text: // Copyright (c) Microsoft. All rights reserved.
  // Licensed under the MIT license. See LICENSE file in the project root for full license information.
  
  #include <stdlib.h>
  #include <stddef.h>
  #include <string.h>
  #include <stdbool.h>
  #include "azure_c_shared_utility/gballoc.h"
  #include "azure_c_shared_utility/buffer_.h"
  #include "azure_c_shared_utility/optimize_size.h"
  #include "azure_c_shared_utility/xlogging.h"
  
  typedef struct BUFFER_TAG
  {
      unsigned char* buffer;
      size_t size;
  } BUFFER;
  
  /* Codes_SRS_BUFFER_07_001: [BUFFER_new shall allocate a BUFFER_HANDLE that will contain a NULL unsigned char*.] */
  BUFFER_HANDLE BUFFER_new(void)
  {
      BUFFER* temp = (BUFFER*)malloc(sizeof(BUFFER));
      /* Codes_SRS_BUFFER_07_002: [BUFFER_new shall return NULL on any error that occurs.] */
      if (temp != NULL)
      {
          temp->buffer = NULL;
          temp->size = 0;
      }
      return (BUFFER_HANDLE)temp;
  }
  
  static int BUFFER_safemalloc(BUFFER* handleptr, size_t size)
  {
      int result;
      size_t sizetomalloc = size;
      if (size == 0)
      {
          sizetomalloc = 1;
      }
      handleptr->buffer = (unsigned char*)malloc(sizetomalloc);
      if (handleptr->buffer == NULL)
      {
          /*Codes_SRS_BUFFER_02_003: [If allocating memory fails, then BUFFER_create shall return NULL.]*/
          LogError("Failure allocating data");
          result = __FAILURE__;
      }
      else
      {
          // we still consider the real buffer size is 0
          handleptr->size = size;
          result = 0;
      }
      return result;
  }
  
  BUFFER_HANDLE BUFFER_create(const unsigned char* source, size_t size)
  {
      BUFFER* result;
      /*Codes_SRS_BUFFER_02_001: [If source is NULL then BUFFER_create shall return NULL.]*/
      if (source == NULL)
      {
          LogError("invalid parameter source: %p", source);
          result = NULL;
      }
      else
      {
          /*Codes_SRS_BUFFER_02_002: [Otherwise, BUFFER_create shall allocate memory to hold size bytes and shall copy from source size bytes into the newly allocated memory.] */
          result = (BUFFER*)malloc(sizeof(BUFFER));
          if (result == NULL)
          {
              /*Codes_SRS_BUFFER_02_003: [If allocating memory fails, then BUFFER_create shall return NULL.] */
              /*fallthrough*/
              LogError("Failure allocating BUFFER structure");
          }
          else
          {
              /* Codes_SRS_BUFFER_02_005: [If size parameter is 0 then 1 byte of memory shall be allocated yet size of the buffer shall be set to 0.]*/
              if (BUFFER_safemalloc(result, size) != 0)
              {
                  LogError("unable to BUFFER_safemalloc ");
                  free(result);
                  result = NULL;
              }
              else
              {
                  /*Codes_SRS_BUFFER_02_004: [Otherwise, BUFFER_create shall return a non-NULL handle.] */
                  (void)memcpy(result->buffer, source, size);
              }
          }
      }
      return (BUFFER_HANDLE)result;
  }
  
  /* Codes_SRS_BUFFER_07_003: [BUFFER_delete shall delete the data associated with the BUFFER_HANDLE along with the Buffer.] */
  void BUFFER_delete(BUFFER_HANDLE handle)
  {
      /* Codes_SRS_BUFFER_07_004: [BUFFER_delete shall not delete any BUFFER_HANDLE that is NULL.] */
      if (handle != NULL)
      {
          BUFFER* b = (BUFFER*)handle;
          if (b->buffer != NULL)
          {
              /* Codes_SRS_BUFFER_07_003: [BUFFER_delete shall delete the data associated with the BUFFER_HANDLE along with the Buffer.] */
              free(b->buffer);
          }
          free(b);
      }
  }
  
