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Diffstat (limited to 'sys/mtio/mtopen.x')
| -rw-r--r-- | sys/mtio/mtopen.x | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/sys/mtio/mtopen.x b/sys/mtio/mtopen.x new file mode 100644 index 00000000..fc5d6c4f --- /dev/null +++ b/sys/mtio/mtopen.x @@ -0,0 +1,188 @@ +# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc. + +include <knet.h> +include <config.h> +include <syserr.h> +include <fset.h> +include <mach.h> +include "mtio.h" + +# MTOPEN -- Open a magtape file, or a regular binary file if the file name is +# not "mt" prefixed. Access modes are restricted to read_only, write_only, +# append, and new_tape. The buffer size argument specifies the size of the +# FIO buffer used to access the tape; a system and device dependent default +# is supplied if the buffer size is given as zero. If the device is a fixed +# block size device the buffer size will be adjusted to an integral multiple +# of the device block size. For variable size record devices, the buffer size +# determines the size of the tape record on a write, or the maximum record +# size on a read. +# +# The device to be accessed is specified as follows: +# +# [node!] mtX [ '[' file[.record] [:attr-list] ']' ] +# +# for example, +# +# mtexb1[4:nb:se@:ts=1200:so=/dev/ttya8] +# +# The "mt" prefix is required for the object to be considered a magtape device +# reference. The device name returned is "mtX" as shown above; there must be +# an entry for device mtX in the tapecap file in DEV. +# +# The file and record numbers are optional. Files and records are numbered +# starting with 1. A sequence such as "mtX[eot]" will cause the tape to be +# positioned to end of tape. "mtX[0]" causes the tape to be opened at the +# current position, i.e., without being moved. +# +# The optional attr-list field consists of a sequence of colon-delimited +# tapecap fields. These will override any values given in the tapecap entry +# for the device. The syntax for attr-list is the same as in tapecap. +# +# If the filespec does not have the prefix "mt", we assume that the file is +# a regular binary file and try to open that. If a tape file is specified +# then the drive must be allocated before we are called. We allocate and +# initialize an MTIO file descriptor and call FOPNBF to install the magtape +# device in FIO and open the device/file. + +int procedure mtopen (mtname, acmode, bufsize) + +char mtname[ARB] #I device to be opened +int acmode #I access mode +int bufsize #I fio buffer size (record size) or 0 + +bool first_time +pointer sp, devcap, fname, gty +int mt, fd, nskip, new_file, new_record + +bool streq() +pointer mt_gtyopen(), gtycaps() +int open(), fopnbf(), gtygets(), access() +int mt_skip_record(), mtfile(), mt_devallocated() +extern zopnmt(), zardmt(), zawrmt(), zawtmt(), zsttmt(), zclsmt() + +errchk open, fopnbf, fseti, syserrs, mtparse +errchk mt_getpos, mt_skip_record, mt_gtyopen, gtygets, mt_glock, mtallocate +data first_time /true/ +include "mtio.com" + +begin + call smark (sp) + call salloc (fname, SZ_PATHNAME, TY_CHAR) + call salloc (devcap, SZ_DEVCAP, TY_CHAR) + + # Runtime initialization of the mtio file descriptor common. + # Make each file descriptor available for use. + + if (first_time) { + call mt_clrcache() + do mt = 1, MT_MAXTAPES + MT_OSCHAN(mt) = NULL + first_time = false + } + + # If regular binary file, we are done. + if (mtfile(mtname) == NO) { + call sfree (sp) + return (open (mtname, acmode, BINARY_FILE)) + } + + # Get mtio file descriptor slot, but do not allocate it until + # we are ready to open the file. + + for (mt=1; mt <= MT_MAXTAPES && MT_OSCHAN(mt) != NULL; mt=mt+1) + ; + if (mt > MT_MAXTAPES) + call syserrs (SYS_MTMULTOPEN, mtname) + + # Break mtname into drive name, file and record number, etc. + call mtparse (mtname, MT_DEVICE(mt), SZ_DEVICE, + new_file, new_record, Memc[devcap], SZ_DEVCAP) + if (new_record == ERR) + new_record = 1 + + # Get tapecap info. + gty = mt_gtyopen (MT_DEVICE(mt), Memc[devcap]) + MT_DEVCAP(mt) = gtycaps (gty) + if (gtygets (gty, "dv", MT_IODEV(mt), SZ_IODEV) <= 0) { + call eprintf ("missing `dv' parameter in tapecap entry for %s\n") + call pargstr (mtname) + call syserrs (SYS_MTTAPECAP, mtname) + } + call ki_xnode (MT_DEVICE(mt), MT_IODEV(mt), SZ_IODEV) + + # If the device has not been allocated, at least write out the + # lock file. This will not physically allocate the device, but + # the lock file is required to be able to access the device. + + call mt_glock (mtname, MT_LKNAME(mt), SZ_LKNAME) + if (mt_devallocated (MT_IODEV(mt)) == NO) + if (access (MT_LKNAME(mt), 0,0) == NO) + call mtallocate (mtname) + + # Get current tape position. + call mt_getpos (mtname, mt) + + MT_FILE(mt) = new_file + MT_RECORD(mt) = new_record + MT_ATEOF(mt) = NO + + # If tape is opened for writing but no file number is given, default + # to EOT. Defaulting to current file or BOT could result in + # destruction of the tape. Note that this default WILL RESULT IN TAPE + # RUNAWAY if used on a blank tape. Blank tapes must be explicitly + # written at file [1], or opened with access mode NEW_TAPE. + + if ((acmode == WRITE_ONLY && MT_FILE(mt) == -1) || (acmode == APPEND)) { + MT_FILE(mt) = EOT + MT_RECORD(mt) = 1 + } else if (acmode == NEW_TAPE) { + MT_FILE(mt) = 1 + MT_RECORD(mt) = 1 + } + + # Make sure that we are not reopening a drive which is already open. + for (fd=1; fd <= MT_MAXTAPES; fd=fd+1) + if (fd != mt && MT_OSCHAN(fd) != NULL) + if (streq (MT_DEVICE(fd), MT_DEVICE(mt))) + call syserrs (SYS_MTMULTOPEN, mtname) + + # Initialize the remaining fields in the file descriptor and open the + # device. ZOPNMT will position the tape. Note that we pass the index + # of the new mtio descriptor slot to ZOPNMT in the common. This is a + # bit ugly, but is safe enough, since we know that FOPNBF is going to + # call ZOPNMT. + + switch (acmode) { + case READ_ONLY: + MT_ACMODE(mt) = READ_ONLY + case WRITE_ONLY, APPEND, NEW_TAPE: + MT_ACMODE(mt) = WRITE_ONLY + default: + call syserrs (SYS_MTACMODE, mtname) + } + + new_mtchan = mt + fd = fopnbf (MT_IODEV(mt), acmode, + zopnmt, zardmt, zawrmt, zawtmt, zsttmt, zclsmt) + + # Set the file buffer size (record size for variable block devices). + if (bufsize > 0) + call fseti (fd, F_BUFSIZE, bufsize) + + # If the user specified a record offset, skip records up to there. + # Zero means leave positioned to old record. + + if (MT_RECORD(mt) == 0) + MT_RECORD(mt) = MT_RECNO(mt) + if (MT_RECORD(mt) > 1) { + nskip = MT_RECORD(mt) - 1 + MT_RECORD(mt) = 1 + if (mt_skip_record (fd, nskip) != nskip) + call syserrs (SYS_MTSKIPREC, mtname) + } + + call mt_savepos (mt) + + call sfree (sp) + return (fd) +end |