sed: fix " echo /usr/lib | sed 's,\(^/\|\)[^/][^/]*,..,g' " bug

function                                             old     new   delta
process_files                                       2102    2091     -11

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

2 files changed, 33 insertions, 19 deletions

diff --git a/editors/sed.c b/editors/sed.c
index de18996b8..8b4f60a8c 100644
--- a/editors/sed.c
+++ b/editors/sed.c
@@ -589,7 +589,7 @@ static void pipe_putc(char c)
 
 static void do_subst_w_backrefs(char *line, char *replace)
 {
-        int i,j;
+        int i, j;
 
         /* go through the replacement string */
         for (i = 0; replace[i]; i++) {
@@ -624,23 +624,24 @@ static void do_subst_w_backrefs(char *line, char *replace)
         }
 }
 
-static int do_subst_command(sed_cmd_t *sed_cmd, char **line)
+static int do_subst_command(sed_cmd_t *sed_cmd, char **line_p)
 {
-        char *oldline = *line;
+        char *line = *line_p;
         int altered = 0;
         unsigned match_count = 0;
         regex_t *current_regex;
 
+        current_regex = sed_cmd->sub_match;
         /* Handle empty regex. */
-        if (sed_cmd->sub_match == NULL) {
+        if (!current_regex) {
                 current_regex = G.previous_regex_ptr;
                 if (!current_regex)
                         bb_error_msg_and_die("no previous regexp");
-        } else
-                G.previous_regex_ptr = current_regex = sed_cmd->sub_match;
+        }
+        G.previous_regex_ptr = current_regex;
 
         /* Find the first match */
-        if (REG_NOMATCH == regexec(current_regex, oldline, 10, G.regmatch, 0))
+        if (REG_NOMATCH == regexec(current_regex, line, 10, G.regmatch, 0))
                 return 0;
 
         /* Initialize temporary output buffer. */
@@ -657,7 +658,7 @@ static int do_subst_command(sed_cmd_t *sed_cmd, char **line)
                    The match_count check is so not to break
                    echo "hi" | busybox sed 's/^/!/g' */
                 if (!G.regmatch[0].rm_so && !G.regmatch[0].rm_eo && match_count) {
-                        pipe_putc(*oldline++);
+                        pipe_putc(*line++);
                         continue;
                 }
 
@@ -669,35 +670,41 @@ static int do_subst_command(sed_cmd_t *sed_cmd, char **line)
                  && (sed_cmd->which_match != match_count)
                 ) {
                         for (i = 0; i < G.regmatch[0].rm_eo; i++)
-                                pipe_putc(*oldline++);
+                                pipe_putc(*line++);
                         continue;
                 }
 
                 /* print everything before the match */
                 for (i = 0; i < G.regmatch[0].rm_so; i++)
-                        pipe_putc(oldline[i]);
+                        pipe_putc(line[i]);
 
                 /* then print the substitution string */
-                do_subst_w_backrefs(oldline, sed_cmd->string);
+                do_subst_w_backrefs(line, sed_cmd->string);
 
                 /* advance past the match */
-                oldline += G.regmatch[0].rm_eo;
+                line += G.regmatch[0].rm_eo;
                 /* flag that something has changed */
                 altered++;
 
                 /* if we're not doing this globally, get out now */
                 if (sed_cmd->which_match)
                         break;
-        } while (*oldline && (regexec(current_regex, oldline, 10, G.regmatch, 0) != REG_NOMATCH));
 
-        /* Copy rest of string into output pipeline */
+                if (*line == '\0')
+                        break;
+//maybe (G.regmatch[0].rm_eo ? REG_NOTBOL : 0) instead of unconditional REG_NOTBOL?
+        } while (regexec(current_regex, line, 10, G.regmatch, REG_NOTBOL) != REG_NOMATCH);
 
-        while (*oldline)
-                pipe_putc(*oldline++);
-        pipe_putc(0);
+        /* Copy rest of string into output pipeline */
+        while (1) {
+                char c = *line++;
+                pipe_putc(c);
+                if (c == '\0')
+                        break;
+        }
 
-        free(*line);
-        *line = G.pipeline.buf;
+        free(*line_p);
+        *line_p = G.pipeline.buf;
         return altered;
 }
 
diff --git a/testsuite/sed.tests b/testsuite/sed.tests
index a9d9ada31..696d980ef 100755
--- a/testsuite/sed.tests
+++ b/testsuite/sed.tests
@@ -241,4 +241,11 @@ testing "sed 2d;2,1p (gnu compat)" \
         "third\n" "" \
         "first\nsecond\nthird\nfourth\n"
 
+# Regex means: "match / at BOL or nothing, then one or more not-slashes".
+# The bug was that second slash in /usr/lib was treated as "at BOL" too.
+testing "sed beginning (^) matches only once" \
+        "sed 's,\(^/\|\)[^/][^/]*,>\0<,g'" \
+        ">/usr</>lib<\n" "" \
+        "/usr/lib\n"
+
 exit $FAILCOUNT