| /* bufio.c - buffered io access */ |
| /* |
| * GRUB -- GRand Unified Bootloader |
| * Copyright (C) 2008 Free Software Foundation, Inc. |
| * |
| * GRUB is free software: you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation, either version 3 of the License, or |
| * (at your option) any later version. |
| * |
| * GRUB 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 General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with GRUB. If not, see <http://www.gnu.org/licenses/>. |
| */ |
| |
| #include <grub/err.h> |
| #include <grub/types.h> |
| #include <grub/mm.h> |
| #include <grub/misc.h> |
| #include <grub/fs.h> |
| #include <grub/bufio.h> |
| #include <grub/dl.h> |
| |
| GRUB_MOD_LICENSE ("GPLv3+"); |
| |
| #define GRUB_BUFIO_DEF_SIZE 8192 |
| #define GRUB_BUFIO_MAX_SIZE 1048576 |
| |
| struct grub_bufio |
| { |
| grub_file_t file; |
| grub_size_t block_size; |
| grub_size_t buffer_len; |
| grub_off_t buffer_at; |
| char buffer[0]; |
| }; |
| typedef struct grub_bufio *grub_bufio_t; |
| |
| static struct grub_fs grub_bufio_fs; |
| |
| grub_file_t |
| grub_bufio_open (grub_file_t io, |
| grub_size_t size) |
| { |
| grub_file_t file; |
| grub_bufio_t bufio = 0; |
| |
| file = (grub_file_t) grub_zalloc (sizeof (*file)); |
| if (! file) |
| return 0; |
| |
| if (size == 0) |
| size = GRUB_BUFIO_DEF_SIZE; |
| else if (size > GRUB_BUFIO_MAX_SIZE) |
| size = GRUB_BUFIO_MAX_SIZE; |
| |
| if (size > io->size) |
| size = ((io->size > GRUB_BUFIO_MAX_SIZE) ? GRUB_BUFIO_MAX_SIZE : |
| io->size); |
| |
| bufio = grub_zalloc (sizeof (struct grub_bufio) + size); |
| if (! bufio) |
| { |
| grub_free (file); |
| return 0; |
| } |
| |
| bufio->file = io; |
| bufio->block_size = size; |
| |
| file->device = io->device; |
| file->size = io->size; |
| file->data = bufio; |
| file->fs = &grub_bufio_fs; |
| file->not_easily_seekable = io->not_easily_seekable; |
| |
| return file; |
| } |
| |
| grub_file_t |
| grub_buffile_open (const char *name, enum grub_file_type type, |
| grub_size_t size) |
| { |
| grub_file_t io, file; |
| |
| io = grub_file_open (name, type); |
| if (! io) |
| return 0; |
| |
| file = grub_bufio_open (io, size); |
| if (! file) |
| { |
| grub_file_close (io); |
| return 0; |
| } |
| |
| return file; |
| } |
| |
| static grub_ssize_t |
| grub_bufio_read (grub_file_t file, char *buf, grub_size_t len) |
| { |
| grub_size_t res = 0; |
| grub_off_t next_buf; |
| grub_bufio_t bufio = file->data; |
| grub_ssize_t really_read; |
| |
| if (file->size == GRUB_FILE_SIZE_UNKNOWN) |
| file->size = bufio->file->size; |
| |
| /* First part: use whatever we already have in the buffer. */ |
| if ((file->offset >= bufio->buffer_at) && |
| (file->offset < bufio->buffer_at + bufio->buffer_len)) |
| { |
| grub_size_t n; |
| grub_uint64_t pos; |
| |
| pos = file->offset - bufio->buffer_at; |
| n = bufio->buffer_len - pos; |
| if (n > len) |
| n = len; |
| |
| grub_memcpy (buf, &bufio->buffer[pos], n); |
| len -= n; |
| res += n; |
| |
| buf += n; |
| } |
| if (len == 0) |
| return res; |
| |
| /* Need to read some more. */ |
| next_buf = (file->offset + res + len - 1) & ~((grub_off_t) bufio->block_size - 1); |
| /* Now read between file->offset + res and bufio->buffer_at. */ |
| if (file->offset + res < next_buf) |
| { |
| grub_size_t read_now; |
| read_now = next_buf - (file->offset + res); |
| grub_file_seek (bufio->file, file->offset + res); |
| really_read = grub_file_read (bufio->file, buf, read_now); |
| if (really_read < 0) |
| return -1; |
| if (file->size == GRUB_FILE_SIZE_UNKNOWN) |
| file->size = bufio->file->size; |
| len -= really_read; |
| buf += really_read; |
| res += really_read; |
| |
| /* Partial read. File ended unexpectedly. Save the last chunk in buffer. |
| */ |
| if (really_read != (grub_ssize_t) read_now) |
| { |
| bufio->buffer_len = really_read; |
| if (bufio->buffer_len > bufio->block_size) |
| bufio->buffer_len = bufio->block_size; |
| bufio->buffer_at = file->offset + res - bufio->buffer_len; |
| grub_memcpy (&bufio->buffer[0], buf - bufio->buffer_len, |
| bufio->buffer_len); |
| return res; |
| } |
| } |
| |
| /* Read into buffer. */ |
| grub_file_seek (bufio->file, next_buf); |
| really_read = grub_file_read (bufio->file, bufio->buffer, |
| bufio->block_size); |
| if (really_read < 0) |
| return -1; |
| bufio->buffer_at = next_buf; |
| bufio->buffer_len = really_read; |
| |
| if (file->size == GRUB_FILE_SIZE_UNKNOWN) |
| file->size = bufio->file->size; |
| |
| if (len > bufio->buffer_len) |
| len = bufio->buffer_len; |
| grub_memcpy (buf, &bufio->buffer[file->offset + res - next_buf], len); |
| res += len; |
| |
| return res; |
| } |
| |
| static grub_err_t |
| grub_bufio_close (grub_file_t file) |
| { |
| grub_bufio_t bufio = file->data; |
| |
| grub_file_close (bufio->file); |
| grub_free (bufio); |
| |
| file->device = 0; |
| |
| return grub_errno; |
| } |
| |
| static struct grub_fs grub_bufio_fs = |
| { |
| .name = "bufio", |
| .dir = 0, |
| .open = 0, |
| .read = grub_bufio_read, |
| .close = grub_bufio_close, |
| .label = 0, |
| .next = 0 |
| }; |