ufs2: Add access() support

Change-Id: I4c2fa12a623f0893c976430893f448f734794548
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6858
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

ufs2: Add size and file_offset sanity check

Change-Id: I33a1d509d9f9cac356982944a2c2491858cc1c14
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6856
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

ufs2: Fix warning

Change-Id: I1eebcf6c5e324f8dbbfe5e80bffdfcd4e8de1f7b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6854
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

ufs2: Fix reading past the end of file and reading overwrite.

Current code forgets to clamp readings to actual file size anf moreover
never adjust the buffer fo subsequent reads. Fix both of those.

Change-Id: I3b8eb98142215ac3b30badfbbbb811147f76563a
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6852
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

ufs2: Fix inode retrieval

The code multiplied fragno by MINBSIZE instead on fragment size.
Moreover IsDirectory and IsSymlink were called before inode was read.

Change-Id: I9e62007c900fb4376812f8ebef508a3f8a8f619b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/6848
Reviewed-by: Adrien Destugues <pulkomandy@pulkomandy.tk>

ufs2: Reading symbolic links

Symbolic links are now showing path and relative path can be tested.

Change-Id: I47820a475d78d8090c02564f698e72dd8fbaa3a1
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3171
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

ufs2: Implementing read function

Attempting to read data from direct blocks and single indirect
blocks even if the data stored is not in continous blocks and
DirectoryIterator now uses ReadAt to iterate through directories.

Change-Id: I8156aba53782da8c2bb4481db611ae26d8881b35
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3088
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

ufs2: implementing open_dir and read_dir function

Root directory is read sucessfully.

Change-Id: I8bdc8c1a52edb679a6cb4b5f70e7f42eb2b2c8f1
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2907
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

ufs2: Reading inodes of ufs2.

Now file system can be mounted sucessfully.

Adding documentation for using the code.

Change-Id: I2bd1b72e06ffc3b5f6306aaa69c59becf4cb882b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2696
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>