Re: [patch libteam] poll instead of select

[Jiri Pirko]

Thu, Jan 30, 2020 at 08:29:22PM CET, [e-mail] wrote:
> Hello,
>
> A firewall application is using libteamdctl to read the configuration of the
> bonding interfaces. This application has a lot of open file descriptors and
> is therefore crashing in the libteadmdctl at this select function.
>
> The select function is a very old function and is using the FD_(*) macros to
> the set the bit of monitored file descriptors in a fixed size array. In the
> glibc this array can only contain 1024 entries ( file descritor 0->1023).
>
> The select function can therefore only monitor the first 1024 file
> descriptors. If the used file descriptor used in the select function is
> greater then 1023, the select can/will crash.

Fair enough, I'm applying this.

Thanks!
> Sincerely,
> Jérôme
>
> On 1/29/20 6:16 PM, Jiri Pirko wrote:
> > Tue, Jan 28, 2020 at 01:11:00AM CET, [e-mail] wrote:
> > > The select function cannot be used in application if the application has
> > > already more than 1024 open files. The select will crash if an file
> > > descriptor greater or equal than 1023 is monitored.
> >
> > Okay, how we can come close that?
> > > Signed-off-by: Jerome Freilinger
> > >
> > > libteamdctl/cli_usock.c | 25 +++++++++----------------
> > > 1 file changed, 9 insertions(+), 16 deletions(-)
> > >
> > > diff --git a/libteamdctl/cli_usock.c b/libteamdctl/cli_usock.c
> > > index 0dc97ae..431b12d 100644
> > > --- a/libteamdctl/cli_usock.c
> > > +++ b/libteamdctl/cli_usock.c
> > > @@ -25,6 +25,7 @@
> > > #include <sys/socket.h>
> > > #include <unistd.h>
> > > #include <teamdctl.h>
> > > +#include <poll.h>
> > > #include "teamdctl_private.h"
> > > #include "../teamd/teamd_usock_common.h"
> > >
> > > @@ -79,26 +80,18 @@ static int cli_usock_send(int sock, char *msg)
> > >    return 0;
> > > }
> > >
> > > -#define WAIT_SEC (TEAMDCTL_REPLY_TIMEOUT / 1000)
> > > -#define WAIT_USEC (TEAMDCTL_REPLY_TIMEOUT % 1000 * 1000)
> > >
> > > static int cli_usock_wait_recv(int sock)
> > > {
> > > fd_set rfds;
> > > int fdmax;
> > > int ret;
> > > struct timeval tv;
> > > struct pollfd fds[1];
> > > fds[0].fd = sock;
> > > fds[0].events = POLLIN;
> > > fds[0].revents = 0;
> > > int ret = poll(fds, 1, TEAMDCTL_REPLY_TIMEOUT);
> > > tv.tv_sec = WAIT_SEC;
> > > tv.tv_usec = WAIT_USEC;
> > > FD_ZERO(&rfds);
> > > FD_SET(sock, &rfds);
> > > fdmax = sock + 1;
> > > ret = select(fdmax, &rfds, NULL, NULL, &tv);
> > > if (ret == -1)
> > > return -errno;
> > > if (!FD_ISSET(sock, &rfds))
> > > if (ret == 0)
> > > return -ETIMEDOUT;
> > > else if (ret < 0)
> > > return -errno;
> > > return 0;
> > >
> > > }
> > >
> > > -- 
> > > 2.20.1