Adding upstream version 4.12.1.upstream/4.12.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 202 insertions, 0 deletions

diff --git a/agents/virt/common/fdops.c b/agents/virt/common/fdops.c
new file mode 100644
index 0000000..329e9b7
--- /dev/null
+++ b/agents/virt/common/fdops.c
@@ -0,0 +1,202 @@
+/*
+  Copyright Red Hat, Inc. 2002-2003
+
+  This program is free software; you can redistribute it and/or modify it
+  under the terms of the GNU General Public License as published by the
+  Free Software Foundation; either version 2, or (at your option) any
+  later version.
+
+  This program is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+  General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program; see the file COPYING.  If not, write to the
+  Free Software Foundation, Inc.,  675 Mass Ave, Cambridge,
+  MA 02139, USA.
+*/
+/** @file
+ * Wrapper functions around read/write/select to retry in the event
+ * of interrupts.
+ */
+
+#include "config.h"
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "fdops.h"
+
+/**
+ * This is a wrapper around select which will retry in the case we receive
+ * EINTR.  This is necessary for _read_retry, since it wouldn't make sense
+ * to have _read_retry terminate if and only if two EINTRs were received
+ * in a row - one during the read() call, one during the select call...
+ *
+ * See select(2) for description of parameters.
+ */
+int
+_select_retry(int fdmax, fd_set * rfds, fd_set * wfds, fd_set * xfds,
+	       struct timeval *timeout)
+{
+	int rv;
+
+	while (1) {
+		rv = select(fdmax, rfds, wfds, xfds, timeout);
+		if (rv == -1) {
+			/* return on EBADF/EINVAL/ENOMEM; continue on EINTR/EAGAIN/ENOMEM */
+			if (errno == EINTR || errno == EAGAIN || errno == ENOMEM)
+				continue;
+		}
+		return rv;
+	}
+}
+
+/**
+ * Retries a write in the event of a non-blocked interrupt signal.
+ *
+ * @param fd		File descriptor to which we are writing.
+ * @param buf		Data buffer to send.
+ * @param count		Number of bytes in buf to send.
+ * @param timeout	(struct timeval) telling us how long we should retry.
+ * @return		The number of bytes written to the file descriptor,
+ * 			or -1 on error (with errno set appropriately).
+ */
+ssize_t
+_write_retry(int fd, void *buf, int count, struct timeval * timeout)
+{
+	int n, total = 0, remain = count, rv = 0;
+	fd_set wfds, xfds;
+	char *tmp_buf = (char *)buf;
+
+	while (total < count) {
+
+		/* Create the write FD set of 1... */
+		FD_ZERO(&wfds);
+		FD_SET(fd, &wfds);
+		FD_ZERO(&xfds);
+		FD_SET(fd, &xfds);
+
+		/* wait for the fd to be available for writing */
+		rv = _select_retry(fd + 1, NULL, &wfds, &xfds, timeout);
+		if (rv == -1)
+			return -1;
+		else if (rv == 0) {
+			errno = ETIMEDOUT;
+			return -1;
+		}
+
+		if (FD_ISSET(fd, &xfds)) {
+			errno = EPIPE;
+			return -1;
+		}
+
+		/* 
+		 * Attempt to write to fd
+		 */
+		n = write(fd, tmp_buf + total, remain);
+
+		/*
+		 * When we know our fd was select()ed and we receive 0 bytes
+		 * when we write, the fd was closed.
+		 */
+		if ((n == 0) && (rv == 1)) {
+			errno = EPIPE;
+			return -1;
+		}
+
+		if (n == -1) {
+			if ((errno == EAGAIN) || (errno == EINTR)) {
+				/* 
+				 * Not ready?
+				 */
+				continue;
+			}
+
+			/* Other errors: EIO, EINVAL, etc */
+			return -1;
+		}
+
+		total += n;
+		remain -= n;
+	}
+
+	return total;
+}
+
+/**
+ * Retry reads until we (a) time out or (b) get our data.  Of course, if
+ * timeout is NULL, it'll wait forever.
+ *
+ * @param sockfd	File descriptor we want to read from.
+ * @param buf		Preallocated buffer into which we will read data.
+ * @param count		Number of bytes to read.
+ * @param timeout	(struct timeval) describing how long we should retry.
+ * @return 		The number of bytes read on success, or -1 on failure.
+ 			Note that we will always return (count) or (-1).
+ */
+ssize_t
+_read_retry(int sockfd, void *buf, int count, struct timeval * timeout)
+{
+	int n, total = 0, remain = count, rv = 0;
+	fd_set rfds, xfds;
+	char *tmp_buf = (char *)buf;
+
+	while (total < count) {
+		FD_ZERO(&rfds);
+		FD_SET(sockfd, &rfds);
+		FD_ZERO(&xfds);
+		FD_SET(sockfd, &xfds);
+		
+		/*
+		 * Select on the socket, in case it closes while we're not
+		 * looking...
+		 */
+		rv = _select_retry(sockfd + 1, &rfds, NULL, &xfds, timeout);
+		if (rv == -1)
+			return -1;
+		else if (rv == 0) {
+			errno = ETIMEDOUT;
+			return -1;
+		}
+
+		if (FD_ISSET(sockfd, &xfds)) {
+			errno = EPIPE;
+			return -1;
+		}
+
+		/* 
+		 * Attempt to read off the socket 
+		 */
+		n = read(sockfd, tmp_buf + total, remain);
+
+		/*
+		 * When we know our socket was select()ed and we receive 0 bytes
+		 * when we read, the socket was closed.
+		 */
+		if ((n == 0) && (rv == 1)) {
+			errno = EPIPE;
+			return -1;
+		}
+
+		if (n == -1) {
+			if ((errno == EAGAIN) || (errno == EINTR)) {
+				/* 
+				 * Not ready? Wait for data to become available
+				 */
+				continue;
+			}
+
+			/* Other errors: EPIPE, EINVAL, etc */
+			return -1;
+		}
+
+		total += n;
+		remain -= n;
+	}
+
+	return total;
+}