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libprobe.c
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libprobe.c
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#define _GNU_SOURCE
#define _POSIX_C_SOURCE 200809L
#define _FILE_OFFSET_BITS 64
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include <assert.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdint.h>
#include <errno.h>
#include <err.h>
#include <linux/fs.h>
#include <linux/usbdevice_fs.h>
#include <libudev.h>
#include "libprobe.h"
static const char const *ftype_to_name[FKTY_MAX] = {
[FKTY_GOOD] = "good",
[FKTY_BAD] = "bad",
[FKTY_LIMBO] = "limbo",
[FKTY_WRAPAROUND] = "wraparound",
[FKTY_CHAIN] = "chain",
};
const char *fake_type_to_name(enum fake_type fake_type)
{
assert(fake_type < FKTY_MAX);
return ftype_to_name[fake_type];
}
int dev_param_valid(uint64_t real_size_byte,
uint64_t announced_size_byte, int wrap, int block_order)
{
int block_size;
/* Check general ranges. */
if (real_size_byte > announced_size_byte || wrap < 0 || wrap >= 64 ||
block_order < 9 || block_order > 20)
return false;
/* Check alignment of the sizes. */
block_size = 1 << block_order;
if (real_size_byte % block_size || announced_size_byte % block_size)
return false;
/* If good, @wrap must make sense. */
if (real_size_byte == announced_size_byte) {
uint64_t two_wrap = ((uint64_t)1) << wrap;
return announced_size_byte <= two_wrap;
}
return true;
}
enum fake_type dev_param_to_type(uint64_t real_size_byte,
uint64_t announced_size_byte, int wrap, int block_order)
{
uint64_t two_wrap;
assert(dev_param_valid(real_size_byte, announced_size_byte,
wrap, block_order));
if (real_size_byte == announced_size_byte)
return FKTY_GOOD;
if (real_size_byte == 0)
return FKTY_BAD;
/* real_size_byte < announced_size_byte */
two_wrap = ((uint64_t)1) << wrap;
if (two_wrap <= real_size_byte)
return FKTY_WRAPAROUND;
if (two_wrap < announced_size_byte)
return FKTY_CHAIN;
return FKTY_LIMBO;
}
struct device {
uint64_t size_byte;
int block_order;
int (*read_block)(struct device *dev, char *buf, int length,
uint64_t offset);
int (*write_block)(struct device *dev, const char *buf, int length,
uint64_t offset);
int (*reset)(struct device *dev);
void (*free)(struct device *dev);
};
static inline uint64_t dev_get_size_byte(struct device *dev)
{
return dev->size_byte;
}
static inline int dev_get_block_order(struct device *dev)
{
return dev->block_order;
}
static inline int dev_get_block_size(struct device *dev)
{
return 1 << dev->block_order;
}
static inline int dev_read_block(struct device *dev, char *buf, uint64_t block)
{
const int block_size = 1 << dev->block_order;
uint64_t offset = block << dev->block_order;
assert(offset + block_size <= dev->size_byte);
return dev->read_block(dev, buf, block_size, offset);
}
static inline int dev_write_block(struct device *dev, const char *buf,
uint64_t block)
{
const int block_size = 1 << dev->block_order;
uint64_t offset = block << dev->block_order;
assert(offset + block_size <= dev->size_byte);
return dev->write_block(dev, buf, block_size, offset);
}
static inline int dev_reset(struct device *dev)
{
return dev->reset ? dev->reset(dev) : 0;
}
static inline int dev_write_and_reset(struct device *dev, const char *buf,
uint64_t block)
{
int rc = dev_write_block(dev, buf, block);
return rc ? rc : dev_reset(dev);
}
void free_device(struct device *dev)
{
dev->free(dev);
free(dev);
}
struct file_device {
/* This must be the first field. See dev_fdev() for details. */
