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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <config.h>
include <syserr.h>
include <finfo.h>
include <fio.h>
define MIN_DELAY 1
define MAX_DELAY 60
define INC_DELAY 1
define SOMEFILE "hlib$iraf.h"
# FWTACC -- Called if a file open fails. Determine if failure to open file
# was due to the file already being open by another task. If so, and file
# waiting is enabled in the environment, wait for file to become accessible,
# otherwise take error action.
procedure fwtacc (fd, fname)
int fd #I file we are trying to open
char fname[ARB] #I name of file
bool locked
pointer sp, osfn
int perm, delay, chan, status, ofd
long fi[LEN_FINFO]
int access(), finfo()
bool streq(), envgetb()
errchk filerr, fmapfn
include <fio.com>
define noacc_ 91
begin
call smark (sp)
call salloc (osfn, SZ_PATHNAME, TY_CHAR)
fp = fiodes[fd]
if (FMODE(fp) == NEW_FILE)
call filerr (fname, SYS_FOPEN)
# If file is blocked for some reason because it is already open
# by this process, waiting would result in a deadlock.
for (ofd=FIRST_FD; ofd <= LAST_FD; ofd=ofd+1)
if (ofd != fd && fiodes[ofd] != NULL)
if (streq (fname, FNAME(fiodes[ofd])))
call filerr (fname, SYS_FWTOPNFIL)
# If file waiting is enabled, the file exists and has write permission
# for us but is not writable at the moment, wait for the file to
# become available. FINFO is used to determine the "permanent"
# permissions for the file and the file owner. ACCESS determines the
# runtime accessibility of the file. The permanent file protection may
# permit writing but the file may not be accessible for writing at
# runtime if opened for exclusive access by another process.
if (finfo (fname, fi) == ERR)
call filerr (fname, SYS_FOPNNEXFIL)
# Directory files are not accessible as files.
if (FI_TYPE(fi) == FI_DIRECTORY)
goto noacc_
# Test if we the open failed because we cannot physically open any
# more files.
call fmapfn (SOMEFILE, Memc[osfn], SZ_PATHNAME)
call zopntx (Memc[osfn], READ_ONLY, chan)
if (chan == ERR)
call filerr (fname, SYS_FTOOMANYFILES)
else
call zclstx (chan, status)
# If the file exists, we cannot access it, and there is no temporary
# read or write lock in place on the file, then the file cannot be
# accessed.
perm = FI_PERM(fi)
locked = false
if (and (fflags[fd], FF_READ) != 0)
locked = locked || (and (perm, FF_RDLOCK) != 0)
if (and (fflags[fd], FF_WRITE) != 0)
locked = locked || (and (perm, FF_WRLOCK) != 0)
# If filewait is enabled, wait for the file to become accessible.
if (envgetb ("filewait") && locked) {
call putline (STDERR, "Waiting for access to file '")
call putline (STDERR, fname)
call putline (STDERR, "'\n")
for (delay=MIN_DELAY; delay > 0; delay=delay+INC_DELAY) {
call tsleep (min (delay, MAX_DELAY))
if (access (fname,0,0) == NO)
call filerr (fname, SYS_FOPNNEXFIL)
else if (access (fname,FMODE(fp),0) == YES) {
call sfree (sp)
return
}
# Verify that the file is still locked.
if (finfo (fname, fi) == ERR)
call filerr (fname, SYS_FOPNNEXFIL)
locked = false
if (and (fflags[fd], FF_READ) != 0)
locked = locked || (and (perm, FF_RDLOCK) != 0)
if (and (fflags[fd], FF_WRITE) != 0)
locked = locked || (and (perm, FF_WRLOCK) != 0)
if (!locked)
break
}
}
noacc_
call sfree (sp)
call filerr (fname, SYS_FWTNOACC)
end
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