ea6dcbe28
Denys Vlasenko
2023-06-15
Subject
shell/math: fix order of expansion of variables to numbers
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shell/hush_test/hush-arith/arith-assign-in-varexp1.right +2 -0shell/hush_test/hush-arith/arith-assign-in-varexp1.tests +9 -0shell/math.c +15 -34
shell/hush_test/hush-arith/arith-assign-in-varexp1.right+2 -0
| @@ -0,0 +1,2 @@ | |
| + | 7:7 |
| + | x=3 |
shell/hush_test/hush-arith/arith-assign-in-varexp1.tests+9 -0
| @@ -0,0 +1,9 @@ | |
| + | exec 2>&1 |
| + | a='x=1' |
| + | b='x=2' |
| + | c='x=3' |
| + | # The variables should evaluate immediately when they encountered, |
| + | # not when they go into an operation. Here, order of evaluation |
| + | # of names to numbers should be a,b,c - not b,c,a: |
| + | echo 7:$((a+b*c)) |
| + | echo "x=$x" |
shell/math.c+15 -34
| @@ -310,7 +310,6 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_ | |
| var_or_num_t *top_of_stack; | |
| arith_t rez; | |
| - | const char *err; |
| /* There is no operator that can work without arguments */ | |
| if (NUMPTR == numstack) | |
| @@ -324,14 +323,8 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_ | |
| NUMPTR = expr1 + 1; | |
| if (expr1 < numstack) /* Example: $((2:3)) */ | |
| return "malformed ?: operator"; | |
| - | err = arith_lookup_val(math_state, expr1); |
| - | if (err) |
| - | return err; |
| if (expr1->val != 0) /* select expr2 or expr3 */ | |
| top_of_stack--; | |
| - | err = arith_lookup_val(math_state, top_of_stack); |
| - | if (err) |
| - | return err; |
| expr1->val = top_of_stack->val; | |
| expr1->var_name = NULL; | |
| return NULL; | |
| @@ -339,24 +332,6 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_ | |
| if (op == TOK_CONDITIONAL) /* Example: $((a ? b)) */ | |
| return "malformed ?: operator"; | |
| - | if (PREC(op) < UNARYPREC) { |
| - | /* In binops a ~ b, variables are resolved left-to-right, |
| - | * resolve top_of_stack[-1] _before_ resolving top_of_stack[0] |
| - | */ |
| - | if (top_of_stack == numstack) /* need two arguments */ |
| - | goto syntax_err; |
| - | /* Unless it is =, resolve top_of_stack[-1] name to value */ |
| - | if (op != TOK_ASSIGN) { |
| - | err = arith_lookup_val(math_state, top_of_stack - 1); |
| - | if (err) |
| - | return err; |
| - | } |
| - | } |
| - | /* Resolve top_of_stack[0] name to value */ |
| - | err = arith_lookup_val(math_state, top_of_stack); |
| - | if (err) |
| - | return err; |
| - | |
| rez = top_of_stack->val; | |
| if (op == TOK_UMINUS) | |
| rez = -rez; | |
| @@ -372,6 +347,9 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_ | |
| /* Binary operators */ | |
| arith_t right_side_val; | |
| + | if (top_of_stack == numstack) /* have two arguments? */ |
| + | goto syntax_err; /* no */ |
| + | |
| /* Pop numstack */ | |
| NUMPTR = top_of_stack; /* this decrements NUMPTR */ | |
| top_of_stack--; /* now points to left side */ | |
| @@ -677,7 +655,16 @@ evaluate_string(arith_state_t *math_state, const char *expr) | |
| numstackptr->var_name = alloca(var_name_size); | |
| safe_strncpy(numstackptr->var_name, expr, var_name_size); | |
| dbg("[%d] var:'%s'", (int)(numstackptr - numstack), numstackptr->var_name); | |
| - | expr = p; |
| + | expr = skip_whitespace(p); |
| + | /* If it is not followed by "=" operator... */ |
| + | if (expr[0] != '=' /* not "=..." */ |
| + | || expr[1] == '=' /* or "==..." */ |
| + | ) { |
| + | /* Evaluate variable to value */ |
| + | errmsg = arith_lookup_val(math_state, numstackptr); |
| + | if (errmsg) |
| + | goto err_with_custom_msg; |
| + | } |
| push_num: | |
| numstackptr++; | |
| lasttok = TOK_NUM; | |
| @@ -819,14 +806,8 @@ evaluate_string(arith_state_t *math_state, const char *expr) | |
| operator prev_op = *--opstackptr; | |
| if (op == TOK_RPAREN) { | |
| if (prev_op == TOK_LPAREN) { | |
| - | if (VALID_NAME(numstackptr[-1].var_name)) { |
| - | /* Expression is (var), lookup now */ |
| - | errmsg = arith_lookup_val(math_state, &numstackptr[-1]); |
| - | if (errmsg) |
| - | goto err_with_custom_msg; |
| - | /* Erase var name: (var) is just a number, for example, (var) = 1 is not valid */ |
| - | numstackptr[-1].var_name = NULL; |
| - | } |
| + | /* Erase var name: (var) is just a number, for example, (var) = 1 is not valid */ |
| + | numstackptr[-1].var_name = NULL; |
| /* Any operator directly after a | |
| * close paren should consider itself binary */ | |
| lasttok = TOK_NUM; | |