Christopher Haster
acfae9e072
This has been a long-time coming, mount flags are just too useful for
configuring a filesystem at runtime.
Currently this is limited to LFS_M_RDONLY and LFS_M_CKPROGS, but there
are a few more planned in the future:
LFS_M_RDWR = 0x0000, // Mount the filesystem as read and write
LFS_M_RDONLY = 0x0001, // Mount the filesystem as readonly
LFS_M_STRICT* = 0x0002, // Error if on-disk config does not match
LFS_M_FORCE* = 0x0004, // Ignore compat flags, mount readonly
LFS_M_FORCEWITHRECKLESSABANDON*
= 0x0008, // Ignore compat flags, mount read write
LFS_M_CKPROGS = 0x0010, // Check progs by reading back progged data
LFS_M_CKREADS* = 0x0020, // Check reads via checksums
* Hypothetical
As a convenience, we also return mount flags in the struct lfs_fsinfo's
flags field as their relevant LFS_I_* variants. Though only to match
statvfs, and only because it's cheap, littlefs's API is low-level and we
should expect users to know what flags they passed to lfsr_mount.
As for the new mount flags:
- LFS_M_RDONLY - For consistency with existing APIs, this just asserts
on write operations, which makes it a bit useless... But the info flag
LFS_I_RDONLY may be useful for falling back to a readonly mode if
we encounter on-disk compat issues.
At least if implement the theoretical LFS_UNTRUSTED_USER mode
LFS_M_RDONLY could become a runtime error.
- LFS_M_RDWR - This really just exists to compliment LFS_M_RDONLY and to
match LFS_O_RDONLY/LFS_O_RDWR. It's just an alias for 0, and I don't
think there will ever be a reason to make it non-0 (but I can always
be wrong!).
- LFS_M_CKPROGS - This replaces the check_progs config option and avoids
using a full byte to store a bool.
We should probably also have a compile-time option to compile this out
(LFS_NO_CKPROGS?), but that's a future thing to do.
This ended up adding a surprising bit of code, considering we're just
moving flags around, and noise in lfs_alloc added a bit of stack again:
code stack
before: 35880 2672
after: 35932 (+0.1%) 2680 (+0.3%)
38 lines
946 B
TOML
38 lines
946 B
TOML
# Advanced mount tests
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after = ['test_mtree', 'test_traversal']
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# test we can mount
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[cases.test_mount_simple]
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code = '''
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lfs_t lfs;
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lfsr_format(&lfs, CFG) => 0;
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lfsr_mount(&lfs, LFS_M_RDWR, CFG) => 0;
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lfsr_unmount(&lfs) => 0;
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'''
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# test that various mount flags are returned by lfsr_fs_stat
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[cases.test_mount_flags]
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defines.RDONLY = [false, true]
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defines.CKPROGS = [false, true]
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code = '''
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lfs_t lfs;
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lfsr_format(&lfs, CFG) => 0;
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lfsr_mount(&lfs,
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((RDONLY) ? LFS_M_RDONLY : LFS_M_RDWR)
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| ((CKPROGS) ? LFS_M_CKPROGS : 0),
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CFG) => 0;
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struct lfs_fsinfo fsinfo;
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lfsr_fs_stat(&lfs, &fsinfo) => 0;
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assert(fsinfo.flags == (
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((RDONLY) ? LFS_I_RDONLY : 0)
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| ((CKPROGS) ? LFS_I_CKPROGS : 0)
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| LFS_I_CANLOOKAHEAD
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| LFS_I_UNCOMPACTED));
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lfsr_unmount(&lfs) => 0;
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'''
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# TODO should we move test_incompat here?
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