struct device dev;
int fd;
uint64_t real_size_byte;
uint64_t address_mask;
};
static inline struct file_device *dev_fdev(struct device *dev)
{
return (struct file_device *)dev;
}
static int fdev_read_block(struct device *dev, char *buf, int length,
uint64_t offset)
{
struct file_device *fdev = dev_fdev(dev);
off_t off_ret;
int done;
offset &= fdev->address_mask;
if (offset >= fdev->real_size_byte) {
memset(buf, 0, length);
return 0;
}
off_ret = lseek(fdev->fd, offset, SEEK_SET);
if (off_ret < 0)
return - errno;
assert((uint64_t)off_ret == offset);
done = 0;
do {
ssize_t rc = read(fdev->fd, buf + done, length - done);
assert(rc >= 0);
if (!rc) {
/* Tried to read beyond the end of the file. */
assert(!done);
memset(buf, 0, length);
done += length;
}
done += rc;
} while (done < length);
return 0;
}
static int write_all(int fd, const char *buf, int count)
{
int done = 0;
do {
ssize_t rc = write(fd, buf + done, count - done);
assert(rc >= 0); /* Did the write() went right? */
done += rc;
} while (done < count);
return 0;
}
static int fdev_write_block(struct device *dev, const char *buf, int length,
uint64_t offset)
{
struct file_device *fdev = dev_fdev(dev);
off_t off_ret;
offset &= fdev->address_mask;
if (offset >= fdev->real_size_byte)
return 0;
off_ret = lseek(fdev->fd, offset, SEEK_SET);
if (off_ret < 0)
return - errno;
assert((uint64_t)off_ret == offset);
return write_all(fdev->fd, buf, length);
}
static void fdev_free(struct device *dev)
{
struct file_device *fdev = dev_fdev(dev);
assert(!close(fdev->fd));
}
struct device *create_file_device(const char *filename,
uint64_t real_size_byte, uint64_t fake_size_byte, int wrap,
int block_order, int keep_file)
{
struct file_device *fdev;
if (!dev_param_valid(real_size_byte, fake_size_byte, wrap, block_order))
goto error;
fdev = malloc(sizeof(*fdev));
if (!fdev)
goto error;
fdev->fd = open(filename, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
if (fdev->fd < 0) {
err(errno, "Can't create file `%s'", filename);
goto fdev;
}
if (!keep_file) {
/* Unlinking the file now guarantees that it won't exist if
* there is a crash.
*/
assert(!unlink(filename));
}
fdev->real_size_byte = real_size_byte;
fdev->address_mask = (((uint64_t)1) << wrap) - 1;
fdev->dev.size_byte = fake_size_byte;
fdev->dev.block_order = block_order;
fdev->dev.read_block = fdev_read_block;
fdev->dev.write_block = fdev_write_block;
fdev->dev.reset = NULL;
fdev->dev.free = fdev_free;
return &fdev->dev;
fdev:
free(fdev);
error:
return NULL;
}
struct block_device {
/* This must be the first field. See dev_bdev() for details. */
struct device dev;
const char *filename;
int fd;
int hw_fd; /* Underlying hardware of the block device. */
};
static inline struct block_device *dev_bdev(struct device *dev)
{
return (struct block_device *)dev;
}
static int read_all(int fd, char *buf, int count)
{
int done = 0;
do {
ssize_t rc = read(fd, buf + done, count - done);
assert(rc >= 0); /* Did the read() went right? */
assert(rc != 0); /* We should never hit the end of the file. */
done += rc;
} while (done < count);
return 0;
}
static int bdev_read_block(struct device *dev, char *buf, int length,
uint64_t offset)
{
struct block_device *bdev = dev_bdev(dev);
off_t off_ret = lseek(bdev->fd, offset, SEEK_SET);
if (off_ret < 0)
return - errno;
assert((uint64_t)off_ret == offset);
return read_all(bdev->fd, buf, length);
}
static int bdev_write_block(struct device *dev, const char *buf, int length,
uint64_t offset)
{
