X-Git-Url: http://andersk.mit.edu/gitweb/openssh.git/blobdiff_plain/aff51935734441207923b8e59fbc3644fc4e7d2c..HEAD:/buffer.c

diff --git a/buffer.c b/buffer.c
index 236aeb0c..e02e1e35 100644
--- a/buffer.c
+++ b/buffer.c
@@ -1,3 +1,4 @@
+/* $OpenBSD: buffer.c,v 1.31 2006/08/03 03:34:41 deraadt Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -12,12 +13,21 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: buffer.c,v 1.21 2003/11/21 11:57:03 djm Exp $");
+
+#include <sys/param.h>
+
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
 
 #include "xmalloc.h"
 #include "buffer.h"
 #include "log.h"
 
+#define	BUFFER_MAX_CHUNK	0x100000
+#define	BUFFER_MAX_LEN		0xa00000
+#define	BUFFER_ALLOCSZ		0x008000
+
 /* Initializes the buffer structure. */
 
 void
@@ -66,6 +76,23 @@ buffer_append(Buffer *buffer, const void *data, u_int len)
 	memcpy(p, data, len);
 }
 
+static int
+buffer_compact(Buffer *buffer)
+{
+	/*
+	 * If the buffer is quite empty, but all data is at the end, move the
+	 * data to the beginning.
+	 */
+	if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) {
+		memmove(buffer->buf, buffer->buf + buffer->offset,
+			buffer->end - buffer->offset);
+		buffer->end -= buffer->offset;
+		buffer->offset = 0;
+		return (1);
+	}
+	return (0);
+}
+
 /*
  * Appends space to the buffer, expanding the buffer if necessary. This does
  * not actually copy the data into the buffer, but instead returns a pointer
@@ -78,7 +105,7 @@ buffer_append_space(Buffer *buffer, u_int len)
 	u_int newlen;
 	void *p;
 
-	if (len > 0x100000)
+	if (len > BUFFER_MAX_CHUNK)
 		fatal("buffer_append_space: len %u not supported", len);
 
 	/* If the buffer is empty, start using it from the beginning. */
@@ -93,29 +120,43 @@ restart:
 		buffer->end += len;
 		return p;
 	}
-	/*
-	 * If the buffer is quite empty, but all data is at the end, move the
-	 * data to the beginning and retry.
-	 */
-	if (buffer->offset > buffer->alloc / 2) {
-		memmove(buffer->buf, buffer->buf + buffer->offset,
-			buffer->end - buffer->offset);
-		buffer->end -= buffer->offset;
-		buffer->offset = 0;
+
+	/* Compact data back to the start of the buffer if necessary */
+	if (buffer_compact(buffer))
 		goto restart;
-	}
+
 	/* Increase the size of the buffer and retry. */
-	
-	newlen = buffer->alloc + len + 32768;
-	if (newlen > 0xa00000)
+	newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ);
+	if (newlen > BUFFER_MAX_LEN)
 		fatal("buffer_append_space: alloc %u not supported",
 		    newlen);
-	buffer->buf = xrealloc(buffer->buf, newlen);
+	buffer->buf = xrealloc(buffer->buf, 1, newlen);
 	buffer->alloc = newlen;
 	goto restart;
 	/* NOTREACHED */
 }
 
+/*
+ * Check whether an allocation of 'len' will fit in the buffer
+ * This must follow the same math as buffer_append_space
+ */
+int
+buffer_check_alloc(Buffer *buffer, u_int len)
+{
+	if (buffer->offset == buffer->end) {
+		buffer->offset = 0;
+		buffer->end = 0;
+	}
+ restart:
+	if (buffer->end + len < buffer->alloc)
+		return (1);
+	if (buffer_compact(buffer))
+		goto restart;
+	if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN)
+		return (1);
+	return (0);
+}
+
 /* Returns the number of bytes of data in the buffer. */
 
 u_int
@@ -126,34 +167,62 @@ buffer_len(Buffer *buffer)
 
 /* Gets data from the beginning of the buffer. */
 
-void
-buffer_get(Buffer *buffer, void *buf, u_int len)
+int
+buffer_get_ret(Buffer *buffer, void *buf, u_int len)
 {
-	if (len > buffer->end - buffer->offset)
-		fatal("buffer_get: trying to get more bytes %d than in buffer %d",
+	if (len > buffer->end - buffer->offset) {
+		error("buffer_get_ret: trying to get more bytes %d than in buffer %d",
 		    len, buffer->end - buffer->offset);
+		return (-1);
+	}
 	memcpy(buf, buffer->buf + buffer->offset, len);
 	buffer->offset += len;
+	return (0);
+}
+
+void
+buffer_get(Buffer *buffer, void *buf, u_int len)
+{
+	if (buffer_get_ret(buffer, buf, len) == -1)
+		fatal("buffer_get: buffer error");
 }
 
 /* Consumes the given number of bytes from the beginning of the buffer. */
 
+int
+buffer_consume_ret(Buffer *buffer, u_int bytes)
+{
+	if (bytes > buffer->end - buffer->offset) {
+		error("buffer_consume_ret: trying to get more bytes than in buffer");
+		return (-1);
+	}
+	buffer->offset += bytes;
+	return (0);
+}
+
 void
 buffer_consume(Buffer *buffer, u_int bytes)
 {
-	if (bytes > buffer->end - buffer->offset)
-		fatal("buffer_consume: trying to get more bytes than in buffer");
-	buffer->offset += bytes;
+	if (buffer_consume_ret(buffer, bytes) == -1)
+		fatal("buffer_consume: buffer error");
 }
 
 /* Consumes the given number of bytes from the end of the buffer. */
 
+int
+buffer_consume_end_ret(Buffer *buffer, u_int bytes)
+{
+	if (bytes > buffer->end - buffer->offset)
+		return (-1);
+	buffer->end -= bytes;
+	return (0);
+}
+
 void
 buffer_consume_end(Buffer *buffer, u_int bytes)
 {
-	if (bytes > buffer->end - buffer->offset)
+	if (buffer_consume_end_ret(buffer, bytes) == -1)
 		fatal("buffer_consume_end: trying to get more bytes than in buffer");
-	buffer->end -= bytes;
 }
 
 /* Returns a pointer to the first used byte in the buffer. */