examples/frameCompress.c

// LZ4frame API example : compress a file
// Based on sample code from Zbigniew Jędrzejewski-Szmek

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

#include <lz4frame.h>

#define BUF_SIZE 16*1024
#define LZ4_HEADER_SIZE 19
#define LZ4_FOOTER_SIZE 4

static const LZ4F_preferences_t lz4_preferences = {
	{ LZ4F_max256KB, LZ4F_blockLinked, LZ4F_noContentChecksum, LZ4F_frame, 0, { 0, 0 } },
	0,   /* compression level */
	0,   /* autoflush */
	{ 0, 0, 0, 0 },  /* reserved, must be set to 0 */
};

static size_t compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out) {
	LZ4F_errorCode_t r;
	LZ4F_compressionContext_t ctx;
	char *src, *buf = NULL;
	size_t size, n, k, count_in = 0, count_out, offset = 0, frame_size;

	r = LZ4F_createCompressionContext(&ctx, LZ4F_VERSION);
	if (LZ4F_isError(r)) {
		printf("Failed to create context: error %zu\n", r);
		return 1;
	}
	r = 1;

	src = malloc(BUF_SIZE);
	if (!src) {
		printf("Not enough memory\n");
		goto cleanup;
	}

	frame_size = LZ4F_compressBound(BUF_SIZE, &lz4_preferences);
	size =  frame_size + LZ4_HEADER_SIZE + LZ4_FOOTER_SIZE;
	buf = malloc(size);
	if (!buf) {
		printf("Not enough memory\n");
		goto cleanup;
	}

	n = offset = count_out = LZ4F_compressBegin(ctx, buf, size, &lz4_preferences);
	if (LZ4F_isError(n)) {
		printf("Failed to start compression: error %zu\n", n);
		goto cleanup;
	}

	printf("Buffer size is %zu bytes, header size %zu bytes\n", size, n);

	for (;;) {
		k = fread(src, 1, BUF_SIZE, in);
		if (k == 0)
			break;
		count_in += k;

		n = LZ4F_compressUpdate(ctx, buf + offset, size - offset, src, k, NULL);
		if (LZ4F_isError(n)) {
			printf("Compression failed: error %zu\n", n);
			goto cleanup;
		}

		offset += n;
		count_out += n;
		if (size - offset < frame_size + LZ4_FOOTER_SIZE) {
			printf("Writing %zu bytes\n", offset);

			k = fwrite(buf, 1, offset, out);
			if (k < offset) {
				if (ferror(out))
					printf("Write failed\n");
				else
					printf("Short write\n");
				goto cleanup;
			}

			offset = 0;
		}
	}

	n = LZ4F_compressEnd(ctx, buf + offset, size - offset, NULL);
	if (LZ4F_isError(n)) {
		printf("Failed to end compression: error %zu\n", n);
		goto cleanup;
	}

	offset += n;
	count_out += n;
	printf("Writing %zu bytes\n", offset);

	k = fwrite(buf, 1, offset, out);
	if (k < offset) {
		if (ferror(out))
			printf("Write failed\n");
		else
			printf("Short write\n");
		goto cleanup;
	}

	*size_in = count_in;
	*size_out = count_out;
	r = 0;
 cleanup:
	if (ctx)
		LZ4F_freeCompressionContext(ctx);
	free(src);
	free(buf);
	return r;
}

static size_t get_block_size(const LZ4F_frameInfo_t* info) {
	switch (info->blockSizeID) {
		case LZ4F_max64KB:  return 1 << 16;
		case LZ4F_max256KB: return 1 << 18;
		case LZ4F_max1MB:   return 1 << 20;
		case LZ4F_max4MB:   return 1 << 22;
		default:
			printf("Impossible unless more block sizes are allowed\n");
			exit(1);
	}
}

static size_t decompress_file(FILE *in, FILE *out) {
	void * const src = malloc(BUF_SIZE);
	void *dst = NULL;
	void *srcPtr = src;
	void *srcEnd = src;
	size_t srcSize = 0;
	size_t dstSize = 0;
	size_t dstCapacity = 0;
	LZ4F_dctx *dctx = NULL;
	size_t ret;

	/* Initialization */
	ret = LZ4F_createDecompressionContext(&dctx, 100);
	if (LZ4F_isError(ret)) {
		printf("LZ4F_dctx creation error: %s\n", LZ4F_getErrorName(ret));
		goto cleanup;
	}

