diff options
Diffstat (limited to 'examples/frameCompress.c')
-rw-r--r-- | examples/frameCompress.c | 150 |
1 files changed, 82 insertions, 68 deletions
diff --git a/examples/frameCompress.c b/examples/frameCompress.c index d66a8dc..35dbde2 100644 --- a/examples/frameCompress.c +++ b/examples/frameCompress.c @@ -1,122 +1,133 @@ -// LZ4frame API example : compress a file -// Based on sample code from Zbigniew Jędrzejewski-Szmek +/* LZ4frame API example : compress a file + * Based on sample code from Zbigniew Jędrzejewski-Szmek + * + * This example streams an input file into an output file + * using a bounded memory budget. + * Input is read in chunks of IN_CHUNK_SIZE */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <errno.h> +#include <assert.h> #include <lz4frame.h> -#define BUF_SIZE 16*1024 -#define LZ4_HEADER_SIZE 19 -#define LZ4_FOOTER_SIZE 4 + +#define IN_CHUNK_SIZE (16*1024) static const LZ4F_preferences_t lz4_preferences = { { LZ4F_max256KB, LZ4F_blockLinked, LZ4F_noContentChecksum, LZ4F_frame, - 0 /* content size unknown */, 0 /* no dictID */ , LZ4F_noBlockChecksum }, - 0, /* compression level */ + 0 /* unknown content size */, 0 /* no dictID */ , LZ4F_noBlockChecksum }, + 0, /* compression level; 0 == default */ 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) { - size_t r=1; /* function result; 1 == error, default (early exit) */ - LZ4F_compressionContext_t ctx; - char *src, *buf = NULL; - size_t size, count_in = 0, count_out, offset = 0, frame_size; +/* safe_fwrite() : + * performs fwrite(), ensure operation success, or immediately exit() */ +static void safe_fwrite(void* buf, size_t eltSize, size_t nbElt, FILE* f) +{ + size_t const writtenSize = fwrite(buf, eltSize, nbElt, f); + size_t const expectedSize = eltSize * nbElt; /* note : should check for overflow */ + if (writtenSize < expectedSize) { + if (ferror(f)) /* note : ferror() must follow fwrite */ + printf("Write failed\n"); + else + printf("Short write\n"); + exit(1); + } +} + + +static size_t +compress_file(FILE* in, FILE* out, + unsigned long long* size_in, + unsigned long long* size_out) +{ + size_t result = 1; /* function result; 1 == error, default (early exit) */ + unsigned long long count_in = 0, count_out; + + /* init */ + LZ4F_compressionContext_t ctx; if (LZ4F_isError( LZ4F_createCompressionContext(&ctx, LZ4F_VERSION) )) { - printf("Failed to create context: error %zu\n", r); - return 1; + printf("error: failed to create context \n"); + return result; } - src = malloc(BUF_SIZE); + char* outbuff = NULL; + void* const src = malloc(IN_CHUNK_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) { + size_t const outbufCapacity = LZ4F_compressBound(IN_CHUNK_SIZE, &lz4_preferences); /* large enough for any input <= IN_CHUNK_SIZE */ + outbuff = malloc(outbufCapacity); + if (!outbuff) { printf("Not enough memory\n"); goto cleanup; } - { size_t const headerSize = LZ4F_compressBegin(ctx, buf, size, &lz4_preferences); + /* write frame header */ + assert(outbufCapacity >= LZ4F_HEADER_SIZE_MAX); + { size_t const headerSize = LZ4F_compressBegin(ctx, outbuff, outbufCapacity, &lz4_preferences); if (LZ4F_isError(headerSize)) { printf("Failed to start compression: error %zu\n", headerSize); goto cleanup; } - offset = count_out = headerSize; - printf("Buffer size is %zu bytes, header size %zu bytes\n", size, headerSize); + count_out = headerSize; + printf("Buffer size is %zu bytes, header size %zu bytes\n", outbufCapacity, headerSize); + safe_fwrite(outbuff, 1, headerSize, out); } - + /* stream file */ for (;;) { - size_t const readSize = fread(src, 1, BUF_SIZE, in); - if (readSize == 0) - break; + size_t const readSize = fread(src, 1, outbufCapacity, in); + if (readSize == 0) break; count_in += readSize; - { size_t const compressedSize = LZ4F_compressUpdate(ctx, buf + offset, size - offset, src, readSize, NULL); - if (LZ4F_isError(compressedSize)) { - printf("Compression failed: error %zu\n", compressedSize); - goto cleanup; - } - offset += compressedSize; - count_out += compressedSize; + size_t const compressedSize = LZ4F_compressUpdate(ctx, + outbuff, outbufCapacity, + src, readSize, + NULL); + if (LZ4F_isError(compressedSize)) { + printf("Compression failed: error %zu\n", compressedSize); + goto cleanup; } - if (size - offset < frame_size + LZ4_FOOTER_SIZE) { - size_t writtenSize; - printf("Writing %zu bytes\n", offset); - - writtenSize = fwrite(buf, 1, offset, out); - if (writtenSize < offset) { - if (ferror(out)) /* note : ferror() must follow fwrite */ - printf("Write failed\n"); - else - printf("Short write\n"); - goto cleanup; - } - - offset = 0; - } + printf("Writing %zu bytes\n", compressedSize); + safe_fwrite(outbuff, 1, compressedSize, out); + count_out += compressedSize; } - { size_t const compressedSize = LZ4F_compressEnd(ctx, buf + offset, size - offset, NULL); + /* flush whatever remains within internal buffers */ + { size_t const compressedSize = LZ4F_compressEnd(ctx, + outbuff, outbufCapacity, + NULL); if (LZ4F_isError(compressedSize)) { printf("Failed to end compression: error %zu\n", compressedSize); goto cleanup; } - offset += compressedSize; + + printf("Writing %zu bytes\n", compressedSize); + safe_fwrite(outbuff, 1, compressedSize, out); count_out += compressedSize; } - printf("Writing %zu bytes\n", offset); - { size_t const writtenSize = fwrite(buf, 1, offset, out); - if (writtenSize < 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; /* success */ + result = 0; /* success */ cleanup: LZ4F_freeCompressionContext(ctx); /* supports free on NULL */ free(src); - free(buf); - return r; + free(outbuff); + return result; } + static size_t get_block_size(const LZ4F_frameInfo_t* info) { switch (info->blockSizeID) { case LZ4F_default: @@ -131,7 +142,7 @@ static size_t get_block_size(const LZ4F_frameInfo_t* info) { } static size_t decompress_file(FILE* in, FILE* out) { - void* const src = malloc(BUF_SIZE); + void* const src = malloc(IN_CHUNK_SIZE); void* dst = NULL; size_t dstCapacity = 0; LZ4F_dctx* dctx = NULL; @@ -148,7 +159,7 @@ static size_t decompress_file(FILE* in, FILE* out) { /* Decompression */ while (ret != 0) { /* Load more input */ - size_t srcSize = fread(src, 1, BUF_SIZE, in); + size_t srcSize = fread(src, 1, IN_CHUNK_SIZE, in); const void* srcPtr = src; const void* const srcEnd = srcPtr + srcSize; if (srcSize == 0 || ferror(in)) { @@ -215,6 +226,7 @@ cleanup: return LZ4F_freeDecompressionContext(dctx); /* note : free works on NULL */ } + int compare(FILE* fp0, FILE* fp1) { int result = 0; @@ -238,6 +250,7 @@ int compare(FILE* fp0, FILE* fp1) return result; } + int main(int argc, const char **argv) { char inpFilename[256] = { 0 }; char lz4Filename[256] = { 0 }; @@ -259,8 +272,8 @@ int main(int argc, const char **argv) { /* compress */ { FILE* const inpFp = fopen(inpFilename, "rb"); FILE* const outFp = fopen(lz4Filename, "wb"); - size_t sizeIn = 0; - size_t sizeOut = 0; + unsigned long long sizeIn = 0; + unsigned long long sizeOut = 0; size_t ret; printf("compress : %s -> %s\n", inpFilename, lz4Filename); @@ -270,7 +283,8 @@ int main(int argc, const char **argv) { return (int)ret; } printf("%s: %zu → %zu bytes, %.1f%%\n", - inpFilename, sizeIn, sizeOut, + inpFilename, + (size_t)sizeIn, (size_t)sizeOut, /* might overflow */ (double)sizeOut / sizeIn * 100); printf("compress : done\n"); |