shrink the allocated memory

//-std=c99 -Wall -Wextra -Wpedantic -Wshadow

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>

int main ()
{

   int32_t blk_1[]={100,101,102,103,104,105,106,107,108};
   int32_t blk_2[]={200,201};
   int32_t blk_3[]={300,301,302,303,304,305,306,307,308,309,310,311,312,313,314};

   uint32_t blkNumE_1 = sizeof(blk_1)/sizeof(blk_1[0]);
   uint32_t blkNumE_2 = sizeof(blk_2)/sizeof(blk_2[0]);

   printf("info: blkNumE_1: %d\n", blkNumE_1);
   printf("info: blkNumE_2: %d\n", blkNumE_2);

   int32_t *p1;
   int32_t *p2;
   int32_t *p3;

   int32_t *buffer;
   int32_t *bufferTmp;
   uint32_t buffSize;

   //in bytes
   buffSize = sizeof(blk_1) + sizeof(blk_2);

   printf("info: buffer size: %d bytes\n", buffSize);

   buffer = malloc(buffSize);

   if(!buffer)
   {
      printf("error: memory allocation (1)\n");
      return 1;
   }

   memcpy(buffer, blk_1, sizeof(blk_1));

   /*
      buffer + blkNumE_1; because buffer is int32_t*;
      buffer + N; in bytes adds number * sizeof(int32_t) to the address of the buffer
   */

   memcpy(buffer + blkNumE_1, blk_2, sizeof(blk_2));

   p1 = buffer;
   p2 = buffer + blkNumE_1;

   printf("info: p1[0]: %d\n", p1[0]);
   printf("info: p2[0]: %d\n", p2[0]);

   buffSize += sizeof(blk_3);

   printf("info: buffer size: %d bytes\n", buffSize);

   bufferTmp = realloc(buffer,buffSize);

   if(!bufferTmp)
   {
      printf("error: memory allocation (2)\n");
      free(buffer);
      return 1;
   }

   buffer = bufferTmp;

   memcpy(buffer + blkNumE_1 + blkNumE_2, blk_3, sizeof(blk_3));

   p1 = buffer;
   p2 = buffer + blkNumE_1;
   p3 = buffer + blkNumE_1 + blkNumE_2;

   printf("info: p1[0]: %d\n", p1[0]);
   printf("info: p2[0]: %d\n", p2[0]);
   printf("info: p3[0]: %d\n", p3[0]);


   //memmove(p2, p3, sizeof(blk_3));
   memmove(buffer + blkNumE_1, buffer + blkNumE_1 + blkNumE_2, sizeof(blk_3));

   buffSize -= sizeof(blk_2);

   printf("info: buffer size: %d bytes\n", buffSize);

   //shrink the allocated memory
   bufferTmp = realloc(buffer,buffSize);

   if(!bufferTmp)
   {
      printf("error: memory allocation (3)\n");
      free(buffer);
      return 1;
   }

   buffer = bufferTmp;

   p1 = buffer;
   p2 = buffer + blkNumE_1;

   printf("info: p1[0]: %d\n", p1[0]);
   printf("info: p2[0]: %d\n", p2[0]);
   printf("info: p2[2]: %d\n", p2[2]);

   free(buffer);

   return 0;
}

/*
output:

info: blkNumE_1: 9
info: blkNumE_2: 2
info: buffer size: 44 bytes
info: p1[0]: 100
info: p2[0]: 200
info: buffer size: 104 bytes
info: p1[0]: 100
info: p2[0]: 200
info: p3[0]: 300
info: buffer size: 96 bytes
info: p1[0]: 100
info: p2[0]: 300
info: p2[2]: 302


valgrind:
HEAP SUMMARY:
in use at exit: 0 bytes in 0 blocks
total heap usage: 4 allocs, 4 frees, 1,268 bytes allocated
All heap blocks were freed -- no leaks are possible
ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

*/