android_kernel_xiaomi_sm8350/arch/um/drivers/cow_user.c
Paolo 'Blaisorblade' Giarrusso 028c0cc16e [PATCH] uml: cleanup byte order macros for COW driver
After restoring the existing code, make it work also when included in
kernelspace code (which isn't currently the case, but at least this will prevent
people from "fixing" it as just happened).
Whitespace is fixed in next patch - it cluttered the diff too much.

Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-10 08:36:00 -07:00

378 lines
9.6 KiB
C

#include <stddef.h>
#include <string.h>
#include <errno.h>
/* _XOPEN_SOURCE is needed for pread, but we define _GNU_SOURCE, which defines
* that.
*/
#include <unistd.h>
#include <byteswap.h>
#include <sys/time.h>
#include <sys/param.h>
#include <sys/user.h>
#include "os.h"
#include "cow.h"
#include "cow_sys.h"
#define PATH_LEN_V1 256
struct cow_header_v1 {
int magic;
int version;
char backing_file[PATH_LEN_V1];
time_t mtime;
__u64 size;
int sectorsize;
};
#define PATH_LEN_V2 MAXPATHLEN
struct cow_header_v2 {
__u32 magic;
__u32 version;
char backing_file[PATH_LEN_V2];
time_t mtime;
__u64 size;
int sectorsize;
};
/* Define PATH_LEN_V3 as the usual value of MAXPATHLEN, just hard-code it in
* case other systems have different values for MAXPATHLEN
*/
#define PATH_LEN_V3 4096
/* Changes from V2 -
* PATH_LEN_V3 as described above
* Explicitly specify field bit lengths for systems with different
* lengths for the usual C types. Not sure whether char or
* time_t should be changed, this can be changed later without
* breaking compatibility
* Add alignment field so that different alignments can be used for the
* bitmap and data
* Add cow_format field to allow for the possibility of different ways
* of specifying the COW blocks. For now, the only value is 0,
* for the traditional COW bitmap.
* Move the backing_file field to the end of the header. This allows
* for the possibility of expanding it into the padding required
* by the bitmap alignment.
* The bitmap and data portions of the file will be aligned as specified
* by the alignment field. This is to allow COW files to be
* put on devices with restrictions on access alignments, such as
* /dev/raw, with a 512 byte alignment restriction. This also
* allows the data to be more aligned more strictly than on
* sector boundaries. This is needed for ubd-mmap, which needs
* the data to be page aligned.
* Fixed (finally!) the rounding bug
*/
struct cow_header_v3 {
__u32 magic;
__u32 version;
__u32 mtime;
__u64 size;
__u32 sectorsize;
__u32 alignment;
__u32 cow_format;
char backing_file[PATH_LEN_V3];
};
/* COW format definitions - for now, we have only the usual COW bitmap */
#define COW_BITMAP 0
union cow_header {
struct cow_header_v1 v1;
struct cow_header_v2 v2;
struct cow_header_v3 v3;
};
#define COW_MAGIC 0x4f4f4f4d /* MOOO */
#define COW_VERSION 3
#define DIV_ROUND(x, len) (((x) + (len) - 1) / (len))
#define ROUND_UP(x, align) DIV_ROUND(x, align) * (align)
void cow_sizes(int version, __u64 size, int sectorsize, int align,
int bitmap_offset, unsigned long *bitmap_len_out,
int *data_offset_out)
{
if(version < 3){
*bitmap_len_out = (size + sectorsize - 1) / (8 * sectorsize);
*data_offset_out = bitmap_offset + *bitmap_len_out;
*data_offset_out = (*data_offset_out + sectorsize - 1) /
sectorsize;
*data_offset_out *= sectorsize;
}
else {
*bitmap_len_out = DIV_ROUND(size, sectorsize);
*bitmap_len_out = DIV_ROUND(*bitmap_len_out, 8);
*data_offset_out = bitmap_offset + *bitmap_len_out;
*data_offset_out = ROUND_UP(*data_offset_out, align);
}
}
static int absolutize(char *to, int size, char *from)
{
char save_cwd[256], *slash;
int remaining;
if(getcwd(save_cwd, sizeof(save_cwd)) == NULL) {
cow_printf("absolutize : unable to get cwd - errno = %d\n",
errno);
return(-1);
}
slash = strrchr(from, '/');
if(slash != NULL){
*slash = '\0';
if(chdir(from)){
*slash = '/';
cow_printf("absolutize : Can't cd to '%s' - "
"errno = %d\n", from, errno);
return(-1);
}
*slash = '/';
if(getcwd(to, size) == NULL){
cow_printf("absolutize : unable to get cwd of '%s' - "
"errno = %d\n", from, errno);
return(-1);
}
remaining = size - strlen(to);
if(strlen(slash) + 1 > remaining){
cow_printf("absolutize : unable to fit '%s' into %d "
"chars\n", from, size);
return(-1);
}
strcat(to, slash);
}
else {
if(strlen(save_cwd) + 1 + strlen(from) + 1 > size){
cow_printf("absolutize : unable to fit '%s' into %d "
"chars\n", from, size);
return(-1);
}
strcpy(to, save_cwd);
strcat(to, "/");
strcat(to, from);
}
chdir(save_cwd);
return(0);
}
int write_cow_header(char *cow_file, int fd, char *backing_file,
int sectorsize, int alignment, unsigned long long *size)
{
struct cow_header_v3 *header;
unsigned long modtime;
int err;
err = cow_seek_file(fd, 0);
if(err < 0){
cow_printf("write_cow_header - lseek failed, err = %d\n", -err);
goto out;
}
err = -ENOMEM;
header = cow_malloc(sizeof(*header));
