Packer::canUnpack() now can return -1.

committer: mfx <mfx> 962126554 +0000

src/except.cpp

@@ -63,6 +63,13 @@ void throwAlreadyPacked(const char *msg)
     throw AlreadyPackedException(msg);
 }
 
+void throwAlreadyPackedByUPX(const char *msg)
+{
+    if (msg == NULL)
+        msg = "already packed by UPX";
+    throwAlreadyPacked(msg);
+}
+
 
 /*************************************************************************
 // decompression
@@ -109,7 +116,15 @@ void throwBadLoader()
 
 void throwIOException(const char *msg, int e)
 {
-    throw IOException(msg,e);
+    throw IOException(msg, e);
+}
+
+
+void throwEOFException(const char *msg, int e)
+{
+    if (msg == NULL && e == 0)
+        msg = "premature end of file";
+    throw EOFException(msg, e);
 }
 
 
@@ -121,7 +136,7 @@ const char *prettyName(const char *n)
 {
     while (*n >= '0' && *n <= '9')              // gcc / egcs
         n++;
-    if (strlen(n) > 6 && memcmp(n, "class ", 6) == 0)   // Visual C++
+    if (strncmp(n, "class ", 6) == 0)           // Visual C++
         n += 6;
     return n;
 }

src/except.h

@@ -192,8 +192,9 @@ public:
 // util
 **************************************************************************/
 
+#undef NORET
 #if 0 && defined(__GNUC__)
-// (noreturn) is probably not the correct semantics
+// (noreturn) is probably not the correct semantics for throwing exceptions
 #define NORET __attribute__((noreturn))
 #else
 #define NORET
@@ -203,6 +204,7 @@ void throwCantPack(const char *msg) NORET;
 void throwUnknownExecutableFormat(const char *msg = 0, bool warn = false) NORET;
 void throwNotCompressible(const char *msg = 0) NORET;
 void throwAlreadyPacked(const char *msg = 0) NORET;
+void throwAlreadyPackedByUPX(const char *msg = 0) NORET;
 void throwCantUnpack(const char *msg) NORET;
 void throwNotPacked(const char *msg = 0) NORET;
 void throwFilterException() NORET;
@@ -211,6 +213,7 @@ void throwChecksumError() NORET;
 void throwCompressedDataViolation() NORET;
 void throwInternalError(const char *msg) NORET;
 void throwIOException(const char *msg = 0, int e = 0) NORET;
+void throwEOFException(const char *msg = 0, int e = 0) NORET;
 
 #undef NORET
 

src/file.cpp

@@ -137,7 +137,7 @@ int FileBase::readx(void *buf, int len)
 {
     int l = this->read(buf,len);
     if (l != len)
-        throw EOFException();
+        throwEOFException();
     return l;
 }
 

src/p_com.cpp

@@ -220,7 +220,7 @@ void PackCom::pack(OutputFile *fo)
 //
 **************************************************************************/
 
-bool PackCom::canUnpack()
+int PackCom::canUnpack()
 {
     if (!readPackHeader(128, 0))
         return false;

src/p_com.h

@@ -48,7 +48,7 @@ public:
     virtual void unpack(OutputFile *fo);
 
     virtual bool canPack();
-    virtual bool canUnpack();
+    virtual int canUnpack();
 
 protected:
     virtual const unsigned getCallTrickOffset() const { return 0x100; }

src/p_djgpp2.cpp

@@ -368,13 +368,13 @@ void PackDjgpp2::pack(OutputFile *fo)
 //
 **************************************************************************/
 
-bool PackDjgpp2::canUnpack()
+int PackDjgpp2::canUnpack()
 {
     if (!readFileHeader())
         return false;
     if (is_dlm(fi,coff_offset))
         throwCantUnpack("can't handle DLM");
-    return readPackHeader(1024, coff_offset);
+    return readPackHeader(1024, coff_offset) ? 1 : -1;
 }
 
 

src/p_djgpp2.h

@@ -49,7 +49,7 @@ public:
     virtual void unpack(OutputFile *fo);
 
     virtual bool canPack();
-    virtual bool canUnpack();
+    virtual int canUnpack();
 
 protected:
     virtual int buildLoader(const Filter *ft);

src/p_exe.cpp

@@ -71,7 +71,7 @@ const int *PackExe::getFilters() const
 //
 **************************************************************************/
 
