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shell/math: fix ?: to not evaluate not-taken branches 

This fixes ash-arith-arith-ternary1/2.tests

function                                             old     new   delta
evaluate_string                                     1271    1432    +161
arith_apply                                          968    1000     +32
arith                                                 22      36     +14
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 207/0)             Total: 207 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
master
Denys Vlasenko 2023-06-16 19:43:53 +02:00
parent f8263528cd
commit e127985839
26 changed files with 131 additions and 24 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
shell/ash_test/ash-arith/arith-ternary-assign.right Normal file
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@ -0,0 +1 @@
42:42

3
shell/ash_test/ash-arith/arith-ternary-assign.tests Executable file
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@ -0,0 +1,3 @@
exec 2>&1
a='@'
echo 42:$((a=1?42:3,a))

1
shell/ash_test/ash-arith/arith-ternary-comma.right Normal file
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@ -0,0 +1 @@
42:42

3
shell/ash_test/ash-arith/arith-ternary-comma.tests Executable file
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@ -0,0 +1,3 @@
exec 2>&1
x='@'
echo 42:$((1?4:x,20*2+2))

1
shell/ash_test/ash-arith/arith-ternary-preincr.right Normal file
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@ -0,0 +1 @@
42:42

3
shell/ash_test/ash-arith/arith-ternary-preincr.tests Executable file
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@ -0,0 +1,3 @@
exec 2>&1
x='@'
echo 42:$((1?42:++x))

1
shell/ash_test/ash-arith/arith-ternary3.right Normal file
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@ -0,0 +1 @@
42:42

4
shell/ash_test/ash-arith/arith-ternary3.tests Executable file
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@ -0,0 +1,4 @@
exec 2>&1
# "EXPR ?..." should check _evaluated_ EXPR,
# not its last value
echo 42:$((1 < 1 ? -1 : 1 > 1 ? 1 : 42))

2
shell/ash_test/ash-arith/arith-ternary_nested3.right Normal file
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@ -0,0 +1,2 @@
42:42
a=2:2

6
shell/ash_test/ash-arith/arith-ternary_nested3.tests Executable file
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@ -0,0 +1,6 @@
exec 2>&1
x='@'
a=2
# After processing nested ?:, outermost ?: should still rememeber to NOT evaluate a*=2
echo 42:$((1?0?41:42:(a*=2)))
echo "a=2:$a"

1
shell/hush_test/hush-arith/arith-ternary-assign.right Normal file
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@ -0,0 +1 @@
42:42

3
shell/hush_test/hush-arith/arith-ternary-assign.tests Executable file
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@ -0,0 +1,3 @@
exec 2>&1
a='@'
echo 42:$((a=1?42:3,a))

1
shell/hush_test/hush-arith/arith-ternary-comma.right Normal file
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@ -0,0 +1 @@
42:42

3
shell/hush_test/hush-arith/arith-ternary-comma.tests Executable file
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@ -0,0 +1,3 @@
exec 2>&1
x='@'
echo 42:$((1?4:x,20*2+2))

1
shell/hush_test/hush-arith/arith-ternary-preincr.right Normal file
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@ -0,0 +1 @@
42:42

3
shell/hush_test/hush-arith/arith-ternary-preincr.tests Executable file
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@ -0,0 +1,3 @@
exec 2>&1
x='@'
echo 42:$((1?42:++x))

2
shell/hush_test/hush-arith/arith-ternary1.right Normal file
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@ -0,0 +1,2 @@
42:42
a=0

5
shell/hush_test/hush-arith/arith-ternary1.tests Executable file
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@ -0,0 +1,5 @@
exec 2>&1
a=0
# The not-taken branch should not evaluate
echo 42:$((1 ? 42 : (a+=2)))
echo "a=$a"

3
shell/hush_test/hush-arith/arith-ternary2.right Normal file
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@ -0,0 +1,3 @@
6:6
a=b=+err+
b=6

7
shell/hush_test/hush-arith/arith-ternary2.tests Executable file
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@ -0,0 +1,7 @@
exec 2>&1
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/hush_test/hush-arith/arith-ternary3.right Normal file
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@ -0,0 +1 @@
42:42

4
shell/hush_test/hush-arith/arith-ternary3.tests Executable file
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@ -0,0 +1,4 @@
exec 2>&1
# "EXPR ?..." should check _evaluated_ EXPR,
# not its last value
echo 42:$((1 < 1 ? -1 : 1 > 1 ? 1 : 42))

2
shell/hush_test/hush-arith/arith-ternary_nested3.right Normal file
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@ -0,0 +1,2 @@
42:42
a=2:2

6
shell/hush_test/hush-arith/arith-ternary_nested3.tests Executable file
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@ -0,0 +1,6 @@
exec 2>&1
x='@'
a=2
# After processing nested ?:, outermost ?: should still rememeber to NOT evaluate a*=2
echo 42:$((1?0?41:42:(a*=2)))
echo "a=2:$a"

