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Re: [PATCH] array_length, array_end macros for internal use
- From: Florian Weimer <fweimer at redhat dot com>
- To: libc-alpha at sourceware dot org
- Date: Mon, 30 Oct 2017 13:58:35 +0100
- Subject: Re: [PATCH] array_length, array_end macros for internal use
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Any further comments on this patch?
Thanks,
Florian
2017-10-21 Florian Weimer <fweimer@redhat.com>
Add array_length and array_end macros.
* include/array_length.h: New file.
* stdio-common/bug16.c (do_test): Use array_length.
* stdio-common/errlist.c (_sys_nerr): Likewise.
* stdio-common/printf_fp.c (PRINTF_FP_FETCH): Likewise.
* stdio-common/printf_fphex.c (__printf_fphex): Use array_end.
* stdio-common/psiginfo.c (psiginfo): Use array_length.
* stdio-common/test-vfprintf.c (nlocs): Remove definition.
(do_test): Use array_length.
* stdio-common/tst-fphex.c (do_test): Use array_end, array_length.
* stdio-common/tst-long-dbl-fphex.c (do_test): Use array_length.
* stdio-common/tst-printf-round.c (do_test): Likewise.
* stdio-common/tst-swprintf.c (nbuf): Remove definition.
(CHECK): Use array_length.
* stdio-common/tstdiomisc.c (t3, F): Likewise.
* stdio-common/tstscanf.c (main): Likewise.
* stdio-common/vfprintf.c (process_string_arg): Likewise.
diff --git a/include/array_length.h b/include/array_length.h
new file mode 100644
index 0000000000..0bcc52bb14
--- /dev/null
+++ b/include/array_length.h
@@ -0,0 +1,36 @@
+/* The array_length and array_end macros.
+ Copyright (C) 1991-2017 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library 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
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#ifndef _ARRAY_LENGTH_H
+#define _ARRAY_LENGTH_H
+
+/* array_length (VAR) is the number of elements in the array VAR. VAR
+ must evaluate to an array, not a pointer. */
+#define array_length(var) \
+ __extension__ ({ \
+ _Static_assert (!__builtin_types_compatible_p \
+ (__typeof (var), __typeof (&(var)[0])), \
+ "argument must be an array"); \
+ sizeof (var) / sizeof ((var)[0]); \
+ })
+
+/* array_end (VAR) is a pointer one past the end of the array VAR.
+ VAR must evaluate to an array, not a pointer. */
+#define array_end(var) (&(var)[array_length (var)])
+
+#endif /* _ARRAY_LENGTH_H */
diff --git a/stdio-common/bug16.c b/stdio-common/bug16.c
index 1112c39d05..91bc452826 100644
--- a/stdio-common/bug16.c
+++ b/stdio-common/bug16.c
@@ -1,3 +1,4 @@
+#include <array_length.h>
#include <stdio.h>
#include <string.h>
@@ -19,7 +20,7 @@ do_test (void)
char buf[100];
int ret = 0;
- for (size_t i = 0; i < sizeof (tests) / sizeof (tests[0]); ++i)
+ for (size_t i = 0; i < array_length (tests); ++i)
{
snprintf (buf, sizeof (buf), "%.0LA", tests[i].val);
diff --git a/stdio-common/errlist.c b/stdio-common/errlist.c
index 0f1b72b37d..e8d0f62519 100644
--- a/stdio-common/errlist.c
+++ b/stdio-common/errlist.c
@@ -15,9 +15,9 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <array_length.h>
#include <stddef.h>
-
const char *const _sys_errlist[] =
{
"Error 0", /* 0 */
@@ -33,4 +33,4 @@ const char *const _sys_errlist[] =
"Too many open files", /* 10 = EMFILE */
