Merge pull request #510 from a740g/compression-fixes

Improve func__deflate() & func__inflate()

Makefile

@@ -324,8 +324,6 @@ else
 endif
 
 ifneq ($(filter y,$(DEP_ZLIB)),)
-	EXE_LIBS += $(MINIZ_OBJS) $(COMPRESSION_OBJS)
-
 	LICENSE_IN_USE += miniz
 endif
 

internal/c/parts/compression/build.mk

@@ -15,4 +15,11 @@ $(PATH_INTERNAL_C)/parts/compression/%.o: $(PATH_INTERNAL_C)/parts/compression/%
 $(PATH_INTERNAL_C)/parts/compression/%.o: $(PATH_INTERNAL_C)/parts/compression/%.cpp
 	$(CXX) -O2 $(CXXFLAGS) -DDEPENDENCY_CONSOLE_ONLY -Wall $< -c -o $@
 
-CLEAN_LIST += $(MINIZ_OBJS) $(COMPRESSION_OBJS)
+COMPRESSION_LIB := $(PATH_INTERNAL_C)/parts/compression/compression.a
+
+$(COMPRESSION_LIB): $(MINIZ_OBJS) $(COMPRESSION_OBJS)
+	$(AR) rcs $@ $(MINIZ_OBJS) $(COMPRESSION_OBJS)
+
+EXE_LIBS += $(COMPRESSION_LIB)
+
+CLEAN_LIST += $(COMPRESSION_LIB) $(MINIZ_OBJS) $(COMPRESSION_OBJS)

internal/c/parts/compression/compression.cpp

@@ -7,52 +7,53 @@
 
 #include "compression.h"
 #include "qbs.h"
+
 #include "miniz.h"
 
+#include <vector>
+
 uint32_t func__adler32(qbs *text) {
-    if (!text->len) return 1;
-    return (uint32_t) adler32(1, text->chr, text->len);
+    if (!text->len)
+        return 1;
+    return (uint32_t)adler32(1, text->chr, text->len);
 }
 
 uint32_t func__crc32(qbs *text) {
-    if (!text->len) return 0;
-    return (uint32_t) crc32(0, text->chr, text->len);
+    if (!text->len)
+        return 0;
+    return (uint32_t)crc32(0, text->chr, text->len);
 }
 
 qbs *func__deflate(qbs *text) {
-    uLongf filesize = (uint32_t)text->len; // length of the text
-    uLongf compsize = compressBound(filesize);
-    unsigned char *dest = (unsigned char *)malloc(compsize);
-    int32_t result = compress(dest, &compsize, text->chr, filesize);
-    qbs *ret = qbs_new(compsize, 1);
-    memcpy(ret->chr, dest, compsize);
-    free(dest);
-    return ret;
+    auto fileSize = uLongf(text->len);
+    auto compSize = compressBound(fileSize);
+    auto dest = qbs_new(compSize, 1);                    // compressing directly to the qbs gives us a performance boost
+    compress(dest->chr, &compSize, text->chr, fileSize); // discard result because we do not do any error checking
+    return qbs_left(dest, compSize);
 }
 
-qbs *func__inflate(qbs *text, int64_t originalsize, int32_t passed) {
-    int32_t result = 0;
-    if (passed == 1) {
-        uLongf uncompsize = originalsize;
-        unsigned char *dest = (unsigned char *)malloc(originalsize);
-        int32_t result = uncompress(dest, &uncompsize, text->chr, text->len);
-        qbs *ret = qbs_new(uncompsize, 1);
-        memcpy(ret->chr, dest, uncompsize);
-        free(dest);
-        return ret;
+qbs *func__inflate(qbs *text, int64_t originalSize, int32_t passed) {
+    if (passed) {
+        // Passing negative values can do bad things to qbs
+        if (originalSize > 0) {
+            auto uncompSize = uLongf(originalSize);
+            auto dest = qbs_new(uncompSize, 1);                               // decompressing directly to the qbs gives us a performance boost
+            uncompress(dest->chr, &uncompSize, text->chr, uLongf(text->len)); // discard result because we do not do any error checking
+            return dest;                                                      // no size adjustment is done assuming the exact original size was passed
+        } else {
+            return qbs_new(0, 1); // simply return an empty qbs if originalSize is zero or negative
+        }
     } else {
-        uLongf uncompsize = 0;
-        unsigned char *dest;
+        static const uLongf InflateChunkSize = 10 * 1024 * 1024;
+        std::vector<Byte> dest; // to get rid of malloc() and free()
+        auto compSize = uLongf(text->len);
+        uLongf uncompSize = 0;
         do {
-            uncompsize = uncompsize + 10000000; // 10 mb original buffer, resized by 10 mb each pass until it's large enough to hold the uncompressed data.
-            dest = (unsigned char *)malloc(uncompsize);
-            result = uncompress(dest, &uncompsize, text->chr, text->len);
-            if (result == Z_BUF_ERROR)
-                free(dest);              // if the buffer is too small, free the old buffer
-        } while (result == Z_BUF_ERROR); // and try again with a larger buffer
-        qbs *ret = qbs_new(uncompsize, 1);
-        memcpy(ret->chr, dest, uncompsize);
-        free(dest);
+            uncompSize += InflateChunkSize; // 10 mb original buffer, resized by 10 mb each pass until it's large enough to hold the uncompressed data.
+            dest.resize(uncompSize);
+        } while (uncompress(&dest[0], &uncompSize, text->chr, compSize) == Z_BUF_ERROR); // and try again with a larger buffer
+        auto ret = qbs_new(uncompSize, 1);
+        memcpy(ret->chr, &dest[0], uncompSize);
         return ret;
     }
 }