diff options
Diffstat (limited to 'sys/fio/nullfile.x')
| -rw-r--r-- | sys/fio/nullfile.x | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/sys/fio/nullfile.x b/sys/fio/nullfile.x new file mode 100644 index 00000000..363984d1 --- /dev/null +++ b/sys/fio/nullfile.x @@ -0,0 +1,251 @@ +# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc. + +include <config.h> +include <fio.h> + +.help nullfile +.nf ___________________________________________________________________________ +NULLFILE -- Text and binary file drivers for the nullfile, "dev$null". +These special drivers behave like regular text or binary drivers but +have the special property that no i/o occurs, i.e., all output is discarded, +making it appear as if the write was successful, and EOF is returned for +all attempts to read from the file. +.endhelp ______________________________________________________________________ + +define MAX_NULLFILES (LAST_FD-FIRST_FD+1) +define SZ_DEFINBUF 1 # buffer size when reading +define SZ_DEFOUTBUF 2048 # buffer size when writing + +define NU_INUSE 01B +define NU_READ 02B +define NU_WRITE 04B + + +# ZOPNNU -- Open a nullfile. Used for both binary and text nullfiles. + +procedure zopnnu (osfn, mode, chan) + +char osfn[ARB] # osfn version of dev$null, presumably +int mode # not used +int chan # assigned channel (output) + +bool first_time +int nu +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count +data first_time /true/ + +begin + # First time initialization. + if (first_time) { + do nu = 1, MAX_NULLFILES + flags[nu] = 0 + first_time = false + } + + # Find open slot. + for (nu=1; nu <= MAX_NULLFILES; nu=nu+1) + if (flags[nu] == 0) + break + if (nu > MAX_NULLFILES) { + chan = ERR + return + } + + switch (mode) { + case READ_ONLY: + flags[nu] = NU_INUSE + NU_READ + case READ_WRITE: + flags[nu] = NU_INUSE + NU_READ + NU_WRITE + default: + flags[nu] = NU_INUSE + NU_WRITE + } + + count[nu] = 0 + chan = nu +end + + +# ZCLSNU -- Close a null file. Used for both text and binary null files. + +procedure zclsnu (chan, status) + +int chan +int status + +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count + +begin + if (flags[chan] == 0) + status = ERR + else { + flags[chan] = 0 + status = OK + } +end + + +# ZSTTNU -- Status of a null file. Used for both text and binary null files. + +procedure zsttnu (chan, param, lvalue) + +int chan +int param +long lvalue +int and() + +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count + +begin + switch (param) { + case FSTT_BLKSIZE: + lvalue = 0 + case FSTT_FILSIZE: + lvalue = 0 + case FSTT_OPTBUFSIZE, FSTT_MAXBUFSIZE: + if (and (flags[chan], NU_WRITE) != 0) + lvalue = SZ_DEFOUTBUF + else + lvalue = SZ_DEFINBUF + } +end + + +# ZARDNU, ZAWRNU, ZAWTNU -- Binary file i/o to the null file. + +procedure zardnu (chan, buf, maxbytes, loffset) + +int chan, maxbytes +char buf[ARB] +long loffset + +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count + +begin + count[chan] = 0 +end + + +procedure zawrnu (chan, buf, nbytes, loffset) + +int chan, nbytes +char buf[ARB] +long loffset + +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count + +begin + count[chan] = nbytes +end + + +procedure zawtnu (chan, status) + +int chan, status + +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count + +begin + if (flags[chan] != 0) + status = count[chan] + else + status = ERR +end + + +# ZGETNU, ZPUTNU, ZFLSNU, ZSEKNU, ZNOTNU -- Text file i/o to the null file. + +procedure zgetnu (chan, buf, maxch, status) + +int chan, maxch, status +char buf[ARB] + +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count + +begin + if (flags[chan] != 0) + status = 0 + else + status = ERR +end + + +procedure zputnu (chan, buf, nchars, status) + +int chan, nchars, status +char buf[ARB] + +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count + +begin + if (flags[chan] != 0) + status = nchars + else + status = ERR +end + + +procedure zflsnu (chan, status) + +int chan +int status + +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count + +begin + if (flags[chan] != 0) + status = OK + else + status = ERR +end + + +procedure zseknu (chan, loffset, status) + +int chan, status +long loffset + +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count + +begin + if (flags[chan] != 0) + status = OK + else + status = ERR +end + + +procedure znotnu (chan, loffset) + +int chan +long loffset + +int flags[MAX_NULLFILES] +int count[MAX_NULLFILES] +common /znucom/ flags, count + +begin + if (flags[chan] != 0) + loffset = 0 + else + loffset = ERR +end |