};
-const int _sys_nerr = sizeof (_sys_errlist) / sizeof (_sys_errlist[0]);
+const int _sys_nerr = array_length (_sys_errlist);
diff --git a/stdio-common/printf_fp.c b/stdio-common/printf_fp.c
index 994497cd22..52ba46bd08 100644
--- a/stdio-common/printf_fp.c
+++ b/stdio-common/printf_fp.c
@@ -21,6 +21,7 @@
/* The gmp headers need some configuration frobs. */
#define HAVE_ALLOCA 1
+#include <array_length.h>
#include <libioP.h>
#include <alloca.h>
#include <ctype.h>
@@ -371,8 +372,7 @@ __printf_fp_l (FILE *fp, locale_t loc,
else \
{ \
p.fracsize = __mpn_extract_##SUFFIX \
- (fp_input, \
- (sizeof (fp_input) / sizeof (fp_input[0])), \
+ (fp_input, array_length (fp_input), \
&p.exponent, &is_neg, VAR); \
to_shift = 1 + p.fracsize * BITS_PER_MP_LIMB - MANT_DIG; \
} \
diff --git a/stdio-common/printf_fphex.c b/stdio-common/printf_fphex.c
index 004d2aa716..938b0b32e0 100644
--- a/stdio-common/printf_fphex.c
+++ b/stdio-common/printf_fphex.c
@@ -17,6 +17,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <array_length.h>
#include <ctype.h>
#include <ieee754.h>
#include <math.h>
@@ -320,8 +321,8 @@ __printf_fphex (FILE *fp,
/* Look for trailing zeroes. */
if (! zero_mantissa)
{
- wnumend = &wnumbuf[sizeof wnumbuf / sizeof wnumbuf[0]];
- numend = &numbuf[sizeof numbuf / sizeof numbuf[0]];
+ wnumend = array_end (wnumbuf);
+ numend = array_end (numbuf);
while (wnumend[-1] == L'0')
{
--wnumend;
diff --git a/stdio-common/psiginfo.c b/stdio-common/psiginfo.c
index 7bf2e2d13f..b9c455b8f5 100644
--- a/stdio-common/psiginfo.c
+++ b/stdio-common/psiginfo.c
@@ -15,6 +15,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <array_length.h>
#include <errno.h>
#include <libintl.h>
#include <signal.h>
@@ -116,7 +117,7 @@ psiginfo (const siginfo_t *pinfo, const char *s)
case sig: \
base = C(codestrs_, sig).str; \
offarr = C (codes_, sig); \
- offarr_len = sizeof (C (codes_, sig)) / sizeof (C (codes_, sig)[0]);\
+ offarr_len = array_length (C (codes_, sig)); \
break
H (SIGILL);
diff --git a/stdio-common/test-vfprintf.c b/stdio-common/test-vfprintf.c
index f8bb9cee58..0fcc1adc0e 100644
--- a/stdio-common/test-vfprintf.c
+++ b/stdio-common/test-vfprintf.c
@@ -17,6 +17,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <array_length.h>
#include <locale.h>
#include <mcheck.h>
#include <stdint.h>
@@ -32,8 +33,6 @@ const char *locs[] =
{
"C", "de_DE.ISO-8859-1", "de_DE.UTF-8", "ja_JP.EUC-JP"
};
-#define nlocs (sizeof (locs) / sizeof (locs[0]))
-
char large[50000];
@@ -56,7 +55,7 @@ do_test (void)
}
unlink (buf);
- for (i = 0; i < nlocs; ++i)
+ for (i = 0; i < array_length (locs); ++i)
{
FILE *fp;
struct stat st;
diff --git a/stdio-common/tst-fphex.c b/stdio-common/tst-fphex.c
index c2e8961d62..efba482537 100644
--- a/stdio-common/tst-fphex.c
+++ b/stdio-common/tst-fphex.c
@@ -1,5 +1,6 @@
/* Test program for %a printf formats. */
+#include <array_length.h>
#include <stdio.h>
#include <string.h>
@@ -49,12 +50,10 @@ do_test (void)
const struct testcase *t;
int result = 0;
- for (t = testcases;
- t < &testcases[sizeof testcases / sizeof testcases[0]];
- ++t)
+ for (t = testcases; t < array_end (testcases); ++t)
{
CHAR_T buf[1024];
- int n = SPRINT (buf, sizeof buf / sizeof (buf[0]), t->fmt, t->value);
