mirror of
https://github.com/eledio-devices/thirdparty-littlefs.git
synced 2025-10-31 16:14:16 +01:00
aeca7667b3
Instead of storing files in an arbitrary order, we now store files in ascending lexicographical order by filename. Although a big change, this actually has little impact on how littlefs works internally. We need to support file insertion, and compare file names to find our position. But since we already need to scan the entire directory block, this adds relatively little overhead. What this does allow, is the potential to add B-tree support in the future in a backwards compatible manner. How could you add B-trees to littlefs? 1. Add an optional "child" tag with a pointer that allows you to skip to a position in the metadata-pair list that composes the directory 2. When splitting a metadata-pair (sound familiar?), we either insert a second child tag in our parent, or we create a new root containing the child tags. 3. Each layer needs a bit stored in the tail-pointer to indicate if we're going to the next layer. This can be created trivially when we create a new root. 4. During lookup we keep two pointers containing the bounds of our search. We may need to iterate through multiple metadata-pairs in our linked-list, but this gives us a O(log n) lookup cost in a balanced tree. 5. During deletion we also delete any children pointers. Note that children pointers must come before the actual file entry. This gives us a B-tree implementation that is compatible with the current directory layout (assuming the files are ordered). This means that B-trees could be supported by a host PC and ignored on a small device. And during power-loss, we never end up with a broken filesystem, just a less-than-optimal tree. Note that we don't handle removes, so it's possible for a tree to become unbalanced. But worst case that's the same as the current linked-list implementation. All we need to do now is keep directories ordered. If we decide to drop B-tree support in the future or the B-tree implementation turns out inherently flawed, we can just drop the ordered requirement without breaking compatibility and recover the code cost.
362 lines
12 KiB
Bash
Executable File
362 lines
12 KiB
Bash
Executable File
#!/bin/bash
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set -eu
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SMALLSIZE=4
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MEDIUMSIZE=128
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LARGESIZE=132
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echo "=== Seek tests ==="
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rm -rf blocks
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tests/test.py << TEST
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lfs_format(&lfs, &cfg) => 0;
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lfs_mount(&lfs, &cfg) => 0;
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lfs_mkdir(&lfs, "hello") => 0;
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for (int i = 0; i < $LARGESIZE; i++) {
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sprintf((char*)buffer, "hello/kitty%03d", i);
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lfs_file_open(&lfs, &file[0], (char*)buffer,
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LFS_O_WRONLY | LFS_O_CREAT | LFS_O_APPEND) => 0;
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size = strlen("kittycatcat");
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memcpy(buffer, "kittycatcat", size);
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for (int j = 0; j < $LARGESIZE; j++) {
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lfs_file_write(&lfs, &file[0], buffer, size);
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}
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lfs_file_close(&lfs, &file[0]) => 0;
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}
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lfs_unmount(&lfs) => 0;
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TEST
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echo "--- Simple dir seek ---"
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tests/test.py << TEST
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lfs_mount(&lfs, &cfg) => 0;
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lfs_dir_open(&lfs, &dir[0], "hello") => 0;
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, ".") => 0;
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, "..") => 0;
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lfs_soff_t pos;
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int i;
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for (i = 0; i < $SMALLSIZE; i++) {
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sprintf((char*)buffer, "kitty%03d", i);
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, (char*)buffer) => 0;
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pos = lfs_dir_tell(&lfs, &dir[0]);
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}
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pos >= 0 => 1;
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lfs_dir_seek(&lfs, &dir[0], pos) => 0;
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sprintf((char*)buffer, "kitty%03d", i);
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, (char*)buffer) => 0;
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lfs_dir_rewind(&lfs, &dir[0]) => 0;
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sprintf((char*)buffer, "kitty%03d", 0);
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, ".") => 0;
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, "..") => 0;
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, (char*)buffer) => 0;
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lfs_dir_seek(&lfs, &dir[0], pos) => 0;
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sprintf((char*)buffer, "kitty%03d", i);
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, (char*)buffer) => 0;
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lfs_dir_close(&lfs, &dir[0]) => 0;
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lfs_unmount(&lfs) => 0;
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TEST
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echo "--- Large dir seek ---"
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tests/test.py << TEST
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lfs_mount(&lfs, &cfg) => 0;
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lfs_dir_open(&lfs, &dir[0], "hello") => 0;
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, ".") => 0;
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, "..") => 0;
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lfs_soff_t pos;
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int i;
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for (i = 0; i < $MEDIUMSIZE; i++) {
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sprintf((char*)buffer, "kitty%03d", i);
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, (char*)buffer) => 0;
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pos = lfs_dir_tell(&lfs, &dir[0]);
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}
