Resources: reject compressed content we can't decompress

This solution is composed of two features:

1) C++ code generated by RCC uses two symbols exported from QtCore that
are only present if the feature was compiled in. If the feature was not
compiled in, this will cause a linker error either at build time or at
load time (if they were functions, the error could be at runtime).

2) Binary files generated by RCC have a new header field containing
flags. We're currently using two flags, one for Zlib and one for
Zstandard.

This means we now have binary RCC format version 3.

Change-Id: I42a48bd64ccc41aebf84fffd156545fb6a4f72d9
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

3 files changed, 74 insertions, 12 deletions

diff --git a/src/tools/rcc/main.cpp b/src/tools/rcc/main.cpp
index 71836b81bd..6e8c13be15 100644
--- a/src/tools/rcc/main.cpp
+++ b/src/tools/rcc/main.cpp
@@ -185,13 +185,13 @@ int runRcc(int argc, char *argv[])
 
     QString errorMsg;
 
-    quint8 formatVersion = 2;
+    quint8 formatVersion = 3;
     if (parser.isSet(formatVersionOption)) {
         bool ok = false;
         formatVersion = parser.value(formatVersionOption).toUInt(&ok);
         if (!ok) {
             errorMsg = QLatin1String("Invalid format version specified");
-        } else if (formatVersion != 1 && formatVersion != 2) {
+        } else if (formatVersion < 1 || formatVersion > 3) {
             errorMsg = QLatin1String("Unsupported format version specified");
         }
     }
@@ -208,6 +208,8 @@ int runRcc(int argc, char *argv[])
 
     if (parser.isSet(compressionAlgoOption))
         library.setCompressionAlgorithm(RCCResourceLibrary::parseCompressionAlgorithm(parser.value(compressionAlgoOption), &errorMsg));
+    if (formatVersion < 3 && library.compressionAlgorithm() == RCCResourceLibrary::CompressionAlgorithm::Zstd)
+        errorMsg = QLatin1String("Zstandard compression requires format version 3 or higher");
     if (parser.isSet(nocompressOption))
         library.setCompressionAlgorithm(RCCResourceLibrary::CompressionAlgorithm::None);
     if (parser.isSet(compressOption) && errorMsg.isEmpty()) {
diff --git a/src/tools/rcc/rcc.cpp b/src/tools/rcc/rcc.cpp
index 5cbc771994..f284749781 100644
--- a/src/tools/rcc/rcc.cpp
+++ b/src/tools/rcc/rcc.cpp
@@ -295,6 +295,7 @@ qint64 RCCFileInfo::writeDataBlob(RCCResourceLibrary &lib, qint64 offset,
                     lib.m_errorDevice->write(msg.toUtf8());
                 }
 
+                lib.m_overallFlags |= CompressedZstd;
                 m_flags |= CompressedZstd;
                 data = std::move(compressed);
                 data.truncate(n);
@@ -321,6 +322,7 @@ qint64 RCCFileInfo::writeDataBlob(RCCResourceLibrary &lib, qint64 offset,
                     lib.m_errorDevice->write(msg.toUtf8());
                 }
                 data = compressed;
+                lib.m_overallFlags |= Compressed;
                 m_flags |= Compressed;
             } else if (lib.verbose()) {
                 QString msg = QString::fromLatin1("%1: note: not compressed\n").arg(m_name);
@@ -438,6 +440,7 @@ RCCResourceLibrary::RCCResourceLibrary(quint8 formatVersion)
     m_treeOffset(0),
     m_namesOffset(0),
     m_dataOffset(0),
+    m_overallFlags(0),
     m_useNameSpace(CONSTANT_USENAMESPACE),
     m_errorDevice(0),
     m_outDevice(0),
@@ -945,6 +948,14 @@ bool RCCResourceLibrary::output(QIODevice &outDevice, QIODevice &tempDevice, QIO
     return true;
 }
 
