ardour/libs/ardour/rdff.c

/*
  RDFF - RDF in RIFF
  Copyright 2011 David Robillard <http://drobilla.net>

  Redistribution and use in source and binary forms, with or without
  modification, are permitted provided that the following conditions are met:

  1. Redistributions of source code must retain the above copyright notice,
     this list of conditions and the following disclaimer.

  2. Redistributions in binary form must reproduce the above copyright
     notice, this list of conditions and the following disclaimer in the
     documentation and/or other materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  THE POSSIBILITY OF SUCH DAMAGE.
*/

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "rdff.h"

#define CHUNK_ID_LEN 4

static const char FILE_TYPE[CHUNK_ID_LEN]  = "RDFF";  /* RDFF File ID */
static const char CHUNK_TRIP[CHUNK_ID_LEN] = "trip";  /* Triple Chunk ID */
static const char CHUNK_URID[CHUNK_ID_LEN] = "urid";  /* URI-ID Chunk ID*/

struct _RDFF {
	FILE*    fd;
	uint32_t size;
	bool     write;
};

RDFF
rdff_open(const char* path, bool write)
{
	FILE* fd = fopen(path, (write ? "w" : "r"));
	if (!fd) {
		fprintf(stderr, "%s\n", strerror(errno));
		return NULL;
	}

	uint32_t size = 0;

	if (write) {
		fwrite("RIFF", CHUNK_ID_LEN, 1, fd);    /* RIFF chunk ID */
		fwrite(&size, sizeof(size), 1, fd);     /* RIFF chunk size */
		fwrite(FILE_TYPE, CHUNK_ID_LEN, 1, fd); /* File type */
	} else {
		char magic[CHUNK_ID_LEN];
		if (fread(magic, CHUNK_ID_LEN, 1, fd) != 1
		    || strncmp(magic, "RIFF", CHUNK_ID_LEN)) {
			fclose(fd);
			fprintf(stderr, "%s: error: not a RIFF file\n", path);
			return NULL;
		}

		if (fread(&size, sizeof(size), 1, fd) != 1) {
			fclose(fd);
			fprintf(stderr, "%s: error: missing RIFF chunk size\n", path);
			return NULL;
		}

		if (fread(magic, CHUNK_ID_LEN, 1, fd) != 1
		    || strncmp(magic, FILE_TYPE, CHUNK_ID_LEN)) {
			fclose(fd);
			fprintf(stderr, "%s: error: not an %s RIFF file\n",
			        FILE_TYPE, path);
			return NULL;
		}
	}

	RDFF ret = (RDFF)malloc(sizeof(struct _RDFF));
	ret->fd    = fd;
	ret->size  = size;
	ret->write = write;
	return ret;
}

#define WRITE(ptr, size, nmemb, stream) \
	if (fwrite(ptr, size, nmemb, stream) != nmemb) { \
		return RDFF_STATUS_UNKNOWN_ERROR; \
	}

RDFFStatus
rdff_write_uri(RDFF        file,
               uint32_t    id,
               uint32_t    len,
               const char* uri)
{
	const uint32_t chunk_size = sizeof(id) + len + 1;
	WRITE(CHUNK_URID,  CHUNK_ID_LEN,       1, file->fd);
	WRITE(&chunk_size, sizeof(chunk_size), 1, file->fd);
	WRITE(&id,         sizeof(id),         1, file->fd);
	WRITE(uri,         len + 1,            1, file->fd);
	if ((chunk_size % 2)) {
		WRITE("", 1, 1, file->fd);  /* pad */
	}
	file->size += 8 + chunk_size;
	return RDFF_STATUS_OK;
}

RDFFStatus
rdff_write_triple(RDFF        file,
                  uint32_t    subject,
                  uint32_t    predicate,
                  uint32_t    object_type,
                  uint32_t    object_size,
                  const void* object)
{
	const uint32_t chunk_size = sizeof(RDFFTripleChunk) + object_size;
	WRITE(CHUNK_TRIP,   CHUNK_ID_LEN,        1, file->fd);
	WRITE(&chunk_size,  sizeof(chunk_size),  1, file->fd);
	WRITE(&subject,     sizeof(subject),     1, file->fd);
	WRITE(&predicate,   sizeof(predicate),   1, file->fd);
	WRITE(&object_type, sizeof(object_type), 1, file->fd);
	WRITE(&object_size, sizeof(object_size), 1, file->fd);
	WRITE(object,       object_size,         1, file->fd);
	if ((object_size % 2)) {
		WRITE("", 1, 1, file->fd);  /* write pad */
	}
	file->size += 8 + chunk_size;
	return RDFF_STATUS_OK;
}

