libcdecl: Implement portable alternative to strtoumax.

It's not really OK for the scanner to use a strtoumax fallback with
limited range, as this means the library can't actually parse its own
output in general.  This causes test failures on systems which don't
have a suitable function in the C library.

Try hard to have a compact implementation, letting the scanner do as
much of the job as possible to reduce the amount of extra checks that
have to happen later.  For the ELF shared library case, the result seems
to be pretty good overall: with GCC, the size savings from the no-longer-
needed PLT entry are similar to the amount of extra code added.

As a bonus, this also avoids any unwanted locale dependency, since the
C standard permits strtoumax et al. to do weird things outside of the
"C" locale, although I'm not sure to what extent any real-world systems
take advantage of that freedom.

diff --git a/Makefile.am b/Makefile.am
index b0ba8bdc927925bb8cb11c33268ed85bdba5f402..eae1366fdb2c58089df2073642d5d3c63e42f038 100644 (file)
--- a/Makefile.am
+++ b/Makefile.am
@@ -31,8 +31,8 @@ EXTRA_DIST = bootstrap $(DX_BASEDIR)/scripts/fix-gnulib.pl m4/gnulib-cache.m4 \
 dist_man_MANS = doc/cdecl99.1 doc/libcdecl.3
 
 noinst_HEADERS = conf_pre.h conf_post.h common/src/help.h common/src/tap.h \
-                 common/src/xtra.h src/cdecl.h src/scan.h src/parse.h \
-                 src/version.h t/declgen.h t/test.h
+                 common/src/xtra.h src/cdecl.h src/intconv.h src/scan.h \
+                 src/parse.h src/version.h t/declgen.h t/test.h
 
 noinst_DATA = $(MOFILES)
 

diff --git a/src/intconv.h b/src/intconv.h
new file mode 100644 (file)
index 0000000..17644f2
--- /dev/null
+++ b/src/intconv.h
@@ -0,0 +1,68 @@
+/*
+ * Copyright © 2023 Nick Bowler
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef CDECL99_INTCONV_H_
+#define CDECL99_INTCONV_H_
+
+#include <string.h>
+#include <stdbool.h>
+#include <inttypes.h>
+
+enum { INTCONV_OCTAL = 8, INTCONV_DECIMAL = 10, INTCONV_HEXADECIMAL = 16 };
+
+/*
+ * Multiply *v by base, which must be one of the above enumeration constants,
+ * and add digit, updating *v with the result.
+ *
+ * If the result does not fit in uintmax_t, then 0 is returned.  Otherwise,
+ * a non-zero result is returned.
+ */
+static inline bool intconv_shift(uintmax_t *v, unsigned base, unsigned digit)
+{
+       uintmax_t old_v = *v;
+
+       if (old_v > (uintmax_t)-1 / base)
+               return false;
+       old_v *= base;
+
+       return (*v = old_v + digit) >= old_v;
+}
+
+/*
+ * Assuming d is a hexadecimal digit character (converted to unsigned char),
+ * return the corresponding value of that digit (between 0 and 15, inclusive).
+ */
+static inline unsigned char intconv_digit(unsigned char d)
+{
+       if (d >= '0' && d <= '9') {
+               return d - '0';
+       } else {
+#if ('A' & 7) == 1 && ('B' & 7) == 2 && ('C' & 7) == 3 \
+ && ('a' & 7) == 1 && ('b' & 7) == 2 && ('c' & 7) == 3 \
+ && ('D' & 7) == 4 && ('E' & 7) == 5 && ('F' & 7) == 6 \
+ && ('d' & 7) == 4 && ('e' & 7) == 5 && ('f' & 7) == 6
+               /* EBCDIC or ASCII-like encoding */
+               return 9 + (d & 7);
+#else
+               /* Something else */
+               static const char idx[] = "abcdef..ABCDEF";
+               return 10 + (((char *)memchr(idx, d, sizeof idx) - idx) & 7);
+#endif
+       }
+}
+
+#endif

diff --git a/src/scan.l b/src/scan.l
index fbe80b2fddae12cc5076a9a0e108497d0b28d7ff..48314d4e00df2203cdba59f2aac0ca5c67009307 100644 (file)
--- a/src/scan.l
+++ b/src/scan.l
@@ -33,20 +33,7 @@
 #include "cdecl-internal.h"
 #include "cdecl.h"
 #include "errmsg.h"
-
-#if HAVE_STRTOUMAX
-/* Best case, implementation provides strtoumax. */
-#  define STRTOUMAX strtoumax
-#elif HAVE_STRTOULL
-/* Fall back to strtoull, with possibly reduced range. */
-#define STRTOUMAX strtoull
-#elif HAVE___STRTOULL
-/* HP-UX 11 has __strtoull in <inttypes.h> */
-#define STRTOUMAX __strtoull
-#else
-/* Fall back to strtoul, with possibly reduced range. */
-#define STRTOUMAX strtoul
-#endif
+#include "intconv.h"
 
 static char *to_octal(char *dst, unsigned val)
 {
@@ -111,11 +98,11 @@ static void to_readable_ch(char *dst, char c)
 %}
 
 IDENT [_[:alpha:]][-_[:alnum:]]*
-INTEGER 0[Xx][[:xdigit:]]*|[[:digit:]]+
 
 %%
 
 %{
+       int intconv_base;
        char *c;
 %}
 
@@ -139,22 +126,29 @@ INTEGER 0[Xx][[:xdigit:]]*|[[:digit:]]+
        return UNPACK_TOKEN(match[sizeof tab[0]]);
 }
 
-{INTEGER} {
-       char *end;
-
-       errno = 0;
-       yylval->uintval = STRTOUMAX(yytext, &end, 0);
-       if (errno == ERANGE) {
-               cdecl__errmsg(CDECL__ERANGE);
-               return T_LEX_ERROR;
-       }
-       if (*end) {
-               cdecl__errmsg(CDECL__EBADINT);
-               return T_LEX_ERROR;
+0[0-7]* { intconv_base = INTCONV_OCTAL; goto int_parse; }
+[1-9][0-9]* { intconv_base = INTCONV_DECIMAL; goto int_parse; }
+0[Xx][[:xdigit:]]+ {
+       unsigned char d;
+       uintmax_t v;
+
+       yytext += 2;
+       intconv_base = INTCONV_HEXADECIMAL;
+int_parse:
+       for (v = 0; (d = *yytext++);) {
+               if (!intconv_shift(&v, intconv_base, intconv_digit(d))) {
+                       cdecl__errmsg(CDECL__ERANGE);
+                       return T_LEX_ERROR;
+               }
        }
 
+       yylval->uintval = v;
        return T_UINT;
 }
+0[Xx]|[0-9]+ {
+       cdecl__errmsg(CDECL__EBADINT);
+       return T_LEX_ERROR;
+}
 
 {IDENT} {
        int len = yyleng, tok;
@@ -180,7 +174,7 @@ INTEGER 0[Xx][[:xdigit:]]*|[[:digit:]]+
                yyless(strcspn(yytext, "-"));
 #endif
                if (!(yylval->item = cdecl__alloc_item(len+1)))
-                       return T_LEX_ERROR; \
+                       return T_LEX_ERROR;
                memcpy(yylval->item->s, yytext, len+1);
        }
        return UNPACK_TOKEN(tok);