-bool PackExe::readExeHeader()
+bool PackExe::readFileHeader()
 {
     ih_exesize = ih_imagesize = ih_overlay = 0;
     fi->readx(&ih,sizeof(ih));
@@ -95,7 +95,7 @@ bool PackExe::canPack()
 {
     if (fn_has_ext(fi->getName(),"sys"))
         return false;
-    if (!readExeHeader())
+    if (!readFileHeader())
         return false;
     if (file_size < 1024)
         throwCantPack("file is too small");
@@ -519,9 +519,9 @@ void PackExe::pack(OutputFile *fo)
 //
 **************************************************************************/
 
-bool PackExe::canUnpack()
+int PackExe::canUnpack()
 {
-    if (!readExeHeader())
+    if (!readFileHeader())
         return false;
     const off_t off = ih.headsize16*16;
     bool b = readPackHeader(128, off);

src/p_exe.h

@@ -48,7 +48,7 @@ public:
     virtual void unpack(OutputFile *fo);
 
     virtual bool canPack();
-    virtual bool canUnpack();
+    virtual int canUnpack();
 
     // unpacker capabilities
     virtual bool canUnpackVersion(int version) const
@@ -62,7 +62,7 @@ public:
     }
 
 protected:
-    virtual bool readExeHeader(void);
+    virtual bool readFileHeader(void);
 
     struct exe_header_t
     {

src/p_lx_elf.cpp

@@ -343,7 +343,7 @@ void PackLinuxI386elf::pack(OutputFile *fo)
     }
 
     if ((off_t)total_in != file_size)
-        throw EOFException();
+        throwEOFException();
 
     // write block end marker (uncompressed size 0)
     fo->write("\x00\x00\x00\x00", 4);
@@ -492,7 +492,7 @@ void PackLinuxI386elf::unpack(OutputFile *fo)
 
     // all bytes must be written
     if (total_out != orig_file_size)
-        throw EOFException();
+        throwEOFException();
 
     // finally test the checksums
     if (ph.c_adler != c_adler || ph.u_adler != u_adler)

src/p_lx_elf.h

@@ -46,11 +46,11 @@ public:
     virtual const char *getName() const { return "linux/elf386"; }
     virtual const int *getFilters() const { return NULL; }
 
-    virtual bool canPack();
-    virtual bool canUnpackFormat(int format) const;
     virtual void pack(OutputFile *fo);
     virtual void unpack(OutputFile *fo);
 
+    virtual bool canPack();
+    virtual bool canUnpackFormat(int format) const;
     virtual bool canUnpackVersion(int version) const
         { return (version >= 11); }
 

src/p_tmt.cpp

@@ -264,11 +264,11 @@ void PackTmt::pack(OutputFile *fo)
 }
 
 
-bool PackTmt::canUnpack()
+int PackTmt::canUnpack()
 {
     if (!PackTmt::readFileHeader())
         return false;
-    return readPackHeader(512,adam_offset);
+    return readPackHeader(512,adam_offset) ? 1 : -1;
 }
 
 

src/p_tmt.h

@@ -48,7 +48,7 @@ public:
     virtual void unpack(OutputFile *fo);
 
     virtual bool canPack();
-    virtual bool canUnpack();
+    virtual int canUnpack();
 
 protected:
     bool readFileHeader();

src/p_tos.cpp

@@ -126,7 +126,7 @@ int PackTos::getLoaderSize() const
 // util
 **************************************************************************/
 
-bool PackTos::readExeHeader()
+bool PackTos::readFileHeader()
 {
     fi->seek(0,SEEK_SET);
     fi->readx(&ih, FH_SIZE);
@@ -138,7 +138,7 @@ bool PackTos::readExeHeader()
 }
 
 
-bool PackTos::checkExeHeader()
+bool PackTos::checkFileHeader()
 {
     const unsigned f = ih.fh_flag;
     //printf("flags: 0x%x, text: %d, data: %d, bss: %d, sym: %d\n", f, (int)ih.fh_text, (int)ih.fh_data, (int)ih.fh_bss, (int)ih.fh_sym);
@@ -235,7 +235,7 @@ static int check_relocs(const upx_byte *relocs, unsigned rsize, unsigned isize,
 
 bool PackTos::canPack()
 {
-    if (!readExeHeader())
+    if (!readFileHeader())
         return false;
 
     unsigned char buf[512];
@@ -243,7 +243,7 @@ bool PackTos::canPack()
     if (find_le32(buf,sizeof(buf),UPX_MAGIC_LE32))
         throwAlreadyPacked();
 
