On Wed, Jul 24, 2024 at 01:32 PM +02, Michal Luczaj wrote:
> Rewrite function to have (unneeded) socket descriptors automatically
> close()d when leaving the scope. Make sure the "ownership" of fds is
> correctly passed via take_fd(); i.e. descriptor returned to caller will
> remain valid.
>
> Suggested-by: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
> Signed-off-by: Michal Luczaj <mhal@xxxxxxx>
> ---
> .../selftests/bpf/prog_tests/sockmap_helpers.h | 57 ++++++++++++----------
> 1 file changed, 32 insertions(+), 25 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_helpers.h b/tools/testing/selftests/bpf/prog_tests/sockmap_helpers.h
> index ead8ea4fd0da..2e0f9fe459be 100644
> --- a/tools/testing/selftests/bpf/prog_tests/sockmap_helpers.h
> +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_helpers.h
> @@ -182,6 +182,21 @@
> __ret; \
> })
>
> +#define take_fd(fd) \
> + ({ \
> + __auto_type __val = (fd); \
> + fd = -EBADF; \
> + __val; \
> + })
Probably should operate on a pointer to fd to avoid side effects, like
__get_and_null macro in include/linux/cleanup.h. take_fd is effectively
__get_and_null(fd, -EBADFD).
> +
> +static inline void close_fd(int *fd)
> +{
> + if (*fd >= 0)
> + xclose(*fd);
> +}
> +
> +#define __close_fd __attribute__((cleanup(close_fd)))
> +
> static inline int poll_connect(int fd, unsigned int timeout_sec)
> {
> struct timeval timeout = { .tv_sec = timeout_sec };
> @@ -369,9 +384,10 @@ static inline int socket_loopback(int family, int sotype)
>
> static inline int create_pair(int family, int sotype, int *p0, int *p1)
> {
> + __close_fd int s, c = -1, p = -1;
> struct sockaddr_storage addr;
> socklen_t len = sizeof(addr);
> - int s, c, p, err;
> + int err;
>
> s = socket_loopback(family, sotype);
> if (s < 0)
> @@ -379,25 +395,23 @@ static inline int create_pair(int family, int sotype, int *p0, int *p1)
>
> err = xgetsockname(s, sockaddr(&addr), &len);
> if (err)
> - goto close_s;
> + return err;
>
> c = xsocket(family, sotype, 0);
> - if (c < 0) {
> - err = c;
> - goto close_s;
> - }
> + if (c < 0)
> + return c;
>
> err = connect(c, sockaddr(&addr), len);
> if (err) {
> if (errno != EINPROGRESS) {
> FAIL_ERRNO("connect");
> - goto close_c;
> + return err;
> }
>
> err = poll_connect(c, IO_TIMEOUT_SEC);
> if (err) {
> FAIL_ERRNO("poll_connect");
> - goto close_c;
> + return err;
> }
> }
>
> @@ -405,36 +419,29 @@ static inline int create_pair(int family, int sotype, int *p0, int *p1)
> case SOCK_DGRAM:
> err = xgetsockname(c, sockaddr(&addr), &len);
> if (err)
> - goto close_c;
> + return err;
>
> err = xconnect(s, sockaddr(&addr), len);
> - if (!err) {
> - *p0 = s;
> - *p1 = c;
> + if (err)
> return err;
> - }
> +
> + *p0 = take_fd(s);
> break;
> case SOCK_STREAM:
> case SOCK_SEQPACKET:
> p = xaccept_nonblock(s, NULL, NULL);
> - if (p >= 0) {
> - *p0 = p;
> - *p1 = c;
> - goto close_s;
> - }
> + if (p < 0)
> + return p;
>
> - err = p;
> + *p0 = take_fd(p);
> break;
> default:
> FAIL("Unsupported socket type %#x", sotype);
> - err = -EOPNOTSUPP;
> + return -EOPNOTSUPP;
> }
>
> -close_c:
> - close(c);
> -close_s:
> - close(s);
> - return err;
> + *p1 = take_fd(c);
> + return 0;
> }
>
> static inline int create_socket_pairs(int family, int sotype, int *c0, int *c1,
This turned out nice and readable, IMHO.