  /*return 0 if the buffer was copied*/
  /*else return different than zero*/
  /* Codes_SRS_BUFFER_07_008: [BUFFER_build allocates size_t bytes, copies the unsigned char* into the buffer and returns zero on success.] */
  int BUFFER_build(BUFFER_HANDLE handle, const unsigned char* source, size_t size)
  {
      int result;
      if (handle == NULL)
      {
          /* Codes_SRS_BUFFER_07_009: [BUFFER_build shall return nonzero if handle is NULL ] */
          result = __FAILURE__;
      }
      /* Codes_SRS_BUFFER_01_002: [The size argument can be zero, in which case the underlying buffer held by the buffer instance shall be freed.] */
      else if (size == 0)
      {
          /* Codes_SRS_BUFFER_01_003: [If size is zero, source can be NULL.] */
          BUFFER* b = (BUFFER*)handle;
          free(b->buffer);
          b->buffer = NULL;
          b->size = 0;
  
          result = 0;
      }
      else
      {
          if (source == NULL)
          {
              /* Codes_SRS_BUFFER_01_001: [If size is positive and source is NULL, BUFFER_build shall return nonzero] */
              result = __FAILURE__;
          }
          else
          {
              BUFFER* b = (BUFFER*)handle;
              /* Codes_SRS_BUFFER_07_011: [BUFFER_build shall overwrite previous contents if the buffer has been previously allocated.] */
              unsigned char* newBuffer = (unsigned char*)realloc(b->buffer, size);
              if (newBuffer == NULL)
              {
                  /* Codes_SRS_BUFFER_07_010: [BUFFER_build shall return nonzero if any error is encountered.] */
                  LogError("Failure reallocating buffer");
                  result = __FAILURE__;
              }
              else
              {
                  b->buffer = newBuffer;
                  b->size = size;
                  /* Codes_SRS_BUFFER_01_002: [The size argument can be zero, in which case nothing shall be copied from source.] */
                  (void)memcpy(b->buffer, source, size);
  
                  result = 0;
              }
          }
      }
  
      return result;
  }
  
  int BUFFER_append_build(BUFFER_HANDLE handle, const unsigned char* source, size_t size)
  {
      int result;
      if (handle == NULL || source == NULL || size == 0)
      {
          /* Codes_SRS_BUFFER_07_029: [ BUFFER_append_build shall return nonzero if handle or source are NULL or if size is 0. ] */
          LogError("BUFFER_append_build failed invalid parameter handle: %p, source: %p, size: %uz", handle, source, size);
          result = __FAILURE__;
      }
      else
      {
          if (handle->buffer == NULL)
          {
              /* Codes_SRS_BUFFER_07_030: [ if handle->buffer is NULL BUFFER_append_build shall allocate the a buffer of size bytes... ] */
              if (BUFFER_safemalloc(handle, size) != 0)
              {
                  /* Codes_SRS_BUFFER_07_035: [ If any error is encountered BUFFER_append_build shall return a non-null value. ] */
                  LogError("Failure with BUFFER_safemalloc");
                  result = __FAILURE__;
              }
              else
              {
                  /* Codes_SRS_BUFFER_07_031: [ ... and copy the contents of source to handle->buffer. ] */
                  (void)memcpy(handle->buffer, source, size);
                  /* Codes_SRS_BUFFER_07_034: [ On success BUFFER_append_build shall return 0 ] */
                  result = 0;
              }
          }
          else
          {
              /* Codes_SRS_BUFFER_07_032: [ if handle->buffer is not NULL BUFFER_append_build shall realloc the buffer to be the handle->size + size ] */
              unsigned char* temp = (unsigned char*)realloc(handle->buffer, handle->size + size);
              if (temp == NULL)
              {
                  /* Codes_SRS_BUFFER_07_035: [ If any error is encountered BUFFER_append_build shall return a non-null value. ] */
                  LogError("Failure reallocating temporary buffer");
                  result = __FAILURE__;
              }
              else
              {
                  /* Codes_SRS_BUFFER_07_033: [ ... and copy the contents of source to the end of the buffer. ] */
                  handle->buffer = temp;
                  // Append the BUFFER
                  (void)memcpy(&handle->buffer[handle->size], source, size);
                  handle->size += size;
                  /* Codes_SRS_BUFFER_07_034: [ On success BUFFER_append_build shall return 0 ] */
                  result = 0;
              }
          }
      }
      return result;
  }
  
