buffer.c

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/*
 * Copyright (C) 2004-2008, 2012, 2014, 2015  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1998-2002  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/*! \file */

#include <config.h>

#include <isc/buffer.h>
#include <isc/mem.h>
#include <isc/region.h>
#include <isc/string.h>
#include <isc/util.h>

void
isc__buffer_init(isc_buffer_t *b, void *base, unsigned int length) {
        /*
         * Make 'b' refer to the 'length'-byte region starting at 'base'.
         * XXXDCL see the comment in buffer.h about base being const.
         */

        REQUIRE(b != NULL);

        ISC__BUFFER_INIT(b, base, length);
}

void
isc__buffer_initnull(isc_buffer_t *b) {
        /*
         * Initialize a new buffer which has no backing store.  This can
         * later be grown as needed and swapped in place.
         */

        ISC__BUFFER_INIT(b, NULL, 0);
}

void
isc_buffer_reinit(isc_buffer_t *b, void *base, unsigned int length) {
        /*
         * Re-initialize the buffer enough to reconfigure the base of the
         * buffer.  We will swap in the new buffer, after copying any
         * data we contain into the new buffer and adjusting all of our
         * internal pointers.
         *
         * The buffer must not be smaller than the length of the original
         * buffer.
         */
        REQUIRE(b->length <= length);
        REQUIRE(base != NULL);

        (void)memmove(base, b->base, b->length);
        b->base = base;
        b->length = length;
}

void
isc__buffer_invalidate(isc_buffer_t *b) {
        /*
         * Make 'b' an invalid buffer.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(!ISC_LINK_LINKED(b, link));
        REQUIRE(b->mctx == NULL);

        ISC__BUFFER_INVALIDATE(b);
}

void
isc__buffer_region(isc_buffer_t *b, isc_region_t *r) {
        /*
         * Make 'r' refer to the region of 'b'.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(r != NULL);

        ISC__BUFFER_REGION(b, r);
}

void
isc__buffer_usedregion(isc_buffer_t *b, isc_region_t *r) {
        /*
         * Make 'r' refer to the used region of 'b'.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(r != NULL);

        ISC__BUFFER_USEDREGION(b, r);
}

void
isc__buffer_availableregion(isc_buffer_t *b, isc_region_t *r) {
        /*
         * Make 'r' refer to the available region of 'b'.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(r != NULL);

        ISC__BUFFER_AVAILABLEREGION(b, r);
}

void
isc__buffer_add(isc_buffer_t *b, unsigned int n) {
        /*
         * Increase the 'used' region of 'b' by 'n' bytes.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->used + n <= b->length);

        ISC__BUFFER_ADD(b, n);
}

void
isc__buffer_subtract(isc_buffer_t *b, unsigned int n) {
        /*
         * Decrease the 'used' region of 'b' by 'n' bytes.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->used >= n);

        ISC__BUFFER_SUBTRACT(b, n);
}

void
isc__buffer_clear(isc_buffer_t *b) {
        /*
         * Make the used region empty.
         */

        REQUIRE(ISC_BUFFER_VALID(b));

        ISC__BUFFER_CLEAR(b);
}

void
isc__buffer_consumedregion(isc_buffer_t *b, isc_region_t *r) {
        /*
         * Make 'r' refer to the consumed region of 'b'.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(r != NULL);

        ISC__BUFFER_CONSUMEDREGION(b, r);
}

void
isc__buffer_remainingregion(isc_buffer_t *b, isc_region_t *r) {
        /*
         * Make 'r' refer to the remaining region of 'b'.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(r != NULL);

        ISC__BUFFER_REMAININGREGION(b, r);
}

void
isc__buffer_activeregion(isc_buffer_t *b, isc_region_t *r) {
        /*
         * Make 'r' refer to the active region of 'b'.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(r != NULL);

        ISC__BUFFER_ACTIVEREGION(b, r);
}

void
isc__buffer_setactive(isc_buffer_t *b, unsigned int n) {
        /*
         * Sets the end of the active region 'n' bytes after current.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->current + n <= b->used);

        ISC__BUFFER_SETACTIVE(b, n);
}

void
isc__buffer_first(isc_buffer_t *b) {
        /*
         * Make the consumed region empty.
         */

        REQUIRE(ISC_BUFFER_VALID(b));

        ISC__BUFFER_FIRST(b);
}

void
isc__buffer_forward(isc_buffer_t *b, unsigned int n) {
        /*
         * Increase the 'consumed' region of 'b' by 'n' bytes.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->current + n <= b->used);

