Minor improvement in wordsplit

* src/wordsplit.c (expvar): Gracefully handle NULL values in
ENV_KV environment.
* src/wordsplit.h: Fix typo in a comment.
* doc/wordsplit.3: Update.

3 files changed, 13 insertions, 7 deletions

diff --git a/doc/wordsplit.3 b/doc/wordsplit.3
index 067ea5e..a391b81 100644
--- a/doc/wordsplit.3
+++ b/doc/wordsplit.3
@@ -14,7 +14,7 @@
 .\" You should have received a copy of the GNU General Public License
 .\" along with Grecs.  If not, see <http://www.gnu.org/licenses/>.
 .\"
-.TH WORDSPLIT 3 "December 3, 2014" "GRECS" "Grecs User Reference"
+.TH WORDSPLIT 3 "February 20, 2018" "GRECS" "Grecs User Reference"
 .SH NAME
 wordsplit \- split string into words 
 .SH SYNOPSIS
@@ -181,7 +181,8 @@ elements in the array:
 .IR ws_env [ n ]
 containing the variable name, and
 .IR ws_env [ "n+1" ]
-containing its value.
+containing its value. If the latter is \fBNULL\fR, the corresponding
+variable is undefined.
 .PP
 More sophisticated variable tables can be implemented using 
 callback function.  The \fIws_getvar\fR member should be set to point
diff --git a/include/wordsplit.h b/include/wordsplit.h
index eed88bc..d8cd461 100644
--- a/include/wordsplit.h
+++ b/include/wordsplit.h
@@ -81,8 +81,8 @@ struct wordsplit
                      void *clos);
                             /* [Input] (!WRDSF_NOCMD) Returns in the memory
                                location pointed to by RET the expansion of
-                               the command CMD (LEN bytes nong).  If WRDSF_ARGV
-                               flag is set, ARGV contains CMD split out to
+                               the command CMD (LEN bytes long).  If WRDSO_ARGV
+                               option is set, ARGV contains CMD split out to
                                words.  Otherwise ARGV is NULL.
 
                                See ws_getvar for a discussion of possible
diff --git a/src/wordsplit.c b/src/wordsplit.c
index 4884a22..5cd8daa 100644
--- a/src/wordsplit.c
+++ b/src/wordsplit.c
@@ -1034,9 +1034,14 @@ expvar (struct wordsplit *wsp, const char *str, size_t len,
       rc = wordsplit_find_env (wsp, str, i, &vptr);
       if (rc == WRDSE_OK)
         {
-          value = strdup (vptr);
-          if (!value)
-            rc = WRDSE_NOSPACE;
+          if (vptr)
+            {
+              value = strdup (vptr);
+              if (!value)
+                rc = WRDSE_NOSPACE;
+            }
+          else
+            rc = WRDSE_UNDEF;
         }
       else if (wsp->ws_flags & WRDSF_GETVAR)
         rc = wsp->ws_getvar (&value, str, i, wsp->ws_closure);