+ int n = SPRINT (buf, array_length (buf), t->fmt, t->value);
if (n != STR_LEN (t->expect) || STR_CMP (buf, t->expect) != 0)
{
PRINT (L_("" S "\tExpected \"" S "\" (%Zu)\n\tGot \""
diff --git a/stdio-common/tst-long-dbl-fphex.c b/stdio-common/tst-long-dbl-fphex.c
index 1170c74c4c..6a402a1c89 100644
--- a/stdio-common/tst-long-dbl-fphex.c
+++ b/stdio-common/tst-long-dbl-fphex.c
@@ -16,6 +16,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <array_length.h>
#include <wchar.h>
/* Prototype for our test function. */
@@ -28,9 +29,9 @@ do_test (void)
int result = 0;
const long double x = 24.5;
wchar_t a[16];
- swprintf (a, sizeof a / sizeof a[0], L"%La\n", x);
+ swprintf (a, array_length (a), L"%La\n", x);
wchar_t A[16];
- swprintf (A, sizeof A / sizeof A[0], L"%LA\n", x);
+ swprintf (A, array_length (a), L"%LA\n", x);
/* Here wprintf can return four valid variants. We must accept all
of them. */
diff --git a/stdio-common/tst-printf-round.c b/stdio-common/tst-printf-round.c
index e0073f2856..a5db3b88c2 100644
--- a/stdio-common/tst-printf-round.c
+++ b/stdio-common/tst-printf-round.c
@@ -16,6 +16,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <array_length.h>
#include <fenv.h>
#include <stdio.h>
#include <string.h>
@@ -167,7 +168,7 @@ do_test (void)
int save_round_mode __attribute__ ((unused)) = fegetround ();
int result = 0;
- for (size_t i = 0; i < sizeof (dec_tests) / sizeof (dec_tests[0]); i++)
+ for (size_t i = 0; i < array_length (dec_tests); i++)
{
result |= test_dec_in_one_mode (dec_tests[i].d, dec_tests[i].fmt,
dec_tests[i].rn, "default rounding mode");
@@ -197,7 +198,7 @@ do_test (void)
#endif
}
- for (size_t i = 0; i < sizeof (hex_tests) / sizeof (hex_tests[0]); i++)
+ for (size_t i = 0; i < array_length (hex_tests); i++)
{
result |= test_hex_in_one_mode (hex_tests[i].d, hex_tests[i].fmt,
hex_tests[i].rn, "default rounding mode");
diff --git a/stdio-common/tst-sscanf.c b/stdio-common/tst-sscanf.c
index c070e14cd7..9ccd86e7b0 100644
--- a/stdio-common/tst-sscanf.c
+++ b/stdio-common/tst-sscanf.c
@@ -16,6 +16,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <array_length.h>
#include <stdlib.h>
#include <stdio.h>
#include <locale.h>
@@ -184,7 +185,7 @@ do_test (void)
break;
}
- for (i = 0; i < sizeof (int_tests) / sizeof (int_tests[0]); ++i)
+ for (i = 0; i < array_length (int_tests); ++i)
{
long dummy;
int ret;
@@ -198,7 +199,7 @@ do_test (void)
}
}
- for (i = 0; i < sizeof (double_tests) / sizeof (double_tests[0]); ++i)
+ for (i = 0; i < array_length (double_tests); ++i)
{
double dummy;
int ret;
@@ -212,7 +213,7 @@ do_test (void)
}
}
- for (i = 0; i < sizeof (double_tests2) / sizeof (double_tests2[0]); ++i)
+ for (i = 0; i < array_length (double_tests2); ++i)
{
double dummy;
int ret;
diff --git a/stdio-common/tst-swprintf.c b/stdio-common/tst-swprintf.c
index ce62c6bf68..07194eb67d 100644
--- a/stdio-common/tst-swprintf.c
+++ b/stdio-common/tst-swprintf.c
@@ -1,3 +1,4 @@
+#include <array_length.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
@@ -16,7 +17,6 @@ static int
do_test (void)
{
wchar_t buf[1000];
-#define nbuf (sizeof (buf) / sizeof (buf[0]))
int result = 0;
ssize_t n;
