diff options
Diffstat (limited to 'libc/sysdeps/linux/common/pread_write.c')
| -rw-r--r-- | libc/sysdeps/linux/common/pread_write.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/common/pread_write.c b/libc/sysdeps/linux/common/pread_write.c new file mode 100644 index 000000000..319de5af1 --- /dev/null +++ b/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 + |