diff options
Diffstat (limited to 'contrib/bind9/lib/lwres/lwbuffer.c')
| -rw-r--r-- | contrib/bind9/lib/lwres/lwbuffer.c | 144 |
1 files changed, 109 insertions, 35 deletions
diff --git a/contrib/bind9/lib/lwres/lwbuffer.c b/contrib/bind9/lib/lwres/lwbuffer.c index 69009f0..5191592 100644 --- a/contrib/bind9/lib/lwres/lwbuffer.c +++ b/contrib/bind9/lib/lwres/lwbuffer.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2004 Internet Systems Consortium, Inc. ("ISC") + * Copyright (C) 2004, 2005 Internet Systems Consortium, Inc. ("ISC") * Copyright (C) 2000, 2001 Internet Software Consortium. * * Permission to use, copy, modify, and distribute this software for any @@ -15,7 +15,99 @@ * PERFORMANCE OF THIS SOFTWARE. */ -/* $Id: lwbuffer.c,v 1.10.206.1 2004/03/06 08:15:31 marka Exp $ */ +/* $Id: lwbuffer.c,v 1.11.18.2 2005/04/29 00:17:18 marka Exp $ */ + +/*! \file */ + +/** + * These functions provide bounds checked access to a region of memory + * where data is being read or written. They are based on, and similar + * to, the isc_buffer_ functions in the ISC library. + * + * A buffer is a region of memory, together with a set of related + * subregions. The used region and the available region are disjoint, and + * their union is the buffer's region. The used region extends from the + * beginning of the buffer region to the last used byte. The available + * region extends from one byte greater than the last used byte to the + * end of the buffer's region. The size of the used region can be changed + * using various buffer commands. Initially, the used region is empty. + * + * The used region is further subdivided into two disjoint regions: the + * consumed region and the remaining region. The union of these two + * regions is the used region. The consumed region extends from the + * beginning of the used region to the byte before the current offset (if + * any). The remaining region the current pointer to the end of the used + * region. The size of the consumed region can be changed using various + * buffer commands. Initially, the consumed region is empty. + * + * The active region is an (optional) subregion of the remaining region. + * It extends from the current offset to an offset in the remaining + * region. Initially, the active region is empty. If the current offset + * advances beyond the chosen offset, the active region will also be + * empty. + * + * + * \verbatim + * /------------entire length---------------\\ + * /----- used region -----\\/-- available --\\ + * +----------------------------------------+ + * | consumed | remaining | | + * +----------------------------------------+ + * a b c d e + * + * a == base of buffer. + * b == current pointer. Can be anywhere between a and d. + * c == active pointer. Meaningful between b and d. + * d == used pointer. + * e == length of buffer. + * + * a-e == entire length of buffer. + * a-d == used region. + * a-b == consumed region. + * b-d == remaining region. + * b-c == optional active region. + * \endverbatim + * + * lwres_buffer_init() initializes the lwres_buffer_t *b and assocates it + * with the memory region of size length bytes starting at location base. + * + * lwres_buffer_invalidate() marks the buffer *b as invalid. Invalidating + * a buffer after use is not required, but makes it possible to catch its + * possible accidental use. + * + * The functions lwres_buffer_add() and lwres_buffer_subtract() + * respectively increase and decrease the used space in buffer *b by n + * bytes. lwres_buffer_add() checks for buffer overflow and + * lwres_buffer_subtract() checks for underflow. These functions do not + * allocate or deallocate memory. They just change the value of used. + * + * A buffer is re-initialised by lwres_buffer_clear(). The function sets + * used , current and active to zero. + * + * lwres_buffer_first() makes the consumed region of buffer *p empty by + * setting current to zero (the start of the buffer). + * + * lwres_buffer_forward() increases the consumed region of buffer *b by n + * bytes, checking for overflow. Similarly, lwres_buffer_back() decreases + * buffer b's consumed region by n bytes and checks for underflow. + * + * lwres_buffer_getuint8() reads an unsigned 8-bit integer from *b and + * returns it. lwres_buffer_putuint8() writes the unsigned 8-bit integer + * val to buffer *b. + * + * lwres_buffer_getuint16() and lwres_buffer_getuint32() are identical to + * lwres_buffer_putuint8() except that they respectively read an unsigned + * 16-bit or 32-bit integer in network byte order from b. Similarly, + * lwres_buffer_putuint16() and lwres_buffer_putuint32() writes the + * unsigned 16-bit or 32-bit integer val to buffer b, in network byte + * order. + * + * Arbitrary amounts of data are read or written from a lightweight + * resolver