@@ -27,7 +27,7 @@ do_test (void)
}
#define CHECK(fmt, nexp, exp) \
- n = swprintf (buf, nbuf, fmt, input); \
+ n = swprintf (buf, array_length (buf), fmt, input); \
if (n != nexp) \
{ \
printf ("swprintf (.., .., L\"%ls\", \"%ls\") return %d, not %d\n", \
diff --git a/stdio-common/tstdiomisc.c b/stdio-common/tstdiomisc.c
index 89009e0549..c2fc73deb1 100644
--- a/stdio-common/tstdiomisc.c
+++ b/stdio-common/tstdiomisc.c
@@ -1,3 +1,4 @@
+#include <array_length.h>
#include <float.h>
#include <math.h>
#include <stdio.h>
@@ -66,8 +67,7 @@ t3 (void)
retval = sprintf (buf, "%p", (char *) NULL);
result |= retval != 5 || strcmp (buf, "(nil)") != 0;
- retval = swprintf (wbuf, sizeof (wbuf) / sizeof (wbuf[0]),
- L"%p", (char *) NULL);
+ retval = swprintf (wbuf, array_length (wbuf), L"%p", (char *) NULL);
result |= retval != 5 || wcscmp (wbuf, L"(nil)") != 0;
return result;
@@ -142,38 +142,38 @@ F (void)
printf ("expected \"-inf -INF -inf -INF -inf -INF -inf -INF\", got \"%s\"\n",
buf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]), L"%a %A %e %E %f %F %g %G",
+ swprintf (wbuf, array_length (wbuf), L"%a %A %e %E %f %F %g %G",
qnanval, qnanval, qnanval, qnanval,
qnanval, qnanval, qnanval, qnanval);
result |= wcscmp (wbuf, L"nan NAN nan NAN nan NAN nan NAN") != 0;
printf ("expected L\"nan NAN nan NAN nan NAN nan NAN\", got L\"%S\"\n", wbuf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]), L"%a %A %e %E %f %F %g %G",
+ swprintf (wbuf, array_length (wbuf), L"%a %A %e %E %f %F %g %G",
-qnanval, -qnanval, -qnanval, -qnanval,
-qnanval, -qnanval, -qnanval, -qnanval);
result |= wcscmp (wbuf, L"-nan -NAN -nan -NAN -nan -NAN -nan -NAN") != 0;
printf ("expected L\"-nan -NAN -nan -NAN -nan -NAN -nan -NAN\", got L\"%S\"\n",
wbuf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]), L"%a %A %e %E %f %F %g %G",
+ swprintf (wbuf, array_length (wbuf), L"%a %A %e %E %f %F %g %G",
snanval, snanval, snanval, snanval,
snanval, snanval, snanval, snanval);
result |= wcscmp (wbuf, L"nan NAN nan NAN nan NAN nan NAN") != 0;
printf ("expected L\"nan NAN nan NAN nan NAN nan NAN\", got L\"%S\"\n", wbuf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]), L"%a %A %e %E %f %F %g %G",
+ swprintf (wbuf, array_length (wbuf), L"%a %A %e %E %f %F %g %G",
msnanval, msnanval, msnanval, msnanval,
msnanval, msnanval, msnanval, msnanval);
result |= wcscmp (wbuf, L"-nan -NAN -nan -NAN -nan -NAN -nan -NAN") != 0;
printf ("expected L\"-nan -NAN -nan -NAN -nan -NAN -nan -NAN\", got L\"%S\"\n",
wbuf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]), L"%a %A %e %E %f %F %g %G",
+ swprintf (wbuf, array_length (wbuf), L"%a %A %e %E %f %F %g %G",
infval, infval, infval, infval, infval, infval, infval, infval);
result |= wcscmp (wbuf, L"inf INF inf INF inf INF inf INF") != 0;
printf ("expected L\"inf INF inf INF inf INF inf INF\", got L\"%S\"\n", wbuf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]), L"%a %A %e %E %f %F %g %G",
+ swprintf (wbuf, array_length (wbuf), L"%a %A %e %E %f %F %g %G",
-infval, -infval, -infval, -infval,
-infval, -infval, -infval, -infval);
result |= wcscmp (wbuf, L"-inf -INF -inf -INF -inf -INF -inf -INF") != 0;
@@ -223,14 +223,14 @@ F (void)
