Extended the llfs file system api

Implemented file extension filters
Implemented newlib stubs to be able to use the POSIX file API

project/Core/Src/llfs.c

@@ -2,34 +2,82 @@
  * @file llfs.c
  * @brief Linked List Filesystem implementation (llfs)
  * @author Lorenz C.
- * @todo Implement file extension filter
+ * @version 0.1.1
  */
 
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
 #include <string.h>
 #define LOGGER_LEVEL_WARN
 #include "llfs.h"
 #include "log.h"
 
+/**
+ * @brief The maximum number of files that can be opened concurrently using the POSIX API
+ */
+#define POSIX_MAX_FILES 10
+
 extern struct llfs_data_file* llfs_root;
 const char* TAG = "llfs";
+size_t file_count = 0;
+FILE* file_table[POSIX_MAX_FILES];
+
+static int new_file_table_entry(void);
+static int free_file_table_entry(int file_id);
+static FILE* file_id_to_stream(int file_id);
+static uint8_t file_ext_cmp(const char* filename, const char* ext);
+
+int8_t llfs_init(void) {
+    LOG_DEBUG(TAG, "Initializing llfs");
+
+    // Initialize the file table
+    for (int i = 0; i < POSIX_MAX_FILES; i++) {
+        file_table[i] = NULL;
+    }
+
+    // Add stdin, stdout and stderr to the file table
+    file_table[STDIN_FILENO] = stdin;
+    file_table[STDOUT_FILENO] = stdout;
+    file_table[STDERR_FILENO] = stderr;
+
+    return 0;
+}
 
-// TODO: Implement file extension filter
 size_t llfs_file_list(llfs_file_t* file_list, size_t max_files, char* filter) {
-    size_t file_count = 0;
-    const struct llfs_data_file* file = llfs_root;
+    size_t count = 0;                              // Number of files found
+    const struct llfs_data_file* file = llfs_root; // Pointer to the current file
 
-    LOG_DEBUG(TAG, "Getting file list with filter: %s", filter);
+    if (filter != NULL) {
+        LOG_DEBUG(TAG, "Filtering files with filter: %s", filter);
 
+        if (filter[0] == '*') {
+            filter++;
+        }
+    }
+
+    // Iterate over all files in the filesystem
     while (file != NULL && file_count < max_files) {
-        file_list[file_count].data = file->data;
-        file_list[file_count].name = file->name;
-        file_list[file_count].len = file->len;
-        file_count++;
+        // Filter out files with a filename that does not match the filter
+        if (filter != NULL) {
+            if (!file_ext_cmp(file->name, filter)) {
+                file = file->next;
+                continue;
+            }
+        }
+
+        // Add the file to the file list
+        file_list[count].data = file->data;
+        file_list[count].name = file->name;
+        file_list[count].len = file->len;
+
+        // Move to the next file
+        count++;
         file = file->next;
     }
 
-    LOG_DEBUG(TAG, "Files found: %d", file_count);
-    return file_count;
+    LOG_DEBUG(TAG, "Files found: %d", count);
+    return count;
 }
 
