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Allow xcb_send_request with >MAX_IOV iovecs 

This allows an application to do a scatter/gather operation on a large
image buffer to avoid the extra memcpy.

Use autoconf to use UIO_MAXIOV where IOV_MAX is not available (and the
POSIX minimum of 16 where neither are available).

Reviewed-by: Uli Schlachter <psychon@znc.in>
Signed-off-by: Peter Harris <pharris@opentext.com>
This commit is contained in:
Peter Harris 2012-08-16 11:59:14 -04:00
parent ff53285ae3
commit 08cc068ead
2 changed files with 13 additions and 1 deletions
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7
configure.ac
View File

@ -117,6 +117,13 @@ dnl check for support for Solaris Trusted Extensions
AC_CHECK_HEADERS([tsol/label.h]) AC_CHECK_HEADERS([tsol/label.h])
AC_CHECK_FUNCS([is_system_labeled]) AC_CHECK_FUNCS([is_system_labeled])
dnl check for IOV_MAX, and fall back to UIO_MAXIOV on BSDish systems
AC_CHECK_DECL([IOV_MAX], [],
[AC_CHECK_DECL([UIO_MAXIOV], [AC_DEFINE([IOV_MAX], [UIO_MAXIOV])],
[AC_DEFINE([IOV_MAX], [16], [Define if not provided by <limits.h>])],
[[#include <sys/uio.h>]])],
[[#include <limits.h>]])
xcbincludedir='${includedir}/xcb' xcbincludedir='${includedir}/xcb'
AC_SUBST(xcbincludedir) AC_SUBST(xcbincludedir)

7
src/xcb_conn.c
View File

@ -36,6 +36,7 @@
#include <stdlib.h> #include <stdlib.h>
#include <fcntl.h> #include <fcntl.h>
#include <errno.h> #include <errno.h>
#include <limits.h>
#include "xcb.h" #include "xcb.h"
#include "xcbint.h" #include "xcbint.h"
@ -209,7 +210,11 @@ static int write_vec(xcb_connection_t *c, struct iovec **vector, int *count)
i++; i++;
} }
#else #else
n = writev(c->fd, *vector, *count); n = *count;
if (n > IOV_MAX)
n = IOV_MAX;
n = writev(c->fd, *vector, n);
if(n < 0 && errno == EAGAIN) if(n < 0 && errno == EAGAIN)
return 1; return 1;
#endif /* _WIN32 */ #endif /* _WIN32 */