printf ("expected \"-inf -INF -inf -INF -inf -INF -inf -INF\", got \"%s\"\n",
buf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]),
+ swprintf (wbuf, array_length (wbuf),
L"%La %LA %Le %LE %Lf %LF %Lg %LG",
lqnanval, lqnanval, lqnanval, lqnanval,
lqnanval, lqnanval, lqnanval, lqnanval);
result |= wcscmp (wbuf, L"nan NAN nan NAN nan NAN nan NAN") != 0;
printf ("expected L\"nan NAN nan NAN nan NAN nan NAN\", got L\"%S\"\n", wbuf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]),
+ swprintf (wbuf, array_length (wbuf),
L"%La %LA %Le %LE %Lf %LF %Lg %LG",
-lqnanval, -lqnanval, -lqnanval, -lqnanval,
-lqnanval, -lqnanval, -lqnanval, -lqnanval);
@@ -238,14 +238,14 @@ F (void)
printf ("expected L\"-nan -NAN -nan -NAN -nan -NAN -nan -NAN\", got L\"%S\"\n",
wbuf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]),
+ swprintf (wbuf, array_length (wbuf),
L"%La %LA %Le %LE %Lf %LF %Lg %LG",
lsnanval, lsnanval, lsnanval, lsnanval,
lsnanval, lsnanval, lsnanval, lsnanval);
result |= wcscmp (wbuf, L"nan NAN nan NAN nan NAN nan NAN") != 0;
printf ("expected L\"nan NAN nan NAN nan NAN nan NAN\", got L\"%S\"\n", wbuf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]),
+ swprintf (wbuf, array_length (wbuf),
L"%La %LA %Le %LE %Lf %LF %Lg %LG",
lmsnanval, lmsnanval, lmsnanval, lmsnanval,
lmsnanval, lmsnanval, lmsnanval, lmsnanval);
@@ -253,14 +253,14 @@ F (void)
printf ("expected L\"-nan -NAN -nan -NAN -nan -NAN -nan -NAN\", got L\"%S\"\n",
wbuf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]),
+ swprintf (wbuf, array_length (wbuf),
L"%La %LA %Le %LE %Lf %LF %Lg %LG",
linfval, linfval, linfval, linfval,
linfval, linfval, linfval, linfval);
result |= wcscmp (wbuf, L"inf INF inf INF inf INF inf INF") != 0;
printf ("expected L\"inf INF inf INF inf INF inf INF\", got L\"%S\"\n", wbuf);
- swprintf (wbuf, sizeof wbuf / sizeof (wbuf[0]),
+ swprintf (wbuf, array_length (wbuf),
L"%La %LA %Le %LE %Lf %LF %Lg %LG",
-linfval, -linfval, -linfval, -linfval,
-linfval, -linfval, -linfval, -linfval);
diff --git a/stdio-common/tstscanf.c b/stdio-common/tstscanf.c
index 50d0f33acf..d2ef4e8dee 100644
--- a/stdio-common/tstscanf.c
+++ b/stdio-common/tstscanf.c
@@ -15,6 +15,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <array_length.h>
#ifdef BSD
#include </usr/include/stdio.h>
#else
@@ -154,7 +155,7 @@ main (int argc, char **argv)
{
int count;
- if (rounds++ >= sizeof (ok) / sizeof (ok[0]))
+ if (rounds++ >= array_length (ok))
{
fputs ("test failed!\n", stdout);
result = 1;
diff --git a/stdio-common/vfprintf.c b/stdio-common/vfprintf.c
index 23d2679f39..e272237307 100644
--- a/stdio-common/vfprintf.c
+++ b/stdio-common/vfprintf.c
@@ -15,6 +15,7 @@
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
+#include <array_length.h>
#include <ctype.h>
#include <limits.h>
#include <printf.h>
@@ -995,11 +996,10 @@ static const uint8_t jump_table[] =
if (string == NULL) \
{ \
/* Write "(null)" if there's space. */ \
- if (prec == -1 \
- || prec >= (int) (sizeof (null) / sizeof (null[0])) - 1) \
+ if (prec == -1 || prec >= (int) array_length (null) - 1) \
{ \
string = (CHAR_T *) null; \
- len = (sizeof (null) / sizeof (null[0])) - 1; \
+ len = array_length (null) - 1; \
} \
else \
{ \