This is the fastest I could do (which is not fast) with the following constraints:
fallocate not available)This is the gist of it...
// include stdlib.h, stdio.h, and stdint.h
int32_t buf[256]; // Block size.
for (int i = 0; i < 256; ++i)
{
buf[i] = rand(); // random to be non-compressible.
}
FILE* file = fopen("/file/on/your/system", "wb");
int blocksToWrite = 1024 * 1024; // 1 GB
for (int i = 0; i < blocksToWrite; ++i)
{
fwrite(buf, sizeof(int32_t), 256, file);
}
In our case this is for an embedded linux system and this works well enough, but would prefer something faster.
FYI the command dd if=/dev/urandom of=outputfile bs=1024 count = XX was so slow as to be unusable.