Rework pread and pwrite support so it should actually work.

Add support for pread64 and pwrite64.  Fixup llseek a bit.
 -Erik

libc/sysdeps/linux/common/Makefile

@@ -33,7 +33,8 @@ CSRC=	waitpid.c statfix.c getdnnm.c gethstnm.c getcwd.c \
 	mkfifo.c setegid.c wait.c getpagesize.c seteuid.c \
 	wait3.c setpgrp.c getdtablesize.c create_module.c ptrace.c \
 	cmsg_nxthdr.c statfix64.c longjmp.c open64.c ftruncate64.c \
-	truncate64.c getrlimit64.c setrlimit64.c creat64.c mmap64.c
+	truncate64.c getrlimit64.c setrlimit64.c creat64.c mmap64.c \
+	pread_write.c
 ifneq ($(strip $(EXCLUDE_BRK)),true)
 CSRC+=sbrk.c
 endif

libc/sysdeps/linux/common/pread_write.c

@@ -0,0 +1,213 @@
+/* vi: set sw=4 ts=4:
+ *
+ * Copyright (C) 2002 by Erik Andersen <andersen@uclibc.org>
+ * Based in part on the files
+ *		./sysdeps/unix/sysv/linux/pwrite.c,
+ *		./sysdeps/unix/sysv/linux/pread.c, 
+ *		sysdeps/posix/pread.c
+ *		sysdeps/posix/pwrite.c
+ * from GNU libc 2.2.5, but reworked considerably...
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Library General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, 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 Library General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Library General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <features.h>
+#if defined _FILE_OFFSET_BITS && _FILE_OFFSET_BITS != 64 
+#undef _FILE_OFFSET_BITS
+#define _FILE_OFFSET_BITS   64
+#endif
+#ifndef __USE_LARGEFILE64
+# define __USE_LARGEFILE64      1
+#endif
+/* We absolutely do _NOT_ want interfaces silently
+ * renamed under us or very bad things will happen... */
+#ifdef __USE_FILE_OFFSET64
+# undef __USE_FILE_OFFSET64
+#endif
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/syscall.h>
+#define _XOPEN_SOURCE 500
+#include <unistd.h>
+
+#ifdef __NR_pread
+#define __NR___syscall_pread __NR_pread
+static inline _syscall5(ssize_t, __syscall_pread, int, fd, void *, buf, size_t, count, 
+		__off_t, offset_hi, __off_t, offset_lo);
+#endif
+
+#ifdef __NR_pwrite
+#define __NR___syscall_pwrite __NR_pwrite
+static inline _syscall5(ssize_t, __syscall_pwrite, int, fd, const void *, buf, size_t, count, 
+		__off_t, offset_hi, __off_t, offset_lo);
+#endif
+
+
+static ssize_t __fake_pread_write(int fd, void *buf, 
+		size_t count, __off_t offset, int do_pwrite)
+{
+	int save_errno;
+	ssize_t result;
+	off64_t old_offset;
+
+	/* Since we must not change the file pointer preserve the 
+	 * value so that we can restore it later.  */
+	if ((old_offset=lseek64(fd, 0, SEEK_CUR)) == (off64_t) -1)
+		return -1;
+
+	/* Set to wanted position.  */
+	if (lseek (fd, offset, SEEK_SET) == (__off_t) -1)
+		return -1;
+
+	if (do_pwrite==1) {
+		/* Write the data.  */
+		result = write(fd, buf, count);
+	} else {
+		/* Read the data.  */
+		result = read(fd, buf, count);
+	}
+
+	/* Now we have to restore the position.  If this fails we 
+	 * have to return this as an error.  */
+	save_errno = errno;
+	if (lseek (fd, old_offset, SEEK_SET) == (__off_t) -1)
+	{
+		if (result == -1)
+			__set_errno (save_errno);
+		return -1;
+	}
+	__set_errno (save_errno);
+	return(result);
+}
+
+ssize_t __libc_pread(int fd, void *buf, size_t count, __off_t offset)
+{
+#ifndef __NR_pread
+	return(__fake_pread_write(fd, buf, count, offset, 0));
+#else
+	ssize_t result;
+
+	/* First try the syscall.  */
+	result = __syscall_pread(fd, buf, count, __LONG_LONG_PAIR(0, offset));
+
+	/* Bummer.  Syscall failed or is missing.  Fake it */
+	if (result == -1 && errno == ENOSYS) {
+		result = __fake_pread_write(fd, buf, count, offset, 0);
+	}
+#endif
+	return result;
+}
+weak_alias (__libc_pread, pread)
+
+ssize_t __libc_pwrite(int fd, const void *buf, size_t count, __off_t offset)
+{
+#ifndef __NR_pwrite
+	return(__fake_pread_write(fd, buf, count, offset, 1));
+#else
+	ssize_t result;
+
+	/* First try the syscall.  */
+	result = __syscall_pwrite(fd, buf, count, __LONG_LONG_PAIR(0, offset));
+
+	/* Bummer.  Syscall failed or is missing.  Fake it */
+	if (result == -1 && errno == ENOSYS) {
+		result = __fake_pread_write(fd, (void*)buf, count, offset, 1);
+	}
+#endif
+	return result;
+}
+weak_alias (__libc_pwrite, pwrite)
+
+
+
+
+#if defined __UCLIBC_HAVE_LFS__ 
+static ssize_t __fake_pread_write64(int fd, void *buf, 
+		size_t count, off64_t offset, int do_pwrite)
+{
+	int save_errno;
+	ssize_t result;
+	off64_t old_offset;
+
+	/* Since we must not change the file pointer preserve the 
+	 * value so that we can restore it later.  */
+	if ((old_offset=lseek64(fd, 0, SEEK_CUR)) == (off64_t) -1)
+		return -1;
+
+	/* Set to wanted position.  */
+	if (lseek64(fd, offset, SEEK_SET) == (off64_t) -1) 
+		return -1;                               
+
+	if (do_pwrite==1) {
+		/* Write the data.  */
+		result = write(fd, buf, count);
+	} else {
+		/* Read the data.  */
+		result = read(fd, buf, count);
+	}
+
+	/* Now we have to restore the position. */
+	save_errno = errno;
+	if (lseek64 (fd, old_offset, SEEK_SET) == (off64_t) -1) {
+		if (result == -1)
+			__set_errno (save_errno);
+		return -1;
+	}
+	__set_errno (save_errno);
+	return result;
+}
+
+ssize_t __libc_pread64(int fd, void *buf, size_t count, off64_t offset)
+{ 
+#ifndef __NR_pread
+	return(__fake_pread_write64(fd, buf, count, offset, 0));
+#else
+	ssize_t result;
+	/* First try the syscall.  */
+	result = __syscall_pread(fd, buf, count, 
+			__LONG_LONG_PAIR((__off_t) (offset >> 32), (__off_t) (offset & 0xffffffff)));
+
+	/* Bummer.  Syscall failed or is missing.  Fake it */
+	if (result == -1 && errno == ENOSYS) {
+		result = __fake_pread_write64(fd, buf, count, offset, 0); 
+	}
+	return result;
+#endif
+}
+weak_alias (__libc_pread64, pread64)
+
+ssize_t __libc_pwrite64(int fd, const void *buf, size_t count, off64_t offset)
+{ 
+#ifndef __NR_pwrite
+	return(__fake_pread_write64(fd, (void*)buf, count, offset, 1));
+#else
+	ssize_t result;
+
+	/* First try the syscall.  */
+	result = __syscall_pwrite(fd, buf, count, 
+			__LONG_LONG_PAIR((__off_t) (offset >> 32), (__off_t) (offset & 0xffffffff)));
+
+	/* Bummer.  Syscall failed or is missing.  Fake it */
+	if (result == -1 && errno == ENOSYS) {
+		result = __fake_pread_write64(fd, (void*)buf, count, offset, 1);
+	}
+	return result;
+#endif
+}
+weak_alias (__libc_pwrite64, pwrite64)
+
+#endif
+

