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authorNick Terrell <terrelln@fb.com>2016-11-11 19:31:52 (GMT)
committerNick Terrell <terrelln@fb.com>2016-11-11 19:37:12 (GMT)
commit7aad356ffded1306492d3b5326ab2c014ba701ed (patch)
treeb3d78dba8cccfe34c547caeacc1130ff680ca07b
parent1f246a98992fa7035823bedf6a0b7612fc290592 (diff)
downloadlz4-7aad356ffded1306492d3b5326ab2c014ba701ed.zip
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Add frame decompression example
-rw-r--r--examples/frameCompress.c249
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);
+ }
}