Change the C wrappers for mmap/lseek/pread/pwrite/truncate/ftruncate to

call the pad-less versions of the corresponding syscalls if the running
kernel supports it.  Check kern.osreldate once per program and cache the
result to select the appropriate syscall.  This maintains userland
compatability with kernel.old's from quite a while back.

Approved by:  re (kensmith)

9 files changed, 119 insertions, 9 deletions

diff --git a/lib/libc/gen/Makefile.inc b/lib/libc/gen/Makefile.inc
index 8881d80ed128..c3f394096001 100644
--- a/lib/libc/gen/Makefile.inc
+++ b/lib/libc/gen/Makefile.inc
@@ -4,7 +4,8 @@
 # machine-independent gen sources
 .PATH: ${.CURDIR}/${MACHINE_ARCH}/gen ${.CURDIR}/gen
 
-SRCS+=  __xuname.c _pthread_stubs.c _rand48.c _spinlock_stub.c _thread_init.c \
+SRCS+=  __getosreldate.c __xuname.c \
+	_pthread_stubs.c _rand48.c _spinlock_stub.c _thread_init.c \
 	alarm.c arc4random.c assert.c basename.c check_utility_compat.c \
 	clock.c closedir.c confstr.c \
 	crypt.c ctermid.c daemon.c devname.c dirname.c disklabel.c \
diff --git a/lib/libc/gen/__getosreldate.c b/lib/libc/gen/__getosreldate.c
new file mode 100644
index 000000000000..69aac07ea7f5
--- /dev/null
+++ b/lib/libc/gen/__getosreldate.c
@@ -0,0 +1,61 @@
+/*-
+ * Copyright (c) 2007 Peter Wemm
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/sysctl.h>
+
+/*
+ * This is private to libc.  It is intended for wrapping syscall stubs in order
+ * to avoid having to put SIGSYS signal handlers in place to test for presence
+ * of new syscalls.  This caches the result in order to be as quick as possible.
+ *
+ * Use getosreldate(3) for public use as it respects the $OSVERSION environment
+ * variable.
+ */
+
+int
+__getosreldate(void)
+{
+	static int osreldate;
+	size_t len;
+	int oid[2];
+	int error, osrel;
+
+	if (osreldate != 0)
+		return (osreldate);
+	
+	oid[0] = CTL_KERN;
+	oid[1] = KERN_OSRELDATE;
+	osrel = 0;
+	len = sizeof(osrel);
+	error = sysctl(oid, 2, &osrel, &len, NULL, 0);
+	if (error == 0 && osrel > 0 && len == sizeof(osrel))
+		osreldate = osrel;
+	return (osreldate);
+}
diff --git a/lib/libc/include/libc_private.h b/lib/libc/include/libc_private.h
index a8b53fecabb3..de4bbe44151c 100644
--- a/lib/libc/include/libc_private.h
+++ b/lib/libc/include/libc_private.h
@@ -169,4 +169,27 @@ void _malloc_postfork(void);
  */
 extern void (*__cleanup)(void);
 
+/*
+ * Get kern.osreldate to detect ABI revisions.  Explicitly
+ * ignores value of $OSVERSION and caches result.  Prototypes
+ * for the wrapped "new" pad-less syscalls are here for now.
+ */
+extern int __getosreldate(void);
+#include <sys/_types.h>
+/* Without pad */
+extern __off_t	__sys_lseek(int, __off_t, int);
+extern int	__sys_ftruncate(int, __off_t);
+extern int	__sys_truncate(const char *, __off_t);
+extern __ssize_t __sys_pread(int, void *, __size_t, __off_t);
+extern __ssize_t __sys_pwrite(int, const void *, __size_t, __off_t);
+extern void *	__sys_mmap(void *, __size_t, int, int, int, __off_t);
+
+/* With pad */
+extern __off_t	__sys_freebsd6_lseek(int, int, __off_t, int);
+extern int	__sys_freebsd6_ftruncate(int, int, __off_t);
+extern int	__sys_freebsd6_truncate(const char *, int, __off_t);
+extern __ssize_t __sys_freebsd6_pread(int, void *, __size_t, int, __off_t);
+extern __ssize_t __sys_freebsd6_pwrite(int, const void *, __size_t, int, __off_t);
+extern void *	__sys_freebsd6_mmap(void *, __size_t, int, int, int, int, __off_t);
+
 #endif /* _LIBC_PRIVATE_H_ */
diff --git a/lib/libc/sys/ftruncate.c b/lib/libc/sys/ftruncate.c
index fcd2ef8da2e2..78b5a36adba6 100644
--- a/lib/libc/sys/ftruncate.c
+++ b/lib/libc/sys/ftruncate.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/syscall.h>
 #include <unistd.h>
+#include "libc_private.h"
 
