Отв.: r+b filemode

[Oleg Moroz]

________________________________
От: Joel Sherrill <joel.sherrill at oarcorp.com>
Кому: Oleg Moroz <oleg_moroz at yahoo.com>; "rtems-users at rtems.org" <rtems-users at rtems.org>
Отправлено: четверг, 26 май 2011 21:57
Тема: Re: r+b filemode

Which filesystem?

Do you have a complete small test case?

Someone else will likely have other ideas.  I am on travel and just wanted to ask the obviuous questions.

--joel

Oleg Moroz <oleg_moroz at yahoo.com> wrote:

>Hello everyone, i have a trouble with opening file. i have opened the file with "wb" mode. Write to it 512 bytes. close it. after this open it with "r+b" mode. then trying:
>
>///
>fseek(file,0,SEEK_END);
>int i = ftell(file);
>///
>
>
>
>after this i=0
>
>but when i'm opening file with "rb" mode - i=512. how i can use "r+b" mode?


int create_ring_buffer_file(char *filename)
{
FILE* outfile=fopen(filename,"wb");

if (outfile==NULL) return -1;

char *block=(char *)malloc(512);
memset(block,0,512);

fwrite(block,512,1,outfile);
free(block);
fclose(outfile);
outfile=fopen(filename,"r+b");
fseek(outfile,0,2);
int i = ftell(outfile); //i=0
fclose(outfile);

outfile=fopen(filename,"rb");
fseek(outfile,0,2);
int i = ftell(outfile); //i=512
fclose(outfile);
return 0;
}
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