From 97e6eab3d71d3c49ee5ae799f4fd88928dae03ce Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Degros?= <fdegros@chromium.org>
Date: Mon, 15 Jun 2020 10:56:27 +1000
Subject: [PATCH] Detect filename encoding and convert filenames to UTF-8 using
 ICU

---
 Makefile            |  15 ++--
 lib/Makefile        |  14 ++--
 lib/fuseZipData.cpp | 192 ++++++++++++++++++++++++++++++++++++++++----
 3 files changed, 193 insertions(+), 28 deletions(-)

diff --git a/Makefile b/Makefile
index 1b40859..e72ce52 100644
--- a/Makefile
+++ b/Makefile
@@ -7,13 +7,14 @@ docdir=$(datarootdir)/doc/$(DEST)
 mandir=$(datarootdir)/man
 man1dir=$(mandir)/man1
 manext=.1
-LIBS=-Llib -lfusezip $(shell $(PKG_CONFIG) fuse --libs) $(shell $(PKG_CONFIG) libzip --libs)
+PKG_CONFIG ?= pkg-config
+PC_DEPS = fuse libzip icu-uc icu-i18n
+PC_CFLAGS := $(shell $(PKG_CONFIG) --cflags $(PC_DEPS))
+LIBS := -Llib -lfusezip $(shell $(PKG_CONFIG) --libs $(PC_DEPS))
+COMMON_CXXFLAGS = -Wall -Wextra -Wconversion -Wno-sign-compare -Wlogical-op -Wshadow -pedantic -std=c++17
+CXXFLAGS = -g -O0 $(COMMON_CXXFLAGS)
+RELEASE_CXXFLAGS = -O2 $(COMMON_CXXFLAGS)
 LIB=lib/libfusezip.a
-CXXFLAGS=-g -O0 -Wall -Wextra -Wconversion -Wsign-conversion -Wlogical-op -Wshadow -pedantic -Werror -std=c++11
-RELEASE_CXXFLAGS=-O2 -Wall -Wextra -Wconversion -Wsign-conversion -Wlogical-op -Wshadow -pedantic -Werror -std=c++11
-PKG_CONFIG?=pkg-config
-FUSEFLAGS=$(shell $(PKG_CONFIG) fuse --cflags)
-ZIPFLAGS=$(shell $(PKG_CONFIG) libzip --cflags)
 SOURCES=main.cpp
 OBJECTS=$(SOURCES:.cpp=.o)
 MANSRC=fuse-zip.1
@@ -35,7 +36,7 @@ $(DEST): $(OBJECTS) $(LIB)
 	    -o $@
 
 main.o: main.cpp
-	$(CXX) -c $(CXXFLAGS) $(FUSEFLAGS) $(ZIPFLAGS) $< \
+	$(CXX) -c $(CXXFLAGS) $(PC_CFLAGS) $< \
 	    -Ilib \
 	    -o $@
 
diff --git a/lib/Makefile b/lib/Makefile
index d092e0e..4e4b23a 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -1,10 +1,10 @@
 DEST=libfusezip.a
-PKG_CONFIG?=pkg-config
-LIBS=$(shell $(PKG_CONFIG) fuse --libs) $(shell $(PKG_CONFIG) libzip --libs)
-CXXFLAGS=-g -O0 -Wall -Wextra -Wconversion -Wsign-conversion -Wlogical-op -Wshadow -pedantic -Werror -std=c++11
-RELEASE_CXXFLAGS=-O2 -Wall -Wextra -Wconversion -Wsign-conversion -Wlogical-op -Wshadow -pedantic -Werror -std=c++11
-FUSEFLAGS=$(shell $(PKG_CONFIG) fuse --cflags)
-ZIPFLAGS=$(shell $(PKG_CONFIG) libzip --cflags)
+PKG_CONFIG ?= pkg-config
+PC_DEPS = fuse libzip icu-uc icu-i18n
+PC_CFLAGS := $(shell $(PKG_CONFIG) --cflags $(PC_DEPS))
+COMMON_CXXFLAGS = -Wall -Wextra -Wconversion -Wno-sign-compare -Wlogical-op -Wshadow -pedantic -std=c++17
+CXXFLAGS = -g -O0 $(COMMON_CXXFLAGS)
+RELEASE_CXXFLAGS = -O2 $(COMMON_CXXFLAGS)
 SOURCES=$(sort $(wildcard *.cpp))
 OBJECTS=$(SOURCES:.cpp=.o)
 CLEANFILES=$(OBJECTS) $(DEST)
@@ -18,7 +18,7 @@ $(DEST): $(OBJECTS)
 	$(AR) -cr $@ $(OBJECTS)
 