  /*return 0 if the buffer was pre-build(that is, had its space allocated)*/
  /*else return different than zero*/
  /* Codes_SRS_BUFFER_07_005: [BUFFER_pre_build allocates size_t bytes of BUFFER_HANDLE and returns zero on success.] */
  int BUFFER_pre_build(BUFFER_HANDLE handle, size_t size)
  {
      int result;
      if (handle == NULL)
      {
          /* Codes_SRS_BUFFER_07_006: [If handle is NULL or size is 0 then BUFFER_pre_build shall return a nonzero value.] */
          result = __FAILURE__;
      }
      else if (size == 0)
      {
          /* Codes_SRS_BUFFER_07_006: [If handle is NULL or size is 0 then BUFFER_pre_build shall return a nonzero value.] */
          result = __FAILURE__;
      }
      else
      {
          BUFFER* b = (BUFFER*)handle;
          if (b->buffer != NULL)
          {
              /* Codes_SRS_BUFFER_07_007: [BUFFER_pre_build shall return nonzero if the buffer has been previously allocated and is not NULL.] */
              LogError("Failure buffer data is NULL");
              result = __FAILURE__;
          }
          else
          {
              if ((b->buffer = (unsigned char*)malloc(size)) == NULL)
              {
                  /* Codes_SRS_BUFFER_07_013: [BUFFER_pre_build shall return nonzero if any error is encountered.] */
                  LogError("Failure allocating buffer");
                  result = __FAILURE__;
              }
              else
              {
                  b->size = size;
                  result = 0;
              }
          }
      }
      return result;
  }
  
  /* Codes_SRS_BUFFER_07_019: [BUFFER_content shall return the data contained within the BUFFER_HANDLE.] */
  int BUFFER_content(BUFFER_HANDLE handle, const unsigned char** content)
  {
      int result;
      if ((handle == NULL) || (content == NULL))
      {
          /* Codes_SRS_BUFFER_07_020: [If the handle and/or content*is NULL BUFFER_content shall return nonzero.] */
          result = __FAILURE__;
      }
      else
      {
          BUFFER* b = (BUFFER*)handle;
          *content = b->buffer;
          result = 0;
      }
      return result;
  }
  
  /*return 0 if everything went ok and whatever was built in the buffer was unbuilt*/
  /* Codes_SRS_BUFFER_07_012: [BUFFER_unbuild shall clear the underlying unsigned char* data associated with the BUFFER_HANDLE this will return zero on success.] */
  extern int BUFFER_unbuild(BUFFER_HANDLE handle)
  {
      int result;
      if (handle == NULL)
      {
          /* Codes_SRS_BUFFER_07_014: [BUFFER_unbuild shall return a nonzero value if BUFFER_HANDLE is NULL.] */
          result = __FAILURE__;
      }
      else
      {
          BUFFER* b = (BUFFER*)handle;
          if (b->buffer != NULL)
          {
              LogError("Failure buffer data is NULL");
              free(b->buffer);
              b->buffer = NULL;
              b->size = 0;
              result = 0;
          }
          else
          {
              /* Codes_SRS_BUFFER_07_015: [BUFFER_unbuild shall return a nonzero value if the unsigned char* referenced by BUFFER_HANDLE is NULL.] */
              result = __FAILURE__;
          }
      }
      return result;
  }
  
