hush: fix a corner case in "case" stmt, ctx_dsemicolon is in fact unused

function                                             old     new   delta
parse_stream                                        2446    2476     +30
done_word                                            797     800      +3
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 33/0)               Total: 33 bytes

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

5 files changed, 55 insertions, 53 deletions

diff --git a/shell/hush.c b/shell/hush.c
index b32d903ae..9ec813df2 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -748,9 +748,6 @@ struct parse_context {
         smallint is_assignment; /* 0:maybe, 1:yes, 2:no, 3:keyword */
 #if HAS_KEYWORDS
         smallint ctx_res_w;
-#if ENABLE_HUSH_CASE
-        smallint ctx_dsemicolon; /* ";;" seen */
-#endif
         /* bitmask of FLAG_xxx, for figuring out valid reserved words */
         int old_flag;
         /* group we are enclosed in:
@@ -4170,7 +4167,7 @@ static const struct reserved_combo* reserved_word(struct parse_context *ctx)
 {
 # if ENABLE_HUSH_CASE
         static const struct reserved_combo reserved_match = {
-                "", RES_MATCH, NOT_ASSIGNMENT , FLAG_MATCH | FLAG_ESAC
+                "", RES_MATCH, NOT_ASSIGNMENT, FLAG_MATCH | FLAG_ESAC
         };
 # endif
         const struct reserved_combo *r;
@@ -4266,7 +4263,7 @@ static const struct reserved_combo* reserved_word(struct parse_context *ctx)
  * Look at it and update current command:
  * update current command's argv/cmd_type/etc, fill in redirect name and type,
  * check reserved-ness and assignment-ness, etc...
- * Normal return is 0. Syntax errors return 1.
+ * Normal return is 0. Syntax errors print error message and return 1.
  * Note: on return, word is reset, but not o_free'd!
  */
 static int done_word(struct parse_context *ctx)
@@ -4324,15 +4321,16 @@ static int done_word(struct parse_context *ctx)
 
 #if HAS_KEYWORDS
 # if ENABLE_HUSH_CASE
-
-        if (ctx->ctx_dsemicolon
+        if (ctx->ctx_res_w == RES_MATCH
          && (ctx->word.has_quoted_part
             || strcmp(ctx->word.data, "esac") != 0
             )
-        ) { /* ";; WORD" but not "... PATTERN) CMD;; esac" */
-                /* already done when ctx_dsemicolon was set to 1: */
-                /* ctx->ctx_res_w = RES_MATCH; */
-                ctx->ctx_dsemicolon = 0;
+        ) { /* ";; WORD" but not ";; esac" */
+                /* Do not match WORD as keyword:
+                 * the WORD is a case match, can be keyword-like:
+                 *  if) echo got_if;;
+                 * is allowed.
+                 */
         } else
 # endif
 # if defined(CMD_TEST2_SINGLEWORD_NOGLOB)
@@ -4345,13 +4343,13 @@ static int done_word(struct parse_context *ctx)
         } else
 # endif
         if (!command->argv      /* if it's the first word of command... */
-         && !command->redirects /* no redirects yet... disallows: </dev/null ! true; echo $? */
+         && !command->redirects /* no redirects yet... disallows: </dev/null if true; then... */
 # if ENABLE_HUSH_LOOPS
          && ctx->ctx_res_w != RES_FOR /* not after FOR or IN */
          && ctx->ctx_res_w != RES_IN
 # endif
 # if ENABLE_HUSH_CASE
-         && ctx->ctx_res_w != RES_CASE /* not after CASE */
+         && ctx->ctx_res_w != RES_CASE  /* not after CASE */
 # endif
         ) {
                 const struct reserved_combo *reserved;
@@ -5648,7 +5646,7 @@ static struct pipe *parse_stream(char **pstring,
                         if (ch == EOF) {
                                 /* Testcase: eval 'echo Ok\' */
                                 /* bash-4.3.43 was removing backslash,
-                                 * but 4.4.19 retains it, most other shells too
+                                 * but 4.4.19 retains it, most other shells retain too
                                  */
                                 break;
                         }
@@ -5749,9 +5747,8 @@ static struct pipe *parse_stream(char **pstring,
                         }
                         /* ch == last eaten whitespace char */
 #endif
-                        if (done_word(&ctx)) {
+                        if (done_word(&ctx))
                                 goto parse_error_exitcode1;
-                        }
                         if (ch == '\n') {
                                 /* Is this a case when newline is simply ignored?
                                  * Some examples:
@@ -5784,10 +5781,10 @@ static struct pipe *parse_stream(char **pstring,
                                         if (pi->num_cmds != 0       /* check #1 */
                                          && pi->followup != PIPE_BG /* check #2 */
                                         ) {
-                                                continue;
+                                                continue; /* ignore newline */
                                         }
                                 }
-                                /* Treat newline as a command separator. */
+                                /* Treat newline as a command separator */
                                 done_pipe(&ctx, PIPE_SEQ);
                                 debug_printf_heredoc("heredoc_cnt:%d\n", heredoc_cnt);
                                 if (heredoc_cnt) {
@@ -5805,11 +5802,11 @@ static struct pipe *parse_stream(char **pstring,
 
