bc: tighten up input NUL handling

function                                             old     new   delta
static.dc_lex_tokens                                   -      90     +90
bc_error_bad_character                                17      31     +14
static.dc_lex_regs                                     -      13     +13
bc_read_line                                         406     410      +4
bc_program_index                                      64      66      +2
dc_lex_regs                                           13       -     -13
zdc_parse_expr                                       671     656     -15
zbc_lex_next                                        2318    2230     -88
dc_lex_tokens                                         91       -     -91
------------------------------------------------------------------------------
(add/remove: 2/2 grow/shrink: 3/2 up/down: 123/-207)          Total: -84 bytes
   text	   data	    bss	    dec	    hex	filename
 981667	    485	   7296	 989448	  f1908	busybox_old
 981599	    485	   7296	 989380	  f18c4	busybox_unstripped

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

1 files changed, 64 insertions, 49 deletions

diff --git a/miscutils/bc.c b/miscutils/bc.c
index 1fb1b00b3..214ea44ab 100644
--- a/miscutils/bc.c
+++ b/miscutils/bc.c
@@ -806,45 +806,6 @@ enum {
 #endif // ENABLE_BC
 
 #if ENABLE_DC
-static const //BcLexType - should be this type, but narrower type saves size:
-uint8_t
-dc_lex_regs[] = {
-        BC_LEX_OP_REL_EQ, BC_LEX_OP_REL_LE, BC_LEX_OP_REL_GE, BC_LEX_OP_REL_NE,
-        BC_LEX_OP_REL_LT, BC_LEX_OP_REL_GT, BC_LEX_SCOLON, BC_LEX_COLON,
-        BC_LEX_ELSE, BC_LEX_LOAD, BC_LEX_LOAD_POP, BC_LEX_OP_ASSIGN,
-        BC_LEX_STORE_PUSH,
-};
-
-static const //BcLexType - should be this type
-uint8_t
-dc_lex_tokens[] = {
-        BC_LEX_OP_MODULUS, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_LPAREN,
-        BC_LEX_INVALID, BC_LEX_OP_MULTIPLY, BC_LEX_OP_PLUS, BC_LEX_INVALID,
-        BC_LEX_OP_MINUS, BC_LEX_INVALID, BC_LEX_OP_DIVIDE,
-        BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
-        BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
-        BC_LEX_INVALID, BC_LEX_INVALID,
-        BC_LEX_COLON, BC_LEX_SCOLON, BC_LEX_OP_REL_GT, BC_LEX_OP_REL_EQ,
-        BC_LEX_OP_REL_LT, BC_LEX_KEY_READ, BC_LEX_INVALID,
-        BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
-        BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_EQ_NO_REG, BC_LEX_INVALID,
-        BC_LEX_KEY_IBASE, BC_LEX_INVALID, BC_LEX_KEY_SCALE, BC_LEX_LOAD_POP,
-        BC_LEX_INVALID, BC_LEX_OP_BOOL_NOT, BC_LEX_KEY_OBASE, BC_LEX_PRINT_STREAM,
-        BC_LEX_NQUIT, BC_LEX_POP, BC_LEX_STORE_PUSH, BC_LEX_INVALID, BC_LEX_INVALID,
-        BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_SCALE_FACTOR, BC_LEX_INVALID,
-        BC_LEX_KEY_LENGTH, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
-        BC_LEX_OP_POWER, BC_LEX_NEG, BC_LEX_INVALID,
-        BC_LEX_ASCIIFY, BC_LEX_INVALID, BC_LEX_CLEAR_STACK, BC_LEX_DUPLICATE,
-        BC_LEX_ELSE, BC_LEX_PRINT_STACK, BC_LEX_INVALID, BC_LEX_INVALID,
-        BC_LEX_STORE_IBASE, BC_LEX_INVALID, BC_LEX_STORE_SCALE, BC_LEX_LOAD,
-        BC_LEX_INVALID, BC_LEX_PRINT_POP, BC_LEX_STORE_OBASE, BC_LEX_KEY_PRINT,
-        BC_LEX_KEY_QUIT, BC_LEX_SWAP, BC_LEX_OP_ASSIGN, BC_LEX_INVALID,
-        BC_LEX_INVALID, BC_LEX_KEY_SQRT, BC_LEX_INVALID, BC_LEX_EXECUTE,
-        BC_LEX_INVALID, BC_LEX_STACK_LEVEL,
-        BC_LEX_LBRACE, BC_LEX_OP_MODEXP, BC_LEX_INVALID, BC_LEX_OP_DIVMOD,
-        BC_LEX_INVALID
-};
-
 static const //BcInst - should be this type. Using signed narrow type since BC_INST_INVALID is -1
 int8_t
 dc_parse_insts[] = {
@@ -1063,6 +1024,8 @@ static ERRORFUNC int bc_error(const char *msg)
 }
 static ERRORFUNC int bc_error_bad_character(char c)
 {
+        if (!c)
+                IF_ERROR_RETURN_POSSIBLE(return) bc_error("NUL character");
         IF_ERROR_RETURN_POSSIBLE(return) bc_error_fmt("bad character '%c'", c);
 }
 static ERRORFUNC int bc_error_bad_expression(void)
@@ -1376,7 +1339,7 @@ static void bc_read_line(BcVec *vec, FILE *fp)
                                 goto intr;
                         }
 #endif
-                        c = fgetc(fp);
+                        do c = fgetc(fp); while (c == '\0');
                         if (c == EOF) {
                                 if (ferror(fp))
                                         bb_perror_msg_and_die("input error");
@@ -3125,11 +3088,11 @@ static BC_STATUS zbc_lex_token(BcLex *l)
 
