On Sun, 22 Jan 2012 11:01:21 -0800 Earl Chew <echew@xxxxxxxxxxx> wrote: > [ Added Maintainers; Added reference to bugzilla.kernel.org in commit log ] > > Also reported in: > > https://bugzilla.kernel.org/show_bug.cgi?id=11856 > > The following program illustrates the problem: > > char buf[8192]; > > int fd = open("/proc/self/maps", O_RDONLY); > > n = pread(fd, buf, sizeof(buf), 0); > printf("%d\n", n); > > /* lseek(fd, 0, SEEK_CUR); */ /* Uncomment to work around */ > > n = pread(fd, buf, sizeof(buf), 0); > printf("%d\n", n); > > The second printf() prints zero, but uncommenting the lseek() > corrects its behaviour. I'm stunned and confused. That sequence of operations is the only sane way in which to poll the contents of a procfs file. Surely there are many applications which open a procfs file then repeatedly read it with pread(fd, ..., 0). How can this problem not have been noticed in the first five minutes?? -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