struct block_device *bdev = dev_bdev(dev);
off_t off_ret = lseek(bdev->fd, offset, SEEK_SET);
if (off_ret < 0)
return - errno;
assert((uint64_t)off_ret == offset);
return write_all(bdev->fd, buf, length);
}
static inline int bdev_open(const char *filename)
{
return open(filename, O_RDWR | O_DIRECT | O_SYNC);
}
static int bdev_reset(struct device *dev)
{
struct block_device *bdev = dev_bdev(dev);
assert(!close(bdev->fd));
assert(!ioctl(bdev->hw_fd, USBDEVFS_RESET));
bdev->fd = bdev_open(bdev->filename);
if (bdev->fd < 0)
err(errno, "Can't REopen device `%s'", bdev->filename);
return 0;
}
static void bdev_free(struct device *dev)
{
struct block_device *bdev = dev_bdev(dev);
assert(!close(bdev->hw_fd));
assert(!close(bdev->fd));
free((void *)bdev->filename);
}
static bool is_block_dev(int fd)
{
struct stat stat;
assert(!fstat(fd, &stat));
return S_ISBLK(stat.st_mode);
}
static char *map_block_to_usb_dev(const char *block_dev)
{
struct udev *udev;
struct udev_enumerate *enumerate;
struct udev_list_entry *devices, *dev_list_entry;
char *usb_dev_path = NULL;
udev = udev_new();
if (!udev)
err(errno, "Can't create udev");
/* XXX Avoid the enumeration using udev_device_new_from_devnum(). */
enumerate = udev_enumerate_new(udev);
assert(enumerate);
assert(!udev_enumerate_add_match_subsystem(enumerate, "block"));
assert(!udev_enumerate_scan_devices(enumerate));
devices = udev_enumerate_get_list_entry(enumerate);
assert(devices);
udev_list_entry_foreach(dev_list_entry, devices) {
const char *sys_path, *dev_path;
struct udev_device *dev, *parent_dev;
/* Get the filename of the /sys entry for the device,
* and create a udev_device object (dev) representing it.
*/
sys_path = udev_list_entry_get_name(dev_list_entry);
dev = udev_device_new_from_syspath(udev, sys_path);
/* usb_device_get_devnode() returns the path to
* the device node itself in /dev.
*/
dev_path = udev_device_get_devnode(dev);
if (strcmp(block_dev, dev_path)) {
assert(!udev_device_unref(dev));
continue;
}
/* The device pointed to by dev contains information about
* the USB device.
* In order to get information about the USB device,
* get the parent device with the subsystem/devtype pair of
* "usb"/"usb_device".
* This will be several levels up the tree,
* but the function will find it.
*/
parent_dev = udev_device_get_parent_with_subsystem_devtype(
dev, "usb", "usb_device");
if (!parent_dev)
err(errno, "Unable to find parent usb device of `%s'",
block_dev);
usb_dev_path = strdup(udev_device_get_devnode(parent_dev));
/* @parent_dev is not referenced, and will be freed when
* the child (i.e. @dev) is freed.
* See udev_device_get_parent_with_subsystem_devtype() for
* details.
*/
assert(!udev_device_unref(dev));
break;
}
/* Free the enumerator object. */
assert(!udev_enumerate_unref(enumerate));
assert(!udev_unref(udev));
return usb_dev_path;
}
/* Count the number of 1 bits. */
static int pop(uint64_t x)
{
int n = 0;
while (x) {
n++;
x = x & (x - 1);
}
return n;
}
static int ilog2(uint64_t x)
{
x = x | (x >> 1);
x = x | (x >> 2);
x = x | (x >> 4);
x = x | (x >> 8);
x = x | (x >> 16);
x = x | (x >> 32);
return pop(x) - 1;
}
/* XXX Test if it's a device, or a partition.
* If a partition, warn user, and ask for confirmation before
* going ahead.
* Suggest how to call f3probe with the correct device name if
* the block device is a partition.
* Use udev to do these tests.
*/
/* XXX Test for write access of the block device to give
* a nice error message.
* If it fails, suggest running f3probe as root.
