Merge pull request #266 from terrelln/frame-ex

Add frame decompression example
This commit is contained in:
Yann Collet 2016-11-11 12:38:54 -08:00 committed by GitHub
commit dbfdd5131c

View File

@ -8,7 +8,7 @@
#include <lz4frame.h> #include <lz4frame.h>
#define BUF_SIZE (16*1024) #define BUF_SIZE 16*1024
#define LZ4_HEADER_SIZE 19 #define LZ4_HEADER_SIZE 19
#define LZ4_FOOTER_SIZE 4 #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 */ { 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_errorCode_t r;
LZ4F_compressionContext_t ctx; LZ4F_compressionContext_t ctx;
char *src, *buf = NULL; 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); r = LZ4F_createCompressionContext(&ctx, LZ4F_VERSION);
if (LZ4F_isError(r)) { if (LZ4F_isError(r)) {
printf("Failed to create context: error %zu", r); printf("Failed to create context: error %zu\n", r);
return 1; return 1;
} }
r = 1; r = 1;
src = malloc(BUF_SIZE); src = malloc(BUF_SIZE);
if (!src) { if (!src) {
printf("Not enough memory"); printf("Not enough memory\n");
goto cleanup; 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; size = frame_size + LZ4_HEADER_SIZE + LZ4_FOOTER_SIZE;
buf = malloc(size); buf = malloc(size);
if (!buf) { if (!buf) {
printf("Not enough memory"); printf("Not enough memory\n");
goto cleanup; goto cleanup;
} }
n = offset = count_out = LZ4F_compressBegin(ctx, buf, size, &lz4_preferences); n = offset = count_out = LZ4F_compressBegin(ctx, buf, size, &lz4_preferences);
if (LZ4F_isError(n)) { if (LZ4F_isError(n)) {
printf("Failed to start compression: error %zu", n); printf("Failed to start compression: error %zu\n", n);
goto cleanup; 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); n = LZ4F_compressUpdate(ctx, buf + offset, size - offset, src, k, NULL);
if (LZ4F_isError(n)) { if (LZ4F_isError(n)) {
printf("Compression failed: error %zu", n); printf("Compression failed: error %zu\n", n);
goto cleanup; 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); k = fwrite(buf, 1, offset, out);
if (k < offset) { if (k < offset) {
if (ferror(out)) if (ferror(out))
printf("Write failed"); printf("Write failed\n");
else else
printf("Short write"); printf("Short write\n");
goto cleanup; 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); n = LZ4F_compressEnd(ctx, buf + offset, size - offset, NULL);
if (LZ4F_isError(n)) { if (LZ4F_isError(n)) {
printf("Failed to end compression: error %zu", n); printf("Failed to end compression: error %zu\n", n);
goto cleanup; 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); k = fwrite(buf, 1, offset, out);
if (k < offset) { if (k < offset) {
if (ferror(out)) if (ferror(out))
printf("Write failed"); printf("Write failed\n");
else else
printf("Short write"); printf("Short write\n");
goto cleanup; goto cleanup;
} }
@ -114,56 +114,205 @@ static int compress_file(FILE *in, FILE *out, size_t *size_in, size_t *size_out)
return r; return r;
} }
static int compress(const char *input, const char *output) { static size_t get_block_size(const LZ4F_frameInfo_t* info) {
char *tmp = NULL; switch (info->blockSizeID) {
FILE *in = NULL, *out = NULL; case LZ4F_max64KB: return 1 << 16;
size_t size_in = 0, size_out = 0; case LZ4F_max256KB: return 1 << 18;
int r = 1; case LZ4F_max1MB: return 1 << 20;
case LZ4F_max4MB: return 1 << 22;
if (!output) { default:
size_t len = strlen(input); printf("Impossible unless more block sizes are allowed\n");
exit(1);
output = tmp = malloc(len + 5);
if (!tmp) {
printf("Not enough memory");
return 1;
}
strcpy(tmp, input);
strcpy(tmp + len, ".lz4");
} }
in = fopen(input, "rb");
if (!in) {
fprintf(stderr, "Failed to open input file %s: %s\n", input, strerror(errno));
goto cleanup;
}
out = fopen(output, "wb");
if (!out) {
fprintf(stderr, "Failed to open output file %s: %s\n", output, strerror(errno));
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;
} }
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) { int main(int argc, char **argv) {
if (argc < 2 || argc > 3) { char inpFilename[256] = { 0 };
fprintf(stderr, "Syntax: %s <input> <output>\n", argv[0]); char lz4Filename[256] = { 0 };
return EXIT_FAILURE; 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);
}
} }