if(header == NULL){
cow_printf("Failed to allocate COW V3 header\n");
goto out;
}
header->magic = htonl(COW_MAGIC);
header->version = htonl(COW_VERSION);
err = -EINVAL;
if(strlen(backing_file) > sizeof(header->backing_file) - 1){
cow_printf("Backing file name \"%s\" is too long - names are "
"limited to %d characters\n", backing_file,
sizeof(header->backing_file) - 1);
goto out_free;
}
if(absolutize(header->backing_file, sizeof(header->backing_file),
backing_file))
goto out_free;
err = os_file_modtime(header->backing_file, &modtime);
if(err < 0){
cow_printf("Backing file '%s' mtime request failed, "
"err = %d\n", header->backing_file, -err);
goto out_free;
}
err = cow_file_size(header->backing_file, size);
if(err < 0){
cow_printf("Couldn't get size of backing file '%s', "
"err = %d\n", header->backing_file, -err);
goto out_free;
}
header->mtime = htonl(modtime);
header->size = htonll(*size);
header->sectorsize = htonl(sectorsize);
header->alignment = htonl(alignment);
header->cow_format = COW_BITMAP;
err = os_write_file(fd, header, sizeof(*header));
if(err != sizeof(*header)){
cow_printf("Write of header to new COW file '%s' failed, "
"err = %d\n", cow_file, -err);
goto out_free;
}
err = 0;
out_free:
cow_free(header);
out:
return(err);
}
int file_reader(__u64 offset, char *buf, int len, void *arg)
{
int fd = *((int *) arg);
return(pread(fd, buf, len, offset));
}
/* XXX Need to sanity-check the values read from the header */
int read_cow_header(int (*reader)(__u64, char *, int, void *), void *arg,
__u32 *version_out, char **backing_file_out,
time_t *mtime_out, unsigned long long *size_out,
int *sectorsize_out, __u32 *align_out,
int *bitmap_offset_out)
{
union cow_header *header;
char *file;
int err, n;
unsigned long version, magic;
header = cow_malloc(sizeof(*header));
if(header == NULL){
cow_printf("read_cow_header - Failed to allocate header\n");
return(-ENOMEM);
}
err = -EINVAL;
n = (*reader)(0, (char *) header, sizeof(*header), arg);
if(n < offsetof(typeof(header->v1), backing_file)){
cow_printf("read_cow_header - short header\n");
goto out;
}
magic = header->v1.magic;
if(magic == COW_MAGIC) {
version = header->v1.version;
}
else if(magic == ntohl(COW_MAGIC)){
version = ntohl(header->v1.version);
}
/* No error printed because the non-COW case comes through here */
else goto out;
*version_out = version;
if(version == 1){
if(n < sizeof(header->v1)){
cow_printf("read_cow_header - failed to read V1 "
"header\n");
goto out;
}
*mtime_out = header->v1.mtime;
*size_out = header->v1.size;
*sectorsize_out = header->v1.sectorsize;
*bitmap_offset_out = sizeof(header->v1);
*align_out = *sectorsize_out;
file = header->v1.backing_file;
}
else if(version == 2){
if(n < sizeof(header->v2)){
cow_printf("read_cow_header - failed to read V2 "
"header\n");
goto out;
}
*mtime_out = ntohl(header->v2.mtime);
*size_out = ntohll(header->v2.size);
*sectorsize_out = ntohl(header->v2.sectorsize);
*bitmap_offset_out = sizeof(header->v2);
*align_out = *sectorsize_out;
file = header->v2.backing_file;
}
else if(version == 3){
if(n < sizeof(header->v3)){
cow_printf("read_cow_header - failed to read V2 "
"header\n");
goto out;
}
*mtime_out = ntohl(header->v3.mtime);
*size_out = ntohll(header->v3.size);
*sectorsize_out = ntohl(header->v3.sectorsize);
*align_out = ntohl(header->v3.alignment);
*bitmap_offset_out = ROUND_UP(sizeof(header->v3), *align_out);
file = header->v3.backing_file;
}
else {
cow_printf("read_cow_header - invalid COW version\n");
goto out;
}
err = -ENOMEM;
*backing_file_out = cow_strdup(file);
if(*backing_file_out == NULL){
cow_printf("read_cow_header - failed to allocate backing "
"file\n");
goto out;
}
err = 0;
out:
cow_free(header);
return(err);
}
int init_cow_file(int fd, char *cow_file, char *backing_file, int sectorsize,
int alignment, int *bitmap_offset_out,
unsigned long *bitmap_len_out, int *data_offset_out)
{
unsigned long long size, offset;
char zero = 0;
int err;
err = write_cow_header(cow_file, fd, backing_file, sectorsize,
alignment, &size);
if(err)
goto out;
*bitmap_offset_out = ROUND_UP(sizeof(struct cow_header_v3), alignment);
cow_sizes(COW_VERSION, size, sectorsize, alignment, *bitmap_offset_out,
bitmap_len_out, data_offset_out);
offset = *data_offset_out + size - sizeof(zero);
err = cow_seek_file(fd, offset);
if(err < 0){
cow_printf("cow bitmap lseek failed : err = %d\n", -err);
goto out;
}
/* does not really matter how much we write it is just to set EOF
* this also sets the entire COW bitmap
* to zero without having to allocate it
*/
err = cow_write_file(fd, &zero, sizeof(zero));
if(err != sizeof(zero)){
cow_printf("Write of bitmap to new COW file '%s' failed, "
"err = %d\n", cow_file, -err);
err = -EINVAL;
goto out;
}
return(0);
out:
return(err);
}
/*
* ---------------------------------------------------------------------------
* Local variables:
* c-file-style: "linux"
* End:
*/