 .cpp.o:
-	$(CXX) -c $(CXXFLAGS) $(FUSEFLAGS) $(ZIPFLAGS) $< -o $@
+	$(CXX) -c $(CXXFLAGS) $(PC_CFLAGS) $< -o $@
 
 clean:
 	rm -f $(DEST) $(OBJECTS)
diff --git a/lib/fuseZipData.cpp b/lib/fuseZipData.cpp
index 36a3451..29ff2c4 100644
--- a/lib/fuseZipData.cpp
+++ b/lib/fuseZipData.cpp
@@ -24,6 +24,13 @@
 #include <cstring>
 #include <iostream>
 #include <stdexcept>
+#include <functional>
+#include <memory>
+#include <vector>
+
+#include <syslog.h>
+#include <unicode/ucnv.h>
+#include <unicode/ucsdet.h>
 
 #include "fuseZipData.h"
 #include "extraField.h"
@@ -53,6 +60,118 @@ static void SetPassword(zip_t *const archive) {
         throw ZipError("Cannot set default password", archive);
 }
 
+namespace {
+
+struct Closer {
+    void operator()(UConverter *const conv) const { ucnv_close(conv); }
+    void operator()(UCharsetDetector *const csd) const { ucsdet_close(csd); }
+};
+
+using ConverterPtr = std::unique_ptr<UConverter, Closer>;
+using CharsetDetectorPtr = std::unique_ptr<UCharsetDetector, Closer>;
+
+class ConverterToUtf8 {
+  public:
+    // Creates a converter that will convert strings from the given encoding to
+    // UTF-8. Allocates internal buffers to handle strings up to
+    // `maxInputLength`. Throws an exception in case of error.
+    ConverterToUtf8(const char *const fromEncoding, const size_t maxInputLength)
+        : from(Open(fromEncoding)), to(Open("UTF-8")) {
+        utf16.resize(maxInputLength + 1);
+        utf8.resize(3 * maxInputLength + 1);
+    }
+
+    // Converts the given string to UTF-8. Returns a pointer to the internal
+    // buffer holding the null-terminated result. Returns a null pointer in case
+    // of error.
+    const char *operator()(const char *const in) {
+        if (!in)
+            return nullptr;
+
+        const int32_t inlen = static_cast<int32_t>(strlen(in));
+
+        UErrorCode error = U_ZERO_ERROR;
+        const int32_t len16 = ucnv_toUChars(from.get(), utf16.data(),
+                                            static_cast<int32_t>(utf16.size()),
+                                            in, inlen, &error);
+
+        if (U_FAILURE(error)) {
+            syslog(LOG_ERR, "Cannot convert to UTF-16: %s", u_errorName(error));
+            return nullptr;
+        }
+
+        const int32_t len8 = ucnv_fromUChars(to.get(), utf8.data(),
+                                             static_cast<int32_t>(utf8.size()),
+                                             utf16.data(), len16, &error);
+
+        if (U_FAILURE(error)) {
+            syslog(LOG_ERR, "Cannot convert to UTF-8: %s", u_errorName(error));
+            return nullptr;
+        }
+
+        assert(!utf8[len8]);
+        return utf8.data();
+    }
+
+  private:
+    // Opens an ICU converter for the given encoding.
+    // Throws a runtime_error in case of error.
+    static ConverterPtr Open(const char *const encoding) {
+        UErrorCode error = U_ZERO_ERROR;
+        ConverterPtr conv(ucnv_open(encoding, &error));
+
+        if (U_FAILURE(error)) {
+            std::string msg = "Cannot open converter for ";
+            msg += encoding;
+            msg += ": ";
+            msg += u_errorName(error);
+            throw std::runtime_error(std::move(msg));
+        }
+
+        assert(conv);
+        return conv;
+    }
+
+    const ConverterPtr from, to;
+    std::vector<UChar> utf16;
+    std::vector<char> utf8;
+};
+
+// Detects the encoding of the given string.
+// Returns the encoding name, or an empty string in case of error.
+std::string DetectEncoding(const std::string_view bytes) {
+    UErrorCode error = U_ZERO_ERROR;
+    const CharsetDetectorPtr csd(ucsdet_open(&error));
+    ucsdet_setText(csd.get(), bytes.data(), static_cast<int32_t>(bytes.size()),
+                   &error);
+
+    // Get most plausible encoding.
+    const UCharsetMatch *const ucm = ucsdet_detect(csd.get(), &error);
+    const char *const encoding = ucsdet_getName(ucm, &error);
+    if (U_FAILURE(error)) {
+        syslog(LOG_ERR, "Cannot detect encoding: %s", u_errorName(error));
+        return std::string();
+    }
+
+    syslog(LOG_INFO, "Detected encoding %s with %d%% confidence", encoding,
+           ucsdet_getConfidence(ucm, &error));
+
+    // Check if we want to convert the detected encoding via ICU.
+    const std::string_view candidates[] = {
+        "Shift_JIS",   "Big5",        "EUC-JP",      "EUC-KR", "GB18030",
+        "ISO-2022-CN", "ISO-2022-JP", "ISO-2022-KR", "KOI8-R"};
+
+    for (const std::string_view candidate : candidates) {
+        if (candidate == encoding)
+            return encoding;
+    }
+
+    // Not handled by ICU.
+    return std::string();
+}
+
+} // namespace
+
 FuseZipData::FuseZipData(const char *archiveName, struct zip *z, const char *cwd,
         bool force_precise_time):
     m_zip(z), m_archiveName(archiveName), m_cwd(cwd), m_force_precise_time(force_precise_time) {
@@ -90,18 +209,56 @@ void FuseZipData::build_tree(bool readonly) {
     m_root->parent = NULL;
     files[m_root->full_name.c_str()] = m_root;
     zip_int64_t n = zip_get_num_entries(m_zip, 0);
+
+    // Concatenate all the names in a buffer in order to guess the encoding.
+    std::string allNames;
+    allNames.reserve(10000);
+
+    size_t maxNameLength = 0;
+
     // search for absolute or parent-relative paths
     bool needPrefix = false;
-    if (readonly) {
-        for (zip_int64_t i = 0; i < n; ++i) {
-            const char *name = zip_get_name(m_zip, static_cast<zip_uint64_t>(i), ZIP_FL_ENC_GUESS);
-            if (!name)
-                throw ZipError("Cannot get file name", m_zip);
-
-            if ((name[0] == '/') || (strncmp(name, "../", 3) == 0)) {
-                needPrefix = true;
-                break;
-            }
+    for (zip_int64_t i = 0; i < n; ++i) {
+        const char *name =
+            zip_get_name(m_zip, static_cast<zip_uint64_t>(i), ZIP_FL_ENC_RAW);
+        if (!name)
+            continue;
+
+        const size_t nameLength = strlen(name);
+        if (maxNameLength < nameLength)
+            maxNameLength = nameLength;
+
+        if (allNames.size() + nameLength <= allNames.capacity())
+            allNames.append(name, nameLength);
+
+        if (readonly && !needPrefix) {
+            needPrefix = (name[0] == '/' || strncmp(name, "../", 3) == 0);
+        }
+    }
+
+    // Detect filename encoding.
+    const std::string encoding = DetectEncoding(allNames);
+    allNames.clear();
+
+    // Prepare functor to convert filenames to UTF-8.
+    // By default, just rely on the conversion to UTF-8 provided by libzip.
+    std::function<const char *(const char *)> toUtf8 = [](const char *s) {
+        return s;
+    };
+    zip_flags_t zipFlags = ZIP_FL_ENC_GUESS;
+
+    // But if the filename encoding is one of the encodings we want to convert
+    // using ICU, prepare and use the ICU converter.
+    if (!encoding.empty()) {
+        try {
+            toUtf8 = [converter = std::make_shared<ConverterToUtf8>(
+                          encoding.c_str(), maxNameLength)](const char *s) {
+                return (*converter)(s);
+            };
+            zipFlags = ZIP_FL_ENC_RAW;
+        } catch (const std::exception &e) {
+            syslog(LOG_ERR, "Cannot create converter for %s: %s",
+                   encoding.c_str(), e.what());
         }
     }
 
