Fail gracefully when multiple inputs are Standard Input

git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@1493 9d0c8265-081b-0410-96cb-a4ca84ce46f8

1 files changed, 10 insertions, 1 deletions

diff --git a/editor/pnmcat.c b/editor/pnmcat.c
index 8e29f52a..6d970c8f 100644
--- a/editor/pnmcat.c
+++ b/editor/pnmcat.c
@@ -16,6 +16,7 @@
 #include "mallocvar.h"
 #include "shhopt.h"
 #include "bitarith.h"
+#include "nstring.h"
 #include "pnm.h"
 
 #define LEFTBITS pm_byteLeftBits
@@ -153,12 +154,20 @@ parseCommandLine(int argc, const char ** const argv,
         cmdlineP->nfiles = 1;
     } else {
         unsigned int i;
+        unsigned int stdinCt;
+            /* Number of input files user specified as Standard Input */
 
         MALLOCARRAY_NOFAIL(cmdlineP->inputFilespec, argc-1);
 
-        for (i = 0; i < argc-1; ++i)
+        for (i = 0, stdinCt = 0; i < argc-1; ++i) {
             cmdlineP->inputFilespec[i] = argv[1+i];
+            if (streq(argv[1+i], "-"))
+                ++stdinCt;
+        }
         cmdlineP->nfiles = argc-1;
+        if (stdinCt > 1)
+            pm_error("At most one input image can come from Standard Input.  "
+                     "You specified %u", stdinCt);
     }
 }