hush: allow nested negation "! ! ! CMD" - bash 5.2.15 allows it

Also, deindent "ch == EOF" code branch in parse_stream()

function                                             old     new   delta
done_word                                            799     797      -2
parse_stream                                        2453    2446      -7
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-9)               Total: -9 bytes

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

3 files changed, 71 insertions, 73 deletions

diff --git a/shell/hush.c b/shell/hush.c
index bca27e038..b32d903ae 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -4190,12 +4190,12 @@ static const struct reserved_combo* reserved_word(struct parse_context *ctx)
 # endif
         if (r->flag == 0) { /* '!' */
                 if (ctx->pipe->cmds != ctx->command /* bash disallows: nice | ! cat */
-                 || ctx->pipe->pi_inverted          /* bash disallows: ! ! true */
+                /* || ctx->pipe->pi_inverted - bash used to disallow "! ! true" bash 5.2.15 allows it */
                 ) {
                         syntax_error_unexpected_ch('!');
                         ctx->ctx_res_w = RES_SNTX;
                 }
-                ctx->pipe->pi_inverted = 1;
+                ctx->pipe->pi_inverted = 1 - ctx->pipe->pi_inverted;
                 return r;
         }
         if (r->flag & FLAG_START) {
@@ -5588,6 +5588,7 @@ static struct pipe *parse_stream(char **pstring,
                 struct in_str *input,
                 int end_trigger)
 {
+        struct pipe *pi;
         struct parse_context ctx;
         int heredoc_cnt;
 
@@ -5622,64 +5623,8 @@ static struct pipe *parse_stream(char **pstring,
                 ch = i_getch(input);
                 debug_printf_parse(": ch:%c (%d) globprotect:%d\n",
                                 ch, ch, !!(ctx.word.o_expflags & EXP_FLAG_GLOBPROTECT_CHARS));
-                if (ch == EOF) {
-                        struct pipe *pi;
-
-                        if (heredoc_cnt) {
-                                syntax_error_unterm_str("here document");
-                                goto parse_error_exitcode1;
-                        }
-                        if (end_trigger == ')') {
-                                syntax_error_unterm_ch('(');
-                                goto parse_error_exitcode1;
-                        }
-                        if (end_trigger == '}') {
-                                syntax_error_unterm_ch('{');
-                                goto parse_error_exitcode1;
-                        }
-
-                        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 |' */
-                                syntax_error_unterm_ch('|');
-                                goto parse_error_exitcode1;
-                        }
-// TODO: catch 'date &&<whitespace><EOF>' and 'date ||<whitespace><EOF>' too
-
-                        /* Do we sit inside of any if's, loops or case's? */
-                        if (HAS_KEYWORDS
-                        IF_HAS_KEYWORDS(&& (ctx.ctx_res_w != RES_NONE || ctx.old_flag != 0))
-                        ) {
-                                syntax_error_unterm_str("compound statement");
-                                goto parse_error_exitcode1;
-                        }
-
-                        pi = ctx.list_head;
-                        /* If we got nothing... */
-                        if (pi->num_cmds == 0
-                        IF_HAS_KEYWORDS(&& pi->res_word == RES_NONE)
-                        ) {
-                                free_pipe_list(pi);
-                                pi = NULL;
-                        }
-#if !BB_MMU
-                        debug_printf_parse("as_string1 '%s'\n", ctx.as_string.data);
-                        if (pstring)
-                                *pstring = ctx.as_string.data;
-                        else
-                                o_free(&ctx.as_string);
-#endif
-                        // heredoc_cnt must be 0 here anyway
-                        //if (heredoc_cnt_ptr)
-                        //      *heredoc_cnt_ptr = heredoc_cnt;
-                        debug_leave();
-                        debug_printf_heredoc("parse_stream return heredoc_cnt:%d\n", heredoc_cnt);
-                        debug_printf_parse("parse_stream return %p: EOF\n", pi);
-                        return pi;
-                }
+                if (ch == EOF)
+                        break;
 
                 /* Handle "'" and "\" first, as they won't play nice with
                  * i_peek_and_eat_bkslash_nl() anyway:
@@ -5705,7 +5650,7 @@ static struct pipe *parse_stream(char **pstring,
                                 /* bash-4.3.43 was removing backslash,
                                  * but 4.4.19 retains it, most other shells too
                                  */
-                                continue; /* get next char */
+                                break;
                         }
                         /* Example: echo Hello \2>file
                          * we need to know that word 2 is quoted
@@ -5719,7 +5664,7 @@ static struct pipe *parse_stream(char **pstring,
                 if (ch == '\'') {
                         ctx.word.has_quoted_part = 1;
                         next = i_getch(input);
-                        if (next == '\'' && !ctx.pending_redirect)
+                        if (next == '\'' && !ctx.pending_redirect/*why?*/)
                                 goto insert_empty_quoted_str_marker;
 
