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- Subject: Re: Bugs in gsub
- From: Edgar Toernig <froese@...>
- Date: Fri, 02 Mar 2001 16:22:36 +0100
"Johansen, Vagn" wrote:
> > >gsub() has a problem with \000
> >
> > >From the manual: "A pattern cannot contain embedded zeros.
> > Use %z instead."
>
> That is a bit surprising. But OK, I guess it simplifies the implementation.
It's not that hard. A patch is attached. Afaics, there's only one
place left that does not handle \0 correctly: the "%s" sequence in
format(). Will look at that later.
Ciao, ET.
PS: The patch is pretty fresh. It compiles and passes some simple tests.
No guaranty ;-)
diff -ruN lua-4.0/include/lualib.h lua-4.0a/include/lualib.h
--- lua-4.0/include/lualib.h Fri Oct 27 18:15:53 2000
+++ lua-4.0a/include/lualib.h Fri Mar 2 15:19:20 2001
@@ -28,7 +28,7 @@
/* Auxiliary functions (private) */
-const char *luaI_classend (lua_State *L, const char *p);
+const char *luaI_classend (lua_State *L, const char *p, const char *p_end);
int luaI_singlematch (int c, const char *p, const char *ep);
#endif
diff -ruN lua-4.0/src/lib/lstrlib.c lua-4.0a/src/lib/lstrlib.c
--- lua-4.0/src/lib/lstrlib.c Fri Oct 27 18:15:53 2000
+++ lua-4.0a/src/lib/lstrlib.c Fri Mar 2 16:05:29 2001
@@ -41,7 +41,7 @@
if (end > (long)l) end = l;
if (start <= end)
lua_pushlstring(L, s+start-1, end-start+1);
- else lua_pushstring(L, "");
+ else lua_pushlstring(L, "", 0);
return 1;
}
@@ -122,7 +122,8 @@
struct Capture {
- const char *src_end; /* end ('\0') of source string */
+ const char *src_end; /* end of source string */
+ const char *pat_end; /* end of pattern string */
int level; /* total number of captures (finished or unfinished) */
struct {
const char *init;
@@ -132,7 +133,6 @@
#define ESC '%'
-#define SPECIALS "^$*+?.([%-"
static int check_capture (lua_State *L, int l, struct Capture *cap) {
@@ -152,18 +152,20 @@
}
-const char *luaI_classend (lua_State *L, const char *p) {
+const char *luaI_classend (lua_State *L, const char *p, const char *p_end) {
switch (*p++) {
case ESC:
- if (*p == '\0') lua_error(L, "malformed pattern (ends with `%')");
- return p+1;
+ if (p < p_end)
+ return p+1;
+ lua_error(L, "malformed pattern (ends with `%')");
case '[':
- if (*p == '^') p++;
- do { /* look for a ']' */
- if (*p == '\0') lua_error(L, "malformed pattern (missing `]')");
- if (*(p++) == ESC && *p != '\0') p++; /* skip escapes (e.g. '%]') */
- } while (*p != ']');
- return p+1;
+ while (p < p_end) {
+ if (*p == ']')
+ return p+1;
+ if (*p++ == ESC && p < p_end)
+ p++;
+ }
+ lua_error(L, "malformed pattern (missing `]')");
default:
return p;
}
@@ -202,7 +204,7 @@
if (match_class(c, (unsigned char)*p))
return sig;
}
- else if ((*(p+1) == '-') && (p+2 < endclass)) {
+ else if (p+2 < endclass && *(p+1) == '-') {
p+=2;
if ((int)(unsigned char)*(p-2) <= c && c <= (int)(unsigned char)*p)
return sig;
@@ -234,7 +236,7 @@
static const char *matchbalance (lua_State *L, const char *s, const char *p,
struct Capture *cap) {
- if (*p == 0 || *(p+1) == 0)
+ if (p+1 >= cap->pat_end)
lua_error(L, "unbalanced pattern");
if (*s != *p) return NULL;
else {
@@ -318,52 +320,55 @@
static const char *match (lua_State *L, const char *s, const char *p,
struct Capture *cap) {
- init: /* using goto's to optimize tail recursion */
- switch (*p) {
- case '(': /* start capture */
- return start_capture(L, s, p, cap);
- case ')': /* end capture */
- return end_capture(L, s, p, cap);
- case ESC: /* may be %[0-9] or %b */
- if (isdigit((unsigned char)(*(p+1)))) { /* capture? */
- s = match_capture(L, s, *(p+1), cap);
- if (s == NULL) return NULL;
- p+=2; goto init; /* else return match(L, s, p+2, cap) */
- }
- else if (*(p+1) == 'b') { /* balanced string? */
- s = matchbalance(L, s, p+2, cap);
- if (s == NULL) return NULL;
- p+=4; goto init; /* else return match(L, s, p+4, cap); */
- }
- else goto dflt; /* case default */
- case '\0': /* end of pattern */
- return s; /* match succeeded */
- case '$':
- if (*(p+1) == '\0') /* is the '$' the last char in pattern? */
- return (s == cap->src_end) ? s : NULL; /* check end of string */
- else goto dflt;
- default: dflt: { /* it is a pattern item */
- const char *ep = luaI_classend(L, p); /* points to what is next */
- int m = s<cap->src_end && luaI_singlematch((unsigned char)*s, p, ep);
- switch (*ep) {
- case '?': { /* optional */