libc/sysdeps/linux/common/syscalls.c

@@ -1254,8 +1254,8 @@ __loff_t __libc_lseek64(int fd, __loff_t offset, int whence)
 	int ret;
 	__loff_t result;
 
-	ret = _llseek(fd, (__off_t) (offset >> 32),
-				  (__off_t) (offset & 0xffffffff), &result, whence);
+	ret = _llseek(fd, __LONG_LONG_PAIR((__off_t) (offset >> 32), 
+				(__off_t) (offset & 0xffffffff)), &result, whence);
 
 	return ret ? (__loff_t) ret : result;
 }
@@ -1574,38 +1574,10 @@ int sigsuspend (const sigset_t *mask)
 #endif
 
 //#define __NR_pread                    180
-#ifdef L___libc_pread
-#ifdef __NR_pread
-#define _XOPEN_SOURCE 500
-#include <unistd.h>
-#define __NR___libc_pread __NR_pread
-_syscall4(ssize_t, __libc_pread, int, fd, void *, buf, size_t, count, __off_t, offset);
-weak_alias (__libc_pread, pread)
-#else
-ssize_t pread(int fd, void *buf, size_t count, off_t offset)                                                
-{                                                                                                           
-	__set_errno(ENOSYS);                                                                                    
-	return -1;                                                                                              
-}                                                                                                           
-#endif
-#endif
+// See pread_write.c
 
 //#define __NR_pwrite                   181
-#ifdef L___libc_pwrite
-#ifdef __NR_pwrite
-#define _XOPEN_SOURCE 500
-#include <unistd.h>
-#define __NR___libc_pwrite __NR_pwrite
-_syscall4(ssize_t, __libc_pwrite, int, fd, const void *, buf, size_t, count, __off_t, offset);
-weak_alias (__libc_pwrite, pwrite)
-#else
-ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset)                                         
-{                                                                                                           
-	__set_errno(ENOSYS);                                                                                    
-	return -1;                                                                                              
-}                                                                                                           
-#endif
-#endif
+// See pread_write.c
 
 //#define __NR_chown                    182
 #ifdef L_chown