[PATCH v4] lib/cobalt: Avoid making mmap offset argument unconditionally 64-bit

From: Jan Kiszka <[email protected]>

When _FILE_OFFSET_BITS is 64, mmap is handled by the mmap64 symbol of
glibc. The original mmap continues to expect native off_t size, i.e.
32 bits on 32-bit archs.

While we require applications to be rebuilt with the same settings
Xenomai was built with as well (either both _TIME_BITS and
_FILE_OFFSET_BITS set to 64 or both left unset) which practically
shadows this issue, it remains wrong to change the wrapped mmap function
in a way that is incompatible with glibc.

To avoid running into conflicts between enabling and disabling
_TIME_BITS=64 and, thus, also _FILE_OFFSET_BITS=64, factor out the
affected mmap wrappers as well as their __real stubs into a separate
code module.

There is one catch: The cobalt-call to mmap in umm.c needs to be forced
to mmap64 to become agnostic to _FILE_OFFSET_BITS used by the cobalt
core internally.

Fixes: fb2bd6e647a9 ("y2038: build: Introduce new build parameter --disable-y2038")
Signed-off-by: Jan Kiszka <[email protected]>
---

Changes in v4:
 - renamed to libcobaltnativeoff in Makefile to align with nativetime
   patches

 lib/cobalt/Makefile.am | 15 ++++++++
 lib/cobalt/mmap.c      | 79 ++++++++++++++++++++++++++++++++++++++++++
 lib/cobalt/rtdm.c      | 38 --------------------
 lib/cobalt/umm.c       |  4 +--
 lib/cobalt/wrappers.c  | 17 ---------
 5 files changed, 96 insertions(+), 57 deletions(-)
 create mode 100644 lib/cobalt/mmap.c

diff --git a/lib/cobalt/Makefile.am b/lib/cobalt/Makefile.am
index 4318adf185..b5b184b555 100644
--- a/lib/cobalt/Makefile.am
+++ b/lib/cobalt/Makefile.am
@@ -7,9 +7,12 @@ noinst_HEADERS =	\
 
 lib_LTLIBRARIES = libcobalt.la libmodechk.la
 
+noinst_LTLIBRARIES = libcobaltnativeoff.la
+
 libcobalt_la_LDFLAGS = @XENO_LIB_LDFLAGS@ -version-info 2:0:0 -lpthread -lrt
 
 libcobalt_la_LIBADD = \
+	libcobaltnativeoff.la			\
 	arch/@XENO_TARGET_ARCH@/libarch.la	\
 	../boilerplate/libboilerplate.la
 
@@ -43,6 +46,18 @@ libcobalt_la_CPPFLAGS =			\
 	-I$(top_srcdir)/include/cobalt	\
 	-I$(top_srcdir)/include
 
+# source files that require native off_t size
+libcobaltnativeoff_la_SOURCES =	\
+	mmap.c
+
+libcobaltnativeoff_la_LDFLAGS = @XENO_LIB_LDFLAGS@
+
+libcobaltnativeoff_la_CPPFLAGS =	\
+	@XENO_COBALT_CFLAGS@		\
+	-I$(top_srcdir)/include/cobalt	\
+	-I$(top_srcdir)/include		\
+	-U_TIME_BITS -U_FILE_OFFSET_BITS
+
 libmodechk_la_LIBADD = libcobalt.la
 
