2 files changed, 25 insertions, 0 deletions
diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc
index 119cd1974..20d2a02f5 100644
--- a/apt-pkg/contrib/fileutl.cc
+++ b/apt-pkg/contrib/fileutl.cc
@@ -852,6 +852,26 @@ bool ExecWait(pid_t Pid,const char *Name,bool Reap)
 }
 									/*}}}*/
 
+// IsPgpClearTextSignature - Check if a file is Pgp/GPG clearsigned     /*{{{*/
+// ---------------------------------------------------------------------
+/* */
+bool IsPgpClearTextSignature(string const &FileName)
+{
+   static const char* SIGMSG = "-----BEGIN PGP SIGNED MESSAGE-----\n";
+   char buffer[sizeof(SIGMSG)];
+   FILE* gpg = fopen(FileName.c_str(), "r");
+   if (gpg == NULL)
+      return false;
+
+   char const * const test = fgets(buffer, sizeof(buffer), gpg);
+   fclose(gpg);
+   if (test == NULL || strcmp(buffer, SIGMSG) != 0)
+      return false;
+
+   return true;
+}
+
+
 // FileFd::Open - Open a file						/*{{{*/
 // ---------------------------------------------------------------------
 /* The most commonly used open mode combinations are given with Mode */
diff --git a/apt-pkg/contrib/fileutl.h b/apt-pkg/contrib/fileutl.h
index 426664d3a..1e16540f7 100644
--- a/apt-pkg/contrib/fileutl.h
+++ b/apt-pkg/contrib/fileutl.h
@@ -180,6 +180,9 @@ bool WaitFd(int Fd,bool write = false,unsigned long timeout = 0);
 pid_t ExecFork();
 bool ExecWait(pid_t Pid,const char *Name,bool Reap = false);
 
+// check if the given file starts with a PGP cleartext signature
+bool IsPgpClearTextSignature(std::string const &FileName);
+
 // File string manipulators
 std::string flNotDir(std::string File);
 std::string flNotFile(std::string File);
@@ -187,4 +190,6 @@ std::string flNoLink(std::string File);
 std::string flExtension(std::string File);
 std::string flCombine(std::string Dir,std::string File);
 
+
+
 #endif