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/* 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

 */

#define _GNU_SOURCE

#define _LARGEFILE64_SOURCE

#include <features.h>

#undef __OPTIMIZE__

/* 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>

#include <unistd.h>

#include <stdint.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);

ssize_t __libc_pread(int fd, void *buf, size_t count, off_t offset)

{

        return(__syscall_pread(fd,buf,count,__LONG_LONG_PAIR (offset >> 31, offset)));

}

weak_alias (__libc_pread, pread)

#if defined __UCLIBC_HAS_LFS__ 

ssize_t __libc_pread64(int fd, void *buf, size_t count, off64_t offset)

{

    uint32_t low = offset & 0xffffffff;

    uint32_t high = offset >> 32;

        return(__syscall_pread(fd, buf, count, __LONG_LONG_PAIR (high, low)));

}

weak_alias (__libc_pread64, pread64)

#endif /* __UCLIBC_HAS_LFS__  */

#endif /* __NR_pread */

#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);

ssize_t __libc_pwrite(int fd, const void *buf, size_t count, off_t offset)

{

        return(__syscall_pwrite(fd,buf,count,__LONG_LONG_PAIR (offset >> 31, offset)));

}

weak_alias (__libc_pwrite, pwrite)

#if defined __UCLIBC_HAS_LFS__ 

ssize_t __libc_pwrite64(int fd, const void *buf, size_t count, off64_t offset)

{

    uint32_t low = offset & 0xffffffff;

    uint32_t high = offset >> 32;

        return(__syscall_pwrite(fd, buf, count, __LONG_LONG_PAIR (high, low)));

}

weak_alias (__libc_pwrite64, pwrite64)

#endif /* __UCLIBC_HAS_LFS__  */

#endif /* __NR_pwrite */

#if ! defined __NR_pread || ! defined __NR_pwrite

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;

        off_t old_offset;

        /* Since we must not change the file pointer preserve the

         * value so that we can restore it later.  */

        if ((old_offset=lseek(fd, 0, SEEK_CUR)) == (off_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);

}

#if defined __UCLIBC_HAS_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;

}

#endif /* __UCLIBC_HAS_LFS__  */

#endif /*  ! defined __NR_pread || ! defined __NR_pwrite */

#ifndef __NR_pread

ssize_t __libc_pread(int fd, void *buf, size_t count, off_t offset)

{

        return(__fake_pread_write(fd, buf, count, offset, 0));

}

weak_alias (__libc_pread, pread)

#if defined __UCLIBC_HAS_LFS__ 

ssize_t __libc_pread64(int fd, void *buf, size_t count, off64_t offset)

{

        return(__fake_pread_write64(fd, buf, count, offset, 0));

}

weak_alias (__libc_pread64, pread64)

#endif /* __UCLIBC_HAS_LFS__  */

#endif /* ! __NR_pread */

#ifndef __NR_pwrite

ssize_t __libc_pwrite(int fd, const void *buf, size_t count, off_t offset)

{

        return(__fake_pread_write(fd, buf, count, offset, 1));

}

weak_alias (__libc_pwrite, pwrite)

#if defined __UCLIBC_HAS_LFS__ 

ssize_t __libc_pwrite64(int fd, const void *buf, size_t count, off64_t offset)

{

        return(__fake_pread_write64(fd, (void*)buf, count, offset, 1));

}

weak_alias (__libc_pwrite64, pwrite64)

#endif /* __UCLIBC_HAS_LFS__  */

#endif /* ! __NR_pwrite */