        ISC__BUFFER_FORWARD(b, n);
}

void
isc__buffer_back(isc_buffer_t *b, unsigned int n) {
        /*
         * Decrease the 'consumed' region of 'b' by 'n' bytes.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(n <= b->current);

        ISC__BUFFER_BACK(b, n);
}

void
isc_buffer_compact(isc_buffer_t *b) {
        unsigned int length;
        void *src;

        /*
         * Compact the used region by moving the remaining region so it occurs
         * at the start of the buffer.  The used region is shrunk by the size
         * of the consumed region, and the consumed region is then made empty.
         */

        REQUIRE(ISC_BUFFER_VALID(b));

        src = isc_buffer_current(b);
        length = isc_buffer_remaininglength(b);
        (void)memmove(b->base, src, (size_t)length);

        if (b->active > b->current)
                b->active -= b->current;
        else
                b->active = 0;
        b->current = 0;
        b->used = length;
}

isc_uint8_t
isc_buffer_getuint8(isc_buffer_t *b) {
        unsigned char *cp;
        isc_uint8_t result;

        /*
         * Read an unsigned 8-bit integer from 'b' and return it.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->used - b->current >= 1);

        cp = isc_buffer_current(b);
        b->current += 1;
        result = ((isc_uint8_t)(cp[0]));

        return (result);
}

void
isc__buffer_putuint8(isc_buffer_t *b, isc_uint8_t val) {
        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->used + 1 <= b->length);

        ISC__BUFFER_PUTUINT8(b, val);
}

isc_uint16_t
isc_buffer_getuint16(isc_buffer_t *b) {
        unsigned char *cp;
        isc_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(ISC_BUFFER_VALID(b));
        REQUIRE(b->used - b->current >= 2);

        cp = isc_buffer_current(b);
        b->current += 2;
        result = ((unsigned int)(cp[0])) << 8;
        result |= ((unsigned int)(cp[1]));

        return (result);
}

void
isc__buffer_putuint16(isc_buffer_t *b, isc_uint16_t val) {
        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->used + 2 <= b->length);

        ISC__BUFFER_PUTUINT16(b, val);
}

void
isc__buffer_putuint24(isc_buffer_t *b, isc_uint32_t val) {
        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->used + 3 <= b->length);

        ISC__BUFFER_PUTUINT24(b, val);
}

isc_uint32_t
isc_buffer_getuint32(isc_buffer_t *b) {
        unsigned char *cp;
        isc_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(ISC_BUFFER_VALID(b));
        REQUIRE(b->used - b->current >= 4);

        cp = isc_buffer_current(b);
        b->current += 4;
        result = ((unsigned int)(cp[0])) << 24;
        result |= ((unsigned int)(cp[1])) << 16;
        result |= ((unsigned int)(cp[2])) << 8;
        result |= ((unsigned int)(cp[3]));

        return (result);
}

void
isc__buffer_putuint32(isc_buffer_t *b, isc_uint32_t val) {
        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->used + 4 <= b->length);

        ISC__BUFFER_PUTUINT32(b, val);
}

isc_uint64_t
isc_buffer_getuint48(isc_buffer_t *b) {
        unsigned char *cp;
        isc_uint64_t result;

        /*
         * Read an unsigned 48-bit integer in network byte order from 'b',
         * convert it to host byte order, and return it.
         */

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->used - b->current >= 6);

        cp = isc_buffer_current(b);
        b->current += 6;
        result = ((isc_int64_t)(cp[0])) << 40;
        result |= ((isc_int64_t)(cp[1])) << 32;
        result |= ((isc_int64_t)(cp[2])) << 24;
        result |= ((isc_int64_t)(cp[3])) << 16;
        result |= ((isc_int64_t)(cp[4])) << 8;
        result |= ((isc_int64_t)(cp[5]));

        return (result);
}

void
isc__buffer_putuint48(isc_buffer_t *b, isc_uint64_t val) {
        isc_uint16_t valhi;
        isc_uint32_t vallo;

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->used + 6 <= b->length);

        valhi = (isc_uint16_t)(val >> 32);
        vallo = (isc_uint32_t)(val & 0xFFFFFFFF);
        ISC__BUFFER_PUTUINT16(b, valhi);
        ISC__BUFFER_PUTUINT32(b, vallo);
}

void
isc__buffer_putmem(isc_buffer_t *b, const unsigned char *base,
                   unsigned int length)
{
        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(b->used + length <= b->length);

        ISC__BUFFER_PUTMEM(b, base, length);
}

void
isc__buffer_putstr(isc_buffer_t *b, const char *source) {
        unsigned int l;
        unsigned char *cp;

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(source != NULL);

