/* This involves allocation of additional memory that normally isn't
/* used.
/* .IP "VSTREAM_CTL_BUFSIZE (ssize_t)"
-/* Specify a non-default buffer size, or zero to implement
-/* a no-op. Requests to resize a fixed-size buffer (stderr)
-/* are not allowed.
+/* Specify a non-default write buffer size, or zero to implement
+/* a no-op. Requests to shrink an existing buffer size are
+/* silently ignored. To get a buffer size smaller than
+/* VSTREAM_BUFSIZE, make the VSTREAM_CTL_BUFSIZE before the
+/* stream has been used. Requests to change a fixed-size buffer
+/* (e.g., stderr) are not allowed.
/*
/* NOTE: the VSTREAM_CTL_BUFSIZE request specifies intent, not
/* reality. Actual buffer sizes are not updated immediately.
-/* Instead, a write buffer size will be updated when writing
-/* to a stream for the first time, or when writing to a full
-/* buffer, and a read buffer size will be updated when reading
-/* from a stream for the first time, or when reading from an
-/* empty buffer.
+/* Instead, an existing write buffer will be resized when it
+/* is full, and an existing read buffer will be resized when
+/* the buffer is filled.
/*
/* NOTE: the vstream_*printf() routines may silently expand a
/* buffer, so that the result of some %letter specifiers can
0, 0, 0, 0, /* buffer */
vstream_buf_get_ready, vstream_buf_put_ready, vstream_buf_space,
}, STDIN_FILENO, (VSTREAM_FN) timed_read, (VSTREAM_FN) timed_write,
- VSTREAM_BUFSIZE,},
+ 0,},
{{
0, /* flags */
0, 0, 0, 0, /* buffer */
vstream_buf_get_ready, vstream_buf_put_ready, vstream_buf_space,
}, STDOUT_FILENO, (VSTREAM_FN) timed_read, (VSTREAM_FN) timed_write,
- VSTREAM_BUFSIZE,},
+ 0,},
{{
VBUF_FLAG_FIXED | VSTREAM_FLAG_WRITE,
vstream_fstd_buf, VSTREAM_BUFSIZE, VSTREAM_BUFSIZE, vstream_fstd_buf,
ssize_t used = bp->ptr - bp->data;
const char *myname = "vstream_buf_alloc";
- /*
- * Don't shrink a non-empty read buffer, or a non-flushed write buffer.
- */
- if (len <= 0)
- msg_panic("%s: bad buffer length: %ld", myname, (long) len);
- if (len < bp->len
- && (((bp->flags & VSTREAM_FLAG_READ) && bp->cnt != 0)
- || ((bp->flags & VSTREAM_FLAG_WRITE) && bp->cnt != bp->len)))
- msg_panic("%s: attempt to shrink non-empty buffer", myname);
+ if (len < bp->len)
+ msg_panic("%s: attempt to shrink buffer", myname);
if (bp->flags & VSTREAM_FLAG_FIXED)
- msg_panic("%s: attempt to resize fixed-length buffer", myname);
+ msg_panic("%s: unable to extend fixed-size buffer", myname);
/*
* Late buffer allocation allows the user to override the default policy.
* If this is the first GET operation, allocate a buffer. Late buffer
* allocation gives the application a chance to override the default
* buffering policy.
+ *
+ * XXX Tricky code to set the preferred buffer size as late as possible.
*/
- if (bp->len != stream->req_bufsize)
+ if (stream->req_bufsize == 0)
+ stream->req_bufsize = VSTREAM_BUFSIZE;
+ if (bp->len < stream->req_bufsize)
vstream_buf_alloc(bp, stream->req_bufsize);
/*
* stream or if the buffer is smaller than the requested size, allocate a
* new buffer; obviously there is no data to be flushed yet. Otherwise,
* flush the buffer.
+ *
+ * XXX Tricky code to set the preferred buffer size as late as possible.
*/
+ if (stream->req_bufsize == 0)
+ stream->req_bufsize = VSTREAM_BUFSIZE;
if (bp->len < stream->req_bufsize) {
vstream_buf_alloc(bp, stream->req_bufsize);
} else if (bp->cnt <= 0) {
if (VSTREAM_FFLUSH_SOME(stream))
return (VSTREAM_EOF);
}
- if (bp->len > stream->req_bufsize)
- vstream_buf_alloc(bp, stream->req_bufsize);
return (0);
}
* VSTREAM_BUFSIZE bytes and resize the buffer to a multiple of
* VSTREAM_BUFSIZE. We flush multiples of VSTREAM_BUFSIZE in an attempt
* to keep file updates block-aligned for better performance.
+ *
+ * XXX Tricky code to set the preferred buffer size as late as possible.
*/
#define VSTREAM_TRUNCATE(count, base) (((count) / (base)) * (base))
#define VSTREAM_ROUNDUP(count, base) VSTREAM_TRUNCATE(count + base - 1, base)
+ if (stream->req_bufsize == 0)
+ stream->req_bufsize = VSTREAM_BUFSIZE;
if (want > bp->cnt) {
if ((used = bp->len - bp->cnt) > stream->req_bufsize)
if (vstream_fflush_some(stream, VSTREAM_TRUNCATE(used, stream->req_bufsize)))
stream->jbuf = 0;
stream->iotime.tv_sec = stream->iotime.tv_usec = 0;
stream->time_limit.tv_sec = stream->time_limit.tv_usec = 0;
- stream->req_bufsize = VSTREAM_BUFSIZE;
+ stream->req_bufsize = 0;
return (stream);
}
if (req_bufsize < 0 || req_bufsize > INT_MAX)
msg_panic("unreasonable VSTREAM_CTL_BUFSIZE request: %ld",
(long) req_bufsize);
- if (req_bufsize > 0 && stream != VSTREAM_ERR)
+ if (stream != VSTREAM_ERR
+ && req_bufsize > stream->req_bufsize)
stream->req_bufsize = req_bufsize;
break;
* Test buffer expansion and shrinking. Formatted print may silently
* expand the write buffer and cause multiple bytes to be written.
*/
- copy_line(1); /* one-byte read/write */
+ copy_line(1); /* one-byte read/write */
copy_line(2); /* two-byte read/write */
- copy_line(1); /* one-byte read/write */
+ copy_line(1); /* two-byte read/write */
printf_number(); /* multi-byte write */
exit(0);
}
projects / thirdparty / postfix.git / commitdiff