- const char *res;
- if (m && ((res=match(L, s+1, ep+1, cap)) != NULL))
- return res;
- p=ep+1; goto init; /* else return match(L, s, ep+1, cap); */
- }
- case '*': /* 0 or more repetitions */
- return max_expand(L, s, p, ep, cap);
- case '+': /* 1 or more repetitions */
- return (m ? max_expand(L, s+1, p, ep, cap) : NULL);
- case '-': /* 0 or more repetitions (minimum) */
- return min_expand(L, s, p, ep, cap);
- default:
- if (!m) return NULL;
- s++; p=ep; goto init; /* else return match(L, s+1, ep, cap); */
+ while (p < cap->pat_end) {
+ const char *ep;
+ int m;
+ switch (*p) {
+ case '(': /* start capture */
+ return start_capture(L, s, p, cap);
+ case ')': /* end capture */
+ return end_capture(L, s, p, cap);
+ case ESC: /* may be %[0-9] or %b */
+ if (p+1 < cap->pat_end)
+ if (isdigit((unsigned char)(*(p+1)))) { /* capture? */
+ s = match_capture(L, s, *(p+1), cap);
+ if (s == NULL) return NULL;
+ p+=2; continue; /* else return match(L, s, p+2, cap) */
+ }
+ else if (*(p+1) == 'b') { /* balanced string? */
+ s = matchbalance(L, s, p+2, cap);
+ if (s == NULL) return NULL;
+ p+=4; continue; /* else return match(L, s, p+4, cap); */
+ }
+ break;
+ case '$': /* end of string (only special at end of pattern) */
+ if (p+1 == cap->pat_end)
+ return (s == cap->src_end) ? s : NULL;
+ break;
+ }
+ /* it is a pattern item */
+ ep = luaI_classend(L, p, cap->pat_end); /* points to what is next */
+ m = s<cap->src_end && luaI_singlematch((unsigned char)*s, p, ep);
+ switch (*ep) {
+ case '?': { /* optional */
+ const char *res;
+ if (m && ((res=match(L, s+1, ep+1, cap)) != NULL))
+ return res;
+ p=ep+1; continue; /* else return match(L, s, ep+1, cap); */
}
+ case '*': /* 0 or more repetitions */
+ return max_expand(L, s, p, ep, cap);
+ case '+': /* 1 or more repetitions */
+ return m ? max_expand(L, s+1, p, ep, cap) : NULL;
+ case '-': /* 0 or more repetitions (minimum) */
+ return min_expand(L, s, p, ep, cap);
+ default:
+ if (!m) return NULL;
+ s++; p=ep; continue; /* else return match(L, s+1, ep, cap); */
}
+ /* not reached */
}
+ return s;
}
@@ -390,6 +395,17 @@
}
+static int hasspecials (const char *p, size_t l) {
+ while (l--)
+ switch (*p++) {
+ case '^': case '$': case '*': case '+': case '-':
+ case '?': case '.': case '(': case '[': case '%':
+ return 1;
+ }
+ return 0;
+}
+
+
static int push_captures (lua_State *L, struct Capture *cap) {
int i;
luaL_checkstack(L, cap->level, "too many captures");
@@ -409,8 +425,8 @@
long init = posrelat(luaL_opt_long(L, 3, 1), l1) - 1;
struct Capture cap;
luaL_arg_check(L, 0 <= init && (size_t)init <= l1, 3, "out of range");
- if (lua_gettop(L) > 3 || /* extra argument? */
- strpbrk(p, SPECIALS) == NULL) { /* or no special characters? */
+ if (lua_gettop(L) > 3 || !hasspecials(p, l2)) {
+ /* extra argument or no specials characters */
const char *s2 = lmemfind(s+init, l1-init, p, l2);
if (s2) {
lua_pushnumber(L, s2-s+1);
@@ -422,6 +438,7 @@
int anchor = (*p == '^') ? (p++, 1) : 0;
const char *s1=s+init;
cap.src_end = s+l1;
+ cap.pat_end = p+l2;
do {
const char *res;
cap.level = 0;
@@ -470,9 +487,9 @@
static int str_gsub (lua_State *L) {
- size_t srcl;
+ size_t srcl, patl;
const char *src = luaL_check_lstr(L, 1, &srcl);
- const char *p = luaL_check_string(L, 2);
+ const char *p = luaL_check_lstr(L, 2, &patl);
int max_s = luaL_opt_int(L, 4, srcl+1);
int anchor = (*p == '^') ? (p++, 1) : 0;
int n = 0;
@@ -483,6 +500,7 @@
3, "string or function expected");
luaL_buffinit(L, &b);
cap.src_end = src+srcl;
+ cap.pat_end = p+patl;
while (n < max_s) {
const char *e;
cap.level = 0;
@@ -541,6 +559,7 @@
else if (*++strfrmt == '%')
luaL_putchar(&b, *strfrmt++); /* %% */
else { /* format item */
+ static const char fmt_spec[] = "[-+ #0]*(%d*)%.?(%d*)";
struct Capture cap;
char form[MAX_FORMAT]; /* to store the format ('%...') */
char buff[MAX_ITEM]; /* to store the formatted item */
@@ -551,9 +570,10 @@
initf += 2; /* skip the 'n$' */
}
arg++;
- cap.src_end = strfrmt+strlen(strfrmt)+1;
+ cap.src_end = strfrmt+strlen(strfrmt);
+ cap.pat_end = fmt_spec+sizeof(fmt_spec)-1;
cap.level = 0;
- strfrmt = match(L, initf, "[-+ #0]*(%d*)%.?(%d*)", &cap);
+ strfrmt = match(L, initf, fmt_spec, &cap);
if (cap.capture[0].len > 2 || cap.capture[1].len > 2 || /* < 100? */
strfrmt-initf > MAX_FORMAT-2)
lua_error(L, "invalid format (width or precision too long)");
