Patch from Matt Kraai <kraai@alumni.carnegiemellon.edu>:

GNU tr complains on the following:

$ tr a ''
tr: when not truncating set1, string2 must be non-empty

BusyBox tr does not complain:

$ tr a ''
a
^D
0

It should result in an error, not in some spurious output.  The attached
patch generates an error.

Matt

2 files changed, 8 insertions, 4 deletions

diff --git a/coreutils/tr.c b/coreutils/tr.c
index 48cdd47bd..5a8116db0 100644
--- a/coreutils/tr.c
+++ b/coreutils/tr.c
@@ -187,10 +187,12 @@ extern int tr_main(int argc, char **argv)
                 expand(argv[index++], input);
                 if (com_fl)
                         complement(input);
-                if (argv[index] != NULL)
+                if (argv[index] != NULL) {
+                        if (*argv[index] == '\0')
+                                fatalError("tr: STRING2 cannot be empty\n");
                         expand(argv[index], output);
-                if (argv[index] != NULL)
                         map(input, output);
+                }
                 for (ptr = input; *ptr; ptr++)
                         invec[*ptr] = TRUE;
                 for (ptr = output; *ptr; ptr++)
diff --git a/tr.c b/tr.c
index 48cdd47bd..5a8116db0 100644
--- a/tr.c
+++ b/tr.c
@@ -187,10 +187,12 @@ extern int tr_main(int argc, char **argv)
                 expand(argv[index++], input);
                 if (com_fl)
                         complement(input);
-                if (argv[index] != NULL)
+                if (argv[index] != NULL) {
+                        if (*argv[index] == '\0')
+                                fatalError("tr: STRING2 cannot be empty\n");
                         expand(argv[index], output);
-                if (argv[index] != NULL)
                         map(input, output);
+                }
                 for (ptr = input; *ptr; ptr++)
                         invec[*ptr] = TRUE;
                 for (ptr = output; *ptr; ptr++)