add header decode and pipeline construction to image reader

src/read.c

@@ -0,0 +1,99 @@
+#include "read.h"
+#include "bin.h"
+#include "pipeline.h"
+
+#include <stdio.h>
+
+struct ec3_reader {
+	unsigned short r_version;
+	unsigned short r_cluster_size;
+	size_t r_tag_table_offset;
+	size_t r_extent_table_offset;
+	size_t r_cluster_table_offset;
+	unsigned int r_nr_tags;
+	unsigned int r_nr_extents;
+	unsigned int r_nr_cluster_groups;
+
+	uint64_t r_id;
+
+	struct ec3_pipeline *r_pipeline;
+};
+
+static void decode_header(const struct ec3_header *in, struct ec3_reader *out)
+{
+	out->r_version = b_i16_btoh(in->h_version);
+	out->r_cluster_size = ec3_get_cluster_size(b_i16_btoh(in->h_cluster_size));
+	out->r_tag_table_offset = b_i64_btoh(in->h_tag_table_offset);
+	out->r_extent_table_offset = b_i64_btoh(in->h_extent_table_offset);
+	out->r_cluster_table_offset = b_i64_btoh(in->h_cluster_table_offset);
+	out->r_nr_tags = b_i32_btoh(in->h_tag_count);
+	out->r_nr_extents = b_i32_btoh(in->h_tag_count);
+	out->r_nr_cluster_groups = b_i32_btoh(in->h_cluster_group_count);
+}
+
+enum ec3_status ec3_reader_create(FILE *inp, struct ec3_reader **out)
+{
+	struct ec3_header header;
+
+	fseek(inp, 0, SEEK_SET);
+	size_t r = fread(&header, sizeof header, 1, inp);
+
+	if (r != 1) {
+		return ferror(inp) ? EC3_ERR_IO_FAILURE : EC3_ERR_BAD_FORMAT;
+	}
+
+	if (b_i32_btoh(header.h_magic) != EC3_SIGNATURE) {
+		return EC3_ERR_BAD_FORMAT;
+	}
+
+	struct ec3_reader *reader = malloc(sizeof *reader);
+	if (!reader) {
+		return EC3_ERR_NO_MEMORY;
+	}
+
+	memset(reader, 0x0, sizeof *reader);
+
+	decode_header(&header, reader);
+
+	unsigned short compression = b_i16_btoh(header.h_compression);
+	unsigned short encryption = b_i16_btoh(header.h_encryption);
+
+	struct ec3_pipeline_stage_args stages[3] = { 0 };
+	stages[0].type = EC3_PIPELINE_FILE;
+
+	if (encryption != EC3_ENCRYPTION_NONE) {
+		stages[1].type = ec3_get_pipeline_stage_for_encryption_func(encryption);
+	}
+
+	if (compression != EC3_COMPRESSION_NONE) {
+		stages[2].type = ec3_get_pipeline_stage_for_compression_func(compression);
+	}
+
+	enum ec3_status status = ec3_pipeline_create(
+		stages,
+		sizeof stages / sizeof stages[0],
+		reader->r_cluster_size,
+		&reader->r_pipeline);
+
+	if (status != EC3_SUCCESS) {
+		free(reader);
+		return status;
+	}
+
+	return EC3_SUCCESS;
+}
+
+void ec3_reader_finish(struct ec3_reader *reader)
+{
+
+}
+
+enum ec3_status ec3_reader_open_tag(struct ec3_reader *reader, uint64_t tag_ident, struct ec3_tag_reader **out)
+{
+
+}
+
+enum ec3_status ec3_tag_reader_close(struct ec3_tag_reader *tag)
+{
+
+}

src/read.h

@@ -0,0 +1,19 @@
+#ifndef READ_H_
+#define READ_H_
+
+#include "status.h"
+
+#include <stdio.h>
+#include <stdint.h>
+
+struct ec3_reader;
+struct ec3_tag_reader;
+
+extern enum ec3_status ec3_reader_create(FILE *inp, struct ec3_reader **out);
+extern void ec3_reader_finish(struct ec3_reader *reader);
+
+extern enum ec3_status ec3_reader_open_tag(struct ec3_reader *reader, uint64_t tag_ident, struct ec3_tag_reader **out);
+
+extern enum ec3_status ec3_tag_reader_close(struct ec3_tag_reader *tag);
+
+#endif

src/status.h

@@ -7,6 +7,7 @@ enum ec3_status {
 	EC3_ERR_NO_ENTRY,
 	EC3_ERR_NOT_SUPPORTED,
 	EC3_ERR_BAD_STATE,
+	EC3_ERR_BAD_FORMAT,
 	EC3_ERR_INVALID_VALUE,
 	EC3_ERR_NAME_EXISTS,
 	EC3_ERR_IO_FAILURE,