Write a structure to a file

[quanganht]

I'm new in C and I'm looking for help.
I have an structure, and I tried to write it to a file, binary mode. Neither of them works:

write(fd, &desc, sizeof(desc))
and

fwrite(&desc, sizeof(desc), 1, fd)

Nothing get written to file.

[napsy]

How do you open the file?

[MadCow108]

please show more code.
those lines seem correct but are probably used wrong in a greater context

[quanganht]

The whole damn thing:

#include <stdio.h>

struct SB_DESC
{
char magic[4];
unsigned int index_num;
unsigned long data_num;
unsigned long total_num;
char name[8];
}

int main()
{
int c,i;
void *code;
FILE *fd, *boot;

struct SB_DESC desc;

printf("Building floppy image with BSFS...\n");

fd=fopen("floppy.img","wb");
boot=fopen("boot","rb");
if (boot==NULL)
{
printf("boot binary does not exist!");
exit(0);
}

while ((c=fgetc(boot))!=EOF) // copy boot binary
{
fputc(c,fd);
}
fclose(boot);

//TODO: add code for inserting missing datas and kernel files.

desc.magic[1]='B';
desc.magic[2]='S';
desc.magic[3]='F';
desc.magic[4]='S';
desc.index_num=32;
desc.data_num=2847;
desc.total_num=2880;

for (i=0;0<=8;i++)
desc.name[i]=' ';

if (fwrite(&desc, sizeof(desc), 1, fd) == NULL)
printf("ERROR!\n");

fputc(0x55,fd); fputc(0xAA,fd);

fflush(fd);

fclose(fd);

printf("Done!\n\n");
}

[quanganht]

I got it working now. Thanks guys for helping.
Close thread plz.

[SledgeHammer_999]

Maybe post the solution for others to benefit too?

[MadCow108]

theres a buffer overrun here:
desc.magic[4]='S';
and an infinite loop (+buffer overrun) here:
for (i=0;0<=8;i++)
desc.name[i]=' ';

and a few signed/unsigned comparisons

otherwise the code should work