-    if (!checkExeHeader())
+    if (!checkFileHeader())
         throwCantPack("unsupported header flags");
     if (file_size < 256)
         throwCantPack("program too small");
@@ -253,7 +253,7 @@ bool PackTos::canPack()
 
 void PackTos::fileInfo()
 {
-    if (!readExeHeader())
+    if (!readFileHeader())
         return;
     con_fprintf(stdout, "    text: %d, data: %d, sym: %d, bss: %d, flags=0x%x\n",
                 (int)ih.fh_text, (int)ih.fh_data, (int)ih.fh_sym, (int)ih.fh_bss, (int)ih.fh_flag);
@@ -490,17 +490,17 @@ void PackTos::pack(OutputFile *fo)
 //
 **************************************************************************/
 
-bool PackTos::canUnpack()
+int PackTos::canUnpack()
 {
-    if (!readPackHeader(512, 0))
+    if (!readFileHeader())
         return false;
-    if (!readExeHeader())
+    if (!readPackHeader(512, 0))
         return false;
     // check header as set by packer
     if ((ih.fh_text & 3) != 0 || (ih.fh_data & 3) != 0 || (ih.fh_bss & 3) != 0
         || ih.fh_sym != 0 || ih.fh_reserved != 0 || ih.fh_reloc > 1)
         throwCantUnpack("file damaged");
-    if (!checkExeHeader())
+    if (!checkFileHeader())
         throwCantUnpack("unsupported header flags");
     return true;
 }

src/p_tos.h

@@ -48,7 +48,7 @@ public:
     virtual void unpack(OutputFile *fo);
 
     virtual bool canPack();
-    virtual bool canUnpack();
+    virtual int canUnpack();
 
     virtual void fileInfo();
 
@@ -56,8 +56,8 @@ protected:
     virtual const upx_byte *getLoader() const;
     virtual int getLoaderSize() const;
 
-    bool readExeHeader();
-    bool checkExeHeader();
+    bool readFileHeader();
+    bool checkFileHeader();
 
     struct tos_header_t
     {

src/p_unix.cpp

@@ -172,7 +172,7 @@ void PackUnix::pack(OutputFile *fo)
         total_out += ph.c_len;
     }
     if ((off_t)total_in != file_size)
-        throw EOFException();
+        throwEOFException();
 
     // write block end marker (uncompressed size 0)
     fo->write("\x00\x00\x00\x00", 4);
@@ -203,7 +203,7 @@ void PackUnix::pack(OutputFile *fo)
 // Generic Unix canUnpack().
 **************************************************************************/
 
-bool PackUnix::canUnpack()
+int PackUnix::canUnpack()
 {
     upx_byte buf[128];
     const int bufsize = sizeof(buf);
@@ -310,7 +310,7 @@ void PackUnix::unpack(OutputFile *fo)
 
     // all bytes must be written
     if (ph.version > 8 && total_out != orig_file_size)
-        throw EOFException();
+        throwEOFException();
 
     // finally test the checksums
     if (ph.c_adler != c_adler || ph.u_adler != u_adler)

src/p_unix.h

@@ -47,7 +47,7 @@ public:
     virtual void unpack(OutputFile *fo);
 
     virtual bool canPack();
-    virtual bool canUnpack();
+    virtual int canUnpack();
 
 protected:
     // called by the generic pack()
@@ -175,7 +175,7 @@ public:
     virtual void unpack(OutputFile *fo);
 
     virtual bool canPack();
-    virtual bool canUnpack();
+    virtual int canUnpack();
 
 protected:
 //    virtual const upx_byte *getLoader() const;

src/p_vmlinux.cpp

@@ -137,7 +137,7 @@ void PackBvmlinuxI386::pack(OutputFile *fo)
 //
 **************************************************************************/
 
-bool PackBvmlinuxI386::canUnpack()
+int PackBvmlinuxI386::canUnpack()
 {
     return false;
 }

src/p_w32pe.h

@@ -56,15 +56,15 @@ public:
     virtual void unpack(OutputFile *fo);
 
     virtual bool canPack();
-    virtual bool canUnpack();
+    virtual int canUnpack();
 
     // unpacker capabilities
     virtual bool canUnpackVersion(int version) const
-    {
-        return (version == 12);
-    }
+        {  return (version == 12); }
 
 protected:
+    virtual bool testUnpackVersion(int version) const;
+
     unsigned pe_offset;
     bool isrtm;
     bool readFileHeader();

src/p_wcle.cpp

@@ -740,12 +740,12 @@ void PackWcle::decodeEntryTable()
 }
 
 
-bool PackWcle::canUnpack()
+int PackWcle::canUnpack()
 {
     if (!LeFile::readFileHeader())
         return false;
     // FIXME: 1024 could be too large for some files
-    return super::readPackHeader(1024, ih.data_pages_offset+exe_offset);
+    return readPackHeader(1024, ih.data_pages_offset+exe_offset) ? 1 : -1;
 }
 
