ensure lists/ files have correct permissions after apt-cdrom add

Its a bit unpredictable which permissons and owners we will encounter on
a CD-ROM (or a USB stick, as apt-cdrom is responsible for those too),
so we have to ensure in this codepath as well that everything is nicely
setup without waiting for a 'apt-get update' to fix up the (potential)
mess.

2 files changed, 31 insertions, 1 deletions

diff --git a/apt-pkg/contrib/fileutl.cc b/apt-pkg/contrib/fileutl.cc
index 47033eadf..afc243b7f 100644
--- a/apt-pkg/contrib/fileutl.cc
+++ b/apt-pkg/contrib/fileutl.cc
@@ -874,6 +874,25 @@ bool StartsWithGPGClearTextSignature(string const &FileName)
    return true;
 }
 									/*}}}*/
+// ChangeOwnerAndPermissionOfFile - set file attributes to requested values /*{{{*/
+bool ChangeOwnerAndPermissionOfFile(char const * const requester, char const * const file, char const * const user, char const * const group, mode_t const mode)
+{
+   if (strcmp(file, "/dev/null") == 0)
+      return true;
+   bool Res = true;
+   if (getuid() == 0 && strlen(user) != 0 && strlen(group) != 0) // if we aren't root, we can't chown, so don't try it
+   {
+      // ensure the file is owned by root and has good permissions
+      struct passwd const * const pw = getpwnam(user);
+      struct group const * const gr = getgrnam(group);
+      if (pw != NULL && gr != NULL && chown(file, pw->pw_uid, gr->gr_gid) != 0)
+	 Res &= _error->WarningE(requester, "chown to %s:%s of file %s failed", user, group, file);
+   }
+   if (chmod(file, mode) != 0)
+      Res &= _error->WarningE(requester, "chmod 0%o of file %s failed", mode, file);
+   return Res;
+}
+									/*}}}*/
 
 class FileFdPrivate {							/*{{{*/
 	public:
diff --git a/apt-pkg/contrib/fileutl.h b/apt-pkg/contrib/fileutl.h
index a64d6cb98..97cb05c56 100644
--- a/apt-pkg/contrib/fileutl.h
+++ b/apt-pkg/contrib/fileutl.h
@@ -195,10 +195,21 @@ pid_t ExecFork(std::set<int> keep_fds);
 void MergeKeepFdsFromConfiguration(std::set<int> &keep_fds);
 bool ExecWait(pid_t Pid,const char *Name,bool Reap = false);
 
-
 // check if the given file starts with a PGP cleartext signature
 bool StartsWithGPGClearTextSignature(std::string const &FileName);
 
+/** change file attributes to requested known good values
+ *
+ * The method skips the user:group setting if not root.
+ *
+ * @param requester is printed as functionname in error cases
+ * @param file is the file to be modified
+ * @param user is the (new) owner of the file, e.g. _apt
+ * @param group is the (new) group owning the file, e.g. root
+ * @param mode is the access mode of the file, e.g. 0644
+ */
+bool ChangeOwnerAndPermissionOfFile(char const * const requester, char const * const file, char const * const user, char const * const group, mode_t const mode);
+
 /**
  * \brief Drop privileges
  *