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shell/math: fix order of expansion of variables to numbers 

This fixes arith-assign-in-varexp1.tests

function                                             old     new   delta
evaluate_string                                     1132    1258    +126
arith_lookup_val                                     143       -    -143
arith_apply                                         1132     977    -155
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 1/1 up/down: 126/-298)         Total: -172 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
master
Denys Vlasenko 2023-06-15 13:56:12 +02:00
parent 22cb0d573a
commit ea6dcbe283
3 changed files with 26 additions and 34 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
shell/hush_test/hush-arith/arith-assign-in-varexp1.right Normal file
View File

@ -0,0 +1,2 @@
7:7
x=3

9
shell/hush_test/hush-arith/arith-assign-in-varexp1.tests Executable file
View File

@ -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"

49
shell/math.c
View File

@ -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;