	/* Decompression */
	ret = 1;
	while (ret != 0) {
		/* INVARIANT: At this point srcPtr == srcEnd */
		/* Load more input */
		srcSize = fread(src, 1, BUF_SIZE, in);
		if (srcSize == 0 || ferror(in)) {
			printf("Decompress: not enough input or error reading file\n");
			goto cleanup;
		}
		srcPtr = src;
		srcEnd = srcPtr + srcSize;
		/* Allocate destination buffer if it isn't already */
		if (!dst) {
			LZ4F_frameInfo_t info;
			ret = LZ4F_getFrameInfo(dctx, &info, src, &srcSize);
			if (LZ4F_isError(ret)) {
				printf("LZ4F_getFrameInfo error: %s\n", LZ4F_getErrorName(ret));
				goto cleanup;
			}
			/* Allocating enough space for an entire block isn't necessary for
			 * correctness, but it allows some memcpy's to be elided.
			 */
			dstCapacity = get_block_size(&info);
			dst = malloc(dstCapacity);
			srcPtr += srcSize;
			srcSize = srcEnd - srcPtr;
		}
		/* Decompress:
		 * Continue while there is more input to read and the frame isn't over.
		 * If srcPtr == srcEnd then we know that there is no more output left in the
		 * internal buffer left to flush.
		 */
		while (srcPtr != srcEnd && ret != 0) {
			/* INVARIANT: Any data left in dst has already been written */
			dstSize = dstCapacity;
			ret = LZ4F_decompress(dctx, dst, &dstSize, srcPtr, &srcSize, /* LZ4F_decompressOptions_t */ NULL);
			if (LZ4F_isError(ret)) {
				printf("Decompression error: %s\n", LZ4F_getErrorName(ret));
				goto cleanup;
			}
			/* Flush output */
			if (dstSize != 0){
				size_t written = fwrite(dst, 1, dstSize, out);
				printf("Writing %zu bytes\n", dstSize);
				if (written != dstSize) {
					printf("Decompress: Failed to write to file\n");
					ret = 1;
					goto cleanup;
				}
			}
			/* Update input */
			srcPtr += srcSize;
			srcSize = srcEnd - srcPtr;
		}
	}
	/* Check that there isn't trailing input data after the frame.
	 * It is valid to have multiple frames in the same file, but this example
	 * doesn't support it.
	 */
	ret = fread(src, 1, 1, in);
	if (ret != 0 || !feof(in)) {
		printf("Decompress: Trailing data left in file after frame\n");
		goto cleanup;
	}

cleanup:
	free(src);
	if (dst) free(dst);
	if (dctx) ret = LZ4F_freeDecompressionContext(dctx);
	return ret;
}

int compare(FILE* fp0, FILE* fp1)
{
	int result = 0;

	while(0 == result) {
		char b0[1024];
		char b1[1024];
		const size_t r0 = fread(b0, 1, sizeof(b0), fp0);
		const size_t r1 = fread(b1, 1, sizeof(b1), fp1);

		result = (int) r0 - (int) r1;

		if (0 == r0 || 0 == r1) {
			break;
		}
		if (0 == result) {
			result = memcmp(b0, b1, r0);
		}
	}

	return result;
}

int main(int argc, char **argv) {
	char inpFilename[256] = { 0 };
	char lz4Filename[256] = { 0 };
	char decFilename[256] = { 0 };

	if(argc < 2) {
		printf("Please specify input filename\n");
		return 0;
	}

	snprintf(inpFilename, 256, "%s", argv[1]);
	snprintf(lz4Filename, 256, "%s.lz4", argv[1]);
	snprintf(decFilename, 256, "%s.lz4.dec", argv[1]);

	printf("inp = [%s]\n", inpFilename);
	printf("lz4 = [%s]\n", lz4Filename);
	printf("dec = [%s]\n", decFilename);

	/* compress */
	{
		FILE* inpFp = fopen(inpFilename, "rb");
		FILE* outFp = fopen(lz4Filename, "wb");
		size_t sizeIn = 0;
		size_t sizeOut = 0;
		size_t ret;

		printf("compress : %s -> %s\n", inpFilename, lz4Filename);
		ret = compress_file(inpFp, outFp, &sizeIn, &sizeOut);
		if (ret) {
			printf("compress : failed with code %zu\n", ret);
			return ret;
		}
		printf("%s: %zu → %zu bytes, %.1f%%\n",
			inpFilename, sizeIn, sizeOut,
			(double)sizeOut / sizeIn * 100);
		printf("compress : done\n");

		fclose(outFp);
		fclose(inpFp);
	}

	/* decompress */
	{
		FILE* inpFp = fopen(lz4Filename, "rb");
		FILE* outFp = fopen(decFilename, "wb");
		size_t ret;

		printf("decompress : %s -> %s\n", lz4Filename, decFilename);
		ret = decompress_file(inpFp, outFp);
		if (ret) {
			printf("decompress : failed with code %zu\n", ret);
			return ret;
		}
		printf("decompress : done\n");

		fclose(outFp);
		fclose(inpFp);
	}

	/* verify */
	{
		FILE* inpFp = fopen(inpFilename, "rb");
		FILE* decFp = fopen(decFilename, "rb");

		printf("verify : %s <-> %s\n", inpFilename, decFilename);
		const int cmp = compare(inpFp, decFp);
		if(0 == cmp) {
			printf("verify : OK\n");
		} else {
			printf("verify : NG\n");
		}

		fclose(decFp);
		fclose(inpFp);
	}
}