buffer with lwres_buffer_getmem() and lwres_buffer_putmem() + * respectively. lwres_buffer_putmem() copies length bytes of memory at + * base to b. Conversely, lwres_buffer_getmem() copies length bytes of + * memory from b to base. + */ #include <config.h> @@ -42,12 +134,10 @@ lwres_buffer_init(lwres_buffer_t *b, void *base, unsigned int length) b->active = 0; } +/* Make 'b' an invalid buffer. */ void lwres_buffer_invalidate(lwres_buffer_t *b) { - /* - * Make 'b' an invalid buffer. - */ REQUIRE(LWRES_BUFFER_VALID(b)); @@ -59,12 +149,10 @@ lwres_buffer_invalidate(lwres_buffer_t *b) b->active = 0; } +/* Increase the 'used' region of 'b' by 'n' bytes. */ void lwres_buffer_add(lwres_buffer_t *b, unsigned int n) { - /* - * Increase the 'used' region of 'b' by 'n' bytes. - */ REQUIRE(LWRES_BUFFER_VALID(b)); REQUIRE(b->used + n <= b->length); @@ -72,12 +160,10 @@ lwres_buffer_add(lwres_buffer_t *b, unsigned int n) b->used += n; } +/* Decrease the 'used' region of 'b' by 'n' bytes. */ void lwres_buffer_subtract(lwres_buffer_t *b, unsigned int n) { - /* - * Decrease the 'used' region of 'b' by 'n' bytes. - */ REQUIRE(LWRES_BUFFER_VALID(b)); REQUIRE(b->used >= n); @@ -89,12 +175,10 @@ lwres_buffer_subtract(lwres_buffer_t *b, unsigned int n) b->active = b->used; } +/* Make the used region empty. */ void lwres_buffer_clear(lwres_buffer_t *b) { - /* - * Make the used region empty. - */ REQUIRE(LWRES_BUFFER_VALID(b)); @@ -103,24 +187,20 @@ lwres_buffer_clear(lwres_buffer_t *b) b->active = 0; } +/* Make the consumed region empty. */ void lwres_buffer_first(lwres_buffer_t *b) { - /* - * Make the consumed region empty. - */ REQUIRE(LWRES_BUFFER_VALID(b)); b->current = 0; } +/* Increase the 'consumed' region of 'b' by 'n' bytes. */ void lwres_buffer_forward(lwres_buffer_t *b, unsigned int n) { - /* - * Increase the 'consumed' region of 'b' by 'n' bytes. - */ REQUIRE(LWRES_BUFFER_VALID(b)); REQUIRE(b->current + n <= b->used); @@ -128,12 +208,10 @@ lwres_buffer_forward(lwres_buffer_t *b, unsigned int n) b->current += n; } +/* Decrease the 'consumed' region of 'b' by 'n' bytes. */ void lwres_buffer_back(lwres_buffer_t *b, unsigned int n) { - /* - * Decrease the 'consumed' region of 'b' by 'n' bytes. - */ REQUIRE(LWRES_BUFFER_VALID(b)); REQUIRE(n <= b->current); @@ -141,15 +219,13 @@ lwres_buffer_back(lwres_buffer_t *b, unsigned int n) b->current -= n; } +/* Read an unsigned 8-bit integer from 'b' and return it. */ lwres_uint8_t lwres_buffer_getuint8(lwres_buffer_t *b) { unsigned char *cp; lwres_uint8_t result; - /* - * Read an unsigned 8-bit integer from 'b' and return it. - */ REQUIRE(LWRES_BUFFER_VALID(b)); REQUIRE(b->used - b->current >= 1); @@ -162,6 +238,7 @@ lwres_buffer_getuint8(lwres_buffer_t *b) return (result); } +/* Put an unsigned 8-bit integer */ void lwres_buffer_putuint8(lwres_buffer_t *b, lwres_uint8_t val) { @@ -176,16 +253,13 @@ lwres_buffer_putuint8(lwres_buffer_t *b, lwres_uint8_t val) cp[0] = (val & 0x00ff); } +/* Read an unsigned 16-bit integer in network byte order from 'b', convert it to host byte order, and return it. */ lwres_uint16_t lwres_buffer_getuint16(lwres_buffer_t *b) { unsigned char *cp; lwres_uint16_t result; - /* - * Read an unsigned 16-bit integer in network byte order from 'b', - * convert it to host byte order, and return it. - */ REQUIRE(LWRES_BUFFER_VALID(b)); REQUIRE(b->used - b->current >= 2); @@ -199,6 +273,7 @@ lwres_buffer_getuint16(lwres_buffer_t *b) return (result); } +/* Put an unsigned 16-bit integer. */ void lwres_buffer_putuint16(lwres_buffer_t *b, lwres_uint16_t val) { @@ -214,17 +289,13 @@ lwres_buffer_putuint16(lwres_buffer_t *b, lwres_uint16_t val) cp[1] = (val & 0x00ff); } +/* Read an unsigned 32-bit integer in network byte order from 'b', convert it to host byte order, and return it. */ lwres_uint32_t lwres_buffer_getuint32(lwres_buffer_t *b) { unsigned char *cp; lwres_uint32_t result; - /* - * Read an unsigned 32-bit integer in network byte order from 'b', - * convert it to host byte order, and return it. - */ - REQUIRE(LWRES_BUFFER_VALID(b)); REQUIRE(b->used - b->current >= 4); @@ -239,6 +310,7 @@ lwres_buffer_getuint32(lwres_buffer_t *b) return (result); } +/* Put an unsigned 32-bit integer. */ void lwres_buffer_putuint32(lwres_buffer_t *b, lwres_uint32_t val) { @@ -256,6 +328,7 @@ lwres_buffer_putuint32(lwres_buffer_t *b, lwres_uint32_t val) cp[3] = (unsigned char)(val & 0x000000ff); } +/* copies length bytes of memory at base to b */ void lwres_buffer_putmem(lwres_buffer_t *b, const unsigned char *base, unsigned int length) @@ -270,6 +343,7 @@ lwres_buffer_putmem(lwres_buffer_t *b, const unsigned char *base, b->used += length; } +/* copies length bytes of memory at b to base */ void lwres_buffer_getmem(lwres_buffer_t *b, unsigned char *base, unsigned int length) |
