Adott a mellekelt kis tesztprogram.
Irasra kellene lockolnia a megadott file-t.
Ha ket peldanyban futtatom, a masodiknak meg kellene varnia,
amig az elso elengedi a file-t.
De nem var.
Kifolyik a szemem, de nem latom mit toltam el.
Igerem, haromszor is megnyomom a lamerszamlalot, ha en vagyok
a hunyo, de kerek egy kis segitseget! :-)
kissg
--------------8<------- plocktest.c ---------8<--------------
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
int main(int argc, char **argv) {
char *filename;
int delay = 10;
struct flock lock;
int fd;
if (argc < 2) {
fprintf(stderr, "Usage: plocktest filename [time]\n");
exit(3);
}
filename = argv[1];
if (argc >= 3) {
delay = atoi(argv[2]);
}
fprintf(stderr,"Opening file %s\n", filename);
if ((fd=open(filename,O_WRONLY|O_APPEND) == -1)) {
fprintf(stderr, "Cannot open file %s: %s\n",
filename, strerror(errno));
exit(1);
}
fprintf(stderr,"Locking file...\n");
lock.l_type = F_WRLCK;
lock.l_whence = SEEK_SET;
lock.l_start = 0;
lock.l_len = 0;
if (fcntl(fd,F_SETLKW,&lock) == -1) {
fprintf(stderr, "Cannot lock file %s: %s\n",
filename, strerror(errno));
exit(1);
}
fprintf(stderr,"Waiting for %d seconds...\n", delay);
sleep(delay);
fprintf(stderr,"Closing file %s\n", filename);
close(fd);
exit(0);
}
-----------------8<------------------8<------------------------
$ make plocktest
$ date > /tmp/lo
$ ./plocktest /tmp/lo
es egy masik ablakban szinten kiadando az utolso parancs.
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