                         ch = next;
@@ -5835,7 +5780,7 @@ static struct pipe *parse_stream(char **pstring,
                                          * a "cmd1 && <nl> cmd2 &" construct,
                                          * cmd1 may need to run in BG).
                                          */
-                                        struct pipe *pi = ctx.list_head;
+                                        pi = ctx.list_head;
                                         if (pi->num_cmds != 0       /* check #1 */
                                          && pi->followup != PIPE_BG /* check #2 */
                                         ) {
@@ -6206,12 +6151,66 @@ static struct pipe *parse_stream(char **pstring,
                 }
         } /* while (1) */
 
+        /* Reached EOF */
+        if (heredoc_cnt) {
+                syntax_error_unterm_str("here document");
+                goto parse_error_exitcode1;
+        }
+        if (end_trigger == ')') {
+                syntax_error_unterm_ch('(');
+                goto parse_error_exitcode1;
+        }
+        if (end_trigger == '}') {
+                syntax_error_unterm_ch('{');
+                goto parse_error_exitcode1;
+        }
+
+        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 |' */
+                syntax_error_unterm_ch('|');
+                goto parse_error_exitcode1;
+        }
+// TODO: catch 'date &&<whitespace><EOF>' and 'date ||<whitespace><EOF>' too
+
+#if HAS_KEYWORDS
+        /* Do we sit inside of any if's, loops or case's? */
+        if (ctx.ctx_res_w != RES_NONE || ctx.old_flag != 0) {
+                syntax_error_unterm_str("compound statement");
+                goto parse_error_exitcode1;
+        }
+#endif
+        pi = ctx.list_head;
+        /* If we got nothing... */
+        if (pi->num_cmds == 0
+        IF_HAS_KEYWORDS(&& pi->res_word == RES_NONE)
+        ) {
+                free_pipe_list(pi);
+                pi = NULL;
+        }
+#if !BB_MMU
+        debug_printf_parse("as_string1 '%s'\n", ctx.as_string.data);
+        if (pstring)
+                *pstring = ctx.as_string.data;
+        else
+                o_free(&ctx.as_string);
+#endif
+        // heredoc_cnt must be 0 here anyway
+        //if (heredoc_cnt_ptr)
+        //      *heredoc_cnt_ptr = heredoc_cnt;
+        debug_leave();
+        debug_printf_heredoc("parse_stream return heredoc_cnt:%d\n", heredoc_cnt);
+        debug_printf_parse("parse_stream return %p: EOF\n", pi);
+        return pi;
+
  parse_error_exitcode1:
         G.last_exitcode = 1;
  parse_error:
         {
-                struct parse_context *pctx;
-                IF_HAS_KEYWORDS(struct parse_context *p2;)
+                struct parse_context *pctx IF_HAS_KEYWORDS(, *p2;);
 
                 /* Clean up allocated tree.
                  * Sample for finding leaks on syntax error recovery path.
@@ -6226,8 +6225,7 @@ static struct pipe *parse_stream(char **pstring,
                         /* Update pipe/command counts,
                          * otherwise freeing may miss some */
                         done_pipe(pctx, PIPE_SEQ);
-                        debug_printf_clean("freeing list %p from ctx %p\n",
-                                        pctx->list_head, pctx);
+                        debug_printf_clean("freeing list %p from ctx %p\n", pctx->list_head, pctx);
                         debug_print_tree(pctx->list_head, 0);
                         free_pipe_list(pctx->list_head);
                         debug_printf_clean("freed list %p\n", pctx->list_head);
@@ -6235,9 +6233,8 @@ static struct pipe *parse_stream(char **pstring,
                         o_free(&pctx->as_string);
 #endif
                         IF_HAS_KEYWORDS(p2 = pctx->stack;)
-                        if (pctx != &ctx) {
+                        if (pctx != &ctx)
                                 free(pctx);
-                        }
                         IF_HAS_KEYWORDS(pctx = p2;)
                 } while (HAS_KEYWORDS && pctx);
 
diff --git a/shell/hush_test/hush-misc/syntax_err_negate.right b/shell/hush_test/hush-misc/syntax_err_negate.right
index 0b8d211c7..39db799ea 100644
--- a/shell/hush_test/hush-misc/syntax_err_negate.right
+++ b/shell/hush_test/hush-misc/syntax_err_negate.right
@@ -1,2 +1,2 @@
-bash 3.2 fails this
-hush: syntax error: unexpected !
+0:0
+1:1
diff --git a/shell/hush_test/hush-misc/syntax_err_negate.tests b/shell/hush_test/hush-misc/syntax_err_negate.tests
index d61b1b09f..64f0f8a75 100755
--- a/shell/hush_test/hush-misc/syntax_err_negate.tests
+++ b/shell/hush_test/hush-misc/syntax_err_negate.tests
@@ -1,2 +1,3 @@
-echo bash 3.2 fails this
-! ! true
+# bash 3.2 fails this, 5.2.15 allows
+! ! true; echo 0:$?
+! ! ! true; echo 1:$?