 

src/p_wcle.h

@@ -48,7 +48,7 @@ public:
     virtual void unpack(OutputFile *fo);
 
     virtual bool canPack();
-    virtual bool canUnpack();
+    virtual int canUnpack();
 
 protected:
     virtual void handleStub(OutputFile *fo);

src/packer.cpp

@@ -39,7 +39,7 @@
 **************************************************************************/
 
 Packer::Packer(InputFile *f) :
-    fi(f), file_size(-1),
+    fi(f), file_size(-1), ph_format(-1), ph_version(-1),
     uip(NULL), pass(0), total_passes(0), linker(NULL),
     last_patch(NULL), last_patch_offset(0)
 {
@@ -119,6 +119,24 @@ void Packer::fileInfo()
 }
 
 
+bool Packer::testUnpackVersion(int version) const
+{
+    if (version != ph_version && ph_version != -1)
+        throwCantUnpack("program has been modified; run a virus checker!");
+    if (!canUnpackVersion(version))
+        throwCantUnpack("I am not compatible with older versions of UPX");
+    return true;
+}
+
+
+bool Packer::testUnpackFormat(int format) const
+{
+    if (format != ph_format && ph_format != -1)
+        throwCantUnpack("program has been modified; run a virus checker!");
+    return canUnpackFormat(format);
+}
+
+
 /*************************************************************************
 // compress
 **************************************************************************/
@@ -575,8 +593,8 @@ bool Packer::readPackHeader(unsigned len, off_t seek_offset, upx_byte *buf)
     // Some formats might be able to unpack old versions because
     // their implementation hasn't changed. Ask them.
     if (opt->cmd != CMD_FILEINFO)
-        if (!canUnpackVersion(ph.version))
-            throwCantUnpack("I am not compatible with older versions of UPX");
+        if (!testUnpackVersion(ph.version))
+            return false;
 
     if (ph.c_len >= ph.u_len || (off_t)ph.c_len >= file_size
         || ph.version <= 0 || ph.version >= 0xff)
@@ -596,7 +614,7 @@ bool Packer::readPackHeader(unsigned len, off_t seek_offset, upx_byte *buf)
         throwCantUnpack("unknown compression method");
 
     // Some formats might be able to unpack "subformats". Ask them.
-    if (!canUnpackFormat(ph.format))
+    if (!testUnpackFormat(ph.format))
         return false;
 
     return true;

src/packer.h

@@ -119,6 +119,11 @@ public:
     virtual bool canUnpackFormat(int format) const
         { return (format == getFormat()); }
 
+protected:
+    // unpacker tests - these may throw exceptions
+    virtual bool testUnpackVersion(int version) const;
+    virtual bool testUnpackFormat(int format) const;
+
 protected:
     virtual void pack(OutputFile *fo) = 0;
     virtual void unpack(OutputFile *fo) = 0;
@@ -127,10 +132,14 @@ protected:
     virtual void fileInfo();
 
 public:
+    // canPack() should throw a cantPackException eplaining why it
+    // cannot pack a recognized format.
+    // canUnpack() can return -1 meaning "format recognized, but file
+    // is definitely not packed" (see packmast.cpp).
     virtual bool canPack() = 0;
-    virtual bool canUnpack() = 0;
-    virtual bool canTest() { return canUnpack(); }
-    virtual bool canList() { return canUnpack(); }
+    virtual int canUnpack() = 0;
+    virtual int canTest() { return canUnpack(); }
+    virtual int canList() { return canUnpack(); }
 
 protected:
     // main compression drivers
@@ -215,6 +224,8 @@ protected:
     InputFile *fi;
     off_t file_size;        // will get set by constructor
     PackHeader ph;          // must be filled by canUnpack()
+    int ph_format;
+    int ph_version;
 
     // compression buffers
     MemBuffer ibuf;         // input

src/packmast.cpp

@@ -112,11 +112,17 @@ static Packer* try_unpack(Packer *p, InputFile *f)
     try {
         p->initPackHeader();
         f->seek(0,SEEK_SET);
-        if (p->canUnpack())
+        int r = p->canUnpack();
+        if (r > 0)
         {
             f->seek(0,SEEK_SET);
             return p;
         }
+        if (r < 0)
+        {
+            // FIXME - could stop testing all other unpackers at this time
+            // see canUnpack() in packer.h
+        }
     } catch (IOException&) {
     } catch (...) {
         delete p;