bc: fix interactive read()

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

1 files changed, 26 insertions, 25 deletions

diff --git a/miscutils/bc.c b/miscutils/bc.c
index 8b44d4425..79f981eaf 100644
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -6753,6 +6753,7 @@ static BC_STATUS zbc_vm_process(const char *text)
         s = zbc_parse_text_init(&G.prs, text); // does the first zbc_lex_next()
         if (s) RETURN_STATUS(s);
 
+ IF_BC(check_eof:)
         while (G.prs.l.lex != XC_LEX_EOF) {
                 BcInstPtr *ip;
                 BcFunc *f;
@@ -6760,34 +6761,34 @@ static BC_STATUS zbc_vm_process(const char *text)
                 dbg_lex("%s:%d G.prs.l.lex:%d, parsing...", __func__, __LINE__, G.prs.l.lex);
                 if (IS_BC) {
 #if ENABLE_BC
+                        if (G.prs.l.lex == BC_LEX_SCOLON
+                         || G.prs.l.lex == XC_LEX_NLINE
+                        ) {
+                                s = zbc_lex_next(&G.prs.l);
+                                if (s) goto err;
+                                goto check_eof;
+                        }
+
                         s = zbc_parse_stmt_or_funcdef(&G.prs);
                         if (s) goto err;
 
-                        // Check that next token is not bogus, and skip over
-                        // stmt delimiter(s) - newlines and semicolons
-                        s = 1; // s == 1 on first iteration only
-                        for (;;) {
-                                if (G.prs.l.lex == XC_LEX_EOF)
-                                        goto execute; // this goto avoids resetting 's' to zero
-                                if (G.prs.l.lex != BC_LEX_SCOLON
-                                 && G.prs.l.lex != XC_LEX_NLINE
-                                ) {
-                                        const char *err_at;
-                                        // Not newline and not semicolon
-                                        if (s == 0) // saw at least one NL/semicolon before it?
-                                                break; // yes, good
-//TODO: commolalize for other parse errors:
-                                        err_at = G.prs.l.lex_next_at ? G.prs.l.lex_next_at : "UNKNOWN";
-                                        bc_error_fmt("bad statement terminator at '%.*s'",
-                                                (int)(strchrnul(err_at, '\n') - err_at),
-                                                err_at
-                                        );
-                                        goto err;
-                                }
-                                // NL or semicolon: skip it, set s = 0, repeat
-                                s = zbc_lex_next(&G.prs.l);
-                                if (s) goto err;
+                        // Check that next token is a correct stmt delimiter -
+                        // disallows "print 1 print 2" and such.
+                        if (G.prs.l.lex != BC_LEX_SCOLON
+                         && G.prs.l.lex != XC_LEX_NLINE
+                         && G.prs.l.lex != XC_LEX_EOF
+                        ) {
+                                const char *err_at;
+//TODO: commonalize for other parse errors:
+                                err_at = G.prs.l.lex_next_at ? G.prs.l.lex_next_at : "UNKNOWN";
+                                bc_error_fmt("bad statement terminator at '%.*s'",
+                                        (int)(strchrnul(err_at, '\n') - err_at),
+                                        err_at
+                                );
+                                goto err;
                         }
+                        // The above logic is fragile. Check these examples:
+                        // - interative read() still works
 #endif
                 } else {
 #if ENABLE_DC
@@ -6807,7 +6808,7 @@ static BC_STATUS zbc_vm_process(const char *text)
                         bc_parse_reset(&G.prs); // includes bc_program_reset()
                         RETURN_STATUS(BC_STATUS_FAILURE);
                 }
- IF_BC(execute:)
+
                 dbg_lex("%s:%d executing...", __func__, __LINE__);
                 s = zbc_program_exec();
                 if (s) {