4 Commits

Author	SHA1	Message	Date
Damien George	e4051a1ca6	extmod/vfs_rom: Implement minimal VfsRom.getcwd() method. ... This is needed if you chdir to a ROMFS and want to query your current directory. Prior to this change, using `os.getcwd()` when in a ROMFS would raise: AttributeError: 'VfsRom' object has no attribute 'getcwd' Signed-off-by: Damien George <damien@micropython.org>	2025-03-27 17:04:12 +11:00
Damien George	14ba32bb20	extmod/vfs_rom: Add bounds checking for all filesystem accesses. ... Testing with ROMFS shows that it is relatively easy to end up with a corrupt filesystem on the device -- eg due to the ROMFS deploy process stopping half way through -- which could lead to hard crashes. Notably, there can be boot loops trying to mount a corrupt filesystem, crashes when importing modules like `os` that first scan the filesystem for `os.py`, and crashing when deploying a new ROMFS in certain cases because the old one is removed while still mounted. The main problem is that `mp_decode_uint()` has an loop that keeps going as long as it reads 0xff byte values, which can happen in the case of erased and unwritten flash. This commit adds full bounds checking in the new `mp_decode_uint_checked()` function, and that makes all ROMFS filesystem accesses robust. Signed-off-by: Damien George <damien@micropython.org>	2025-02-26 16:11:19 +11:00
Damien George	30acb16ad3	extmod/vfs_rom: Remove ability to create VfsRom from an address. ... It's not necessary to support this, which allows an arbitrary memory address to be specified and potentially allows invalid memory accesses. Requiring an object with the buffer protocol is safer, and also means that the length of the region is always specified. Signed-off-by: Damien George <damien@micropython.org>	2025-02-11 17:56:13 +11:00
Damien George	50637ff239	extmod/vfs_rom: Add VfsRom filesystem object. ... This commit defines a new ROMFS filesystem for storing read-only files that can be memory mapped, and a new VfsRom driver. Files opened from this filesystem support the buffer protocol. This allows naturally getting the memory-mapped address of the file using: - memoryview(file) - uctypes.addressof(file) Furthermore, if these files are .mpy files then their content can be referenced in-place when importing. Such imports take up a lot less RAM than importing from a normal filesystem. This is essentially dynamically frozen .mpy files, building on the revamped v6 .mpy file format. Signed-off-by: Damien George <damien@micropython.org>	2024-12-23 13:04:54 +11:00