 llfs_file_t* llfs_file_open(const char* name) {
@@ -48,3 +96,341 @@ llfs_file_t* llfs_file_open(const char* name) {
     LOG_DEBUG(TAG, "File not found: %s", name);
     return NULL;
 }
+
+llfs_file_t* llfs_next_file(void** mem, char* filter) {
+    struct llfs_data_file* prev_file = (struct llfs_data_file*)*mem;
+    uint8_t filter_ok = 0;
+
+    if (prev_file == NULL) {
+        prev_file = llfs_root;
+    } else {
+        prev_file = (struct llfs_data_file*)prev_file->next;
+    }
+
+    // If a filter is specified, only return files that match the filter
+    if (filter != NULL) {
+        LOG_DEBUG(TAG, "Filtering files with filter: %s", filter);
+
+        // Remove the '*' from the filter
+        if (filter[0] == '*') {
+            filter++;
+        }
+
+        while (prev_file != NULL) {
+            if (file_ext_cmp(prev_file->name, filter)) {
+                filter_ok = 1;
+                break;
+            }
+            prev_file = (struct llfs_data_file*)prev_file->next;
+        }
+    }
+
+    *mem = (void*)prev_file;
+    return (llfs_file_t*)prev_file;
+}
+
+size_t llfs_file_count(void) {
+    if (file_count == 0) {
+        const struct llfs_data_file* file = llfs_root;
+        while (file != NULL) {
+            file_count++;
+            file = file->next;
+        }
+    }
+    return file_count;
+}
+
+/**
+ * @brief Newlib open implementation
+ *
+ * @param path
+ * @param flags
+ * @param mode
+ * @return
+ */
+int _open(char* path, int flags, int mode) {
+    int file_id;
+    FILE* stream;
+    errno = 0;
+    llfs_file_t* llfs_file;
+
+    // Add a new entry to the file table
+    file_id = new_file_table_entry();
+    if (file_id < 0) {
+        LOG_WARN(TAG, "Failed to add new file table entry. %s", strerror(errno));
+        return -1;
+    }
+
+    // Get the stream associated with the file id
+    stream = file_id_to_stream(file_id);
+    if (stream == NULL) {
+        LOG_WARN(TAG, "Failed to get file table entry. %s", strerror(errno));
+        free_file_table_entry(file_id);
+        return -1;
+    }
+
+    // Get the file from the llfs filesystem
+    llfs_file = llfs_file_open(path);
+    if (llfs_file == NULL) {
+        LOG_DEBUG(TAG, "Failed to open file: %s", path);
+        free_file_table_entry(file_id);
+        return -1;
+    }
+
+    // Initialize the stream
+    stream->_cookie = (void*)llfs_file;
+    stream->_offset = 0;
+    stream->_flags = __SRD;
+
+    return file_id;
+}
+
+/**
+ * @brief Newlib close implementation
+ *
+ * @param file_id
+ * @return
+ */
+int _close(int file_id) {
+    FILE* stream;
+
+    // Get the stream associated with the file id
+    stream = file_id_to_stream(file_id);
+    if (stream == NULL) {
+        LOG_WARN(TAG, "Failed to get file table entry. %s", strerror(errno));
+        return -1;
+    }
+
+    // Remove the entry from the file table
+    if (free_file_table_entry(file_id) < 0) {
+        LOG_WARN(TAG, "Failed to remove file table entry. %s", strerror(errno));
+        return -1;
+    }
+
+    return 0;
+}
+
+/**
+ * @brief Newlib read implementation
+ *
+ * @param file_id
+ * @param ptr
+ * @param len
+ * @return
+ */
+int _read(int file_id, char* ptr, int len) {
+    FILE* stream;
+    llfs_file_t* llfs_file;
+    size_t bytes_read;
+
+    // Read from stdin, stdout and stderr is not supported
+    if (file_id == STDIN_FILENO || file_id == STDOUT_FILENO || file_id == STDERR_FILENO) {
+        LOG_DEBUG(TAG, "Trying to read from stdin, stdout or stderr: %d", file_id);
+        return -1;
+    }
+
+    // Get the stream associated with the file id
+    stream = file_id_to_stream(file_id);
+    if (stream == NULL) {
+        LOG_WARN(TAG, "Failed to get file table entry. %s", strerror(errno));
+        return -1;
+    }
+
+    // Get the file from the llfs filesystem associated with the stream
+    llfs_file = (llfs_file_t*)stream->_cookie;
+    if (llfs_file == NULL) {
+        LOG_WARN(TAG, "Failed to get llfs file associated with stream: %d", file_id);
+        return -1;
+    }
+
+    // Calculate the number of bytes to read (limited by the file size)
+    bytes_read = llfs_file->len - stream->_offset;
+    if (bytes_read > len) {
+        bytes_read = len;
+    } else if (bytes_read == 0) { // End of file
+        stream->_flags |= __SEOF;
+        return 0;
+    }
+
+    // Copy the data over to the dst buffer
+    memcpy(ptr, llfs_file->data + stream->_offset, bytes_read);
+
+    stream->_offset += (off_t)bytes_read;
+    return (int)bytes_read;
+}
+
+/**
+ * @brief Newlib isatty implementation
