buf.h

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#pragma once
/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: deae54c1bda80d1163fabb64e8db5e53373a10cb $
 * @file lib/bio/buf.h
 * @brief Binary IO abstractions for buffers
 *
 *  The #fr_bio_buf_t allows readers and writers to use a shared buffer, without overflow.
 *
 * @copyright 2024 Network RADIUS SAS (legal@networkradius.com)
 */
RCSIDH(lib_bio_buf_h, "$Id: deae54c1bda80d1163fabb64e8db5e53373a10cb $")
 
typedef struct {
        uint8_t         *start;         //!< start of the buffer
        uint8_t         *end;           //!< end of the buffer
 
        uint8_t         *read;          //!< where in the buffer reads are taken from
        uint8_t         *write;         //!< where in the buffer writes are sent to
} fr_bio_buf_t;
 
static inline void fr_bio_buf_init(fr_bio_buf_t *bio_buf, uint8_t *buffer, size_t size)
{
        bio_buf->start = bio_buf->read = bio_buf->write = buffer;
        bio_buf->end = buffer + size;
}
 
size_t          fr_bio_buf_make_room(fr_bio_buf_t *bio_buf);
 
size_t          fr_bio_buf_read(fr_bio_buf_t *bio_buf, void *buffer, size_t size) CC_HINT(nonnull(1));
ssize_t         fr_bio_buf_write(fr_bio_buf_t *bio_buf, const void *buffer, size_t size) CC_HINT(nonnull);
 
 
#ifndef NDEBUG
static inline void CC_HINT(nonnull) fr_bio_buf_verify(fr_bio_buf_t const *bio_buf)
{
        fr_assert(bio_buf->start != NULL);
        fr_assert(bio_buf->start <= bio_buf->read);
        fr_assert(bio_buf->read <= bio_buf->write);
        fr_assert(bio_buf->write <= bio_buf->end);
}
#else
#define fr_bio_buf_verify(_x)
#endif
 
static inline void CC_HINT(nonnull) fr_bio_buf_reset(fr_bio_buf_t *bio_buf)
{
        fr_bio_buf_verify(bio_buf);
 
        bio_buf->read = bio_buf->write = bio_buf->start;
}
 
static inline bool CC_HINT(nonnull) fr_bio_buf_initialized(fr_bio_buf_t const *bio_buf)
{
        return (bio_buf->start != NULL);
}
 
static inline size_t CC_HINT(nonnull) fr_bio_buf_used(fr_bio_buf_t const *bio_buf)
{
        if (!fr_bio_buf_initialized(bio_buf)) return 0;
 
        fr_bio_buf_verify(bio_buf);
 
        return (bio_buf->write - bio_buf->read);
}
 
static inline size_t CC_HINT(nonnull) fr_bio_buf_write_room(fr_bio_buf_t const *bio_buf)
{
        fr_bio_buf_verify(bio_buf);
 
        return bio_buf->end - bio_buf->write;
}
 
static inline uint8_t *CC_HINT(nonnull) fr_bio_buf_write_reserve(fr_bio_buf_t *bio_buf, size_t size)
{
        fr_bio_buf_verify(bio_buf);
 
        if (fr_bio_buf_write_room(bio_buf) < size) return NULL;
 
        return bio_buf->write;
}
 
static inline int CC_HINT(nonnull) fr_bio_buf_write_alloc(fr_bio_buf_t *bio_buf, size_t size)
{
        fr_bio_buf_verify(bio_buf);
 
        if (fr_bio_buf_write_room(bio_buf) < size) return -1;
 
        bio_buf->write += size;
 
        fr_bio_buf_verify(bio_buf);
 
        return 0;
}
 
static inline void CC_HINT(nonnull) fr_bio_buf_write_undo(fr_bio_buf_t *bio_buf, size_t size)
{
        fr_bio_buf_verify(bio_buf);
 
        fr_assert(bio_buf->read + size <= bio_buf->write);
 
        bio_buf->write -= size;
        fr_bio_buf_verify(bio_buf);
 
        if (bio_buf->read == bio_buf->write) {
                fr_bio_buf_reset(bio_buf);
        }
}
 
static inline bool fr_bio_buf_contains(fr_bio_buf_t *bio_buf, void const *buffer)
{
        return ((uint8_t const *) buffer >= bio_buf->start) && ((uint8_t const *) buffer <= bio_buf->end);
}
 
#if 0
static inline void CC_HINT(nonnull) fr_bio_buf_write_update(fr_bio_buf_t *bio_buf, void const *buffer, size_t size, size_t written)
{
        if (!fr_bio_buf_initialized(bio_buf)) return;
 
        fr_bio_buf_verify(bio_buf);
 
        if (bio_buf->read == buffer) {
                fr_assert(fr_bio_buf_used(bio_buf) >= size);
 
                (void) fr_bio_buf_read(bio_buf, NULL, written);
        } else {
                /*
                 *      If we're not writing from the start of write_buffer, then the data to
                 *      be written CANNOT appear anywhere in the buffer.
                 */
                fr_assert(!fr_bio_buf_contains(bio_buf, buffer));
        }
}
#endif
 
static inline size_t CC_HINT(nonnull) fr_bio_buf_size(fr_bio_buf_t const *bio_buf)
{
        fr_bio_buf_verify(bio_buf);
 
        return (bio_buf->end - bio_buf->start);
}
 
int     fr_bio_buf_alloc(TALLOC_CTX *ctx, fr_bio_buf_t *bio_buf, size_t size) CC_HINT(nonnull);