                 /* "cmd}" or "cmd }..." without semicolon or &:
                  * } is an ordinary char in this case, even inside { cmd; }
-                 * Pathological example: { ""}; } should exec "}" cmd
+                 * Pathological example: { ""}; } should run "}" command.
                  */
                 if (ch == '}') {
-                        if (ctx.word.length != 0 /* word} */
-                         || ctx.word.has_quoted_part    /* ""} */
+                        if (ctx.word.length != 0     /* word} */
+                         || ctx.word.has_quoted_part /* ""} */
                         ) {
                                 goto ordinary_char;
                         }
@@ -5842,9 +5839,8 @@ static struct pipe *parse_stream(char **pstring,
                     )
 #endif
                 ) {
-                        if (done_word(&ctx)) {
+                        if (done_word(&ctx))
                                 goto parse_error_exitcode1;
-                        }
                         if (done_pipe(&ctx, PIPE_SEQ)) {
                                 /* Testcase: sh -c 'date|;not_reached' */
                                 syntax_error_unterm_ch('|');
@@ -5889,9 +5885,8 @@ static struct pipe *parse_stream(char **pstring,
                 switch (ch) {
                 case '>':
                         redir_fd = redirect_opt_num(&ctx.word);
-                        if (done_word(&ctx)) {
+                        if (done_word(&ctx))
                                 goto parse_error_exitcode1;
-                        }
                         redir_style = REDIRECT_OVERWRITE;
                         if (next == '>') {
                                 redir_style = REDIRECT_APPEND;
@@ -5909,9 +5904,8 @@ static struct pipe *parse_stream(char **pstring,
                         continue; /* get next char */
                 case '<':
                         redir_fd = redirect_opt_num(&ctx.word);
-                        if (done_word(&ctx)) {
+                        if (done_word(&ctx))
                                 goto parse_error_exitcode1;
-                        }
                         redir_style = REDIRECT_INPUT;
                         if (next == '<') {
                                 redir_style = REDIRECT_HEREDOC;
@@ -5951,7 +5945,7 @@ static struct pipe *parse_stream(char **pstring,
                                         }
                                         ch = i_getch(input);
                                         if (ch == EOF)
-                                                break;
+                                                goto eof;
                                 }
                                 continue; /* get next char */
                         }
@@ -6026,27 +6020,17 @@ static struct pipe *parse_stream(char **pstring,
                 }
 #endif
                 case ';':
-#if ENABLE_HUSH_CASE
- case_semi:
-#endif
-                        if (done_word(&ctx)) {
+                        if (done_word(&ctx))
                                 goto parse_error_exitcode1;
-                        }
                         done_pipe(&ctx, PIPE_SEQ);
 #if ENABLE_HUSH_CASE
-                        /* Eat multiple semicolons, detect
-                         * whether it means something special */
-                        while (1) {
-                                ch = i_peek_and_eat_bkslash_nl(input);
-                                if (ch != ';')
-                                        break;
+                        if (ctx.ctx_res_w == RES_CASE_BODY
+                         && !is_blank /* is it really actual semicolon? */
+                         && i_peek_and_eat_bkslash_nl(input) == ';' /* and next char is ';' too? */
+                        ) {
                                 ch = i_getch(input);
                                 nommu_addchr(&ctx.as_string, ch);
-                                if (ctx.ctx_res_w == RES_CASE_BODY) {
-                                        ctx.ctx_dsemicolon = 1;
-                                        ctx.ctx_res_w = RES_MATCH;
-                                        break;
-                                }
+                                ctx.ctx_res_w = RES_MATCH; /* "we are in PATTERN)" */
                         }
 #endif
  new_cmd:
@@ -6056,9 +6040,8 @@ static struct pipe *parse_stream(char **pstring,
                         debug_printf_parse("ctx.is_assignment='%s'\n", assignment_flag[ctx.is_assignment]);
                         continue; /* get next char */
                 case '&':
-                        if (done_word(&ctx)) {
+                        if (done_word(&ctx))
                                 goto parse_error_exitcode1;
-                        }
                         if (ctx.pipe->num_cmds == 0 && IS_NULL_CMD(ctx.command)) {
                                 /* Testcase: sh -c '&& date' */
                                 /* Testcase: sh -c '&' */
@@ -6082,9 +6065,8 @@ static struct pipe *parse_stream(char **pstring,
                         }
                         goto new_cmd;
                 case '|':
-                        if (done_word(&ctx)) {
+                        if (done_word(&ctx))
                                 goto parse_error_exitcode1;
-                        }
 #if ENABLE_HUSH_CASE
                         if (ctx.ctx_res_w == RES_MATCH)
                                 break; /* we are in case's "word | word)" */
@@ -6135,8 +6117,12 @@ static struct pipe *parse_stream(char **pstring,
                 }
                 case ')':
 #if ENABLE_HUSH_CASE
-                        if (ctx.ctx_res_w == RES_MATCH)
-                                goto case_semi;
+                        if (ctx.ctx_res_w == RES_MATCH) {
+                                if (done_word(&ctx))
+                                        goto parse_error_exitcode1;
+                                done_pipe(&ctx, PIPE_SEQ);
+                                goto new_cmd;
+                        }
 #endif
                 case '}':
                         /* proper use of this character is caught by end_trigger:
@@ -6150,7 +6136,7 @@ static struct pipe *parse_stream(char **pstring,
                                 bb_error_msg_and_die("BUG: unexpected %c", ch);
                 }
         } /* while (1) */
-
+ eof:
         /* Reached EOF */
         if (heredoc_cnt) {
                 syntax_error_unterm_str("here document");
@@ -6165,9 +6151,8 @@ static struct pipe *parse_stream(char **pstring,
                 goto parse_error_exitcode1;
         }
 