 libmodechk_la_SOURCES =	\
diff --git a/lib/cobalt/mmap.c b/lib/cobalt/mmap.c
new file mode 100644
index 0000000000..069163a855
--- /dev/null
+++ b/lib/cobalt/mmap.c
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2005 Jan Kiszka <[email protected]>.
+ * Copyright (C) 2005 Heikki Lindholm <[email protected]>.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
+  USA.
+ */
+
+#include <sys/mman.h>
+#include <rtdm/rtdm.h>
+#include <cobalt/uapi/syscall.h>
+#include <asm/xenomai/syscall.h>
+
+COBALT_IMPL(void *, mmap64, (void *addr, size_t length, int prot, int flags,
+			     int fd, off64_t offset))
+{
+	struct _rtdm_mmap_request rma;
+	int ret;
+
+	if (fd < 0) /* We don't do anonymous mappings. */
+		goto regular;
+
+	/* RTDM ignores the address hint, and rejects MAP_FIXED. */
+	rma.length = length;
+	rma.offset = offset;
+	rma.prot = prot;
+	rma.flags = flags;
+
+	ret = XENOMAI_SYSCALL3(sc_cobalt_mmap, fd, &rma, &addr);
+	if (ret != -EADV && ret != -ENOSYS) {
+		if (ret) {
+			errno = -ret;
+			return MAP_FAILED;
+		}
+
+		return addr;
+	}
+
+regular:
+#if mmap64 == mmap
+	return __STD(mmap(addr, length, prot, flags, fd, offset));
+#else
+	return __STD(mmap64(addr, length, prot, flags, fd, offset));
+#endif
+}
+
+COBALT_IMPL(void *, mmap, (void *addr, size_t length, int prot, int flags,
+			   int fd, off_t offset))
+{
+	return __COBALT(mmap64(addr, length, prot, flags, fd, offset));
+}
+
+__weak
+void *__real_mmap(void *addr, size_t length, int prot, int flags,
+		  int fd, off_t offset)
+{
+	return mmap(addr, length, prot, flags, fd, offset);
+}
+
+#if mmap64 != mmap
+__weak
+void *__real_mmap64(void *addr, size_t length, int prot, int flags,
+		  int fd, off64_t offset)
+{
+	return mmap64(addr, length, prot, flags, fd, offset);
+}
+#endif
diff --git a/lib/cobalt/rtdm.c b/lib/cobalt/rtdm.c
index 00c1aaf4b2..119ba3f83d 100644
--- a/lib/cobalt/rtdm.c
+++ b/lib/cobalt/rtdm.c
@@ -541,41 +541,3 @@ COBALT_IMPL(int, shutdown, (int fd, int how))
 
 	return __STD(shutdown(fd, how));
 }
-
-COBALT_IMPL(void *, mmap64, (void *addr, size_t length, int prot, int flags,
-			     int fd, off64_t offset))
-{
-	struct _rtdm_mmap_request rma;
-	int ret;
-
-	if (fd < 0) /* We don't do anonymous mappings. */
-		goto regular;
-
-	/* RTDM ignores the address hint, and rejects MAP_FIXED. */
-	rma.length = length;
-	rma.offset = offset;
-	rma.prot = prot;
-	rma.flags = flags;
-
-	ret = XENOMAI_SYSCALL3(sc_cobalt_mmap, fd, &rma, &addr);
-	if (ret != -EADV && ret != -ENOSYS) {
-		ret = set_errno(ret);
-		if (ret)
-			return MAP_FAILED;
-
-		return addr;
-	}
-
-regular:
-#if mmap64 == mmap
-	return __STD(mmap(addr, length, prot, flags, fd, offset));
-#else
-	return __STD(mmap64(addr, length, prot, flags, fd, offset));
-#endif
-}
-
-COBALT_IMPL(void *, mmap, (void *addr, size_t length, int prot, int flags,
-			   int fd, off_t offset))
-{
-	return __COBALT(mmap64(addr, length, prot, flags, fd, offset));
-}
diff --git a/lib/cobalt/umm.c b/lib/cobalt/umm.c
index c0d4489d34..6b4303b727 100644
--- a/lib/cobalt/umm.c
+++ b/lib/cobalt/umm.c
@@ -58,8 +58,8 @@ static void *__map_umm(const char *name, uint32_t *size_r)
 		return MAP_FAILED;
 	}
 
-	addr = __RT(mmap(NULL, statbuf.size, PROT_READ|PROT_WRITE,
-			 MAP_SHARED, fd, 0));
+	addr = __RT(mmap64(NULL, statbuf.size, PROT_READ|PROT_WRITE,
+			   MAP_SHARED, fd, 0));
 	__RT(close(fd));
 
 	*size_r = statbuf.size;
diff --git a/lib/cobalt/wrappers.c b/lib/cobalt/wrappers.c
index 18c237734f..3a0063f051 100644
--- a/lib/cobalt/wrappers.c
+++ b/lib/cobalt/wrappers.c
@@ -28,7 +28,6 @@
 #include <sys/select.h>
 #include <sys/socket.h>
 #include <sys/time.h>
-#include <sys/mman.h>
 #include <stdio.h>
 #include <stdarg.h>
 #include <stdlib.h>
@@ -384,22 +383,6 @@ int __real_select (int __nfds, fd_set *__restrict __readfds,
 	return select(__nfds, __readfds, __writefds, __exceptfds, __timeout);
 }
 
-__weak
-void *__real_mmap(void *addr, size_t length, int prot, int flags,
-		  int fd, off_t offset)
-{
-	return mmap(addr, length, prot, flags, fd, offset);
-}
-
-#if mmap64 != mmap
-__weak
-void *__real_mmap64(void *addr, size_t length, int prot, int flags,
-		  int fd, off64_t offset)
-{
-	return mmap64(addr, length, prot, flags, fd, offset);
-}
-#endif
-
 __weak
 int __real_vfprintf(FILE *stream, const char *fmt, va_list args)
 {
-- 
2.47.3