From e0596715dcf57cd431394d923d63dfe5aaf49749 Mon Sep 17 00:00:00 2001
From: =?utf8?q?P=C3=A1draig=20Brady?= <P@draigBrady.com>
Date: Tue, 2 Jan 2018 15:17:32 +0000
Subject: [PATCH] zstd: fix crash when not overwriting existing files

This fixes the following crash:
  $ touch exists
  $ programs/zstd -r examples/ -o exists
  zstd: exists already exists; not overwritten
  Segmentation fault (core dumped)

* programs/fileio.c (FIO_compressMultipleFilenames):
Handle the case where we're not overwriting the destination.

Reported at https://bugzilla.redhat.com/1530049
---
 programs/fileio.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/programs/fileio.c b/programs/fileio.c
index b57ce14d2..f9c9087ba 100644
--- a/programs/fileio.c
+++ b/programs/fileio.c
@@ -951,10 +951,14 @@ int FIO_compressMultipleFilenames(const char** inFileNamesTable, unsigned nbFile
     if (outFileName != NULL) {
         unsigned u;
         ress.dstFile = FIO_openDstFile(outFileName);
-        for (u=0; u<nbFiles; u++)
-            missed_files += FIO_compressFilename_srcFile(ress, outFileName, inFileNamesTable[u], compressionLevel);
-        if (fclose(ress.dstFile))
-            EXM_THROW(29, "Write error : cannot properly close stdout");
+        if (ress.dstFile==NULL) {  /* could not open outFileName */
+            missed_files = nbFiles;
+        } else {
+            for (u=0; u<nbFiles; u++)
+                missed_files += FIO_compressFilename_srcFile(ress, outFileName, inFileNamesTable[u], compressionLevel);
+            if (fclose(ress.dstFile))
+                EXM_THROW(29, "Write error : cannot properly close stdout");
+        }
     } else {
         unsigned u;
         for (u=0; u<nbFiles; u++) {
-- 
2.47.2