feat: (twimap) provide an easy way for mapping kernel objects into filesystem

[lunaix-os.git] / lunaix-os / kernel / fs / twifs / twimap.c

diff --git a/lunaix-os/kernel/fs/twifs/twimap.c b/lunaix-os/kernel/fs/twifs/twimap.c
new file mode 100644 (file)
index 0000000..2446014
--- /dev/null
+++ b/lunaix-os/kernel/fs/twifs/twimap.c
@@ -0,0 +1,110 @@
+#include <lunaix/fs/twifs.h>
+#include <lunaix/mm/valloc.h>
+
+#include <klibc/stdio.h>
+#include <klibc/string.h>
+
+#define TWIMAP_BUFFER_SIZE 1024
+
+void
+__twimap_default_reset(struct twimap* map)
+{
+    map->index = NULL;
+}
+
+int
+__twimap_default_gonext(struct twimap* map)
+{
+    return 0;
+}
+
+int
+__twimap_read(struct v_inode* inode, void* buffer, size_t len, size_t fpos)
+{
+    struct twimap* map = twinode_getdata(inode, struct twimap*);
+    map->buffer = valloc(TWIMAP_BUFFER_SIZE);
+    map->reset(map);
+
+    // FIXME what if TWIMAP_BUFFER_SIZE is not big enough?
+
+    size_t pos = 0;
+    do {
+        map->size_acc = 0;
+        map->read(map);
+        pos += map->size_acc;
+    } while (pos < fpos && map->go_next(map));
+
+    if (pos < fpos) {
+        vfree(map->buffer);
+        return 0;
+    }
+
+    if (!fpos) {
+        pos = 0;
+    }
+
+    size_t acc_size = MIN(len, map->size_acc - (pos - fpos)), rdlen = acc_size;
+    memcpy(buffer, map->buffer + (pos - fpos), acc_size);
+
+    while (acc_size < len && map->go_next(map)) {
+        map->size_acc = 0;
+        map->read(map);
+        rdlen = MIN(len - acc_size, map->size_acc);
+        memcpy(buffer + acc_size, map->buffer, rdlen);
+        acc_size += rdlen;
+    }
+
+    vfree(map->buffer);
+    return acc_size;
+}
+
+struct twimap*
+twifs_mapping(struct twifs_node* parent, void* data, const char* fmt, ...)
+{
+    va_list args;
+    va_start(args, fmt);
+
+    struct twimap* map = vzalloc(sizeof(struct twimap));
+    struct twifs_node* node = twifs_file_node_vargs(parent, fmt, args);
+    node->ops.read = __twimap_read;
+    node->data = map;
+
+    map->reset = __twimap_default_reset;
+    map->go_next = __twimap_default_gonext;
+    map->data = data;
+
+    return map;
+}
+
+void
+twimap_printf(struct twimap* mapping, const char* fmt, ...)
+{
+    va_list args;
+    va_start(args, fmt);
+
+    char* buf = mapping->buffer + mapping->size_acc;
+
+    mapping->size_acc +=
+      __ksprintf_internal(buf, fmt, TWIMAP_BUFFER_SIZE, args);
+
+    va_end(args);
+}
+
+int
+twimap_memcpy(struct twimap* mapping, const void* src, const size_t len)
+{
+    mapping->size_acc = MIN(TWIMAP_BUFFER_SIZE, len);
+    memcpy(mapping->buffer, src, mapping->size_acc);
+
+    return mapping->size_acc;
+}
+
+int
+twimap_memappend(struct twimap* mapping, const void* src, const size_t len)
+{
+    size_t cpy_len = MIN(TWIMAP_BUFFER_SIZE - mapping->size_acc, len);
+    memcpy(mapping->buffer + mapping->size_acc, src, cpy_len);
+    mapping->size_acc += cpy_len;
+
+    return cpy_len;
+}
\ No newline at end of file