feature (proc): implemented file descriptors

kernel/inc/proc/file_descriptor.h

@@ -0,0 +1,41 @@
+// This file is part of noxos and licensed under the MIT open source license
+
+#ifndef NOX_FILE_DESCRIPTOR_H
+#define NOX_FILE_DESCRIPTOR_H
+
+#include "utils/stdtypes.h"
+#include "utils/bitmap.h"
+#include "drivers/fs/vfs.h"
+
+#define FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE 2
+
+typedef int32_t file_descriptor_t;
+
+typedef enum {
+    FILE_DESCRIPTOR_INVALID = -1
+} std_file_descriptors_E;
+
+typedef struct file_descriptor_array_chunk_T file_descriptor_array_chunk_T;
+struct file_descriptor_array_chunk_T {
+    file_descriptor_array_chunk_T*  prev;
+    file_descriptor_array_chunk_T*  next;
+    vfs_node_T*                     lookup  [FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE];
+    bitmap_T                        bitmap;
+    uint32_t                        amount;
+};
+
+typedef struct {
+    file_descriptor_array_chunk_T*  base_chunk;
+} file_descriptor_array_T;
+
+file_descriptor_t               file_descriptor_request                 (file_descriptor_array_T* fd_array, vfs_node_T* node);
+vfs_node_T*                     file_descriptor_resolve                 (file_descriptor_array_T* fd_array, file_descriptor_t fd);
+void                            file_descriptor_free                    (file_descriptor_array_T* fd_array, file_descriptor_t fd);
+
+file_descriptor_array_T*        file_descriptor_array_alloc             ();
+void                            file_descriptor_array_destruct          (file_descriptor_array_T* fd_array);
+
+file_descriptor_array_chunk_T*  file_descriptor_array_chunk_alloc       (file_descriptor_array_chunk_T* prev);
+void                            file_descriptor_array_chunk_destruct    (file_descriptor_array_chunk_T* chunk);
+
+#endif //NOX_FILE_DESCRIPTOR_H

kernel/src/proc/file_descriptor.c

@@ -0,0 +1,110 @@
+// This file is part of noxos and licensed under the MIT open source license
+
+#include "proc/file_descriptor.h"
+#include "utils/memory.h"
+
+
+file_descriptor_t file_descriptor_request(file_descriptor_array_T* fd_array, vfs_node_T* node) {
+    file_descriptor_t fd = 0;
+
+    file_descriptor_array_chunk_T* chunk = fd_array->base_chunk;
+    while (chunk->amount == FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE) {
+        if (chunk->next == NULL) file_descriptor_array_chunk_alloc(chunk);
+        chunk = chunk->next;
+        fd +=FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE;
+    }
+
+    for (int i = 0; i < FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE; i++) {
+        if (bitmap_get(&chunk->bitmap, i)) continue;
+
+        bitmap_set(&chunk->bitmap, i, true);
+        chunk->lookup[i] = node;
+        chunk->amount++;
+        fd += i;
+
+        return fd;
+    }
+
+    // this should never happen
+    return FILE_DESCRIPTOR_INVALID;
+}
+
+vfs_node_T* file_descriptor_resolve(file_descriptor_array_T* fd_array, file_descriptor_t fd) {
+    if (fd == FILE_DESCRIPTOR_INVALID) return NULL;
+
+
+    uint32_t chunk_selector = fd / FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE;
+    file_descriptor_array_chunk_T* chunk = fd_array->base_chunk;
+    for (int i = 0; i < chunk_selector; i++) {
+        chunk = chunk->next;
+        if (chunk == NULL) return NULL;
+    }
+
+    uint32_t fd_selector = fd % FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE;
+
+    // Check if the file descriptor exists
+    if (!bitmap_get(&chunk->bitmap, fd_selector)) return NULL;
+
+    return chunk->lookup[fd_selector];
+}
+
+void file_descriptor_free(file_descriptor_array_T* fd_array, file_descriptor_t fd) {
+    if (fd == FILE_DESCRIPTOR_INVALID) return;
+
+    uint32_t chunk_selector = fd / FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE;
+    file_descriptor_array_chunk_T* chunk = fd_array->base_chunk;
+    for (int i = 0; i < chunk_selector; i++) {
+        chunk = chunk->next;
+        if (chunk == NULL) return;
+    }
+
+    bitmap_set(&chunk->bitmap, fd % FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE, false);
+
+    chunk->amount--;
+}
+
+
+file_descriptor_array_T* file_descriptor_array_alloc() {
+    file_descriptor_array_T* fd_array = memory_allocate(sizeof(file_descriptor_array_T));
+
+    fd_array->base_chunk = file_descriptor_array_chunk_alloc(NULL);
+
+    return fd_array;
+}
+
+void file_descriptor_array_destruct(file_descriptor_array_T* fd_array) {
+    file_descriptor_array_chunk_T*      chunk = fd_array->base_chunk;
+    file_descriptor_array_chunk_T* next_chunk;
+
+    while (chunk != NULL) {
+        next_chunk = chunk->next;
+        file_descriptor_array_chunk_destruct(chunk);
+        chunk = next_chunk;
+    }
+
+    memory_free(fd_array);
+}
+
+
+file_descriptor_array_chunk_T* file_descriptor_array_chunk_alloc(file_descriptor_array_chunk_T* prev) {
+    file_descriptor_array_chunk_T* chunk = memory_allocate(sizeof(file_descriptor_array_chunk_T));
+
+    chunk->bitmap = bitmap_init(FILE_DESCRIPTOR_ARRAY_CHUNK_SIZE);
+    chunk->amount = 0;
+    chunk->prev   = prev;
+
+    if (chunk->prev != NULL) {
+        chunk->prev->next = chunk;
+    }
+
+    return chunk;
+}
+
+void file_descriptor_array_chunk_destruct(file_descriptor_array_chunk_T* chunk) {
+    if (chunk->prev != NULL) {
+        chunk->prev->next = NULL;
+    }
+
+    bitmap_destruct(&chunk->bitmap);
+    memory_free(chunk);
+}