*/
struct device *create_block_device(const char *filename)
{
const char *usb_filename;
struct block_device *bdev;
int block_size;
bdev = malloc(sizeof(*bdev));
if (!bdev)
goto error;
bdev->filename = strdup(filename);
if (!bdev->filename)
goto bdev;
bdev->fd = bdev_open(filename);
if (bdev->fd < 0) {
err(errno, "Can't open device `%s'", filename);
goto filename;
}
if (!is_block_dev(bdev->fd)) {
err(EINVAL, "File `%s' is not a block device", filename);
goto fd;
}
/* XXX Add support for block devices backed by SCSI, SATA, and ATA. */
usb_filename = map_block_to_usb_dev(filename);
if (!usb_filename) {
err(EINVAL, "Block device `%s' is not backed by a USB device",
filename);
goto fd;
}
bdev->hw_fd = open(usb_filename, O_WRONLY | O_NONBLOCK);
if (bdev->hw_fd < 0) {
err(errno, "Can't open device `%s'", usb_filename);
goto usb_filename;
}
assert(!ioctl(bdev->fd, BLKGETSIZE64, &bdev->dev.size_byte));
assert(!ioctl(bdev->fd, BLKBSZGET, &block_size));
bdev->dev.block_order = ilog2(block_size);
assert(block_size == (1 << bdev->dev.block_order));
bdev->dev.read_block = bdev_read_block;
bdev->dev.write_block = bdev_write_block;
bdev->dev.reset = bdev_reset;
bdev->dev.free = bdev_free;
free((void *)usb_filename);
return &bdev->dev;
usb_filename:
free((void *)usb_filename);
fd:
assert(!close(bdev->fd));
filename:
free((void *)bdev->filename);
bdev:
free(bdev);
error:
return NULL;
}
#define SDEV_BITMAP_WORD long
#define SDEV_BITMAP_BITS_PER_WORD (8*sizeof(SDEV_BITMAP_WORD))
struct safe_device {
/* This must be the first field. See dev_sdev() for details. */
struct device dev;
struct device *shadow_dev;
char *saved_blocks;
uint64_t *sb_offsets;
SDEV_BITMAP_WORD *sb_bitmap;
int sb_n;
int sb_max;
};
static inline struct safe_device *dev_sdev(struct device *dev)
{
return (struct safe_device *)dev;
}
static int sdev_read_block(struct device *dev, char *buf, int length,
uint64_t offset)
{
struct safe_device *sdev = dev_sdev(dev);
return sdev->shadow_dev->read_block(sdev->shadow_dev, buf,
length, offset);
}
static inline void *align_512(void *p)
{
uintptr_t ip = (uintptr_t)p;
return (void *)( (ip + 511) & ~511 );
}
static int sdev_write_block(struct device *dev, const char *buf, int length,
uint64_t offset)
{
struct safe_device *sdev = dev_sdev(dev);
const int block_order = dev_get_block_order(sdev->shadow_dev);
lldiv_t idx = lldiv(offset >> block_order, SDEV_BITMAP_BITS_PER_WORD);
SDEV_BITMAP_WORD set_bit = (SDEV_BITMAP_WORD)1 << idx.rem;
/* The current implementation doesn't support variable lengths. */
assert(length == dev_get_block_size(sdev->shadow_dev));
/* Is this block already saved? */
if (!(sdev->sb_bitmap[idx.quot] & set_bit)) {
/* No. Save this block. */
char *block = (char *)align_512(sdev->saved_blocks) +
(sdev->sb_n << block_order);
int rc;
assert(sdev->sb_n < sdev->sb_max);
rc = sdev->shadow_dev->read_block(sdev->shadow_dev, block,
length, offset);
if (rc)
return rc;
sdev->sb_bitmap[idx.quot] |= set_bit;
sdev->sb_offsets[sdev->sb_n] = offset;
sdev->sb_n++;
}
return sdev->shadow_dev->write_block(sdev->shadow_dev, buf,
length, offset);
}
static int sdev_reset(struct device *dev)
{
return dev_reset(dev_sdev(dev)->shadow_dev);
}
static void sdev_free(struct device *dev)
{
struct safe_device *sdev = dev_sdev(dev);
if (sdev->sb_n > 0) {
char *first_block = align_512(sdev->saved_blocks);
char *block = first_block +
((sdev->sb_n - 1) <<
dev_get_block_order(sdev->shadow_dev));
uint64_t *poffset = &sdev->sb_offsets[sdev->sb_n - 1];
int block_size = dev_get_block_size(sdev->shadow_dev);
int failed = false;
/* Restore blocks in reverse order to cope with
* wraparound and chain drives.
