commit 23bdcb4ad4ef19d99b729e5282fd15df6300a3b5
parent 828159d33b8ced9e016470c61ffd66bbef048e06
Author: Laurent Bercot <ska-skaware@skarnet.org>
Date: Sun, 21 Dec 2014 00:26:40 +0000
So the non-portable MSG_DONTWAIT may alleviate the problem... might
as well use it on architectures that support it.
Diffstat:
5 files changed, 147 insertions(+), 130 deletions(-)
diff --git a/configure b/configure
@@ -442,7 +442,8 @@ EOF
choose cl getpeerucred GETPEERUCRED 'getpeerucred()'
choose cl ipv6 IPV6 'IPv6 support' $socket_lib
choose clr malloc0 MALLOC0 'non-NULL malloc(0)'
- choose clr okwaitall OKWAITALL 'a usable MSG_WAITALL flag'
+ choose c msgdontwait MSGDONTWAIT 'MSG_DONTWAIT'
+ choose clr nbwaitall NBWAITALL 'non-blocking MSG_WAITALL'
choose cl openat OPENAT 'openat()'
choose cl linkat LINKAT 'linkat()'
choose clr pipe2 PIPE2 'pipe2()'
diff --git a/src/libunixonacid/unixmessage_receive.c b/src/libunixonacid/unixmessage_receive.c
@@ -14,19 +14,18 @@
#include <skalibs/siovec.h>
#include <skalibs/unixmessage.h>
-#ifdef SKALIBS_HASOKWAITALL
-# ifdef SKALIBS_HASCMSGCLOEXEC
-# define RECV(fd, hdr) recvmsg(fd, (hdr), MSG_WAITALL | MSG_CMSG_CLOEXEC)
-# else
-# define RECV(fd, hdr) recvmsg(fd, (hdr), MSG_WAITALL)
-# endif
+static int const awesomeflags =
+#ifdef SKALIBS_HASMSGDONTWAIT
+ MSG_WAITALL | MSG_DONTWAIT
+#elif defined (SKALIBS_HASNBWAITALL)
+ MSG_WAITALL
#else
-# ifdef SKALIBS_HASCMSGCLOEXEC
-# define RECV(fd, hdr) recvmsg(fd, (hdr), MSG_CMSG_CLOEXEC)
-# else
-# define RECV(fd, hdr) recvmsg(fd, (hdr), 0)
-# endif
+ 0
#endif
+#ifdef SKALIBS_HASCMSGCLOEXEC
+ | MSG_CMSG_CLOEXEC
+#endif
+ ;
static int unixmessage_receiver_fill (unixmessage_receiver_t *b)
{
@@ -51,7 +50,7 @@ static int unixmessage_receiver_fill (unixmessage_receiver_t *b)
cbuffer_wpeek(&b->mainb, v) ;
iovec_from_siovec(iov, v, 2) ;
}
- r = RECV(b->fd, &msghdr) ;
+ r = recvmsg(b->fd, &msghdr, awesomeflags) ;
if (r <= 0) return r ;
{
struct cmsghdr *c = CMSG_FIRSTHDR(&msghdr) ;
diff --git a/src/sysdeps/trymsgdontwait.c b/src/sysdeps/trymsgdontwait.c
@@ -0,0 +1,17 @@
+/* ISC license. */
+
+#undef _POSIX_C_SOURCE
+#undef _XOPEN_SOURCE
+
+#ifndef _XPG4_2
+# define _XPG4_2
+#endif
+
+#ifndef _BSD_SOURCE
+#define _BSD_SOURCE
+#endif
+
+#include <sys/types.h>
+#include <sys/socket.h>
+
+int value = MSG_DONTWAIT ;
diff --git a/src/sysdeps/trynbwaitall.c b/src/sysdeps/trynbwaitall.c
@@ -0,0 +1,117 @@
+/* ISC license. */
+
+#undef _POSIX_C_SOURCE
+#undef _XOPEN_SOURCE
+
+#ifndef _XPG4_2
+# define _XPG4_2
+#endif
+
+#ifndef _BSD_SOURCE
+#define _BSD_SOURCE
+#endif
+
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <signal.h>
+#include <sys/socket.h>
+#include <sys/select.h>
+#include <sys/uio.h>
+#if defined(__FreeBSD__)
+#include <sys/param.h>
+#endif
+
+#ifndef MSG_NOSIGNAL
+#define MSG_NOSIGNAL 0
+#endif
+
+static int ndelay_on (int fd)
+{
+ register int got = fcntl(fd, F_GETFL) ;
+ return (got == -1) ? -1 : fcntl(fd, F_SETFL, got | O_NONBLOCK) ;
+}
+
+static int child (int p, int fd)
+{
+ char c ;
+ struct iovec v = { .iov_base = &c, .iov_len = 1 } ;
+ struct msghdr msg =
+ {
+ .msg_name = 0,
+ .msg_namelen = 0,
+ .msg_iov = &v,
+ .msg_iovlen = 1,
+ .msg_control = 0,
+ .msg_controllen = 0
+ } ;
+ fd_set rfds ;
+ if (ndelay_on(fd) < 0) return 111 ;
+ FD_ZERO(&rfds) ;
+ FD_SET(fd, &rfds) ;
+ if (write(p, "", 1) < 1) return 111 ; /* sync with the parent */
+ if (select(fd+1, &rfds, 0, 0, 0) < 1) return 111 ;
+
+ /* The following recvmsg may block, despite setting the fd
+ non-blocking. That is what we're testing. */
+
+ if (recvmsg(fd, &msg, MSG_WAITALL) < 1) return 111 ;
+ if (write(p, "", 1) < 1) return 111 ;
+ return 0 ;
+}
+
