default_llseek():
* allows 32-bit overflows
* allows file pointers larger than supported by the filesystem.
* prevents negativ file pointers
ext2_file_lseek() is the exact opposite:
* prevents 32-bit overflows.
* prevents files offsets larger than supported by the fs.
* allows negativ values on 64-bit platforms.
* doesn't allow negativ values on 32-bit platform.
What's by other OS'es, what's required by SUS/POSIX?
--
Manfred
PS: Here is my current (alpha) patch:
>>>>>>>>>>>>>>>>>>
// Kernel Version:
// VERSION = 2
// PATCHLEVEL = 3
// SUBLEVEL = 14
// EXTRAVERSION =
diff -r -u -P -x CVS -x *,v 2.3/fs/ext2/file.c build-2.3/fs/ext2/file.c
--- 2.3/fs/ext2/file.c Thu Jul 1 14:11:44 1999
+++ build-2.3/fs/ext2/file.c Fri Aug 20 20:53:13 1999
@@ -37,58 +37,9 @@
#define MIN(a,b) (((a)<(b))?(a):(b))
#define MAX(a,b) (((a)>(b))?(a):(b))
-static long long ext2_file_lseek(struct file *, long long, int);
#if BITS_PER_LONG < 64
static int ext2_open_file (struct inode *, struct file *);
-
-#else
-
-#define
EXT2_MAX_SIZE(bits) \
- (((EXT2_NDIR_BLOCKS + (1LL << (bits - 2))
+ \
- (1LL << (bits - 2)) * (1LL << (bits - 2))
+ \
- (1LL << (bits - 2)) * (1LL << (bits - 2)) * (1LL << (bits -
2))) * \
- (1LL << bits)) - 1)
-
-static long long ext2_max_sizes[] = {
-0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-EXT2_MAX_SIZE(10), EXT2_MAX_SIZE(11), EXT2_MAX_SIZE(12),
EXT2_MAX_SIZE(13)
-};
-
-#endif
-
-
-/*
- * Make sure the offset never goes beyond the 32-bit mark..
- */
-static long long ext2_file_lseek(
- struct file *file,
- long long offset,
- int origin)
-{
- struct inode *inode = file->f_dentry->d_inode;
-
- switch (origin) {
- case 2:
- offset += inode->i_size;
- break;
- case 1:
- offset += file->f_pos;
- }
- if (((unsigned long long) offset >> 32) != 0) {
-#if BITS_PER_LONG < 64
- return -EINVAL;
-#else
- if (offset >
ext2_max_sizes[EXT2_BLOCK_SIZE_BITS(inode->i_sb)])
- return -EINVAL;
#endif
- }
- if (offset != file->f_pos) {
- file->f_pos = offset;
- file->f_reada = 0;
- file->f_version = ++event;
- }
- return offset;
-}
static inline void remove_suid(struct inode *inode)
{
@@ -154,7 +105,7 @@
* the ext2 filesystem.
*/
static struct file_operations ext2_file_operations = {
- ext2_file_lseek, /* lseek */
+ NULL, /* lseek */
generic_file_read, /* read */
ext2_file_write, /* write */
NULL, /* readdir - bad */
diff -r -u -P -x CVS -x *,v 2.3/fs/ext2/super.c
build-2.3/fs/ext2/super.c
--- 2.3/fs/ext2/super.c Tue Jun 15 20:15:05 1999
+++ build-2.3/fs/ext2/super.c Fri Aug 20 20:52:10 1999
@@ -376,6 +376,18 @@
#define log2(n) ffz(~(n))
+#define
EXT2_MAX_SIZE(bits) \
+ (((EXT2_NDIR_BLOCKS + (1LL << (bits - 2))
+ \
+ (1LL << (bits - 2)) * (1LL << (bits - 2))
+ \
+ (1LL << (bits - 2)) * (1LL << (bits - 2)) * (1LL << (bits -
2))) * \
+ (1LL << bits)) - 1)
+
+static long long ext2_max_sizes[] = {
+0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+EXT2_MAX_SIZE(10), EXT2_MAX_SIZE(11), EXT2_MAX_SIZE(12),
EXT2_MAX_SIZE(13)
+};
+
+
struct super_block * ext2_read_super (struct super_block * sb, void *
data,
int silent)
{
@@ -470,6 +482,7 @@
}
sb->s_blocksize_bits =
le32_to_cpu(sb->u.ext2_sb.s_es->s_log_block_size) + 10;
sb->s_blocksize = 1 << sb->s_blocksize_bits;
+ sb->s_maxfilesize = ext2_max_sizes[EXT2_BLOCK_SIZE_BITS(sb)];
if (sb->s_blocksize != BLOCK_SIZE &&
(sb->s_blocksize == 1024 || sb->s_blocksize == 2048 ||
sb->s_blocksize == 4096)) {
diff -r -u -P -x CVS -x *,v 2.3/fs/read_write.c
build-2.3/fs/read_write.c
--- 2.3/fs/read_write.c Thu Jul 1 14:11:46 1999
+++ build-2.3/fs/read_write.c Fri Aug 20 21:53:29 1999
@@ -16,6 +16,7 @@
static loff_t default_llseek(struct file *file, loff_t offset, int
origin)
{
long long retval;
+ long long max;
switch (origin) {
case 2:
@@ -24,8 +25,18 @@
case 1:
offset += file->f_pos;
}
+ max = ((long long)(~0ULL>>1));
+ if(S_ISREG(file->f_dentry->d_inode->i_mode) &&
file->f_dentry->d_inode->i_sb)
+ {
+ if(file->f_dentry->d_inode->i_sb->s_maxfilesize!=0)
+ max =
file->f_dentry->d_inode->i_sb->s_maxfilesize;
+ }
+#if BITS_PER_LONG < 64
+ if(max > INT_MAX)
+ max = INT_MAX;
+#endif
retval = -EINVAL;
- if (offset >= 0) {
+ if (offset >= 0 && offset <= max) {
if (offset != file->f_pos) {
file->f_pos = offset;
file->f_reada = 0;
diff -r -u -P -x CVS -x *,v 2.3/include/linux/fs.h
build-2.3/include/linux/fs.h
--- 2.3/include/linux/fs.h Mon Aug 9 23:58:27 1999
+++ build-2.3/include/linux/fs.h Fri Aug 20 19:35:54 1999
@@ -519,6 +519,7 @@
kdev_t s_dev;
unsigned long s_blocksize;
unsigned char s_blocksize_bits;
+ loff_t s_maxfilesize;
unsigned char s_lock;
unsigned char s_rd_only;
unsigned char s_dirt;
<<<<<<<<<<<<<<<<<<
-
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