shell: shrink arith code; and prepare for returning text error codes
function old new delta
arith 701 680 -21
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
diff --git a/shell/math.c b/shell/math.c
index a4c55a4..2f09339 100644
--- a/shell/math.c
+++ b/shell/math.c
@@ -124,9 +124,6 @@
#define setvar (math_hooks->setvar )
//#define endofname (math_hooks->endofname)
-#define arith_isspace(arithval) \
- (arithval == ' ' || arithval == '\n' || arithval == '\t')
-
typedef unsigned char operator;
/* An operator's token id is a bit of a bitfield. The lower 5 bits are the
@@ -156,7 +153,7 @@
#define TOK_REM_ASSIGN tok_decl(3,2)
/* all assign is right associativity and precedence eq, but (7+3)<<5 > 256 */
-#define convert_prec_is_assing(prec) do { if (prec == 3) prec = 2; } while (0)
+#define convert_prec_is_assign(prec) do { if (prec == 3) prec = 2; } while (0)
/* conditional is right associativity too */
#define TOK_CONDITIONAL tok_decl(4,0)
@@ -223,7 +220,7 @@
{
operator prec = PREC(op);
- convert_prec_is_assing(prec);
+ convert_prec_is_assign(prec);
return (prec == PREC(TOK_ASSIGN) ||
prec == PREC_PRE || prec == PREC_POST);
}
@@ -477,7 +474,7 @@
0
};
/* ptr to ")" */
-#define endexpression (&op_tokens[sizeof(op_tokens)-7])
+#define ptr_to_rparen (&op_tokens[sizeof(op_tokens)-7])
const char* FAST_FUNC
endofname(const char *name)
@@ -494,32 +491,36 @@
arith_t
arith(const char *expr, int *perrcode, a_e_h_t *math_hooks)
{
- char arithval; /* Current character under analysis */
- operator lasttok, op;
- operator prec;
- operator *stack, *stackptr;
- const char *p = endexpression;
+ operator lasttok;
int errcode;
- v_n_t *numstack, *numstackptr;
- unsigned datasizes = strlen(expr) + 2;
-
+ const char *start_expr = expr = skip_whitespace(expr);
+ unsigned expr_len = strlen(expr) + 2;
/* Stack of integers */
/* The proof that there can be no more than strlen(startbuf)/2+1 integers
* in any given correct or incorrect expression is left as an exercise to
* the reader. */
- numstackptr = numstack = alloca((datasizes / 2) * sizeof(numstack[0]));
+ v_n_t *const numstack = alloca((expr_len / 2) * sizeof(numstack[0]));
+ v_n_t *numstackptr = numstack;
/* Stack of operator tokens */
- stackptr = stack = alloca(datasizes * sizeof(stack[0]));
+ operator *const stack = alloca(expr_len * sizeof(stack[0]));
+ operator *stackptr = stack;
*stackptr++ = lasttok = TOK_LPAREN; /* start off with a left paren */
- *perrcode = errcode = 0;
+ errcode = 0;
while (1) {
+ const char *p;
+ operator op;
+ operator prec;
+ char arithval;
+
+ expr = skip_whitespace(expr);
arithval = *expr;
- if (arithval == 0) {
- if (p == endexpression) {
+ if (arithval == '\0') {
+ if (expr == start_expr) {
/* Null expression. */
- return 0;
+ numstack->val = 0;
+ goto ret;
}
/* This is only reached after all tokens have been extracted from the
@@ -527,38 +528,29 @@
* are to be applied in order. At the end, there should be a final
* result on the integer stack */
- if (expr != endexpression + 1) {
+ if (expr != ptr_to_rparen + 1) {
/* If we haven't done so already, */
/* append a closing right paren */
- expr = endexpression;
+ expr = ptr_to_rparen;
/* and let the loop process it. */
continue;
}
/* At this point, we're done with the expression. */
- if (numstackptr != numstack+1) {
+ if (numstackptr != numstack + 1) {
/* ... but if there isn't, it's bad */
- err:
- *perrcode = -1;
- return *perrcode;
+ goto err;
}
if (numstack->var) {
/* expression is $((var)) only, lookup now */
errcode = arith_lookup_val(numstack, math_hooks);
}
- ret:
- *perrcode = errcode;
- return numstack->val;
+ goto ret;
}
- /* Continue processing the expression. */
- if (arith_isspace(arithval)) {
- /* Skip whitespace */
- goto prologue;
- }
p = endofname(expr);
if (p != expr) {
- size_t var_name_size = (p-expr) + 1; /* trailing zero */
-
+ /* Name */
+ size_t var_name_size = (p-expr) + 1; /* +1 for NUL */
numstackptr->var = alloca(var_name_size);
safe_strncpy(numstackptr->var, expr, var_name_size);
expr = p;
@@ -568,36 +560,37 @@
lasttok = TOK_NUM;
continue;
}
+
if (isdigit(arithval)) {
+ /* Number */
numstackptr->var = NULL;
errno = 0;
- /* call strtoul[l]: */
- numstackptr->val = strto_arith_t(expr, (char **) &expr, 0);
+ numstackptr->val = strto_arith_t(expr, (char**) &expr, 0);
if (errno)
numstackptr->val = 0; /* bash compat */
goto num;
}
- for (p = op_tokens; ; p++) {
- const char *o;
- if (*p == 0) {
- /* strange operator not found */
- goto err;
- }
- for (o = expr; *p && *o == *p; p++)
- o++;
- if (!*p) {
- /* found */
- expr = o - 1;
+ /* Should be an operator */
+ p = op_tokens;
+ while (1) {
+ const char *e = expr;
+ /* Compare expr to current op_tokens[] element */
+ while (*p && *e == *p)
+ p++, e++;
+ if (*p == '\0') { /* match: operator is found */
+ expr = e;
break;
}
- /* skip tail uncompared token */
+ /* Go to next element of op_tokens[] */
while (*p)
p++;
- /* skip zero delim */
- p++;
+ p += 2; /* skip NUL and TOK_foo bytes */
+ if (*p == '\0') /* no next element, operator not found */
+ goto err;
}
- op = p[1];
+ op = p[1]; /* fetch TOK_foo value */
+ /* NB: expr now points past the operator */
/* post grammar: a++ reduce to num */
if (lasttok == TOK_POST_INC || lasttok == TOK_POST_DEC)
@@ -651,13 +644,12 @@
/* Any operator directly after a */
lasttok = TOK_NUM;
/* close paren should consider itself binary */
- goto prologue;
+ goto next;
}
} else {
operator prev_prec = PREC(stackptr[-1]);
-
- convert_prec_is_assing(prec);
- convert_prec_is_assing(prev_prec);
+ convert_prec_is_assign(prec);
+ convert_prec_is_assign(prev_prec);
if (prev_prec < prec)
break;
/* check right assoc */
@@ -665,7 +657,8 @@
break;
}
errcode = arith_apply(*--stackptr, numstack, &numstackptr, math_hooks);
- if (errcode) goto ret;
+ if (errcode)
+ goto ret;
}
if (op == TOK_RPAREN) {
goto err;
@@ -674,9 +667,14 @@
/* Push this operator to the stack and remember it. */
*stackptr++ = lasttok = op;
- prologue:
- ++expr;
- } /* while */
+ next: ;
+ } /* while (1) */
+
+ err:
+ numstack->val = errcode = -1;
+ ret:
+ *perrcode = errcode;
+ return numstack->val;
}
/*