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 /*

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.

  *

  * Copyright 2015 Olaf Wintermann. All rights reserved.

  *

  * Redistribution and use in source and binary forms, with or without

  * modification, are permitted provided that the following conditions are met:

  *

  *   1. Redistributions of source code must retain the above copyright

  *      notice, this list of conditions and the following disclaimer.

  *

  *   2. Redistributions in binary form must reproduce the above copyright

  *      notice, this list of conditions and the following disclaimer in the

  *      documentation and/or other materials provided with the distribution.

  *

  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

  * POSSIBILITY OF SUCH DAMAGE.

  */

 #include "buffer.h"

 #include <stdarg.h>

 #include <stdlib.h>

 #include <string.h>

 UcxBuffer *ucx_buffer_new(void *space, size_t capacity, int flags) {

     UcxBuffer *buffer = (UcxBuffer*) malloc(sizeof(UcxBuffer));

     if (buffer) {

         buffer->flags = flags;

         if (!space) {

             buffer->space = (char*)malloc(capacity);

             if (!buffer->space) {

                 free(buffer);

                 return NULL;

             }

             memset(buffer->space, 0, capacity);

             buffer->flags |= UCX_BUFFER_AUTOFREE;

         } else {

             buffer->space = (char*)space;

         }

         buffer->capacity = capacity;

         buffer->size = 0;

         buffer->pos = 0;

     }

     return buffer;

 }

 void ucx_buffer_free(UcxBuffer *buffer) {

     if ((buffer->flags & UCX_BUFFER_AUTOFREE) == UCX_BUFFER_AUTOFREE) {

         free(buffer->space);

     }

     free(buffer);

 }

 UcxBuffer* ucx_buffer_extract(

         UcxBuffer *src, size_t start, size_t length, int flags) {

     if (src->size == 0 || length == 0 || start+length > src->capacity) {

         return NULL;

     }

     UcxBuffer *dst = (UcxBuffer*) malloc(sizeof(UcxBuffer));

     if (dst) {

         dst->space = (char*)malloc(length);

         if (!dst->space) {

             free(dst);

             return NULL;

         }

         dst->capacity = length;

         dst->size = length;

         dst->flags = flags | UCX_BUFFER_AUTOFREE;

         dst->pos = 0;

         memcpy(dst->space, src->space+start, length);

     }

     return dst;

 }

 int ucx_buffer_seek(UcxBuffer *buffer, off_t offset, int whence) {

     size_t npos;

     switch (whence) {

     case SEEK_CUR:

         npos = buffer->pos;

         break;

     case SEEK_END:

         npos = buffer->size;

         break;

     case SEEK_SET:

         npos = 0;

         break;

     default:

         return -1;

     }

     size_t opos = npos;

     npos += offset;

     if ((offset > 0 && npos < opos) || (offset < 0 && npos > opos)) {

         return -1;

     }

     if (npos >= buffer->size) {

         return -1;

     } else {

         buffer->pos = npos;

         return 0;

     }

 }

 int ucx_buffer_eof(UcxBuffer *buffer) {

     return buffer->pos >= buffer->size;

 }

 int ucx_buffer_extend(UcxBuffer *buffer, size_t len) {

     size_t newcap = buffer->capacity;

     if (buffer->capacity + len < buffer->capacity) {

         return -1;

     }

     while (buffer->capacity + len > newcap) {

         newcap <<= 1;

         if (newcap < buffer->capacity) {

             return -1;

         }

     }

     char *newspace = (char*)realloc(buffer->space, newcap);

     if (newspace) {

         memset(newspace+buffer->size, 0, newcap-buffer->size);

         buffer->space = newspace;

         buffer->capacity = newcap;

     } else {

         return -1;

     }

     return 0;

 }

 size_t ucx_buffer_write(const void *ptr, size_t size, size_t nitems,

         UcxBuffer *buffer) {

     size_t len = size * nitems;

     size_t required = buffer->pos + len;

     if (buffer->pos > required) {

         return 0;

     }

     if (required > buffer->capacity) {

         if ((buffer->flags & UCX_BUFFER_AUTOEXTEND) == UCX_BUFFER_AUTOEXTEND) {

             if (ucx_buffer_extend(buffer, required - buffer->capacity)) {

                 return 0;

             }

         } else {

             len = buffer->capacity - buffer->pos;

             if (size > 1) {

                 len -= len%size;

             }

         }

     }

     if (len == 0) {

         return len;

     }

     memcpy(buffer->space + buffer->pos, ptr, len);

     buffer->pos += len;

     if(buffer->pos > buffer->size) {

         buffer->size = buffer->pos;

     }

     return len / size;

 }

 size_t ucx_buffer_read(void *ptr, size_t size, size_t nitems,

         UcxBuffer *buffer) {

     size_t len = size * nitems;

     if (buffer->pos + len > buffer->size) {

         len = buffer->size - buffer->pos;

         if (size > 1) len -= len%size;

     }

     if (len <= 0) {

         return len;

     }

     memcpy(ptr, buffer->space + buffer->pos, len);

     buffer->pos += len;

     return len / size;

 }

 int ucx_buffer_putc(UcxBuffer *buffer, int c) {

     if(buffer->pos >= buffer->capacity) {

         if ((buffer->flags & UCX_BUFFER_AUTOEXTEND) == UCX_BUFFER_AUTOEXTEND) {

             if(ucx_buffer_extend(buffer, 1)) {

                 return EOF;

             }

         } else {

             return EOF;

         }

     }

     c &= 0xFF;

     buffer->space[buffer->pos] = (char) c;

     buffer->pos++;

     if(buffer->pos > buffer->size) {

         buffer->size = buffer->pos;

     }

     return c;

 }

 int ucx_buffer_getc(UcxBuffer *buffer) {

     if (ucx_buffer_eof(buffer)) {

         return EOF;

     } else {

         int c = buffer->space[buffer->pos];

         buffer->pos++;

         return c;

     }

 }

 size_t ucx_buffer_puts(UcxBuffer *buffer, char *str) {

     return ucx_buffer_write((const void*)str, 1, strlen(str), buffer);

 }