Question

isn’t it possible to read bytes left in a file that is smaller than buffer size?

char * buffer = (char *)malloc(size);
FILE * fp = fopen(filename, "rb");

while(fread(buffer, size, 1, fp)){
     // do something
}

Let’s assume size is 4 and file size is 17 bytes. I thought fread can handle last operation as well even if bytes left in file is smaller than buffer size, but apparently it just terminates while loop without reading one last byte.

I tried to use lower system call read() but I couldn’t read any byte for some reason.

What should I do if fread cannot handle last part of bytes that is smaller than buffer size?

Answer 1

Yep, turn your parameters around.

Instead of requesting one block of size bytes, you should request size blocks of 1 bytes. Then the function will return how many blocks (bytes) it was able to read:

int nread;
while( 0 < (nread = fread(buffer, 1, size, fp)) ) ...