1 files changed, 137 insertions, 0 deletions
diff --git a/src/lib/sendfile-util.c b/src/lib/sendfile-util.c
new file mode 100644
index 0000000..662285b
--- /dev/null
+++ b/src/lib/sendfile-util.c
@@ -0,0 +1,137 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+/* kludge a bit to remove _FILE_OFFSET_BITS definition from config.h.
+   It's required to be able to include sys/sendfile.h with Linux. */
+#include "config.h"
+#undef HAVE_CONFIG_H
+
+#ifdef HAVE_LINUX_SENDFILE
+#  undef _FILE_OFFSET_BITS
+#endif
+
+#include "lib.h"
+#include "sendfile-util.h"
+
+#ifdef HAVE_LINUX_SENDFILE
+
+#include <sys/sendfile.h>
+
+ssize_t safe_sendfile(int out_fd, int in_fd, uoff_t *offset, size_t count)
+{
+	/* REMEMBER: uoff_t and off_t may not be of same size. */
+	off_t safe_offset;
+	ssize_t ret;
+
+	i_assert(count > 0);
+
+	/* make sure given offset fits into off_t */
+	if (sizeof(off_t) * CHAR_BIT == 32) {
+		/* 32bit off_t */
+		if (*offset >= 2147483647L) {
+			errno = EINVAL;
+			return -1;
+		}
+		if (count > 2147483647L - *offset)
+			count = 2147483647L - *offset;
+	} else {
+		/* they're most likely the same size. if not, fix this
+		   code later */
+		i_assert(sizeof(off_t) == sizeof(uoff_t));
+
+		if (*offset >= OFF_T_MAX) {
+			errno = EINVAL;
+			return -1;
+		}
+		if (count > OFF_T_MAX - *offset)
+			count = OFF_T_MAX - *offset;
+	}
+
+	safe_offset = (off_t)*offset;
+	ret = sendfile(out_fd, in_fd, &safe_offset, count);
+	/* ret=0 : trying to read past EOF */
+	*offset = (uoff_t)safe_offset;
+	return ret;
+}
+
+#elif defined(HAVE_FREEBSD_SENDFILE)
+
+#include <sys/socket.h>
+#include <sys/uio.h>
+
+ssize_t safe_sendfile(int out_fd, int in_fd, uoff_t *offset, size_t count)
+{
+	struct sf_hdtr hdtr;
+	off_t sbytes;
+	int ret;
+
+	/* if count=0 is passed to sendfile(), it sends everything
+	   from in_fd until EOF. We don't want that. */
+	i_assert(count > 0);
+	i_assert(count <= SSIZE_T_MAX);
+
+	i_zero(&hdtr);
+	ret = sendfile(in_fd, out_fd, *offset, count, &hdtr, &sbytes, 0);
+
+	*offset += sbytes;
+
+	if (ret == 0 || (ret < 0 && errno == EAGAIN && sbytes > 0))
+		return (ssize_t)sbytes;
+	else {
+		if (errno == ENOTSOCK) {
+			/* out_fd wasn't a socket. behave as if sendfile()
+			   wasn't supported at all. */
+			errno = EINVAL;
+		}
+		return -1;
+	}
+}
+
+#elif defined (HAVE_SOLARIS_SENDFILE)
+
+#include <sys/sendfile.h>
+#include "net.h"
+
+ssize_t safe_sendfile(int out_fd, int in_fd, uoff_t *offset, size_t count)
+{
+	ssize_t ret;
+	off_t s_offset;
+
+	i_assert(count > 0);
+	i_assert(count <= SSIZE_T_MAX);
+
+	/* NOTE: if outfd is not a socket, some Solaris versions will
+	   kernel panic */
+
+	s_offset = (off_t)*offset;
+	ret = sendfile(out_fd, in_fd, &s_offset, count);
+
+	if (ret < 0) {
+		/* if remote is gone, EPIPE is returned */
+		if (errno == EINVAL) {
+			/* most likely trying to read past EOF */
+			ret = 0;
+		} else if (errno == EAFNOSUPPORT || errno == EOPNOTSUPP) {
+			/* not supported, return Linux-like EINVAL so caller
+			   sees only consistent errnos. */
+			errno = EINVAL;
+		} else if (s_offset != (off_t)*offset) {
+			/* some data was sent, return it */
+			i_assert(s_offset > (off_t)*offset);
+			ret = s_offset - (off_t)*offset;
+		}
+	}
+	*offset = (uoff_t)s_offset;
+	i_assert(ret < 0 || (size_t)ret <= count);
+	return ret;
+}
+
+#else
+ssize_t safe_sendfile(int out_fd ATTR_UNUSED, int in_fd ATTR_UNUSED,
+		      uoff_t *offset ATTR_UNUSED,
+		      size_t count ATTR_UNUSED)
+{
+	errno = EINVAL;
+	return -1;
+}
+
+#endif