expr: improvements

- handle divide by zero.
- use eregcomp().
- use emalloc().
- use snprintf() for safety and add a buffer size argument to valstr() just
  to be sure.
- code-style fixes.
This commit is contained in:
Hiltjo Posthuma 2014-11-16 15:19:50 +01:00 committed by sin
parent 1822f70d12
commit b3ae1a7b4b

183
expr.c
View File

@ -2,10 +2,11 @@
#include <inttypes.h>
#include <limits.h>
#include <regex.h>
#include <stdio.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "util.h"
enum {
@ -13,7 +14,7 @@ enum {
};
typedef struct {
char *s;
char *s;
intmax_t n;
} Val;
@ -21,7 +22,7 @@ static void doop(int*, int**, Val*, Val**);
static Val match(Val, Val);
static void num(Val);
static int valcmp(Val, Val);
static char *valstr(Val, char*);
static char *valstr(Val, char*, size_t);
static int yylex(void);
static int yyparse(int);
@ -29,6 +30,13 @@ static char **args;
static size_t intlen;
static Val yylval;
static void
ezero(intmax_t n)
{
if(n == 0)
enprintf(2, "division by zero\n");
}
/* otop points to one past last op
* vtop points to one past last val
* guaranteed otop != ops
@ -40,43 +48,47 @@ doop(int *ops, int **otop, Val *vals, Val **vtop)
Val ret, a, b;
int op;
if((*otop)[-1] == '(')
if ((*otop)[-1] == '(')
enprintf(2, "syntax error: extra (\n");
if(*vtop - vals < 2)
if (*vtop - vals < 2)
enprintf(2, "syntax error: missing expression or extra operator\n");
a = (*vtop)[-2];
b = (*vtop)[-1];
a = (*vtop)[-2];
b = (*vtop)[-1];
op = (*otop)[-1];
switch (op) {
case '|':
if ( a.s && *a.s) ret = (Val){ a.s , 0 };
else if(!a.s && a.n) ret = (Val){ NULL, a.n };
else if( b.s && *b.s) ret = (Val){ b.s , 0 };
else ret = (Val){ NULL, b.n };
break;
case '|':
if (a.s && *a.s)
ret = (Val){ a.s, 0 };
else if (!a.s && a.n)
ret = (Val){ NULL, a.n };
else if (b.s && *b.s)
ret = (Val){ b.s, 0 };
else
ret = (Val){ NULL, b.n };
break;
case '&':
if (((a.s && *a.s) || a.n) &&
((b.s && *b.s) || b.n))
ret = a;
else
ret = (Val){ NULL, 0 };
break;
case '=': ret = (Val){ NULL, valcmp(a, b) == 0 }; break;
case '>': ret = (Val){ NULL, valcmp(a, b) > 0 }; break;
case GE : ret = (Val){ NULL, valcmp(a, b) >= 0 }; break;
case '<': ret = (Val){ NULL, valcmp(a, b) < 0 }; break;
case LE : ret = (Val){ NULL, valcmp(a, b) <= 0 }; break;
case NE : ret = (Val){ NULL, valcmp(a, b) != 0 }; break;
case '&':
if(((a.s && *a.s) || a.n) &&
((b.s && *b.s) || b.n)) ret = a;
else ret = (Val){ NULL, 0 };
break;
case '+': num(a); num(b); ret = (Val){ NULL, a.n + b.n }; break;
case '-': num(a); num(b); ret = (Val){ NULL, a.n - b.n }; break;
case '*': num(a); num(b); ret = (Val){ NULL, a.n * b.n }; break;
case '/': num(a); num(b); ezero(b.n); ret = (Val){ NULL, a.n / b.n }; break;
case '%': num(a); num(b); ezero(b.n); ret = (Val){ NULL, a.n % b.n }; break;
case '=': ret = (Val){ NULL, valcmp(a, b) == 0 }; break;
case '>': ret = (Val){ NULL, valcmp(a, b) > 0 }; break;
case GE : ret = (Val){ NULL, valcmp(a, b) >= 0 }; break;
case '<': ret = (Val){ NULL, valcmp(a, b) < 0 }; break;
case LE : ret = (Val){ NULL, valcmp(a, b) <= 0 }; break;
case NE : ret = (Val){ NULL, valcmp(a, b) != 0 }; break;
case '+': num(a); num(b); ret = (Val){ NULL, a.n + b.n }; break;
case '-': num(a); num(b); ret = (Val){ NULL, a.n - b.n }; break;
case '*': num(a); num(b); ret = (Val){ NULL, a.n * b.n }; break;
case '/': num(a); num(b); ret = (Val){ NULL, a.n / b.n }; break;
case '%': num(a); num(b); ret = (Val){ NULL, a.n % b.n }; break;
case ':': ret = match(a, b); break;
case ':': ret = match(a, b); break;
}
(*vtop)[-2] = ret;
@ -87,33 +99,29 @@ doop(int *ops, int **otop, Val *vals, Val **vtop)
static Val
match(Val vstr, Val vregx)
{
char b1[intlen], *str = valstr(vstr , b1);
char b2[intlen], *regx = valstr(vregx, b2);
intmax_t d;
char *ret, *p;
regoff_t len;
char b1[intlen], *str = valstr(vstr, b1, sizeof(b1));
char b2[intlen], *regx = valstr(vregx, b2, sizeof(b2));