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pos >= 0 => 1;
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lfs_dir_seek(&lfs, &dir[0], pos) => 0;
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sprintf((char*)buffer, "kitty%03d", i);
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, (char*)buffer) => 0;
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lfs_dir_rewind(&lfs, &dir[0]) => 0;
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sprintf((char*)buffer, "kitty%03d", 0);
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, ".") => 0;
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, "..") => 0;
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, (char*)buffer) => 0;
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lfs_dir_seek(&lfs, &dir[0], pos) => 0;
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sprintf((char*)buffer, "kitty%03d", i);
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lfs_dir_read(&lfs, &dir[0], &info) => 1;
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strcmp(info.name, (char*)buffer) => 0;
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lfs_dir_close(&lfs, &dir[0]) => 0;
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lfs_unmount(&lfs) => 0;
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TEST
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echo "--- Simple file seek ---"
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tests/test.py << TEST
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lfs_mount(&lfs, &cfg) => 0;
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lfs_file_open(&lfs, &file[0], "hello/kitty042", LFS_O_RDONLY) => 0;
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lfs_soff_t pos;
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size = strlen("kittycatcat");
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for (int i = 0; i < $SMALLSIZE; i++) {
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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pos = lfs_file_tell(&lfs, &file[0]);
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}
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pos >= 0 => 1;
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lfs_file_seek(&lfs, &file[0], pos, LFS_SEEK_SET) => pos;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_rewind(&lfs, &file[0]) => 0;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_CUR) => size;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], size, LFS_SEEK_CUR) => 3*size;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], pos, LFS_SEEK_SET) => pos;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], -size, LFS_SEEK_CUR) => pos;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], -size, LFS_SEEK_END) >= 0 => 1;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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size = lfs_file_size(&lfs, &file[0]);
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lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_CUR) => size;
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lfs_file_close(&lfs, &file[0]) => 0;
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lfs_unmount(&lfs) => 0;
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TEST
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echo "--- Large file seek ---"
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tests/test.py << TEST
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lfs_mount(&lfs, &cfg) => 0;
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lfs_file_open(&lfs, &file[0], "hello/kitty042", LFS_O_RDONLY) => 0;
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lfs_soff_t pos;
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size = strlen("kittycatcat");
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for (int i = 0; i < $MEDIUMSIZE; i++) {
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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pos = lfs_file_tell(&lfs, &file[0]);
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}
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pos >= 0 => 1;
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lfs_file_seek(&lfs, &file[0], pos, LFS_SEEK_SET) => pos;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_rewind(&lfs, &file[0]) => 0;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_CUR) => size;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], size, LFS_SEEK_CUR) => 3*size;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], pos, LFS_SEEK_SET) => pos;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], -size, LFS_SEEK_CUR) => pos;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], -size, LFS_SEEK_END) >= 0 => 1;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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size = lfs_file_size(&lfs, &file[0]);
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lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_CUR) => size;
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lfs_file_close(&lfs, &file[0]) => 0;
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lfs_unmount(&lfs) => 0;
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TEST
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echo "--- Simple file seek and write ---"
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tests/test.py << TEST
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lfs_mount(&lfs, &cfg) => 0;
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lfs_file_open(&lfs, &file[0], "hello/kitty042", LFS_O_RDWR) => 0;
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lfs_soff_t pos;
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size = strlen("kittycatcat");
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for (int i = 0; i < $SMALLSIZE; i++) {
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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pos = lfs_file_tell(&lfs, &file[0]);
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}
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pos >= 0 => 1;
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memcpy(buffer, "doggodogdog", size);
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lfs_file_seek(&lfs, &file[0], pos, LFS_SEEK_SET) => pos;
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lfs_file_write(&lfs, &file[0], buffer, size) => size;
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lfs_file_seek(&lfs, &file[0], pos, LFS_SEEK_SET) => pos;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "doggodogdog", size) => 0;
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lfs_file_rewind(&lfs, &file[0]) => 0;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], pos, LFS_SEEK_SET) => pos;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "doggodogdog", size) => 0;
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lfs_file_seek(&lfs, &file[0], -size, LFS_SEEK_END) >= 0 => 1;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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size = lfs_file_size(&lfs, &file[0]);
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lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_CUR) => size;