@@ -114,13 +271,16 @@ void FuseZipData::build_tree(bool readonly) {
         zip_uint64_t id = static_cast<zip_uint64_t>(i);
         bool isHardlink;
 
-        if (zip_stat_index(m_zip, id, ZIP_FL_ENC_GUESS, &sb) < 0)
+        if (zip_stat_index(m_zip, id, zipFlags, &sb) < 0)
             throw ZipError("Cannot read file entry", m_zip);
 
         if ((sb.valid & ZIP_STAT_NAME) == 0)
             continue;
 
-        const char *const name = sb.name;
+        const char *name = toUtf8(sb.name);
+        if (!name)
+            continue;
+
         mode_t mode = getEntryAttributes(id, name, isHardlink);
         if (S_ISLNK(mode))
             continue;
@@ -153,7 +313,11 @@ void FuseZipData::build_tree(bool readonly) {
     for (zip_int64_t i = 0; i < n; ++i) {
         zip_uint64_t id = static_cast<zip_uint64_t>(i);
         bool isHardlink;
-        const char *name = zip_get_name(m_zip, id, ZIP_FL_ENC_GUESS);
+
+        const char *name = toUtf8(zip_get_name(m_zip, id, zipFlags));
+        if (!name)
+            continue;
+
         mode_t mode = getEntryAttributes(id, name, isHardlink);
         if (S_ISLNK(mode))
             continue;
@@ -570,7 +734,7 @@ void FuseZipData::save () {
             if (node->isTemporaryDir()) {
                 // persist temporary directory
                 zip_int64_t idx = zip_dir_add(m_zip,
-                        node->full_name.c_str(), ZIP_FL_ENC_GUESS);
+                        node->full_name.c_str(), ZIP_FL_ENC_UTF_8);
                 if (idx < 0) {
                     syslog(LOG_ERR, "Unable to save directory %s in ZIP archive",
                         node->full_name.c_str());
-- 
2.33.0.464.g1972c5931b-goog