+ *
+ * @param file
+ * @return 1 if the file is stdin, stdout or stderr, 0 otherwise
+ */
+int isatty(int file) {
+    if (file == STDIN_FILENO || file == STDOUT_FILENO || file == STDERR_FILENO) {
+        return 1;
+    }
+
+    return 0;
+}
+
+/**
+ * @brief Newlib lseek implementation
+ *
+ * @param file
+ * @param ptr
+ * @param dir
+ * @return
+ */
+int _lseek(int file, int ptr, int dir) {
+    FILE* stream;
+
+    if (file == STDIN_FILENO || file == STDOUT_FILENO || file == STDERR_FILENO) {
+        LOG_DEBUG(TAG, "Trying to seek stdin, stdout or stderr: %d", file);
+        return -1;
+    }
+
+    stream = file_id_to_stream(file);
+    if (stream == NULL) {
+        LOG_WARN(TAG, "Failed to get file table entry. %s", strerror(errno));
+        return -1;
+    }
+
+    switch (dir) {
+        case SEEK_SET:
+            stream->_offset = ptr;
+            break;
+        case SEEK_CUR:
+            stream->_offset += ptr;
+            break;
+        case SEEK_END:
+            stream->_offset = (off_t)((llfs_file_t*)stream->_cookie)->len + ptr;
+            break;
+        default:
+            LOG_WARN(TAG, "Invalid seek direction: %d", dir);
+            return -1;
+    }
+
+    return 0;
+}
+
+/**
+ * @brief Newlib fstat implementation
+ *
+ * @param[in] file
+ * @param[out] st
+ * @return
+ */
+int _fstat(int file, struct stat* st) {
+    FILE* stream;
+    llfs_file_t *llfs_file;
+
+    // Check if the file is stdin, stdout or stderr
+    if (file == STDIN_FILENO || file == STDOUT_FILENO || file == STDERR_FILENO) {
+        st->st_mode = S_IFCHR; // Character special file
+        return 0;
+    }
+
+    // Get the stream associated with the file id
+    stream = file_id_to_stream(file);
+    if (stream == NULL) {
+        LOG_WARN(TAG, "Failed to get file table entry. %s", strerror(errno));
+        return -1;
+    }
+
+    // Get the file from the llfs filesystem associated with the stream
+    llfs_file = (llfs_file_t*)stream->_cookie;
+    if (llfs_file == NULL) {
+        LOG_WARN(TAG, "Failed to get llfs file associated with stream: %d", file);
+        return -1;
+    }
+
+    st->st_mode = S_IFREG;  // Regular file
+    st->st_size = (off_t)llfs_file->len;
+    return 0;
+}
+
+/**
+ * @brief Create a new entry in the file table
+ *
+ * @return The file id or -1 if an error occurred. See errno for more information.
+ */
+static int new_file_table_entry(void) {
+    FILE* stream;
+
+    // Try to find an empty entry in the file table
+    for (int i = 0; i < POSIX_MAX_FILES; i++) {
+        if (file_table[i] == NULL) {
+            stream = (FILE*)malloc(sizeof(FILE));
+            if (stream == NULL) {
+                errno = ENOMEM; // Out of memory
+                return -1;
+            }
+            file_table[i] = stream;
+            return i;
+        }
+    }
+
+    // No empty entry found
+    errno = ENFILE; // Too many open files
+    return -1;
+}
+
+/**
+ * @brief Remove an entry from the file table
+ *
+ * @param[in] file_id The file id to remove
+ * @return 0 if successful, -1 if an error occurred. See errno for more information.
+ */
+static int free_file_table_entry(int file_id) {
+    // Check if the file id is valid
+    if (file_id < 0 || file_id >= POSIX_MAX_FILES) {
+        errno = EBADF; // Bad file number
+        return -1;
+    }
+
+    // Remove the entry from the file table
+    free(file_table[file_id]);
+    file_table[file_id] = NULL;
+
+    return 0;
+}
+
+/**
+ * @brief Get the stream associated with a file id
+ *
+ * @param[in] file_id The file id to get the stream for
+ * @return The stream or NULL if an error occurred. See errno for more information.
+ */
+static FILE* file_id_to_stream(int file_id) {
+    if (file_id < 0 || file_id >= POSIX_MAX_FILES) {
+        errno = EBADF; // Bad file number
+        return NULL;
+    }
+    return file_table[file_id];
+}
+
+
+
+/**
+ * @brief Check if a filename ends with a given extension
+ *
+ * @param[in] filename The filename to check
+ * @param[in] ext The extension to check for
+ * @return 1 if the filename ends with the extension, 0 otherwise
+ */
+static uint8_t file_ext_cmp(const char* const filename, const char* const ext) {
+    uint8_t ext_len = strlen(ext);
+    uint8_t filename_len = strlen(filename);
+
+    if (filename_len < ext_len) {
+        return 0;
+    }
+
+    // Compare backwards
+    for (uint8_t i = 0; i < ext_len; i++) {
+        if (filename[filename_len - i] != ext[ext_len - i]) {
+            return 0;
+        }
+    }
+    return 1;
+}