sed: yet another fix on top of zero length match code

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 15 insertions, 6 deletions

diff --git a/editors/sed.c b/editors/sed.c
index 0fe82f337..652aaf573 100644
--- a/editors/sed.c
+++ b/editors/sed.c
@@ -768,8 +768,11 @@ static int do_subst_command(sed_cmd_t *sed_cmd, char **line_p)
                  * Second match is NOT replaced!
                  */
                 if (prev_match_empty || start != 0 || start != end) {
+                        //dbg("%d %d %d", prev_match_empty, start, end);
                         dbg("inserting replacement at %d in '%s'", start, line);
                         do_subst_w_backrefs(line, sed_cmd->string);
+                        /* Flag that something has changed */
+                        altered = 1;
                 } else {
                         dbg("NOT inserting replacement at %d in '%s'", start, line);
                 }
@@ -778,16 +781,18 @@ static int do_subst_command(sed_cmd_t *sed_cmd, char **line_p)
                  * copy verbatim one char after it before attempting more matches
                  */
                 prev_match_empty = (start == end);
-                if (prev_match_empty && line[end]) {
-                        pipe_putc(line[end]);
-                        end++;
+                if (prev_match_empty) {
+                        if (!line[end]) {
+                                tried_at_eol = 1;
+                        } else {
+                                pipe_putc(line[end]);
+                                end++;
+                        }
                 }
 
                 /* Advance past the match */
                 dbg("line += %d", end);
                 line += end;
-                /* Flag that something has changed */
-                altered = 1;
 
                 /* if we're not doing this globally, get out now */
                 if (sed_cmd->which_match != 0)
diff --git a/testsuite/sed.tests b/testsuite/sed.tests
index 12b36ae18..468565f47 100755
--- a/testsuite/sed.tests
+++ b/testsuite/sed.tests
@@ -302,10 +302,14 @@ testing "sed zero chars match/replace advances correctly 2" \
         "sed 's [^ .]* x g'" \
         "x x.x\n" "" " a.b\n"
 
-testing "sed zero chars match/replace logic must not falsely trigger here" \
+testing "sed zero chars match/replace logic must not falsely trigger here 1" \
         "sed 's/a/A/g'" \
         "_AAA1AA\n" "" "_aaa1aa\n"
 
+testing "sed zero chars match/replace logic must not falsely trigger here 2" \
+        "sed 's/ *$/_/g'" \
+        "qwerty_\n" "" "qwerty\n"
+
 # testing "description" "commands" "result" "infile" "stdin"
 
 exit $FAILCOUNT