*/
do {
failed |= sdev->shadow_dev->write_block(
sdev->shadow_dev, block, block_size, *poffset);
block -= block_size;
poffset--;
} while (block >= first_block);
/* Try to recover all bocks before failing. */
assert(!failed);
}
free(sdev->sb_bitmap);
free(sdev->sb_offsets);
free(sdev->saved_blocks);
free_device(sdev->shadow_dev);
}
struct device *create_safe_device(struct device *dev, int max_blocks)
{
struct safe_device *sdev;
const int block_order = dev_get_block_order(dev);
lldiv_t idx = lldiv(dev_get_size_byte(dev) >> block_order,
SDEV_BITMAP_BITS_PER_WORD);
uint64_t length;
sdev = malloc(sizeof(*sdev));
if (!sdev)
goto error;
length = 511 + (max_blocks << block_order);
sdev->saved_blocks = malloc(length);
if (!sdev->saved_blocks)
goto sdev;
sdev->sb_offsets = malloc(max_blocks * sizeof(*sdev->sb_offsets));
if (!sdev->sb_offsets)
goto saved_blocks;
length = (idx.quot + (idx.rem ? 1 : 0)) * sizeof(SDEV_BITMAP_WORD);
sdev->sb_bitmap = malloc(length);
if (!sdev->sb_bitmap)
goto offsets;
memset(sdev->sb_bitmap, 0, length);
sdev->shadow_dev = dev;
sdev->sb_n = 0;
sdev->sb_max = max_blocks;
sdev->dev.size_byte = dev->size_byte;
sdev->dev.block_order = block_order;
sdev->dev.read_block = sdev_read_block;
sdev->dev.write_block = sdev_write_block;
sdev->dev.reset = sdev_reset;
sdev->dev.free = sdev_free;
return &sdev->dev;
offsets:
free(sdev->sb_offsets);
saved_blocks:
free(sdev->saved_blocks);
sdev:
free(sdev);
error:
return NULL;
}
static inline int equal_blk(struct device *dev, const char *b1, const char *b2)
{
return !memcmp(b1, b2, dev_get_block_size(dev));
}
/* Minimum size of the memory chunk used to build flash drives.
* It must be a power of two.
*/
static inline uint64_t initial_high_bit_block(struct device *dev)
{
int block_order = dev_get_block_order(dev);
assert(block_order <= 20);
return 1ULL << (20 - block_order);
}
/* Caller must guarantee that the left bock is good, and written. */
static int search_wrap(struct device *dev,
uint64_t left_pos, uint64_t *pright_pos,
const char *stamp_blk, char *probe_blk)
{
uint64_t high_bit = initial_high_bit_block(dev);
uint64_t pos = high_bit + left_pos;
/* The left block must be in the first memory chunk. */
assert(left_pos < high_bit);
/* Check that the drive has at least one memory chunk. */
assert((high_bit - 1) <= *pright_pos);
while (pos < *pright_pos) {
if (dev_read_block(dev, probe_blk, pos) &&
dev_read_block(dev, probe_blk, pos))
return true;
/* XXX Deal with flipped bit on reception. */
if (equal_blk(dev, stamp_blk, probe_blk)) {
/* XXX Test wraparound hypothesis. */
*pright_pos = high_bit - 1;
return false;
}
high_bit <<= 1;
pos = high_bit + left_pos;
}
return false;
}
/* Return true if @b1 and b2 are at most @tolerance_byte bytes different. */
static int similar_blk(struct device *dev, const char *b1, const char *b2,
int tolerance_byte)
{
const int block_size = dev_get_block_size(dev);
int i;
for (i = 0; i < block_size; i++) {
if (*b1 != *b2) {
tolerance_byte--;
if (tolerance_byte <= 0)
return false;
}
b1++;
b2++;
}
return true;
}
/* Return true if the block @pos is damaged. */
static int test_block(struct device *dev,
const char *stamp_blk, char *probe_blk, uint64_t pos)
{
/* Write block. */
if (dev_write_block(dev, stamp_blk, pos) &&
dev_write_block(dev, stamp_blk, pos))
return true;
/* Reset. */
if (dev_reset(dev) && dev_reset(dev))
return true;
/*
* Test block.
