shell/math: do not accept $((36#@))

function                                             old     new   delta
parse_with_base                                      170     174      +4
arith_apply                                          996     991      -5
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 4/-5)               Total: -1 bytes

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

1 files changed, 22 insertions, 16 deletions

diff --git a/shell/math.c b/shell/math.c
index beb89d140..b06d1ae3c 100644
--- a/shell/math.c
+++ b/shell/math.c
@@ -128,7 +128,8 @@ typedef unsigned char operator;
  * Consider * and /
  */
 #define tok_decl(prec,id)       (((id)<<5) | (prec))
-#define PREC(op)                ((op) & 0x1F)
+#define ID_SHIFT                5
+#define PREC(op)                ((op) & 0x1f)
 
 #define PREC_LPAREN             0
 #define TOK_LPAREN              tok_decl(0,0)
@@ -146,14 +147,16 @@ typedef unsigned char operator;
 #define TOK_AND_ASSIGN          tok_decl(2,1)
 #define TOK_OR_ASSIGN           tok_decl(2,2)
 #define TOK_XOR_ASSIGN          tok_decl(2,3)
-#define TOK_PLUS_ASSIGN         tok_decl(2,4)
-#define TOK_MINUS_ASSIGN        tok_decl(2,5)
+#define TOK_ADD_ASSIGN          tok_decl(2,4)
+#define TOK_SUB_ASSIGN          tok_decl(2,5)
 #define TOK_LSHIFT_ASSIGN       tok_decl(2,6)
 #define TOK_RSHIFT_ASSIGN       tok_decl(2,7)
 
 #define PREC_ASSIGN2            3
 #define TOK_MUL_ASSIGN          tok_decl(3,0)
-#define TOK_DIV_ASSIGN          tok_decl(3,1)
+/* "/" and "/=" ops have the same id bits */
+#define DIV_ID1                  1
+#define TOK_DIV_ASSIGN          tok_decl(3,DIV_ID1)
 #define TOK_REM_ASSIGN          tok_decl(3,2)
 
 #define fix_assignment_prec(prec) do { prec -= (prec == 3); } while (0)
@@ -198,7 +201,7 @@ typedef unsigned char operator;
 #define TOK_SUB                 tok_decl(13,1)
 
 #define TOK_MUL                 tok_decl(14,0)
-#define TOK_DIV                 tok_decl(14,1)
+#define TOK_DIV                 tok_decl(14,DIV_ID1)
 #define TOK_REM                 tok_decl(14,2)
 
 /* Exponent is right associative */
@@ -408,9 +411,9 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_
                         rez = (rez <= right_side_val);
                 else if (op == TOK_MUL || op == TOK_MUL_ASSIGN)
                         rez *= right_side_val;
-                else if (op == TOK_ADD || op == TOK_PLUS_ASSIGN)
+                else if (op == TOK_ADD || op == TOK_ADD_ASSIGN)
                         rez += right_side_val;
-                else if (op == TOK_SUB || op == TOK_MINUS_ASSIGN)
+                else if (op == TOK_SUB || op == TOK_SUB_ASSIGN)
                         rez -= right_side_val;
                 else if (op == TOK_ASSIGN || op == TOK_COMMA)
                         rez = right_side_val;
@@ -439,11 +442,11 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_
                          * Make sure to at least not SEGV here:
                          */
                         if (right_side_val == -1
-                         && rez << 1 == 0 /* MAX_NEGATIVE_INT or 0 */
+                         && (rez << 1) == 0 /* MAX_NEGATIVE_INT or 0 */
                         ) {
                                 right_side_val = 1;
                         }
-                        if (op == TOK_DIV || op == TOK_DIV_ASSIGN)
+                        if (op & (DIV_ID1 << ID_SHIFT)) /* DIV or DIV_ASSIGN? */
                                 rez /= right_side_val;
                         else
                                 rez %= right_side_val;
@@ -505,8 +508,8 @@ static const char op_tokens[] ALIGN1 = {
         '*','=',    0, TOK_MUL_ASSIGN,
         '/','=',    0, TOK_DIV_ASSIGN,
         '%','=',    0, TOK_REM_ASSIGN,
-        '+','=',    0, TOK_PLUS_ASSIGN,
-        '-','=',    0, TOK_MINUS_ASSIGN,
+        '+','=',    0, TOK_ADD_ASSIGN,
+        '-','=',    0, TOK_SUB_ASSIGN,
         '-','-',    0, TOK_POST_DEC,
         '^','=',    0, TOK_XOR_ASSIGN,
         '+','+',    0, TOK_POST_INC,
@@ -542,12 +545,15 @@ static arith_t parse_with_base(const char *nptr, char **endptr, unsigned base)
         for (;;) {
                 unsigned digit = (unsigned)*nptr - '0';
                 if (digit >= 10 /* not 0..9 */
-                 && digit <= 'z' - '0' /* needed to reject e.g. $((64#~)) */
+                 && digit <= 'z' - '0' /* reject e.g. $((64#~)) */
                 ) {
-                        /* in bases up to 36, case does not matter for a-z */
+                        /* current char is one of :;<=>?@A..Z[\]^_`a..z */
+
+                        /* in bases up to 36, case does not matter for a-z,
+                         * map A..Z and a..z to 10..35: */
                         digit = (unsigned)(*nptr | 0x20) - ('a' - 10);
                         if (base > 36 && *nptr <= '_') {
-                                /* otherwise, A-Z,@,_ are 36-61,62,63 */
+                                /* base > 36: A-Z,@,_ are 36-61,62,63 */
                                 if (*nptr == '_')
                                         digit = 63;
                                 else if (*nptr == '@')
@@ -558,8 +564,8 @@ static arith_t parse_with_base(const char *nptr, char **endptr, unsigned base)
                                         break; /* error: one of [\]^ */
                         }
                         //bb_error_msg("ch:'%c'%d digit:%u", *nptr, *nptr, digit);
-                        //if (digit < 10) - example where we need this?
-                        //      break;
+                        if (digit < 10) /* reject e.g. $((36#@)) */
+                                break;
                 }
                 if (digit >= base)
                         break;