ensure generation of valid EDSP error stanzas

The crude way of preparing a message to be a multiline value failed at
generation valid deb822 in case the error message ended with a new line
like the resolving errors from apt do. apt itself can parse these, but
other tools like grep-dctrl choke on it, so be nice and print valid.

Reported-By: Johannes 'josch' Schauer on IRC
(cherry picked from commit 0161280405fe5aa256dc9df6a56106dd3a1a6f38)

1 files changed, 6 insertions, 2 deletions

diff --git a/apt-pkg/edsp.cc b/apt-pkg/edsp.cc
index b80b9a456..a2520441b 100644
--- a/apt-pkg/edsp.cc
+++ b/apt-pkg/edsp.cc
@@ -931,14 +931,18 @@ bool EDSP::WriteProgress(unsigned short const percent, const char* const message
 }
 									/*}}}*/
 // EDSP::WriteError - format an error message to be send to file descriptor /*{{{*/
+static std::string formatMessage(std::string const &msg)
+{
+	return SubstVar(SubstVar(APT::String::Strip(msg), "\n\n", "\n.\n"), "\n", "\n ");
+}
 bool EDSP::WriteError(char const * const uuid, std::string const &message, FILE* output) {
 	fprintf(output, "Error: %s\n", uuid);
-	fprintf(output, "Message: %s\n\n", SubstVar(SubstVar(message, "\n\n", "\n.\n"), "\n", "\n ").c_str());
+	fprintf(output, "Message: %s\n\n", formatMessage(message).c_str());
 	return true;
 }
 bool EDSP::WriteError(char const * const uuid, std::string const &message, FileFd &output) {
 	return WriteOkay(output, "Error: ", uuid, "\n",
-	      "Message: ", SubstVar(SubstVar(message, "\n\n", "\n.\n"), "\n", "\n "),
+	      "Message: ", formatMessage(message),
 	      "\n\n");
 }
 									/*}}}*/