  /* Codes_SRS_BUFFER_07_016: [BUFFER_enlarge shall increase the size of the unsigned char* referenced by BUFFER_HANDLE.] */
  int BUFFER_enlarge(BUFFER_HANDLE handle, size_t enlargeSize)
  {
      int result;
      if (handle == NULL)
      {
          /* Codes_SRS_BUFFER_07_017: [BUFFER_enlarge shall return a nonzero result if any parameters are NULL or zero.] */
          LogError("Failure: handle is invalid.");
          result = __FAILURE__;
      }
      else if (enlargeSize == 0)
      {
          /* Codes_SRS_BUFFER_07_017: [BUFFER_enlarge shall return a nonzero result if any parameters are NULL or zero.] */
          LogError("Failure: enlargeSize size is 0.");
          result = __FAILURE__;
      }
      else
      {
          BUFFER* b = (BUFFER*)handle;
          unsigned char* temp = (unsigned char*)realloc(b->buffer, b->size + enlargeSize);
          if (temp == NULL)
          {
              /* Codes_SRS_BUFFER_07_018: [BUFFER_enlarge shall return a nonzero result if any error is encountered.] */
              LogError("Failure: allocating temp buffer.");
              result = __FAILURE__;
          }
          else
          {
              b->buffer = temp;
              b->size += enlargeSize;
              result = 0;
          }
      }
      return result;
  }
  
  int BUFFER_shrink(BUFFER_HANDLE handle, size_t decreaseSize, bool fromEnd)
  {
      int result;
      if (handle == NULL)
      {
          /* Codes_SRS_BUFFER_07_036: [ if handle is NULL, BUFFER_shrink shall return a non-null value ]*/
          LogError("Failure: handle is invalid.");
          result = __FAILURE__;
      }
      else if (decreaseSize == 0)
      {
          /* Codes_SRS_BUFFER_07_037: [ If decreaseSize is equal zero, BUFFER_shrink shall return a non-null value ] */
          LogError("Failure: decrease size is 0.");
          result = __FAILURE__;
      }
      else if (decreaseSize > handle->size)
      {
          /* Codes_SRS_BUFFER_07_038: [ If decreaseSize is less than the size of the buffer, BUFFER_shrink shall return a non-null value ] */
          LogError("Failure: decrease size is less than buffer size.");
          result = __FAILURE__;
      }
      else
      {
          /* Codes_SRS_BUFFER_07_039: [ BUFFER_shrink shall allocate a temporary buffer of existing buffer size minus decreaseSize. ] */
          size_t alloc_size = handle->size - decreaseSize;
          if (alloc_size == 0)
          {
              /* Codes_SRS_BUFFER_07_043: [ If the decreaseSize is equal the buffer size , BUFFER_shrink shall deallocate the buffer and set the size to zero. ] */
              free(handle->buffer);
              handle->buffer = NULL;
              handle->size = 0;
              result = 0;
          }
          else
          {
              unsigned char* tmp = malloc(alloc_size);
              if (tmp == NULL)
              {
                  /* Codes_SRS_BUFFER_07_042: [ If a failure is encountered, BUFFER_shrink shall return a non-null value ] */
                  LogError("Failure: allocating temp buffer.");
                  result = __FAILURE__;
              }
              else
              {
                  if (fromEnd)
                  {
                      /* Codes_SRS_BUFFER_07_040: [ if the fromEnd variable is true, BUFFER_shrink shall remove the end of the buffer of size decreaseSize. ] */
                      memcpy(tmp, handle->buffer, alloc_size);
                      free(handle->buffer);
                      handle->buffer = tmp;
                      handle->size = alloc_size;
                      result = 0;
                  }
                  else
                  {
                      /* Codes_SRS_BUFFER_07_041: [ if the fromEnd variable is false, BUFFER_shrink shall remove the beginning of the buffer of size decreaseSize. ] */
                      memcpy(tmp, handle->buffer + decreaseSize, alloc_size);
                      free(handle->buffer);
                      handle->buffer = tmp;
                      handle->size = alloc_size;
                      result = 0;
                  }
              }
          }
      }
      return result;
  }
  