*/
if (dev_read_block(dev, probe_blk, pos) &&
dev_read_block(dev, probe_blk, pos))
return true;
if (equal_blk(dev, stamp_blk, probe_blk))
return false;
/* Save time with certainly damaged blocks. */
if (!similar_blk(dev, stamp_blk, probe_blk, 8)) {
/* The probe block is damaged. */
return true;
}
/* The probe block seems to be damaged.
* Trying a second time...
*/
return dev_write_and_reset(dev, stamp_blk, pos) ||
dev_read_block(dev, probe_blk, pos) ||
!equal_blk(dev, stamp_blk, probe_blk);
}
/* Caller must guarantee that the left bock is good, and written. */
static int search_edge(struct device *dev,
uint64_t *pleft_pos, uint64_t right_pos,
const char *stamp_blk, char *probe_blk)
{
uint64_t pos = right_pos;
do {
if (test_block(dev, stamp_blk, probe_blk, pos))
right_pos = pos;
else
*pleft_pos = pos;
pos = (*pleft_pos + right_pos) / 2;
} while (right_pos - *pleft_pos >= 2);
return false;
}
/* XXX Write random data to make it harder for fake chips to become "smarter".
* There would be a random seed.
* Buffer cannot be all 0x00 or all 0xFF.
*/
static void fill_buffer(char *buf, int len)
{
memset(buf, 0xAA, len);
}
/* Least power of 2 greater than or equal to x. */
static uint64_t clp2(uint64_t x)
{
x = x - 1;
x = x | (x >> 1);
x = x | (x >> 2);
x = x | (x >> 4);
x = x | (x >> 8);
x = x | (x >> 16);
x = x | (x >> 32);
return x + 1;
}
static int ceiling_log2(uint64_t x)
{
return ilog2(clp2(x));
}
int probe_device_max_blocks(struct device *dev)
{
return 4 * ceiling_log2(dev_get_size_byte(dev));
}
/* XXX Properly handle read and write errors.
* Review each assert to check if them can be removed.
*/
void probe_device(struct device *dev, uint64_t *preal_size_byte,
uint64_t *pannounced_size_byte, int *pwrap, int *pblock_order)
{
uint64_t dev_size_byte = dev_get_size_byte(dev);
const int block_size = dev_get_block_size(dev);
const int block_order = dev_get_block_order(dev);
char stack[511 + (2 << block_order)];
char *stamp_blk, *probe_blk;
/* XXX Don't write at the very beginning of the card to avoid
* losing the partition table.
* But write at a random locations to make harder for fake chips
* to become "smarter".
* And try a couple of blocks if they keep failing.
*/
uint64_t left_pos = 10;
uint64_t right_pos = (dev_size_byte >> block_order) - 1;
assert(dev_size_byte % block_size == 0);
assert(left_pos < right_pos);
/* Aligning these pointers is necessary to directly read and write
* the block device.
* For the file device, this is superfluous.
*/
stamp_blk = align_512(stack);
probe_blk = stamp_blk + block_size;
fill_buffer(stamp_blk, block_size);
/* Make sure that there is at least a good block at the beginning
* of the drive.
*/
if (test_block(dev, stamp_blk, probe_blk, left_pos))
goto bad;
if (search_wrap(dev, left_pos, &right_pos, stamp_blk, probe_blk))
goto bad;
if (search_edge(dev, &left_pos, right_pos, stamp_blk, probe_blk))
goto bad;
*preal_size_byte = (left_pos + 1) << block_order;
*pannounced_size_byte = dev_size_byte;
*pwrap = ceiling_log2(right_pos << block_order);
*pblock_order = block_order;
return;
bad:
*preal_size_byte = 0;
*pannounced_size_byte = dev_size_byte;
*pwrap = ceiling_log2(dev_size_byte);
*pblock_order = block_order;
}