From 046df6da76219653e51e9f94ab5d64d62ecda530 Mon Sep 17 00:00:00 2001
From: "Markus F.X.J. Oberhumer" <markus@oberhumer.com>
Date: Thu, 21 Dec 2000 19:46:28 +0000
Subject: [PATCH] Added Packer::checkAlreadyPacked().

committer: mfx <mfx> 977427988 +0000
---
 src/p_com.cpp    |  5 ++---
 src/p_exe.cpp    |  3 +--
 src/p_sys.cpp    |  5 ++---
 src/p_tos.cpp    |  5 ++---
 src/p_unix.cpp   |  5 ++---
 src/p_vmlinz.cpp |  3 +--
 src/packer.cpp   | 21 +++++++++++++++++++++
 src/packer.h     |  1 +
 8 files changed, 32 insertions(+), 16 deletions(-)

diff --git a/src/p_com.cpp b/src/p_com.cpp
index 3e320aa7..18e41aa3 100644
--- a/src/p_com.cpp
+++ b/src/p_com.cpp
@@ -72,14 +72,13 @@ bool PackCom::canPack()
 {
     unsigned char buf[128];
 
-    fi->readx(buf,128);
+    fi->readx(buf, sizeof(buf));
     if (memcmp(buf,"MZ",2) == 0 || memcmp(buf,"ZM",2) == 0 // .exe
         || memcmp (buf,"\xff\xff\xff\xff",4) == 0) // .sys
         return false;
     if (!fn_has_ext(fi->getName(),"com"))
         return false;
-    if (find_le32(buf,128,UPX_MAGIC_LE32) >= 0)
-        throwAlreadyPacked();
+    checkAlreadyPacked(buf, sizeof(buf));
     if (file_size < 1024)
         throwCantPack("file is too small");
     if (file_size > 0xFF00)
diff --git a/src/p_exe.cpp b/src/p_exe.cpp
index cefa8332..90f5b300 100644
--- a/src/p_exe.cpp
+++ b/src/p_exe.cpp
@@ -264,8 +264,7 @@ void PackExe::pack(OutputFile *fo)
     fi->seek(ih.headsize16*16,SEEK_SET);
     fi->readx(ibuf,imagesize);
 
-    if (find_le32(ibuf, UPX_MIN(imagesize, 127u), UPX_MAGIC_LE32) >= 0)
-        throwAlreadyPacked();
+    checkAlreadyPacked(ibuf, UPX_MIN(imagesize, 127u));
 
     // relocations
     has_9a = false;
diff --git a/src/p_sys.cpp b/src/p_sys.cpp
index 14ea1383..77308432 100644
--- a/src/p_sys.cpp
+++ b/src/p_sys.cpp
@@ -45,13 +45,12 @@ bool PackSys::canPack()
 {
     unsigned char buf[128];
 
-    fi->readx(buf,128);
+    fi->readx(buf, sizeof(buf));
     if (memcmp (buf,"\xff\xff\xff\xff",4) != 0)
         return false;
     if (!fn_has_ext(fi->getName(),"sys"))
         return false;
-    if (find_le32(buf,128,UPX_MAGIC_LE32) >= 0)
-        throwAlreadyPacked();
+    checkAlreadyPacked(buf, sizeof(buf));
     if (file_size < 1024)
         throwCantPack("file is too small");
     if (file_size > 0x10000)
diff --git a/src/p_tos.cpp b/src/p_tos.cpp
index 67335327..2732b618 100644
--- a/src/p_tos.cpp
+++ b/src/p_tos.cpp
@@ -295,9 +295,8 @@ bool PackTos::canPack()
         return false;
 
     unsigned char buf[512];
-    fi->readx(buf,sizeof(buf));
-    if (find_le32(buf,sizeof(buf),UPX_MAGIC_LE32) >= 0)
-        throwAlreadyPacked();
+    fi->readx(buf, sizeof(buf));
+    checkAlreadyPacked(buf, sizeof(buf));
 
     if (!checkFileHeader())
         throwCantPack("unsupported header flags");
diff --git a/src/p_unix.cpp b/src/p_unix.cpp
index b8617db2..8e84b758 100644
--- a/src/p_unix.cpp
+++ b/src/p_unix.cpp
@@ -68,9 +68,8 @@ bool PackUnix::canPack()
     // info: currently the header is 36 (32+4) bytes before EOF
     unsigned char buf[256];
     fi->seek(-(long)sizeof(buf), SEEK_END);
-    fi->readx(buf,sizeof(buf));
-    if (find_le32(buf,sizeof(buf),UPX_MAGIC_LE32) >= 0)  // note: always le32
-        throwAlreadyPacked();
+    fi->readx(buf, sizeof(buf));
+    checkAlreadyPacked(buf, sizeof(buf));
 
     return true;
 }
diff --git a/src/p_vmlinz.cpp b/src/p_vmlinz.cpp
index 181c73df..63632bc3 100644
--- a/src/p_vmlinz.cpp
+++ b/src/p_vmlinz.cpp
@@ -123,8 +123,7 @@ int PackVmlinuzI386::uncompressKernel()
     fi->seek(0, SEEK_SET);
     fi->readx(obuf, file_size);
 
-    if (find_le32(obuf + setup_size, UPX_MIN(file_size - setup_size, 1024), UPX_MAGIC_LE32) >= 0)
-        throwAlreadyPacked();
+    checkAlreadyPacked(obuf + setup_size, UPX_MIN(file_size - setup_size, 1024));
 
     // estimate gzip-uncompressed kernel size & alloc buffer
     ibuf.alloc((file_size - setup_size) * 3);
diff --git a/src/packer.cpp b/src/packer.cpp
index a9f0ff5f..66558416 100644
--- a/src/packer.cpp
+++ b/src/packer.cpp
@@ -643,6 +643,27 @@ bool Packer::readPackHeader(int len)
 }
 
 
+void Packer::checkAlreadyPacked(void *b, int blen)
+{
+    int boff = find_le32(b, blen, UPX_MAGIC_LE32);
+    if (boff < 0)
+        return;
+
+    // FIXME: could add some more checks to verify that this
+    //   is a real PackHeader, e.g.
+    //
+    //PackHeader tmp;
+    //tmp.magic = UPX_MAGIC_LE32;
+    //if (!tmp.fillPackHeader((unsigned char *)b + boff, blen - boff))
+    //    return;
+    //
+    // This also would require that the buffer in `b' holds
+    // the full PackHeader, and not only the magic.
+
+    throwAlreadyPacked();
+}
+
+
 /*************************************************************************
 // patch util for loader
 **************************************************************************/
diff --git a/src/packer.h b/src/packer.h
index 0d475609..d8b94e58 100644
--- a/src/packer.h
+++ b/src/packer.h
@@ -182,6 +182,7 @@ protected:
     virtual int patchPackHeader(void *b, int blen);
     virtual bool getPackHeader(void *b, int blen);
     virtual bool readPackHeader(int len);
+    virtual void checkAlreadyPacked(void *b, int blen);
 
     // filter handling
     virtual bool isValidFilter(int filter_id) const;