+static int parent (pid_t pid, int p, int fd)
+{
+ char c ;
+ struct iovec v = { .iov_base = &c, .iov_len = 1 } ;
+ struct msghdr msg =
+ {
+ .msg_name = 0,
+ .msg_namelen = 0,
+ .msg_iov = &v,
+ .msg_iovlen = 1,
+ .msg_control = 0,
+ .msg_controllen = 0
+ } ;
+ struct timeval tv = { .tv_sec = 2, .tv_usec = 0 } ;
+ fd_set rfds ;
+ unsigned int n = p > fd ? p : fd ;
+ int r ;
+ FD_ZERO(&rfds) ;
+ FD_SET(p, &rfds) ;
+ if (read(p, &c, 1) < 1) return 111 ;
+ if (sendmsg(fd, &msg, MSG_NOSIGNAL) < 1) return 111 ;
+ for (;;)
+ {
+ r = select(n+1, &rfds, 0, 0, &tv) ;
+ if (r >= 0 || errno != EINTR) break ;
+ }
+ if (!r) /* child is still blocking on recvmsg() after 2 seconds */
+ {
+ kill(pid, SIGTERM) ;
+ return 1 ;
+ }
+ if (read(p, &c, 1) < 1) return 111 ;
+ return 0 ;
+}
+
+int main (void)
+{
+ pid_t pid ;
+ int fd[2] ;
+ int p[2] ;
+ if (pipe(p) < 0) return 111 ;
+ if (socketpair(AF_UNIX, SOCK_STREAM, 0, fd) < 0) return 111 ;
+ pid = fork() ;
+ if (pid < 0) return 111 ;
+ if (!pid)
+ {
+ close(p[0]) ;
+ close(fd[0]) ;
+ return child(p[1], fd[1]) ;
+ }
+ close(p[1]) ;
+ close(fd[1]) ;
+ return parent(pid, p[0], fd[0]) ;
+}
diff --git a/src/sysdeps/tryokwaitall.c b/src/sysdeps/tryokwaitall.c
@@ -1,117 +0,0 @@
-/* ISC license. */
-
-#undef _POSIX_C_SOURCE
-#undef _XOPEN_SOURCE
-
-#ifndef _XPG4_2
-# define _XPG4_2
-#endif
-
-#ifndef _BSD_SOURCE
-#define _BSD_SOURCE
-#endif
-
-#include <sys/types.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <errno.h>
-#include <signal.h>
-#include <sys/socket.h>
-#include <sys/select.h>
-#include <sys/uio.h>
-#if defined(__FreeBSD__)
-#include <sys/param.h>
-#endif
-
-#ifndef MSG_NOSIGNAL
-#define MSG_NOSIGNAL 0
-#endif
-
-static int ndelay_on (int fd)
-{
- register int got = fcntl(fd, F_GETFL) ;
- return (got == -1) ? -1 : fcntl(fd, F_SETFL, got | O_NONBLOCK) ;
-}
-
-static int child (int p, int fd)
-{
- char c ;
- struct iovec v = { .iov_base = &c, .iov_len = 1 } ;
- struct msghdr msg =
- {
- .msg_name = 0,
- .msg_namelen = 0,
- .msg_iov = &v,
- .msg_iovlen = 1,
- .msg_control = 0,
- .msg_controllen = 0
- } ;
- fd_set rfds ;
- if (ndelay_on(fd) < 0) return 111 ;
- FD_ZERO(&rfds) ;
- FD_SET(fd, &rfds) ;
- if (write(p, "", 1) < 1) return 111 ; /* sync with the parent */
- if (select(fd+1, &rfds, 0, 0, 0) < 1) return 111 ;
-
- /* On buggy systems, the following recvmsg will block, despite
- setting the fd non-blocking */
-
- if (recvmsg(fd, &msg, MSG_WAITALL) < 1) return 111 ;
- if (write(p, "", 1) < 1) return 111 ;
- return 0 ;
-}
-
-static int parent (pid_t pid, int p, int fd)
-{
- char c ;
- struct iovec v = { .iov_base = &c, .iov_len = 1 } ;
- struct msghdr msg =
- {
- .msg_name = 0,
- .msg_namelen = 0,
- .msg_iov = &v,
- .msg_iovlen = 1,
- .msg_control = 0,
- .msg_controllen = 0
- } ;
- struct timeval tv = { .tv_sec = 2, .tv_usec = 0 } ;
- fd_set rfds ;
- unsigned int n = p > fd ? p : fd ;
- int r ;
- FD_ZERO(&rfds) ;
- FD_SET(p, &rfds) ;
- if (read(p, &c, 1) < 1) return 111 ;
- if (sendmsg(fd, &msg, MSG_NOSIGNAL) < 1) return 111 ;
- for (;;)
- {
- r = select(n+1, &rfds, 0, 0, &tv) ;
- if (r >= 0 || errno != EINTR) break ;
- }
- if (!r) /* child is still blocking on recvmsg() after 2 seconds */
- {
- kill(pid, SIGTERM) ;
- return 1 ;
- }
- if (read(p, &c, 1) < 1) return 111 ;
- return 0 ;
-}
-
-int main (void)
-{
- pid_t pid ;
- int fd[2] ;
- int p[2] ;
- if (pipe(p) < 0) return 111 ;
- if (socketpair(AF_UNIX, SOCK_STREAM, 0, fd) < 0) return 111 ;
- pid = fork() ;
- if (pid < 0) return 111 ;
- if (!pid)
- {
- close(p[0]) ;
- close(fd[0]) ;
- return child(p[1], fd[1]) ;
- }
- close(p[1]) ;
- close(fd[1]) ;
- return parent(pid, p[0], fd[0]) ;
-}