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lfs_file_close(&lfs, &file[0]) => 0;
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lfs_unmount(&lfs) => 0;
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TEST
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echo "--- Large file seek and write ---"
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tests/test.py << TEST
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lfs_mount(&lfs, &cfg) => 0;
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lfs_file_open(&lfs, &file[0], "hello/kitty042", LFS_O_RDWR) => 0;
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lfs_soff_t pos;
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size = strlen("kittycatcat");
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for (int i = 0; i < $MEDIUMSIZE; i++) {
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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if (i != $SMALLSIZE) {
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memcmp(buffer, "kittycatcat", size) => 0;
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}
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pos = lfs_file_tell(&lfs, &file[0]);
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}
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pos >= 0 => 1;
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memcpy(buffer, "doggodogdog", size);
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lfs_file_seek(&lfs, &file[0], pos, LFS_SEEK_SET) => pos;
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lfs_file_write(&lfs, &file[0], buffer, size) => size;
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lfs_file_seek(&lfs, &file[0], pos, LFS_SEEK_SET) => pos;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "doggodogdog", size) => 0;
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lfs_file_rewind(&lfs, &file[0]) => 0;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_seek(&lfs, &file[0], pos, LFS_SEEK_SET) => pos;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "doggodogdog", size) => 0;
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lfs_file_seek(&lfs, &file[0], -size, LFS_SEEK_END) >= 0 => 1;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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size = lfs_file_size(&lfs, &file[0]);
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lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_CUR) => size;
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lfs_file_close(&lfs, &file[0]) => 0;
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lfs_unmount(&lfs) => 0;
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TEST
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echo "--- Boundary seek and write ---"
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tests/test.py << TEST
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lfs_mount(&lfs, &cfg) => 0;
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lfs_file_open(&lfs, &file[0], "hello/kitty042", LFS_O_RDWR) => 0;
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size = strlen("hedgehoghog");
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const lfs_soff_t offsets[] = {512, 1020, 513, 1021, 511, 1019};
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for (int i = 0; i < sizeof(offsets) / sizeof(offsets[0]); i++) {
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lfs_soff_t off = offsets[i];
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memcpy(buffer, "hedgehoghog", size);
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lfs_file_seek(&lfs, &file[0], off, LFS_SEEK_SET) => off;
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lfs_file_write(&lfs, &file[0], buffer, size) => size;
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lfs_file_seek(&lfs, &file[0], off, LFS_SEEK_SET) => off;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "hedgehoghog", size) => 0;
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lfs_file_seek(&lfs, &file[0], 0, LFS_SEEK_SET) => 0;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "kittycatcat", size) => 0;
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lfs_file_sync(&lfs, &file[0]) => 0;
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}
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lfs_file_close(&lfs, &file[0]) => 0;
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lfs_unmount(&lfs) => 0;
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TEST
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echo "--- Out-of-bounds seek ---"
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tests/test.py << TEST
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lfs_mount(&lfs, &cfg) => 0;
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lfs_file_open(&lfs, &file[0], "hello/kitty042", LFS_O_RDWR) => 0;
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size = strlen("kittycatcat");
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lfs_file_size(&lfs, &file[0]) => $LARGESIZE*size;
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lfs_file_seek(&lfs, &file[0], ($LARGESIZE+$SMALLSIZE)*size,
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LFS_SEEK_SET) => ($LARGESIZE+$SMALLSIZE)*size;
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lfs_file_read(&lfs, &file[0], buffer, size) => 0;
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memcpy(buffer, "porcupineee", size);
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lfs_file_write(&lfs, &file[0], buffer, size) => size;
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lfs_file_seek(&lfs, &file[0], ($LARGESIZE+$SMALLSIZE)*size,
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LFS_SEEK_SET) => ($LARGESIZE+$SMALLSIZE)*size;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "porcupineee", size) => 0;
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lfs_file_seek(&lfs, &file[0], $LARGESIZE*size,
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LFS_SEEK_SET) => $LARGESIZE*size;
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lfs_file_read(&lfs, &file[0], buffer, size) => size;
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memcmp(buffer, "\0\0\0\0\0\0\0\0\0\0\0", size) => 0;
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lfs_file_seek(&lfs, &file[0], -(($LARGESIZE+$SMALLSIZE)*size),
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LFS_SEEK_CUR) => LFS_ERR_INVAL;
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lfs_file_tell(&lfs, &file[0]) => ($LARGESIZE+1)*size;
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lfs_file_seek(&lfs, &file[0], -(($LARGESIZE+2*$SMALLSIZE)*size),
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LFS_SEEK_END) => LFS_ERR_INVAL;
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lfs_file_tell(&lfs, &file[0]) => ($LARGESIZE+1)*size;
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lfs_file_close(&lfs, &file[0]) => 0;
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lfs_unmount(&lfs) => 0;
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TEST
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echo "--- Results ---"
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tests/stats.py
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