 /*
  * This function provides 64-bit offset padding that
@@ -47,5 +48,8 @@ ftruncate(fd, length)
 	off_t	length;
 {
 
-	return(__syscall((quad_t)SYS_ftruncate, fd, 0, length));
+	if (__getosreldate() >= 700051)
+		return(__sys_ftruncate(fd, length));
+	else
+		return(__sys_freebsd6_ftruncate(fd, 0, length));
 }
diff --git a/lib/libc/sys/lseek.c b/lib/libc/sys/lseek.c
index 86136785f053..a086be18e537 100644
--- a/lib/libc/sys/lseek.c
+++ b/lib/libc/sys/lseek.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/syscall.h>
 #include <unistd.h>
+#include "libc_private.h"
 
 /*
  * This function provides 64-bit offset padding that
@@ -47,5 +48,9 @@ lseek(fd, offset, whence)
 	off_t	offset;
 	int	whence;
 {
-	return(__syscall((quad_t)SYS_lseek, fd, 0, offset, whence));
+
+	if (__getosreldate() >= 700051)
+		return(__sys_lseek(fd, offset, whence));
+	else
+		return(__sys_freebsd6_lseek(fd, 0, offset, whence));
 }
diff --git a/lib/libc/sys/mmap.c b/lib/libc/sys/mmap.c
index 8b22147acbd4..cfdb9448ea38 100644
--- a/lib/libc/sys/mmap.c
+++ b/lib/libc/sys/mmap.c
@@ -37,6 +37,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/mman.h>
 #include <sys/syscall.h>
 #include <unistd.h>
+#include "libc_private.h"
 
 /*
  * This function provides 64-bit offset padding that
@@ -52,6 +53,9 @@ mmap(addr, len, prot, flags, fd, offset)
 	off_t	offset;
 {
 
-	return ((void *)(intptr_t)__syscall((quad_t)SYS_mmap, addr, len, prot,
-	    flags, fd, 0, offset));
+	if (__getosreldate() >= 700051)
+		return (__sys_mmap(addr, len, prot, flags, fd, offset));
+	else
+
+		return (__sys_freebsd6_mmap(addr, len, prot, flags, fd, 0, offset));
 }
diff --git a/lib/libc/sys/pread.c b/lib/libc/sys/pread.c
index 1d2fee693fe6..7566566d3e1d 100644
--- a/lib/libc/sys/pread.c
+++ b/lib/libc/sys/pread.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/syscall.h>
 #include <unistd.h>
+#include "libc_private.h"
 
 /*
  * This function provides 64-bit offset padding that
@@ -48,5 +49,9 @@ pread(fd, buf, nbyte, offset)
 	size_t	nbyte;
 	off_t	offset;
 {
-	return ((ssize_t)__syscall((quad_t)SYS_pread, fd, buf, nbyte, 0, offset));
+
+	if (__getosreldate() >= 700051)
+		return (__sys_pread(fd, buf, nbyte, offset));
+	else
+		return (__sys_freebsd6_pread(fd, buf, nbyte, 0, offset));
 }
diff --git a/lib/libc/sys/pwrite.c b/lib/libc/sys/pwrite.c
index ebbb1ec1102a..d17ed2938f77 100644
--- a/lib/libc/sys/pwrite.c
+++ b/lib/libc/sys/pwrite.c
@@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/types.h>
 #include <sys/syscall.h>
 #include <unistd.h>
+#include "libc_private.h"
 
 /*
  * This function provides 64-bit offset padding that
@@ -48,5 +49,8 @@ pwrite(fd, buf, nbyte, offset)
 	size_t	nbyte;
 	off_t	offset;
 {
-	return ((ssize_t)__syscall((quad_t)SYS_pwrite, fd, buf, nbyte, 0, offset));
+	if (__getosreldate() >= 700051)
+		return (__sys_pwrite(fd, buf, nbyte, offset));
+	else
+		return (__sys_freebsd6_pwrite(fd, buf, nbyte, 0, offset));
 }
diff --git a/lib/libc/sys/truncate.c b/lib/libc/sys/truncate.c
index e26f3f59a48b..375c9d933c60 100644
--- a/lib/libc/sys/truncate.c
+++ b/lib/libc/sys/truncate.c
@@ -35,8 +35,8 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/types.h>
 #include <sys/syscall.h>
-
 #include <unistd.h>
+#include "libc_private.h"
 
 /*
  * This function provides 64-bit offset padding that
@@ -48,5 +48,8 @@ truncate(path, length)
 	off_t	length;
 {
 
-	return(__syscall((quad_t)SYS_truncate, path, 0, length));
+	if (__getosreldate() >= 700051)
+		return(__sys_truncate(path, length));
+	else
+		return(__sys_freebsd6_truncate(path, 0, length));
 }