regex_t re;
regmatch_t matches[2];
char anchreg[strlen(regx) + 2];
sprintf(anchreg, "^%s", regx);
snprintf(anchreg, sizeof(anchreg), "^%s", regx);
enregcomp(3, &re, anchreg, 0);
if(regcomp(&re, anchreg, 0))
enprintf(3, "regcomp failed\n");
if(regexec(&re, str, 2, matches, 0))
if (regexec(&re, str, 2, matches, 0))
return (Val){ (re.re_nsub ? "" : NULL), 0 };
if(re.re_nsub) {
intmax_t d;
char *ret, *p;
regoff_t len = matches[1].rm_eo - matches[1].rm_so + 1;
if(!(ret = malloc(len))) // FIXME: free
enprintf(3, "malloc failed\n");
if (re.re_nsub) {
len = matches[1].rm_eo - matches[1].rm_so + 1;
ret = emalloc(len); /* TODO: free ret */
d = strtoimax(ret, &p, 10);
strlcpy(ret, str + matches[1].rm_so, len);
if(*ret && !*p)
if (*ret && !*p)
return (Val){ NULL, d };
return (Val){ ret, 0 };
}
@ -123,27 +131,27 @@ match(Val vstr, Val vregx)
static void
num(Val v)
{
if(v.s)
if (v.s)
enprintf(2, "syntax error: expected integer got `%s'\n", v.s);
}
static int
valcmp(Val a, Val b)
{
char b1[intlen], *p = valstr(a, b1);
char b2[intlen], *q = valstr(b, b2);
char b1[intlen], *p = valstr(a, b1, sizeof(b1));
char b2[intlen], *q = valstr(b, b2, sizeof(b2));
if(!a.s && !b.s)
if (!a.s && !b.s)
return (a.n > b.n) - (a.n < b.n);
return strcmp(p, q);
}
static char *
valstr(Val val, char *buf)
valstr(Val val, char *buf, size_t bufsiz)
{
char *p = val.s;
if(!p) {
sprintf(buf, "%"PRIdMAX, val.n);
if (!p) {
snprintf(buf, bufsiz, "%"PRIdMAX, val.n);
p = buf;
}
return p;
@ -155,21 +163,24 @@ yylex(void)
intmax_t d;
char *q, *p, *ops = "|&=><+-*/%():";
if(!(p = *args++))
if (!(p = *args++))
return 0;
d = strtoimax(p, &q, 10);
if(*p && !*q) {
if (*p && !*q) {
yylval = (Val){ NULL, d };
return VAL;
}
if(*p && !p[1] && strchr(ops, *p))
if (*p && !p[1] && strchr(ops, *p))
return *p;
if(strcmp(p, ">=") == 0) return GE;
if(strcmp(p, "<=") == 0) return LE;
if(strcmp(p, "!=") == 0) return NE;
if (strcmp(p, ">=") == 0)
return GE;
if (strcmp(p, "<=") == 0)
return LE;
if (strcmp(p, "!=") == 0)
return NE;
yylval = (Val){ p, 0 };
return VAL;
@ -192,38 +203,40 @@ yyparse(int argc)
while((type = yylex())) {
switch (type) {
case VAL: *vtop++ = yylval; break;
case '(': *otop++ = '(' ; break;
case ')':
if(last == '(')
enprintf(2, "syntax error: empty ( )\n");
while(otop > ops && otop[-1] != '(')
doop(ops, &otop, vals, &vtop);
if(otop == ops)
enprintf(2, "syntax error: extra )\n");
otop--;
break;
default :
if(prec[last])
enprintf(2, "syntax error: extra operator\n");
while(otop > ops && prec[otop[-1]] >= prec[type])
doop(ops, &otop, vals, &vtop);
*otop++ = type;
break;
case VAL: *vtop++ = yylval; break;
case '(': *otop++ = '(' ; break;
case ')':
if (last == '(')
enprintf(2, "syntax error: empty ( )\n");
while(otop > ops && otop[-1] != '(')
doop(ops, &otop, vals, &vtop);
if (otop == ops)
enprintf(2, "syntax error: extra )\n");
otop--;
break;
default :
if (prec[last])
enprintf(2, "syntax error: extra operator\n");
while (otop > ops && prec[otop[-1]] >= prec[type])
doop(ops, &otop, vals, &vtop);
*otop++ = type;
break;
}
last = type;
}
while(otop > ops)
doop(ops, &otop, vals, &vtop);
if(vtop == vals)
if (vtop == vals)
enprintf(2, "syntax error: missing expression\n");
if(vtop - vals > 1)
if (vtop - vals > 1)
enprintf(2, "syntax error: extra expression\n");
vtop--;
if(vtop->s) printf("%s\n" , vtop->s);
else printf("%"PRIdMAX"\n", vtop->n);
if (vtop->s)
printf("%s\n", vtop->s);
else
printf("%"PRIdMAX"\n", vtop->n);
return (vtop->s && *vtop->s) || vtop->n;
}
@ -231,11 +244,11 @@ yyparse(int argc)
int
main(int argc, char **argv)
{
if(!(intlen = snprintf(NULL, 0, "%"PRIdMAX, INTMAX_MIN) + 1))
if (!(intlen = snprintf(NULL, 0, "%"PRIdMAX, INTMAX_MIN) + 1))
enprintf(3, "failed to get max digits\n");
args = argv + 1;
if(*args && !strcmp("--", *args))
if (*args && !strcmp("--", *args))
++args;
return !yyparse(argc);