Very Computer

> I'm relatively new to programming, I'm learning C.  I'm working with
> text files for CGI currently, and I heard about file locking, it sounds
> like something that I could use.  Does anyone have a snippet code of
> this function? I saw an example for it in a dos based program, but the
> library in unix does not exist (or is different, I don't know what), so
> I got a an error.  I have no idea how to write it from scractch so any
> help will be greatly appreciated, thank you!

>> I'm relatively new to programming, I'm learning C.  I'm working with
>> text files for CGI currently, and I heard about file locking, it sounds
>> like something that I could use.  Does anyone have a snippet code of
>> this function? I saw an example for it in a dos based program, but the
>> library in unix does not exist (or is different, I don't know what), so
>> I got a an error.  I have no idea how to write it from scractch so any
>> help will be greatly appreciated, thank you!
>This code snippet is the function for reading and updating the visitor
>counter in a CGI:
>#include <stdio.h>
>#include <sys/file.h>
>#include <sys/types.h>
>#include <sys/stat.h>
>#include <fcntl.h>
>#include <unistd.h>
>#define COUNTER "/var/run/counter"
>int update_counter(void)
>{
>    int     fd, counter;
>    FILE    *file;
>    if ((fd = open(COUNTER, O_RDWR)) == -1)
>            return -1;
>    if (flock(fd, LOCK_EX) == -1)
>            return -1;
>    if ((file = fdopen(fd, "r+")) == NULL)
>            return -1;
>    fscanf(file, "%i", &counter);
>    counter ++;
>    rewind(file);
>    fprintf(file, "%i\n", counter);
>    fclose(file);
>    flock(fd, LOCK_UN);
>    close(fd);
>    return counter;
>}
>The use of fdopen() is to make it possible to use fscanf(), rewind() and
>fprintf() so although not necessary I think it makes things easier.
>H?lsningar // Fredrik Roubert
>--


>http://www.efd.lth.se/~d95fr/         SE-222 40 Lund