2.11BSD/ingres/source/iutil/rdpipe.c
# include "../ingres.h"
# include "../pipes.h"
/*
** Buffered Read From Pipe
**
** Reads from the pipe with the UNIX file descriptor `des' into
** the buffer `buf'. `Mode' tells what is to be done. `Msg' is
** the address of the input buffer, and `n' is the length of the
** info. If `n' is zero, the data is assumed to be a null-
** terminated string.
**
** `Buf' is defined in "../pipes.h" together with the modes.
** The pipe should be written by wrpipe() to insure that the
** pipe formats match.
**
** Modes:
**
** P_PRIME -- Primes the buffer. This involves cleaning out all
** the header stuff so that a physical read is forced
** on the next normal call to rdpipe(). It also resets
** the error flag, etc.
**
** P_NORM -- This is the normal mode. If the buffer is empty,
** it is filled from the pipe. `N' bytes are moved into
** `msg'. If `n' is zero, bytes are moved into `msg' up
** to and including the first null byte. The pipe is
** read whenever necessary, so the size of the data
** buffer (controlled by PBUFSIZ) has absolutely no
** effect on operation.
**
** P_SYNC -- This mode reads the buffer, filling the pipe as
** necessary, until an End Of Pipe (EOP) is encountered.
** An EOP is defined as an empty buffer with a mode
** ("hdrstat") of "END_STAT". Any data left in the pipe
** is thrown away, but error messages are not. Anything
** not already read by the user is read by P_SYNC, so if
** you are not certain that you have already read the
** previous EOP.
**
** P_EXECID -- The first (exec_id) field of the pipe buffer header
** is read and returned. This is used (for instance) by
** the DBU routines, which must get the exec_id, but must
** not read the rest of the pipe in case they must overlay
** themselves. It must ALWAYS be followed by a rdpipe of
** mode P_FUNCID!!
**
** P_FUNCID -- The second through last bytes of the pipe are read
** into the buffer, and the function code ("func_id") is
** returned. This is the second half of a P_EXECID call.
**
** P_INT -- In the event of an interrupt, a wrpipe() call should
** be made to all writable pipes of mode P_INT, and then
** rdpipe() calls should be made on all readable pipes
** of this mode. This clears out the pipe up until a
** special type of pipe header ("SYNC_STAT") is read. It
** is absolutely critical that this is called in conjunc-
** tion with all other processes. This mode is used in
** resyncpipes(), which performs all the correct calls
** in the correct order.
**
** In all cases except P_INT mode, if an error is read from the
** pipe it is automatically passed to proc_error(). This routine
** is responsible for passing the error message to the next higher
** process.
**
** If an end of file is read from the pipe, the end_job() routine
** is called. This routine should do any necessary end of job
** processing needed (closing relations, etc.) and return with
** a zero value.
**
** Default proc_error() and end_job() routines exist in the
** library, so if you don't want any extra processing, you can
** just not bother to define them.
**
** In general, the number of bytes actually read is returned. If
** you read an EOP, zero is returned.
*/
extern int (*Exitfn)(); /* defined in syserr */
extern int read(); /* standard read routine */
int (*Pi_rd_fn)() = &read; /* fn to read from pipe */
rdpipe(mode, buf1, des, msg, n)
int mode;
char *msg;
int n;
int des; /* UNIX file descriptor for pipe */
struct pipfrmt *buf1;
{
register int knt;
register int syncflg;
int i;
extern char *Proc_name;
register struct pipfrmt *buf;
buf = buf1;
# ifdef xATR1
if (tTf(99, 0))
printf("\n%s ent rdpipe md %d buf %u des %d\n", Proc_name, mode, buf, des);
# endif
syncflg = 0;
switch (mode)
{
case P_PRIME:
buf->pbuf_pt = buf->buf_len = buf->err_id = 0;
buf->hdrstat = NORM_STAT;
return (0);
case P_NORM:
break;
case P_SYNC:
syncflg++;
break;
case P_EXECID:
# ifdef xATR3
if (tTf(99, 1))
printf("%s rdpipe ret %c\n", Proc_name, buf->exec_id);
# endif
syncflg++;
break;
case P_FUNCID:
return (buf->func_id);
case P_INT:
syncflg--;
buf->hdrstat = NORM_STAT;
break;
case P_PARAM:
/* If there is currently some data, return param_id.
** else read next block are return its param_id
*/
if (buf->pbuf_pt < buf->buf_len || buf->hdrstat == LAST_STAT)
return (buf->param_id);
break;
default:
syserr("rdpipe: bad call %d", mode);
}
knt = 0;
do
{
/* check for buffer empty */
while (buf->pbuf_pt >= buf->buf_len || syncflg)
{
/* read a new buffer full */
if (buf->hdrstat == LAST_STAT && syncflg >= 0)
{
goto out;
}
# ifdef xATR3
if (tTf(99, 2))
{
printf("%s rdng %d w len %d pt %d err %d sf %d\n",
Proc_name, des, buf->buf_len, buf->pbuf_pt, buf->err_id, syncflg);
}
# endif
i = (*Pi_rd_fn)(des, buf, HDRSIZ+PBUFSIZ);
if (i == 0)
{
eoj:
# ifdef xATR3
if (tTf(99, 1))
printf("%s rdpipe exit\n", Proc_name);
# endif
if (syncflg < 0)
syserr("rdpipe: EOF %d", des);
close(W_down);
if (des != R_up)
{
# ifdef xATR1
if (tTf(99, -1))
syserr("EOF on buf=%u fd=%d", buf, des);
# endif
(*Exitfn)(-1);
}
exit(end_job());
}
buf->pbuf_pt = 0;
# ifdef xATR2
if (tTf(99, 2))
prpipe(buf);
# endif
if (i < HDRSIZ+PBUFSIZ)
syserr("rdpipe: rd err buf %u des %d", buf, des);
if (buf->hdrstat == SYNC_STAT)
{
if (syncflg < 0)
return (1);
else
syserr("rdpipe: unexpected SYNC_STAT");
}
if (buf->err_id != 0 && syncflg >= 0)
{
# ifdef xATR2
if (tTf(99, 3))
printf("%s rdpipe err %d\n", Proc_name, buf->err_id);
# endif
proc_error(buf, des);
# ifdef xATR3
if (tTf(99, 3))
printf("%s pe ret\n", Proc_name);
# endif
buf->pbuf_pt = buf->buf_len;
buf->hdrstat = NORM_STAT;
continue;
}
if (mode == P_PARAM)
return (buf->param_id);
if (mode == P_EXECID)
return (buf->exec_id);
}
/* get a byte of information */
msg[knt++] = buf->pbuf[buf->pbuf_pt++];
} while ((n == 0) ? (msg[knt-1]) : (knt < n));
out:
# ifdef xATR1
if (tTf(99, 1))
{
printf("%s rdpipe ret %d", Proc_name, knt);
if (n == 0 && syncflg == 0)
printf(", str `%s'", msg);
printf("\n");
}
# endif
return(knt);
}