  /* Codes_SRS_BUFFER_07_021: [BUFFER_size shall place the size of the associated buffer in the size variable and return zero on success.] */
  int BUFFER_size(BUFFER_HANDLE handle, size_t* size)
  {
      int result;
      if ((handle == NULL) || (size == NULL))
      {
          /* Codes_SRS_BUFFER_07_022: [BUFFER_size shall return a nonzero value for any error that is encountered.] */
          result = __FAILURE__;
      }
      else
      {
          BUFFER* b = (BUFFER*)handle;
          *size = b->size;
          result = 0;
      }
      return result;
  }
  
  /* Codes_SRS_BUFFER_07_024: [BUFFER_append concatenates b2 onto b1 without modifying b2 and shall return zero on success.] */
  int BUFFER_append(BUFFER_HANDLE handle1, BUFFER_HANDLE handle2)
  {
      int result;
      if ( (handle1 == NULL) || (handle2 == NULL) || (handle1 == handle2) )
      {
          /* Codes_SRS_BUFFER_07_023: [BUFFER_append shall return a nonzero upon any error that is encountered.] */
          result = __FAILURE__;
      }
      else
      {
          BUFFER* b1 = (BUFFER*)handle1;
          BUFFER* b2 = (BUFFER*)handle2;
          if (b1->buffer == NULL)
          {
              /* Codes_SRS_BUFFER_07_023: [BUFFER_append shall return a nonzero upon any error that is encountered.] */
              result = __FAILURE__;
          }
          else if (b2->buffer == NULL)
          {
              /* Codes_SRS_BUFFER_07_023: [BUFFER_append shall return a nonzero upon any error that is encountered.] */
              result = __FAILURE__;
          }
          else
          {
              if (b2->size ==0)
              {
                  // b2->size = 0, whatever b1->size is, do nothing
                  result = 0;
              }
              else
              {
                  // b2->size != 0, whatever b1->size is
                  unsigned char* temp = (unsigned char*)realloc(b1->buffer, b1->size + b2->size);
                  if (temp == NULL)
                  {
                      /* Codes_SRS_BUFFER_07_023: [BUFFER_append shall return a nonzero upon any error that is encountered.] */
                      LogError("Failure: allocating temp buffer.");
                      result = __FAILURE__;
                  }
                  else
                  {
                      /* Codes_SRS_BUFFER_07_024: [BUFFER_append concatenates b2 onto b1 without modifying b2 and shall return zero on success.]*/
                      b1->buffer = temp;
                      // Append the BUFFER
                      (void)memcpy(&b1->buffer[b1->size], b2->buffer, b2->size);
                      b1->size += b2->size;
                      result = 0;
                  }
              }
          }
      }
      return result;
  }
  
  int BUFFER_prepend(BUFFER_HANDLE handle1, BUFFER_HANDLE handle2)
  {
      int result;
      if ((handle1 == NULL) || (handle2 == NULL) || (handle1 == handle2))
      {
          /* Codes_SRS_BUFFER_01_005: [ BUFFER_prepend shall return a non-zero upon value any error that is encountered. ]*/
          result = __FAILURE__;
      }
      else
      {
          BUFFER* b1 = (BUFFER*)handle1;
          BUFFER* b2 = (BUFFER*)handle2;
          if (b1->buffer == NULL)
          {
              /* Codes_SRS_BUFFER_01_005: [ BUFFER_prepend shall return a non-zero upon value any error that is encountered. ]*/
              result = __FAILURE__;
          }
          else if (b2->buffer == NULL)
          {
              /* Codes_SRS_BUFFER_01_005: [ BUFFER_prepend shall return a non-zero upon value any error that is encountered. ]*/
              result = __FAILURE__;
          }
          else
          {
              //put b2 ahead of b1: [b2][b1], return b1
              if (b2->size ==0)
              {
                  // do nothing
                  result = 0;
              }
              else
              {
                  // b2->size != 0
                  unsigned char* temp = (unsigned char*)malloc(b1->size + b2->size);
                  if (temp == NULL)
                  {
                      /* Codes_SRS_BUFFER_01_005: [ BUFFER_prepend shall return a non-zero upon value any error that is encountered. ]*/
                      LogError("Failure: allocating temp buffer.");
                      result = __FAILURE__;
                  }
                  else
                  {
                      /* Codes_SRS_BUFFER_01_004: [ BUFFER_prepend concatenates handle1 onto handle2 without modifying handle1 and shall return zero on success. ]*/
                      // Append the BUFFER
                      (void)memcpy(temp, b2->buffer, b2->size);
                      // start from b1->size to append b1
                      (void)memcpy(&temp[b2->size], b1->buffer, b1->size);
                      free(b1->buffer);
                      b1->buffer = temp;
                      b1->size += b2->size;
                      result = 0;
                  }
              }
          }
      }
      return result;
  }
  