+void RCCResourceLibrary::writeDecimal(int value)
+{
+    Q_ASSERT(m_format != RCCResourceLibrary::Binary);
+    char buf[std::numeric_limits<int>::digits10 + 2];
+    int n = snprintf(buf, sizeof(buf), "%d", value);
+    write(buf, n + 1);  // write() takes a size including terminating NUL
+}
+
 void RCCResourceLibrary::writeHex(quint8 tmp)
 {
     const char digits[] = "0123456789abcdef";
@@ -1039,6 +1050,8 @@ bool RCCResourceLibrary::writeHeader()
         writeNumber4(0);
         writeNumber4(0);
         writeNumber4(0);
+        if (m_formatVersion >= 3)
+            writeNumber4(m_overallFlags);
     }
     return true;
 }
@@ -1241,10 +1254,35 @@ bool RCCResourceLibrary::writeInitializer()
         if (m_root) {
             writeString("bool qRegisterResourceData"
                 "(int, const unsigned char *, "
-                "const unsigned char *, const unsigned char *);\n\n");
+                "const unsigned char *, const unsigned char *);\n");
             writeString("bool qUnregisterResourceData"
                 "(int, const unsigned char *, "
                 "const unsigned char *, const unsigned char *);\n\n");
+
+            if (m_overallFlags & (RCCFileInfo::Compressed | RCCFileInfo::CompressedZstd)) {
+                // use variable relocations with ELF and Mach-O
+                writeString("#if defined(__ELF__) || defined(__APPLE__)\n");
+                if (m_overallFlags & RCCFileInfo::Compressed) {
+                    writeString("static inline unsigned char qResourceFeatureZlib()\n"
+                                "{\n"
+                                "    extern const unsigned char qt_resourceFeatureZlib;\n"
+                                "    return qt_resourceFeatureZlib;\n"
+                                "}\n");
+                }
+                if (m_overallFlags & RCCFileInfo::CompressedZstd) {
+                    writeString("static inline unsigned char qResourceFeatureZstd()\n"
+                                "{\n"
+                                "    extern const unsigned char qt_resourceFeatureZstd;\n"
+                                "    return qt_resourceFeatureZstd;\n"
+                                "}\n");
+                }
+                writeString("#else\n");
+                if (m_overallFlags & RCCFileInfo::Compressed)
+                    writeString("unsigned char qResourceFeatureZlib();\n");
+                if (m_overallFlags & RCCFileInfo::CompressedZstd)
+                    writeString("unsigned char qResourceFeatureZstd();\n");
+                writeString("#endif\n\n");
+            }
         }
 
         if (m_useNameSpace)
@@ -1263,12 +1301,12 @@ bool RCCResourceLibrary::writeInitializer()
         writeString("()\n{\n");
 
         if (m_root) {
-            writeString("    ");
+            writeString("    int version = ");
+            writeDecimal(m_formatVersion);
+            writeString(";\n    ");
             writeAddNamespaceFunction("qRegisterResourceData");
-            writeString("\n        (");
-            writeHex(m_formatVersion);
-            writeString(" qt_resource_struct, "
-                       "qt_resource_name, qt_resource_data);\n");
+            writeString("\n        (version, qt_resource_struct, "
+                        "qt_resource_name, qt_resource_data);\n");
         }
         writeString("    return 1;\n");
         writeString("}\n\n");
@@ -1286,11 +1324,24 @@ bool RCCResourceLibrary::writeInitializer()
         writeMangleNamespaceFunction(cleanResources);
         writeString("()\n{\n");
         if (m_root) {
-            writeString("    ");
+            writeString("    int version = ");
+            writeDecimal(m_formatVersion);
+            writeString(";\n    ");
+
+            // ODR-use certain symbols from QtCore if we require optional features
+            if (m_overallFlags & RCCFileInfo::Compressed) {
+                writeString("version += ");
+                writeAddNamespaceFunction("qResourceFeatureZlib()");
+                writeString(";\n    ");
+            }
+            if (m_overallFlags & RCCFileInfo::CompressedZstd) {
+                writeString("version += ");
+                writeAddNamespaceFunction("qResourceFeatureZstd()");
+                writeString(";\n    ");
+            }
+
             writeAddNamespaceFunction("qUnregisterResourceData");
-            writeString("\n       (");
-            writeHex(m_formatVersion);
-            writeString(" qt_resource_struct, "
+            writeString("\n       (version, qt_resource_struct, "
                       "qt_resource_name, qt_resource_data);\n");
         }
         writeString("    return 1;\n");
@@ -1326,6 +1377,13 @@ bool RCCResourceLibrary::writeInitializer()
         p[i++] = (m_namesOffset >> 16) & 0xff;
         p[i++] = (m_namesOffset >>  8) & 0xff;
         p[i++] = (m_namesOffset >>  0) & 0xff;
+
+        if (m_formatVersion >= 3) {
+            p[i++] = (m_overallFlags >> 24) & 0xff;
+            p[i++] = (m_overallFlags >> 16) & 0xff;
+            p[i++] = (m_overallFlags >>  8) & 0xff;
+            p[i++] = (m_overallFlags >>  0) & 0xff;
+        }
     }
     return true;
 }
diff --git a/src/tools/rcc/rcc.h b/src/tools/rcc/rcc.h
index 7603a41cde..ad1c5cd166 100644
--- a/src/tools/rcc/rcc.h
+++ b/src/tools/rcc/rcc.h
@@ -134,6 +134,7 @@ private:
     bool writeInitializer();
     void writeMangleNamespaceFunction(const QByteArray &name);
     void writeAddNamespaceFunction(const QByteArray &name);
+    void writeDecimal(int value);
     void writeHex(quint8 number);
     void writeNumber2(quint16 number);
     void writeNumber4(quint32 number);
@@ -160,6 +161,7 @@ private:
     int m_treeOffset;
     int m_namesOffset;
     int m_dataOffset;
+    quint32 m_overallFlags;
     bool m_useNameSpace;
     QStringList m_failedResources;
     QIODevice *m_errorDevice;