=tapecap;  Memc[ip] != EOS;  ip=ip+1) {
+	    if (Memc[ip] == ':' && !capseen) {
+		Memc[op] = EOS
+		op = devcap + len_ufields
+		capseen = true
+	    }
+	    Memc[op] = Memc[ip]
+	    op = op + 1
+	}
+	Memc[op] = EOS
+
+	# Supply default filename if none given.
+	if (Memc[fname] == EOS)
+	    call strcpy (TAPECAP, Memc[fname], SZ_PATHNAME)
+
+	# If no node is specified for the tapecap file, access the tapecap
+	# file on the same node as the magtape device file.
+
+	if (stridxs ("!", Memc[fname]) <= 0)
+	    call ki_xnode (device, Memc[fname], SZ_PATHNAME)
+
+	# Get the node name the device is on.
+	remote = (ki_gnode (Memc[fname], Memc[nname], junk) != 0)
+
+	# Get the tapecap device name minus any node prefix.
+	call strcpy (device, Memc[dname], SZ_FNAME)
+	call ki_xnode ("", Memc[dname], SZ_FNAME)
+
+	# Open the tapecap entry.  Try "tapecap.<node>" first then "tapecap".
+	# <node> is the hostname of the host the tape device is on, i.e. the
+	# network server on which the drive is located.  The "tapecap.<node>"
+	# feature allows a shared common IRAF installation to support distinct
+	# tapecap files for different servers, falling back on the standard
+	# tapecap file if no node-specific file is found.
+
+	call strcpy (Memc[fname], Memc[tname], SZ_PATHNAME)
+	call strcat (".", Memc[tname], SZ_PATHNAME)
+	call strcat (Memc[nname], Memc[tname], SZ_PATHNAME)
+
+	iferr (gty = gtyopen (Memc[tname], Memc[dname], Memc[devcap]))
+	    iferr (gty = gtyopen (Memc[fname], Memc[dname], Memc[devcap]))
+		call syserrs (SYS_MTTAPECAP, device)
+	if (gty == NULL)
+	    call syserrs (SYS_MTTAPECAP, device)
+
+	# Update the cache.
+	if (strlen(ufields) <= SZ_DEVCAP) {
+	    call strcpy (device, c_device, SZ_DEVICE)
+	    call strcpy (Memc[devcap], c_ufields, SZ_DEVCAP)
+	    c_gty = gty
+	}
+
+	call sfree (sp)
+	return (gty)
+end