-        if (done_word(&ctx)) {
+        if (done_word(&ctx))
                 goto parse_error_exitcode1;
-        }
         o_free_and_set_NULL(&ctx.word);
         if (done_pipe(&ctx, PIPE_SEQ)) {
                 /* Testcase: sh -c 'date |' */
diff --git a/shell/hush_test/hush-misc/case2.right b/shell/hush_test/hush-misc/case2.right
new file mode 100644
index 000000000..4780199de
--- /dev/null
+++ b/shell/hush_test/hush-misc/case2.right
@@ -0,0 +1 @@
+hush: syntax error: unexpected )
diff --git a/shell/hush_test/hush-misc/case2.tests b/shell/hush_test/hush-misc/case2.tests
new file mode 100755
index 000000000..b9475392e
--- /dev/null
+++ b/shell/hush_test/hush-misc/case2.tests
@@ -0,0 +1,6 @@
+# had a parser bug which incorrectly detected ";;"
+case w in
+a);
+b);;
+esac
+echo Should not be reached
diff --git a/shell/hush_test/hush-misc/case3.right b/shell/hush_test/hush-misc/case3.right
new file mode 100644
index 000000000..02a29ccbc
--- /dev/null
+++ b/shell/hush_test/hush-misc/case3.right
@@ -0,0 +1,2 @@
+Keyword-like word may be in pattern
+Ok:0
diff --git a/shell/hush_test/hush-misc/case3.tests b/shell/hush_test/hush-misc/case3.tests
new file mode 100755
index 000000000..63b9dfd99
--- /dev/null
+++ b/shell/hush_test/hush-misc/case3.tests
@@ -0,0 +1,8 @@
+if=if
+case if in
+if) echo "Keyword-like word may be in pattern";;
+fi) echo "Not reached";;
+# esac) echo "Not reached";; # not accepted by bash 5.2.15
+do) echo "Not reached"
+esac
+echo Ok:$?