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shell/math: fix nested ?: and do not parse variables in not-taken branch

Browse source 
Fixes arith-ternary1.tests and arith-ternary_nested.tests

function                                             old     new   delta
evaluate_string                                     1043    1101     +58
arith_apply                                         1087    1137     +50
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 108/0)             Total: 108 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2023-06-14 11:05:48 +02:00
parent a02450ff0b
commit 46dccd2ec0
7 changed files with 61 additions and 43 deletions
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3
shell/ash_test/ash-arith/arith-ternary1.right
View file

@ -1,5 +1,2 @@
42:42
a=0
6:6
a=b=+err+
b=6

7
shell/ash_test/ash-arith/arith-ternary1.tests
View file

@ -3,10 +3,3 @@ a=0
# The not-taken branch should not evaluate
echo 42:$((1 ? 42 : (a+=2)))
echo "a=$a"
a='b=+err+'
b=5
# The not-taken branch should not even parse variables
echo 6:$((0 ? a : ++b))
echo "a=$a"
echo "b=$b"

4
shell/ash_test/ash-arith/arith-ternary2.right
View file

@ -1 +1,3 @@
5:5
6:6
a=b=+err+
b=6

7
shell/ash_test/ash-arith/arith-ternary2.tests
View file

@ -1,2 +1,7 @@
exec 2>&1
echo 5:$((1?2?3?4?5:6:7:8:9))
a='b=+err+'
b=5
# The not-taken branch should not parse variables
echo 6:$((0 ? a : ++b))
echo "a=$a"
echo "b=$b"

1
shell/ash_test/ash-arith/arith-ternary_nested.right Normal file
View file

@ -0,0 +1 @@
5:5

2
shell/ash_test/ash-arith/arith-ternary_nested.tests Executable file
View file

@ -0,0 +1,2 @@
exec 2>&1
echo 5:$((1?2?3?4?5:6:7:8:9))

80
shell/math.c
View file

@ -331,6 +331,28 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_
top_of_stack = NUMPTR - 1;
if (op == TOK_CONDITIONAL_SEP) {
/* "expr1 ? expr2 : expr3" operation */
var_or_num_t *expr1 = &top_of_stack[-2];
if (expr1 < numstack) {
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;
NUMPTR = expr1 + 1;
expr1->val = top_of_stack->val;
expr1->var_name = NULL;
return NULL;
}
if (op == TOK_CONDITIONAL) /* Example: $((a ? b)) */
return "malformed ?: operator";
/* Resolve name to value, if needed */
err = arith_lookup_val(math_state, top_of_stack);
if (err)
@ -350,25 +372,12 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_
else if (op != TOK_UPLUS) {
/* Binary operators */
arith_t right_side_val;
int bad_second_val;
/* Binary operators need two arguments */
if (top_of_stack == numstack)
goto syntax_err;
/* ...and they pop one */
NUMPTR = top_of_stack; /* this decrements NUMPTR */
bad_second_val = (top_of_stack->var_name == SECOND_VAL_VALID);
if (op == TOK_CONDITIONAL) { /* ? operation */
/* Make next if (...) protect against
* $((expr1 ? expr2)) - that is, missing ": expr" */
bad_second_val = !bad_second_val;
}
if (bad_second_val) {
/* Protect against $((expr <not_?_op> expr1 : expr2)) */
return "malformed ?: operator";
}
top_of_stack--; /* now points to left side */
if (op != TOK_ASSIGN) {
@ -380,19 +389,7 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_
right_side_val = rez;
rez = top_of_stack->val;
if (op == TOK_CONDITIONAL) /* ? operation */
rez = (rez ? right_side_val : top_of_stack[1].second_val);
else if (op == TOK_CONDITIONAL_SEP) { /* : operation */
if (top_of_stack == numstack) {
/* Protect against $((expr : expr)) */
return "malformed ?: operator";
}
top_of_stack->val = rez;
top_of_stack->second_val = right_side_val;
top_of_stack->var_name = SECOND_VAL_VALID;
return NULL;
}
else if (op == TOK_BOR || op == TOK_OR_ASSIGN)
if (op == TOK_BOR || op == TOK_OR_ASSIGN)
rez |= right_side_val;
else if (op == TOK_OR)
rez = right_side_val || rez;
@ -833,7 +830,7 @@ evaluate_string(arith_state_t *math_state, const char *expr)
lasttok = TOK_NUM;
goto next;
}
/* Not (y), but ...x~y): fall through to evaluate x~y */
/* Not (y), but ...x~y). Fall through to evaluate x~y */
} else {
operator prev_prec = PREC(prev_op);
fix_assignment_prec(prec);
@ -841,11 +838,17 @@ evaluate_string(arith_state_t *math_state, const char *expr)
if (prev_prec < prec
|| (prev_prec == prec && is_right_associative(prec))
) {
/* ...x~y@: push @ on opstack */
opstackptr++; /* undo removal of ~ op */
goto push_op;
/* Unless a?b?c:d:... and we are at the second : */
if (op != TOK_CONDITIONAL_SEP
|| prev_op != TOK_CONDITIONAL_SEP
) {
/* ...x~y@: push @ on opstack */
opstackptr++; /* undo removal of ~ op */
goto push_op;
}
/* else: a?b?c:d:. Evaluate b?c:d, replace it on stack with result. Then repeat */
}
/* ...x~y@: evaluate x~y, replace it on stack with result. Then repeat */
/* else: ...x~y@. Evaluate x~y, replace it on stack with result. Then repeat */
}
dbg("arith_apply(prev_op:%02x, numstack:%d)", prev_op, (int)(numstackptr - numstack));
errmsg = arith_apply(math_state, prev_op, numstack, &numstackptr);
@ -856,6 +859,21 @@ dbg(" numstack:%d val:%lld %lld %p", (int)(numstackptr - numstack),
numstackptr[-1].var_name == SECOND_VAL_VALID ? numstackptr[-1].second_val : 0,
numstackptr[-1].var_name
);
/* For ternary ?: we need to remove ? from opstack too, not just : */
if (prev_op == TOK_CONDITIONAL_SEP) {
// This is caught in arith_apply()
//if (opstackptr == opstack) {
// /* Example: $((2:3)) */
// errmsg = "where is your ? in ?:";
// goto err_with_custom_msg;
//}
opstackptr--;
if (*opstackptr != TOK_CONDITIONAL) {
/* Example: $((1,2:3)) */
errmsg = "malformed ?: operator";
goto err_with_custom_msg;
}
}
} /* while (opstack not empty) */
if (op == TOK_RPAREN) /* unpaired RPAREN? */
goto err;