commit b3ae1a7b4b9832d1978fe4676758e53887248c5e
Author: Hiltjo Posthuma <[email protected]>
Date: Sun Nov 16 15:19:50 2014 +0100
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.
diff --git a/expr.c b/expr.c
index 679ad38..49fa040 100644
--- a/expr.c
+++ b/expr.c
@@ -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) || 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 '+': 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 '|':
+ 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 '+': 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 = 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);
-
- if(regcomp(&re, anchreg, 0))
- enprintf(3, "regcomp failed\n");
+ snprintf(anchreg, sizeof(anchreg), "^%s", regx);
+ enregcomp(3, &re, anchreg, 0);
- 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);
