Filesystem APIs

APIs to read and write files on the Dev Board Micro flash memory, based on littlefs.

For example, the following code demonstrates a variety of file operations (from examples/file_read_write/):

namespace coralmicro { namespace { void PrintDirectory(lfs_dir_t* dir, const char* path, int num_tabs) { constexpr int kMaxDepth = 3; if (num_tabs > kMaxDepth) { return; } lfs_info info; while (lfs_dir_read(Lfs(), dir, &info) > 0) { if (info.name[0] == '.') { continue; } for (int i = 0; i < num_tabs; ++i) { printf("\t"); } printf("%s", info.name); if (info.type == LFS_TYPE_DIR) { char subpath[LFS_NAME_MAX]; printf("/\r\n"); lfs_dir_t subdir; snprintf(subpath, LFS_NAME_MAX, "%s/%s", path, info.name); CHECK(lfs_dir_open(Lfs(), &subdir, subpath) >= 0); PrintDirectory(&subdir, subpath, num_tabs + 1); CHECK(lfs_dir_close(Lfs(), &subdir) >= 0); } else { printf("\t\t%ld\r\n", info.size); } } } void PrintFilesystemContents() { lfs_dir_t root; CHECK(lfs_dir_open(Lfs(), &root, "/") >= 0); printf("Printing filesystem:\r\n"); PrintDirectory(&root, "", 0); printf("Finished printing filesystem.\r\n"); CHECK(lfs_dir_close(Lfs(), &root) >= 0); } bool Mkdir(const char* path) { int ret = lfs_mkdir(Lfs(), path); if (ret == LFS_ERR_EXIST) { printf("Error dir exists"); return false; } return (ret == LFS_ERR_OK); } void Main() { printf("Begin filesystem example\r\n"); // Turn on Status LED to show the board is on. LedSet(Led::kStatus, true); PrintFilesystemContents(); printf("Creating some sample directories\r\n"); CHECK(Mkdir("/dir")); CHECK(LfsDirExists("/dir")); constexpr char kFileStr[] = "HelloWorld"; CHECK(LfsWriteFile("/dir/file", reinterpret_cast<const uint8_t*>(kFileStr), std::strlen(kFileStr))); PrintFilesystemContents(); std::string readstr; CHECK(LfsReadFile("/dir/file", &readstr)); CHECK(readstr.length() == std::strlen(kFileStr)); printf("File contents: %s\r\n", readstr.c_str()); CHECK(lfs_remove(Lfs(), "/dir/file") >= 0); CHECK(lfs_remove(Lfs(), "/dir") >= 0); PrintFilesystemContents(); printf("End filesystem example\r\n"); } } // namespace } // namespace coralmicro extern "C" void app_main(void* param) { (void)param; coralmicro::Main(); vTaskSuspend(nullptr); } 

[filesystem.h source]

namespace coralmicro

Functions

lfs_t *Lfs()¶

Returns littlefs instance to use with functions from lfs.h.

Returns

Pointer to littlefs instance.

bool LfsMakeDirs(const char *path)¶

Creates directory, similar to mkdir -p <path>.

Parameters

path – Directory path.

Returns

True upon success, false otherwise.

std::string LfsDirname(const char *path)¶

Returns the string up to, but not including, the final ‘/’ in the path.

Parameters

path – Path.

Returns

The string up to, but not including, the final ‘/’ in the path.

ssize_t LfsSize(const char *path)¶

Returns file size.

Parameters

path – File path.

Returns

File size in bytes.

bool LfsDirExists(const char *path)¶

Returns whether path exists and represents a directory.

Parameters

path – Path to check

Returns

True if path exists and represents a directory, false otherwise.

bool LfsFileExists(const char *path)¶

Returns whether path exists and represents a file.

Parameters

path – Path to check

Returns

true if path exists and represents a file, false otherwise.

bool LfsReadFile(const char *path, std::vector<uint8_t> *buf)¶

Reads content of the file and stores it in std::vector<uint8_t>.

Parameters

• path – File path to read.

• buf – Instance of std::vector<uint8_t> to read data in.

Returns

True upon success, false otherwise.

bool LfsReadFile(const char *path, std::string *str)¶

Reads content of the file and stores it in std::string.

Parameters

• path – File path to read.

• str – Instance of std::string to read data in.

Returns

True upon success, false otherwise.

size_t LfsReadFile(const char *path, uint8_t *buf, size_t size)¶

Reads content of the file and stores it in memory buffer.

Parameters

• path – File path to read.

• buf – Memory buffer to read data in.

• size – Memory buffer size.

Returns

Number of read bytes not exceeding size.

bool LfsWriteFile(const char *path, const uint8_t *buf, size_t size)¶

Writes content of the memory buffer to file.

Parameters

• path – File path to write.

• buf – Memory buffer to write data from.

• size – Memory buffer size.

Returns

True upon success, false otherwise.

bool LfsWriteFile(const char *path, const std::string &str)¶

Writes content of the string to file.

Parameters

• path – File path to write.

• str – String to write data from.

Returns

True upon success, false otherwise.