Add frame decompression example

1 files changed, 199 insertions, 50 deletions

diff --git a/examples/frameCompress.c b/examples/frameCompress.c
index b52b042..b7a3576 100644
--- a/examples/frameCompress.c
+++ b/examples/frameCompress.c
@@ -8,7 +8,7 @@
 
 #include <lz4frame.h>
 
-#define BUF_SIZE (16*1024)
+#define BUF_SIZE 16*1024
 #define LZ4_HEADER_SIZE 19
 #define LZ4_FOOTER_SIZE 4
 
@@ -19,7 +19,7 @@ static const LZ4F_preferences_t lz4_preferences = {
 	{ 0, 0, 0, 0 },  /* reserved, must be set to 0 */
 };
 
-static int compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out) {
+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;
@@ -27,14 +27,14 @@ static int compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out)
 
 	r = LZ4F_createCompressionContext(&ctx, LZ4F_VERSION);
 	if (LZ4F_isError(r)) {
-		printf("Failed to create context: error %zu", r);
+		printf("Failed to create context: error %zu\n", r);
 		return 1;
 	}
 	r = 1;
 
 	src = malloc(BUF_SIZE);
 	if (!src) {
-		printf("Not enough memory");
+		printf("Not enough memory\n");
 		goto cleanup;
 	}
 
@@ -42,13 +42,13 @@ static int compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out)
 	size =  frame_size + LZ4_HEADER_SIZE + LZ4_FOOTER_SIZE;
 	buf = malloc(size);
 	if (!buf) {
-		printf("Not enough memory");
+		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);
+		printf("Failed to start compression: error %zu\n", n);
 		goto cleanup;
 	}
 
@@ -62,7 +62,7 @@ static int compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out)
 
 		n = LZ4F_compressUpdate(ctx, buf + offset, size - offset, src, k, NULL);
 		if (LZ4F_isError(n)) {
-			printf("Compression failed: error %zu", n);
+			printf("Compression failed: error %zu\n", n);
 			goto cleanup;
 		}
 
@@ -74,9 +74,9 @@ static int compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out)
 			k = fwrite(buf, 1, offset, out);
 			if (k < offset) {
 				if (ferror(out))
-					printf("Write failed");
+					printf("Write failed\n");
 				else
-					printf("Short write");
+					printf("Short write\n");
 				goto cleanup;
 			}
 
@@ -86,7 +86,7 @@ static int compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out)
 
 	n = LZ4F_compressEnd(ctx, buf + offset, size - offset, NULL);
 	if (LZ4F_isError(n)) {
-		printf("Failed to end compression: error %zu", n);
+		printf("Failed to end compression: error %zu\n", n);
 		goto cleanup;
 	}
 
@@ -97,9 +97,9 @@ static int compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out)
 	k = fwrite(buf, 1, offset, out);
 	if (k < offset) {
 		if (ferror(out))
-			printf("Write failed");
+			printf("Write failed\n");
 		else
-			printf("Short write");
+			printf("Short write\n");
 		goto cleanup;
 	}
 
@@ -114,56 +114,205 @@ static int compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out)
 	return r;
 }
 
-static int compress(const char *input, const char *output) {
-	char *tmp = NULL;
-	FILE *in = NULL, *out = NULL;
-	size_t size_in = 0, size_out = 0;
-	int r = 1;
-
-	if (!output) {
-		size_t len = strlen(input);
-
-		output = tmp = malloc(len + 5);
-		if (!tmp) {
-			printf("Not enough memory");
-			return 1;
-		}
-		strcpy(tmp, input);
-		strcpy(tmp + len, ".lz4");
+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;
 
-	in = fopen(input, "rb");
-	if (!in) {
-		fprintf(stderr, "Failed to open input file %s: %s\n", input, strerror(errno));
+	/* Initialization */
+	ret = LZ4F_createDecompressionContext(&dctx, 100);
+	if (LZ4F_isError(ret)) {
+		printf("LZ4F_dctx creation error: %s\n", LZ4F_getErrorName(ret));
 		goto cleanup;
 	}
 
-	out = fopen(output, "wb");
-	if (!out) {
-		fprintf(stderr, "Failed to open output file %s: %s\n", output, strerror(errno));
+	/* 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;
 	}
 
-	r = compress_file(in, out, &size_in, &size_out);
-	if (r == 0)
-		printf("%s: %zu → %zu bytes, %.1f%%\n",
-		       input, size_in, size_out,
-		       (double)size_out / size_in * 100);
- cleanup:
-	if (in)
-		fclose(in);
-	if (out)
-		fclose(out);
-	free(tmp);
-	return r;
+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) {
-	if (argc < 2 || argc > 3) {
-		fprintf(stderr, "Syntax: %s <input> <output>\n", argv[0]);
-		return EXIT_FAILURE;
+	char inpFilename[256] = { 0 };
+	char lz4Filename[256] = { 0 };
+	char decFilename[256] = { 0 };
+
+	if(argc < 2) {
+		printf("Please specify input filename\n");
+		return 0;
 	}
 
-	return compress(argv[1], argv[2]);
+	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);
+	}
 }