  int BUFFER_fill(BUFFER_HANDLE handle, unsigned char fill_char)
  {
      int result;
      if (handle == NULL)
      {
          /* Codes_SRS_BUFFER_07_002: [ If handle is NULL BUFFER_fill shall return a non-zero value. ] */
          LogError("Invalid parameter specified, handle == NULL.");
          result = __FAILURE__;
      }
      else
      {
          size_t index;
          /* Codes_SRS_BUFFER_07_001: [ BUFFER_fill shall fill the supplied BUFFER_HANDLE with the supplied fill character. ] */
          BUFFER* buffer_data = (BUFFER*)handle;
          for (index = 0; index < buffer_data->size; index++)
          {
              buffer_data->buffer[index] = fill_char;
          }
          result = 0;
      }
      return result;
  }
  
  
  /* Codes_SRS_BUFFER_07_025: [BUFFER_u_char shall return a pointer to the underlying unsigned char*.] */
  unsigned char* BUFFER_u_char(BUFFER_HANDLE handle)
  {
      BUFFER* handleData = (BUFFER*)handle;
      unsigned char* result;
      if (handle == NULL || handleData->size == 0)
      {
          /* Codes_SRS_BUFFER_07_026: [BUFFER_u_char shall return NULL for any error that is encountered.] */
          /* Codes_SRS_BUFFER_07_029: [BUFFER_u_char shall return NULL if underlying buffer size is zero.] */
          result = NULL;
      }
      else
      {
          result = handleData->buffer;
      }
      return result;
  }
  
  /* Codes_SRS_BUFFER_07_027: [BUFFER_length shall return the size of the underlying buffer.] */
  size_t BUFFER_length(BUFFER_HANDLE handle)
  {
      size_t result;
      if (handle == NULL)
      {
          /* Codes_SRS_BUFFER_07_028: [BUFFER_length shall return zero for any error that is encountered.] */
          result = 0;
      }
      else
      {
          BUFFER* b = (BUFFER*)handle;
          result = b->size;
      }
      return result;
  }
  
  BUFFER_HANDLE BUFFER_clone(BUFFER_HANDLE handle)
  {
      BUFFER_HANDLE result;
      if (handle == NULL)
      {
          result = NULL;
      }
      else
      {
          BUFFER* suppliedBuff = (BUFFER*)handle;
          BUFFER* b = (BUFFER*)malloc(sizeof(BUFFER));
          if (b != NULL)
          {
              if (BUFFER_safemalloc(b, suppliedBuff->size) != 0)
              {
                  free(b);
                  LogError("Failure: allocating temp buffer.");
                  result = NULL;
              }
              else
              {
                  (void)memcpy(b->buffer, suppliedBuff->buffer, suppliedBuff->size);
                  b->size = suppliedBuff->size;
                  result = (BUFFER_HANDLE)b;
              }
          }
          else
          {
              result = NULL;
          }
      }
      return result;
  }
  