CODEWITHSUNDEEP
csendfile
sliter
sliter

Reputation: 1093

A simple sendfile program, but not works

#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <sys/sendfile.h>
#include <sys/stat.h>
#include <fcntl.h>

int main(){
    int fd1,fd2,rc;
    off_t offset = 0;
    struct stat stat_buf;

    fd1=open("./hello.txt",O_RDONLY); //read only
    fd2=open("../",O_RDWR);           //both read and write
    fstat(fd1, &stat_buf);            //get the size of hello.txt
    printf("file size: %d\n",(int)stat_buf.st_size);
    rc=sendfile (fd2, fd1, &offset, stat_buf.st_size);
}

So as you have seen, it's quite a simple program. But I just can't find hello.txt in ../ My aim is to see what happens if I put a whatever number, says 10, instead of st_size which may be hundreds of bytes.

Edit:

Thanks for your answers. Well, I followed your advice and changed

 fd2=open("../",O_RDWR);

to

 fd2=open("../hello.txt",O_RDWR);

Also, I checked the return value of fstat and sendfile, everything is ok.

But the problem is still the same.

Upvotes: 0

Views: 342

Answers (3)

Jeegar Patel
Jeegar Patel

Reputation: 27210

1>

  fd1=open("./hello.txt",O_RDONLY); //read only
  fd2=open("../",O_RDWR);           //both read and write

replace with

 fd1=open("../hello.txt",O_RDONLY); //read only
  fd2=open("../your_file_name",O_RDWR);

2> 

 fstat(fd1, &stat_buf);

will fill up some info related to fd1 file in stat_buf . Here size of that file is also return in that structure with st_size element.

now in 

 rc=sendfile (fd2, fd1, &offset, stat_buf.st_size);

total stat_buf.st_size bytes are going to send on fd2 file. if here if you write 10 then only 10 bytes will go in fd2.

Upvotes: 0

CharlesB
CharlesB

Reputation: 90316

Have you tried fd2 = open("../hello.txt",O_RDWR);?

Upvotes: 2

Mat
Mat

Reputation: 206689

You need to specify the filename in the second open, not just the directory name.

Please be sure to check the return values of all these functions, including fstat.

Upvotes: 2

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