capture: implement directory structure capture

src/image.c

@@ -4,11 +4,13 @@
 #include "pipeline.h"
 #include "shadow-image.h"
 #include "status.h"
+#include "tag.h"
 
 #include <blue/io/directory.h>
 #include <blue/io/file.h>
 #include <blue/io/path.h>
 #include <blue/object/buffer.h>
+#include <blue/object/string.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -600,6 +602,82 @@ const struct ec3_extent_info *ec3_image_ioctx_get_extent_info(
 	return b_buffer_ptr(image->io_extent_table);
 }
 
+enum ec3_status ec3_image_ioctx_get_string(
+	struct ec3_image_ioctx *image,
+	size_t key,
+	struct b_string *out)
+{
+	enum ec3_status status = EC3_SUCCESS;
+	if (!image->io_stab) {
+		status = ec3_image_ioctx_open_tag_by_type(
+			image,
+			EC3_TAG_STAB,
+			0,
+			EC3_TAG_IO_READ,
+			&image->io_stab);
+	}
+
+	if (status != EC3_SUCCESS) {
+		return status;
+	}
+
+	if (!image->io_stab_buf) {
+		image->io_stab_buf = malloc(image->io_header.img_cluster_size);
+
+		if (!image->io_stab_buf) {
+			return EC3_ERR_NO_MEMORY;
+		}
+	}
+
+	size_t nr_clusters = 0;
+	ec3_tag_ioctx_get_nr_clusters(image->io_stab, &nr_clusters);
+	size_t max_key = nr_clusters * image->io_header.img_cluster_size;
+
+	if (key >= max_key) {
+		return EC3_ERR_OUT_OF_BOUNDS;
+	}
+
+	size_t cluster = key / image->io_header.img_cluster_size;
+	size_t byte = key % image->io_header.img_cluster_size;
+	size_t nr_read;
+	char *buf = image->io_stab_buf;
+	bool done = false;
+
+	while (!done) {
+		status = ec3_tag_ioctx_read_cluster(
+			image->io_stab,
+			cluster,
+			buf,
+			&nr_read);
+
+		if (status != EC3_SUCCESS) {
+			return status;
+		}
+
+		for (;;) {
+			char c = buf[byte];
+
+			if (c == 0) {
+				done = true;
+				break;
+			}
+
+			char s[] = {c, 0};
+			b_string_append_cstr(out, s);
+
+			byte++;
+
+			if (byte >= nr_read) {
+				byte = 0;
+				cluster++;
+				break;
+			}
+		}
+	}
+
+	return EC3_SUCCESS;
+}
+
 static uint64_t allocate_tag_id(struct ec3_image_ioctx *image)
 {
 	uint64_t id = 0;