Improving handling of empty files (uncompressed_size == 0) inside of various archives:

    libmerge will not copy such entries from update archives to library ones.
    lib2inpx will give a proper warning about empty file rather then attempt to parse FB2 and fail.
Using "internal/zip" from up to date go distro "archive/zip" rather then old files from "https://github.com/rsc/zipmerge".
Using go 1.20.4 tool chain.

Author: rupor-github

CMakeLists.txt

@@ -13,7 +13,7 @@ set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${CMAKE_SOURCE_DIR}/cmake)
 
 # Project version number
 set(PRJ_VERSION_MAJOR 9)
-set(PRJ_VERSION_MINOR 46)
+set(PRJ_VERSION_MINOR 47)
 
 if(WIN32 AND NOT DEFINED ENV{MSYSTEM})
     message(FATAL_ERROR "Currently unsuppored environment. Use MINGW for Windows builds. CMake willl exit now.")

docker/Dockerfile.build

@@ -66,10 +66,9 @@ COPY get-maria.sh .
 RUN ./get-maria.sh
 
 #  ---------- download golang
-
-RUN curl -LO https://go.dev/dl/go1.20.2.linux-amd64.tar.gz \
-   && tar -xvf go1.20.2.linux-amd64.tar.gz \
-   && rm go1.20.2.linux-amd64.tar.gz \
+RUN curl -LO https://go.dev/dl/go1.20.4.linux-amd64.tar.gz \
+   && tar -xvf go1.20.4.linux-amd64.tar.gz \
+   && rm go1.20.4.linux-amd64.tar.gz \
    && sed -i -e '$a export PATH=$PATH:/root/go/bin' .bashrc \
    && sed -i -e '$a export GOROOT=/root/go' .bashrc
 

lib2inpx/lib2inpx.cpp

@@ -627,6 +627,10 @@ bool read_fb2(const unzip& uz, const string& book_id, fb2_parser& fb, unz_file_i
 
         uz.current(fi);
 
+        if (fi.uncompressed_size == 0) {
+            throw runtime_error("Empty fb2 file");
+        }
+
         int  len                 = 0;
         bool continue_processing = true;
 

src/inpxcreator/cmd/libmerge/main.go

@@ -259,7 +259,7 @@ func main() {
 		tmpOut = f.Name()
 		w = zip.NewWriter(f)
 
-		if (sizeBytes - last.info.Size()) > 0 {
+		if last.info != nil && (sizeBytes-last.info.Size()) > 0 {
 			fmt.Printf("Merging last archive, possibly fist time processing: %s\n", filepath.Join(last.dir, last.info.Name()))
 			skipFirst = true
 			tmp := make([]archive, len(updates)+1, len(updates)+1)
@@ -301,60 +301,66 @@ func main() {
 		}
 		fmt.Printf("\tProcessing update: %s\n", filepath.Join(u.dir, u.info.Name()))
 		for _, file := range rc.File {
-			if id := name2id(file.Name); id > 0 {
 
-				if firstBook == 0 {
-					firstBook = id
-				}
-				lastBook = id
-
-				// I know this is wrong, leftBytes could already be negative, but to repeat what libsplit did
-				// always copy first file...
-
-				if err := w.Copy(file); err != nil {
-					log.Printf("Error copying from %s (%s): %v", name, file.Name, err)
-				} else {
-
-					leftBytes -= int64(file.CompressedSize64)
-
-					if leftBytes <= 0 {
-						if err := w.Close(); err != nil {
-							log.Fatalf("Finishing zip file: %v", err)
-						}
-						if err := f.Close(); err != nil {
-							log.Fatalf("Finishing zip file: %v", err)
-						}
-						newName := fmt.Sprintf("fb2-%06d-%06d.zip", firstBook, lastBook)
-						fmt.Printf("\t--> Finalizing archive: %s\n", newName)
-
-						newName = filepath.Join(last.dir, newName)
-						if err := os.Rename(tmpOut, newName); err != nil {
-							log.Fatalf("Renaming archive: %v", err)
-						}
-
-						last.info, err = os.Stat(newName)
-						if err != nil {
-							log.Fatalf("Stat failed: %v", err)
-						}
-						last.begin = firstBook
-						last.end = lastBook
-						fmt.Printf("\t--> New last archive: %s\n", newName)
-
-						// We may want to rebuild inpx - have new "last" archive ready
-						code = 2
-
-						f, err = ioutil.TempFile(last.dir, "merge-")
-						if err != nil {
-							log.Fatalf("Unable to create temp file: %v", err)
-						}
-						tmpOut = f.Name()
-						w = zip.NewWriter(f)
-						leftBytes = sizeBytes
-						firstBook = 0
+			if file.FileInfo().Size() == 0 {
+				log.Printf("\t\tWrong book size - %d, skipping: \"%s\"\n", file.FileInfo().Size(), file.FileInfo().Name())
+				continue
+			}
+			id := int(0)
+			if id = name2id(file.FileInfo().Name()); id <= 0 {
+				log.Printf("\t\tWrong book name, skipping: \"%s\"\n", file.FileInfo().Name())
+				continue
+			}
+
+			if firstBook == 0 {
+				firstBook = id
+			}
+			lastBook = id
+
+			// I know this is wrong, leftBytes could already be negative, but to repeat what libsplit did
+			// always copy first file...
+
+			if err := w.Copy(file); err != nil {
+				log.Printf("Error copying from %s (%s): %v", name, file.FileInfo().Name(), err)
+			} else {
+
+				leftBytes -= int64(file.CompressedSize64)
+
+				if leftBytes <= 0 {
+					if err := w.Close(); err != nil {
+						log.Fatalf("Finishing zip file: %v", err)
+					}
+					if err := f.Close(); err != nil {
+						log.Fatalf("Finishing zip file: %v", err)
+					}
+					newName := fmt.Sprintf("fb2-%06d-%06d.zip", firstBook, lastBook)
+					fmt.Printf("\t--> Finalizing archive: %s\n", newName)
+
+					newName = filepath.Join(last.dir, newName)
+					if err := os.Rename(tmpOut, newName); err != nil {
+						log.Fatalf("Renaming archive: %v", err)
+					}
+
+					last.info, err = os.Stat(newName)
+					if err != nil {
+						log.Fatalf("Stat failed: %v", err)
 					}
+					last.begin = firstBook
+					last.end = lastBook
+					fmt.Printf("\t--> New last archive: %s\n", newName)
+
+					// We may want to rebuild inpx - have new "last" archive ready
+					code = 2
+
+					f, err = ioutil.TempFile(last.dir, "merge-")
+					if err != nil {
+						log.Fatalf("Unable to create temp file: %v", err)
+					}
+					tmpOut = f.Name()
+					w = zip.NewWriter(f)
+					leftBytes = sizeBytes
+					firstBook = 0
 				}
-			} else {
-				log.Printf("\t\tWrong book name, skipping: \"%s\"\n", file.Name)
 			}
 		}
 		if err := rc.Close(); err != nil {