Can't save file! [NULL Byte termination]

[q6z4k]

Hi!
I writed a simple server, that sends an ELF file everytime someone connects to it. But the problem is that this file containts NULL bytes:

char code[947]={ 127, 69, 76, 70, 1, 1, 1, 0, 0..

The recv(); returns 947. Thats the size of the ELF file. But the problem is when I try to save this file. I try to save it like this:

recv(sock_fd, buffer, sizeof(buffer..
FILE *fd;
fd = fopen("DATA", "w");
fprintf(fd, buffer);
close(fd)

But it only saves the first 7 bytes, and ends on NULL character. Is there any way to ignore NULL termination? I also try to save it like this:

FILE *fd;
fd = fopen("DATA", "a");
int i;
for(i=0; i<recv_data_size; i++){
     fprintf(fd, &buffer[i]);
}
close(fd);

But then data somehow repeats:

.ELF...ELF...LF...F........
€€4€4444

4 (

There are double ELF's and 4 F's, but there should only be one! Thank you!

[Salem]

> fd = fopen("DATA", "w");
> fprintf(fd, buffer);
1. Use "wb" if you want to write a binary file.
2. Use fwrite (not fprintf) to write binary data.

[q6z4k]

Thanks, that worked! But why this doesn't work with reading binary files!?
I try it like this:

fd = fopen("pass", "rb");
fread(buffer, 13790, 1, fd);
printf("strlen: %i\n", strlen(buffer));

It reads only first 14 bytes. The 15th character is NULL. Why doesn't ir read, I opened it as "rb", but still it reads only until it reaches NULL character!

I have another question! I created a loop, where client recives data, and with strcmp the recived data is compared with the old data, so it fits all in one big buffer. But the problem is that after the compering, the big buffer is only 140 bytes long, it should be 13790. Here is the code:

char buffer[65535];
char data[65545];

while(1){
     recv_data_size = recv(sock_fd, data, sizeof(data), 0);
     strncat(buffer, data, recv_data_size);
     memset(data, 0, sizeof(data);
}

printf("size: %i\n", strlen(buffer));  //140 bytes

Thank you!

[Devil Panther]

2. Use fwrite (not fprintf) to write binary data.

why is fwrite better than fprintf ?

[q6z4k]

fread, fwrite - binary stream input/output
fprintf, printf, sprintf.... - formatted output conversion

[Salem]

> It reads only first 14 bytes
Because you used a string function to find out the length - remember, it's binary data.
Use the return result of fread (which you're currently ignoring) to find out how much data you read.

> why is fwrite better than fprintf ?
It's different, not better.

> and with strcmp the recived data
YET more string functions on binary data.
Use memcmp() if you want to compare binary data!

[q6z4k]

Is there a function like strcat(), but only with binary data?

[Salem]

Yes, it's called memcpy

[Hammer]

... or maybe memmove() if you're arrays overlap.