        /*
         * Do not use ISC__BUFFER_PUTSTR(), so strlen is only done once.
         */
        l = strlen(source);

        REQUIRE(l <= isc_buffer_availablelength(b));

        cp = isc_buffer_used(b);
        memmove(cp, source, l);
        b->used += l;
}

isc_result_t
isc_buffer_copyregion(isc_buffer_t *b, const isc_region_t *r) {
        unsigned char *base;
        unsigned int available;

        REQUIRE(ISC_BUFFER_VALID(b));
        REQUIRE(r != NULL);

        /*
         * XXXDCL
         */
        base = isc_buffer_used(b);
        available = isc_buffer_availablelength(b);
        if (r->length > available)
                return (ISC_R_NOSPACE);
        memmove(base, r->base, r->length);
        b->used += r->length;

        return (ISC_R_SUCCESS);
}

isc_result_t
isc_buffer_allocate(isc_mem_t *mctx, isc_buffer_t **dynbuffer,
                    unsigned int length)
{
        isc_buffer_t *dbuf;

        REQUIRE(dynbuffer != NULL);
        REQUIRE(*dynbuffer == NULL);

        dbuf = isc_mem_get(mctx, length + sizeof(isc_buffer_t));
        if (dbuf == NULL)
                return (ISC_R_NOMEMORY);

        isc_buffer_init(dbuf, ((unsigned char *)dbuf) + sizeof(isc_buffer_t),
                        length);
        dbuf->mctx = mctx;

        *dynbuffer = dbuf;

        return (ISC_R_SUCCESS);
}

isc_result_t
isc_buffer_reallocate(isc_buffer_t **dynbuffer, unsigned int length) {
        isc_buffer_t *dbuf;

        REQUIRE(dynbuffer != NULL);
        REQUIRE(ISC_BUFFER_VALID(*dynbuffer));
        REQUIRE((*dynbuffer)->mctx != NULL);

        if ((*dynbuffer)->length > length)
                return (ISC_R_NOSPACE);

        /*
         * XXXMUKS: This is far more expensive than plain realloc() as
         * it doesn't remap pages, but does ordinary copy. So is
         * isc_mem_reallocate(), which has additional issues.
         */
        dbuf = isc_mem_get((*dynbuffer)->mctx, length + sizeof(isc_buffer_t));
        if (dbuf == NULL)
                return (ISC_R_NOMEMORY);

        memmove(dbuf, *dynbuffer, (*dynbuffer)->length + sizeof(isc_buffer_t));
        isc_mem_put(dbuf->mctx, *dynbuffer,
                    (*dynbuffer)->length + sizeof(isc_buffer_t));

        dbuf->base = ((unsigned char *)dbuf) + sizeof(isc_buffer_t);
        dbuf->length = length;

        INSIST(ISC_BUFFER_VALID(dbuf));

        *dynbuffer = dbuf;

        return (ISC_R_SUCCESS);
}

isc_result_t
isc_buffer_reserve(isc_buffer_t **dynbuffer, unsigned int size) {
        isc_uint64_t len;

        REQUIRE(dynbuffer != NULL);
        REQUIRE(ISC_BUFFER_VALID(*dynbuffer));

        len = (*dynbuffer)->length;
        if ((len - (*dynbuffer)->used) >= size)
                return (ISC_R_SUCCESS);

        if ((*dynbuffer)->mctx == NULL)
                return (ISC_R_NOSPACE);

        /* Round to nearest buffer size increment */
        len = size + (*dynbuffer)->used;
        len = (len + ISC_BUFFER_INCR - 1 - ((len - 1) % ISC_BUFFER_INCR));

        /* Cap at UINT_MAX */
        if (len > UINT_MAX) {
                len = UINT_MAX;
        }

        if ((len - (*dynbuffer)->used) < size)
                return (ISC_R_NOMEMORY);

        return (isc_buffer_reallocate(dynbuffer, (unsigned int) len));
}

void
isc_buffer_free(isc_buffer_t **dynbuffer) {
        unsigned int real_length;
        isc_buffer_t *dbuf;
        isc_mem_t *mctx;

        REQUIRE(dynbuffer != NULL);
        REQUIRE(ISC_BUFFER_VALID(*dynbuffer));
        REQUIRE((*dynbuffer)->mctx != NULL);

        dbuf = *dynbuffer;
        *dynbuffer = NULL;      /* destroy external reference */

        real_length = dbuf->length + sizeof(isc_buffer_t);
        mctx = dbuf->mctx;
        dbuf->mctx = NULL;
        isc_buffer_invalidate(dbuf);

        isc_mem_put(mctx, dbuf, real_length);
}

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