         // This is the workhorse of the lexer.
         switch (c) {
-                case '\0': // probably never reached
-                        l->i--;
-                        l->t.t = BC_LEX_EOF;
-                        l->newline = true;
-                        break;
+//              case '\0': // probably never reached
+//                      l->i--;
+//                      l->t.t = BC_LEX_EOF;
+//                      l->newline = true;
+//                      break;
                 case '\n':
                         l->t.t = BC_LEX_NLINE;
                         l->newline = true;
@@ -3370,6 +3333,58 @@ static BC_STATUS zdc_lex_string(BcLex *l)
 
 static BC_STATUS zdc_lex_token(BcLex *l)
 {
+        static const //BcLexType - should be this type, but narrower type saves size:
+        uint8_t
+        dc_lex_regs[] = {
+                BC_LEX_OP_REL_EQ, BC_LEX_OP_REL_LE, BC_LEX_OP_REL_GE, BC_LEX_OP_REL_NE,
+                BC_LEX_OP_REL_LT, BC_LEX_OP_REL_GT, BC_LEX_SCOLON, BC_LEX_COLON,
+                BC_LEX_ELSE, BC_LEX_LOAD, BC_LEX_LOAD_POP, BC_LEX_OP_ASSIGN,
+                BC_LEX_STORE_PUSH,
+        };
+        static const //BcLexType - should be this type
+        uint8_t
+        dc_lex_tokens[] = {
+                /* %&'( */
+                BC_LEX_OP_MODULUS, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_LPAREN,
+                /* )*+, */
+                BC_LEX_INVALID, BC_LEX_OP_MULTIPLY, BC_LEX_OP_PLUS, BC_LEX_INVALID,
+                /* -./ */
+                BC_LEX_OP_MINUS, BC_LEX_INVALID, BC_LEX_OP_DIVIDE,
+                /* 0123456789 */
+                BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
+                BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
+                BC_LEX_INVALID, BC_LEX_INVALID,
+                /* :;<=>?@ */
+                BC_LEX_COLON, BC_LEX_SCOLON, BC_LEX_OP_REL_GT, BC_LEX_OP_REL_EQ,
+                BC_LEX_OP_REL_LT, BC_LEX_KEY_READ, BC_LEX_INVALID,
+                /* ABCDEFGH */
+                BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
+                BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_EQ_NO_REG, BC_LEX_INVALID,
+                /* IJKLMNOP */
+                BC_LEX_KEY_IBASE, BC_LEX_INVALID, BC_LEX_KEY_SCALE, BC_LEX_LOAD_POP,
+                BC_LEX_INVALID, BC_LEX_OP_BOOL_NOT, BC_LEX_KEY_OBASE, BC_LEX_PRINT_STREAM,
+                /* QRSTUVWXY */
+                BC_LEX_NQUIT, BC_LEX_POP, BC_LEX_STORE_PUSH, BC_LEX_INVALID, BC_LEX_INVALID,
+                BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_SCALE_FACTOR, BC_LEX_INVALID,
+                /* Z[\] */
+                BC_LEX_KEY_LENGTH, BC_LEX_INVALID, BC_LEX_INVALID, BC_LEX_INVALID,
+                /* ^_` */
+                BC_LEX_OP_POWER, BC_LEX_NEG, BC_LEX_INVALID,
+                /* abcdefgh */
+                BC_LEX_ASCIIFY, BC_LEX_INVALID, BC_LEX_CLEAR_STACK, BC_LEX_DUPLICATE,
+                BC_LEX_ELSE, BC_LEX_PRINT_STACK, BC_LEX_INVALID, BC_LEX_INVALID,
+                /* ijklmnop */
+                BC_LEX_STORE_IBASE, BC_LEX_INVALID, BC_LEX_STORE_SCALE, BC_LEX_LOAD,
+                BC_LEX_INVALID, BC_LEX_PRINT_POP, BC_LEX_STORE_OBASE, BC_LEX_KEY_PRINT,
+                /* qrstuvwx */
+                BC_LEX_KEY_QUIT, BC_LEX_SWAP, BC_LEX_OP_ASSIGN, BC_LEX_INVALID,
+                BC_LEX_INVALID, BC_LEX_KEY_SQRT, BC_LEX_INVALID, BC_LEX_EXECUTE,
+                /* yz */
+                BC_LEX_INVALID, BC_LEX_STACK_LEVEL,
+                /* {|}~ */
+                BC_LEX_LBRACE, BC_LEX_OP_MODEXP, BC_LEX_INVALID, BC_LEX_OP_DIVMOD,
+        };
+
         BcStatus s = BC_STATUS_SUCCESS;
         char c = l->buf[l->i++], c2;
         size_t i;
@@ -3380,16 +3395,16 @@ static BC_STATUS zdc_lex_token(BcLex *l)
         }
 
         if (c >= '%' && c <= '~'
-         && (l->t.t = dc_lex_tokens[(c - '%')]) != BC_LEX_INVALID
+         && (l->t.t = dc_lex_tokens[c - '%']) != BC_LEX_INVALID
         ) {
                 RETURN_STATUS(s);
         }
 
         // This is the workhorse of the lexer.
         switch (c) {
-                case '\0':
-                        l->t.t = BC_LEX_EOF;
-                        break;
+//              case '\0': // probably never reached
+//                      l->t.t = BC_LEX_EOF;
+//                      break;
                 case '\n':
                 case '\t':
                 case '\v':