RDFFStatus
rdff_read_chunk(RDFF        file,
                RDFFChunk** buf)
{
	if (feof(file->fd))
		return RDFF_STATUS_EOF;

#define READ(ptr, size, nmemb, stream) \
	if (fread(ptr, size, nmemb, stream) != nmemb) { \
		return RDFF_STATUS_CORRUPT; \
	}

	const uint32_t alloc_size = (*buf)->size;

	READ((*buf)->type,  sizeof((*buf)->type), 1, file->fd);
	READ(&(*buf)->size, sizeof((*buf)->size), 1, file->fd);
	if ((*buf)->size > alloc_size) {
		*buf = realloc(*buf, sizeof(RDFFChunk) + (*buf)->size);
	}
	READ((*buf)->data, (*buf)->size, 1, file->fd);
	if (((*buf)->size % 2)) {
		char pad;
		READ(&pad, 1, 1, file->fd);  /* skip pad */
	}
	return RDFF_STATUS_OK;
}

bool
rdff_chunk_is_uri(RDFFChunk* chunk)

{
	return !strncmp(chunk->type, CHUNK_URID, CHUNK_ID_LEN);
}

bool
rdff_chunk_is_triple(RDFFChunk* chunk)
{
	return !strncmp(chunk->type, CHUNK_TRIP, CHUNK_ID_LEN);
}

void
rdff_close(RDFF file)
{
	if (file) {
		if (file->write) {
			fseek(file->fd, 4, SEEK_SET);
			if (fwrite(&file->size, sizeof(file->size), 1, file->fd) != 1) {
				fprintf(stderr, "failed to write RIFF header size\n");
			}
		}
		fclose(file->fd);
	}

	free(file);
}

#ifdef STANDALONE
// Test program
int
main(int argc, char** argv)
{
	if (argc != 2) {
		fprintf(stderr, "Usage: %s FILENAME\n", argv[0]);
		return 1;
	}

	const char* const filename = argv[1];

	RDFF file = rdff_open(filename, true);
	if (!file)
		goto fail;

	static const int N_URIS    = 16;
	static const int N_RECORDS = 16;

	char uri[64];
	for (int i = 0; i < N_URIS; ++i) {
		snprintf(uri, sizeof(uri), "http://example.org/uri%02d", i + 1);
		rdff_write_uri(file, i + 1, strlen(uri), uri);
	}

	char val[6];
	for (int i = 0; i < N_RECORDS; ++i) {
		snprintf(val, sizeof(val), "VAL%02d", i);
		rdff_write_triple(file,
		                  0,
		                  rand() % N_URIS,
		                  0,
		                  sizeof(val),
		                  val);
	}

	rdff_close(file);

	file = rdff_open(filename, false);
	if (!file)
		goto fail;

	RDFFChunk* chunk = malloc(sizeof(RDFFChunk));
	chunk->size = 0;
	for (int i = 0; i < N_URIS; ++i) {
		if (rdff_read_chunk(file, &chunk)
		    || strncmp(chunk->type, CHUNK_URID, 4)) {
			fprintf(stderr, "error: expected %s chunk\n", CHUNK_URID);
			goto fail;
		}
		RDFFURIChunk* body = (RDFFURIChunk*)chunk->data;
		printf("URI: %s\n", body->uri);
	}

	for (int i = 0; i < N_RECORDS; ++i) {
		if (rdff_read_chunk(file, &chunk)
		    || strncmp(chunk->type, CHUNK_TRIP, 4)) {
			fprintf(stderr, "error: expected %s chunk\n", CHUNK_TRIP);
			goto fail;
		}
		RDFFTripleChunk* body = (RDFFTripleChunk*)chunk->data;
		printf("KEY %d = %s\n", body->predicate, body->object);
	}

	free(chunk);
	rdff_close(file);

	return 0;

fail:
	rdff_close(file);
	fprintf(stderr, "Test failed\n");
	return 1;
}
#endif // STANDALONE