85
shell/math.c
View File

@ -356,6 +356,11 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_
NUMPTR = top_of_stack; /* this decrements NUMPTR */
top_of_stack--; /* now points to left side */
if (math_state->evaluation_disabled) {
dbg("binary op %02x skipped", op);
goto ret_NULL;
}
right_side_val = rez;
rez = top_of_stack->val;
if (op == TOK_BOR || op == TOK_OR_ASSIGN)
@ -428,6 +433,11 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_
}
}
if (math_state->evaluation_disabled) {
dbg("unary op %02x skipped", op);
goto ret_NULL;
}
if (is_assign_op(op)) {
char buf[sizeof(arith_t)*3 + 2];
@ -446,6 +456,7 @@ arith_apply(arith_state_t *math_state, operator op, var_or_num_t *numstack, var_
}
top_of_stack->val = rez;
ret_NULL:
/* Erase var name, it is just a number now */
top_of_stack->var_name = NULL;
return NULL;
@ -594,8 +605,10 @@ static arith_t strto_arith_t(const char *nptr, char **endptr)
static arith_t
evaluate_string(arith_state_t *math_state, const char *expr)
{
#define EVAL_DISABLED ((unsigned long long)math_state->evaluation_disabled)
#define TOP_BIT_ULL ((unsigned long long)LLONG_MAX + 1)
operator lasttok;
const char *errmsg;
const char *errmsg = NULL;
const char *start_expr = expr = skip_whitespace(expr);
unsigned expr_len = strlen(expr) + 2;
/* Stack of integers/names */
@ -614,7 +627,6 @@ evaluate_string(arith_state_t *math_state, const char *expr)
/* Start with a left paren */
dbg("(%d) op:TOK_LPAREN", (int)(opstackptr - opstack));
*opstackptr++ = lasttok = TOK_LPAREN;
errmsg = NULL;
while (1) {
const char *p;
@ -653,19 +665,26 @@ evaluate_string(arith_state_t *math_state, const char *expr)
p = endofname(expr);
if (p != expr) {
/* Name */
size_t var_name_size = (p - expr) + 1; /* +1 for NUL */
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 = 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;
if (!math_state->evaluation_disabled) {
size_t var_name_size = (p - expr) + 1; /* +1 for NUL */
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 = 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;
}
} else {
dbg("[%d] var:IGNORED", (int)(numstackptr - numstack));
numstackptr->var_name = NULL;
numstackptr->val = 0; //paranoia, probably not needed
expr = p;
}
push_num:
numstackptr++;
@ -814,10 +833,11 @@ evaluate_string(arith_state_t *math_state, const char *expr)
* pop prev_op
* if can't evaluate prev_op (it is lower precedence than op):
* push prev_op back
* goto P
* goto C
* evaluate prev_op on top of numstack
* P: push op
* N: loop to parse the rest of string
* C:if op is "?": check result, set disable flag if needed
* push op
* N:loop to parse the rest of string
*/
while (opstackptr != opstack) {
operator prev_op = *--opstackptr;
@ -840,7 +860,7 @@ evaluate_string(arith_state_t *math_state, const char *expr)
) {
/* ...x~y@. push @ on opstack */
opstackptr++; /* undo removal of ~ op */
goto push_op;
goto check_cond;
}
/* else: ...x~y@. Evaluate x~y, replace it on stack with result. Then repeat */
}
@ -863,21 +883,41 @@ dbg(" numstack:%d val:%lld '%s'", (int)(numstackptr - numstack), numstackptr[
errmsg = "malformed ?: operator";
goto err_with_custom_msg;
}
/* Example: a=1?2:3,a. We just executed ":".
* Prevent assignment from being still disabled.
*/
math_state->evaluation_disabled >>= 1;
dbg("':' executed: evaluation_disabled=%llx (restored)", EVAL_DISABLED);
}
} /* while (opstack not empty) */
if (op == TOK_RPAREN) /* unpaired RPAREN? */
goto err;
}
check_cond:
if (op == TOK_CONDITIONAL) {
/* We know the value of EXPR in "EXPR ? ..."
* Should we stop evaluating now? */
if (math_state->evaluation_disabled & TOP_BIT_ULL)
goto err; /* >63 levels of ?: nesting not supported */
math_state->evaluation_disabled <<= 1;
if (numstackptr[-1].val == 0)
math_state->evaluation_disabled |= 1;
dbg("'?' entered: evaluation_disabled=%llx", EVAL_DISABLED);
}
} /* if */
/* else: LPAREN or UNARY: push it on opstack */
push_op:
/* Push this operator to opstack */
dbg("(%d) op:%02x insert_op:%02x", (int)(opstackptr - opstack), op, insert_op);
*opstackptr++ = lasttok = op;
next: ;
next:
if (insert_op != 0xff) {
op = insert_op;
insert_op = 0xff;
dbg("inserting %02x", op);
if (op == TOK_CONDITIONAL_SEP) {
math_state->evaluation_disabled ^= 1;
dbg("':' entered: evaluation_disabled=%llx (negated)", EVAL_DISABLED);
}
goto tok_found1;
}
} /* while (1) */
@ -896,6 +936,7 @@ arith(arith_state_t *math_state, const char *expr)
{
math_state->errmsg = NULL;
math_state->list_of_recursed_names = NULL;
math_state->evaluation_disabled = 0;
return evaluate_string(math_state, expr);
}

3
shell/math.h
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@ -73,13 +73,12 @@ typedef long arith_t;
typedef const char* FAST_FUNC (*arith_var_lookup_t)(const char *name);
typedef void FAST_FUNC (*arith_var_set_t)(const char *name, const char *val);
//typedef const char* FAST_FUNC (*arith_var_endofname_t)(const char *name);
typedef struct arith_state_t {
const char *errmsg;
arith_var_lookup_t lookupvar;
arith_var_set_t setvar;
// arith_var_endofname_t endofname;
uint64_t evaluation_disabled;
void *list_of_recursed_names;
} arith_state_t;