In our various supported host OSes, the time_t type may be either 32
or 64 bit, and could in theory also be either signed or unsigned.
Notably, in OpenBSD time_t is a 64 bit type even if 'long' is 32
bits, so using LONG_MAX for TIME_MAX is incorrect.
Use an approach suggested by Paolo Bonzini which calculates
the maximum value of the type rather than hardcoding it;
to do this we use the TYPE_MAXIMUM macro from Gnulib.
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
include/qemu/osdep.h | 29 ++++++++++++++++++++++++++++-
1 file changed, 28 insertions(+), 1 deletion(-)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index 281782d..e8568a0 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -147,8 +147,35 @@ extern int daemon(int, int);
#if !defined(ESHUTDOWN)
#define ESHUTDOWN 4099
#endif
+
+/* time_t may be either 32 or 64 bits depending on the host OS, and
+ * can be either signed or unsigned, so we can't just hardcode a
+ * specific maximum value. This is not a C preprocessor constant,
+ * so you can't use TIME_MAX in an #ifdef, but for our purposes
+ * this isn't a problem.
+ */
+
+/* The macros TYPE_SIGNED, TYPE_WIDTH, and TYPE_MAXIMUM are from
+ * Gnulib, and are under the LGPL v2.1 or (at your option) any
+ * later version.
+ */
+
+/* True if the real type T is signed. */
+#define TYPE_SIGNED(t) (!((t)0 < (t)-1))
+
+/* The width in bits of the integer type or expression T.
+ * Padding bits are not supported.
+ */
+#define TYPE_WIDTH(t) (sizeof(t) * CHAR_BIT)
+
+/* The maximum and minimum values for the integer type T. */
+#define TYPE_MAXIMUM(t) \
+ ((t) (!TYPE_SIGNED(t) \
+ ? (t)-1 \
+ : ((((t)1 << (TYPE_WIDTH(t) - 2)) - 1) * 2 + 1)))
+
#ifndef TIME_MAX
-#define TIME_MAX LONG_MAX
+#define TIME_MAX TYPE_MAXIMUM(time_t)
#endif
/* HOST_LONG_BITS is the size of a native pointer in bits. */
--
2.7.4
Hi,
This series seems to have some coding style problems. See output below for
more information:
Subject: [Qemu-devel] [PATCH for-2.11?] osdep.h: Make TIME_MAX handle different time_t types
Type: series
Message-id: 1511452598-6077-1-git-send-email-peter.maydell@linaro.org
=== TEST SCRIPT BEGIN ===
#!/bin/bash
BASE=base
n=1
total=$(git log --oneline $BASE.. | wc -l)
failed=0
git config --local diff.renamelimit 0
git config --local diff.renames True
commits="$(git log --format=%H --reverse $BASE..)"
for c in $commits; do
echo "Checking PATCH $n/$total: $(git log -n 1 --format=%s $c)..."
if ! git show $c --format=email | ./scripts/checkpatch.pl --mailback -; then
failed=1
echo
fi
n=$((n+1))
done
exit $failed
=== TEST SCRIPT END ===
Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
From https://github.com/patchew-project/qemu
* [new tag] patchew/1511452598-6077-1-git-send-email-peter.maydell@linaro.org -> patchew/1511452598-6077-1-git-send-email-peter.maydell@linaro.org
Switched to a new branch 'test'
1fc46e38d0 osdep.h: Make TIME_MAX handle different time_t types
=== OUTPUT BEGIN ===
Checking PATCH 1/1: osdep.h: Make TIME_MAX handle different time_t types...
ERROR: spaces required around that '-' (ctx:VxV)
#41: FILE: include/qemu/osdep.h:164:
+#define TYPE_SIGNED(t) (!((t)0 < (t)-1))
^
ERROR: spaces required around that '-' (ctx:VxV)
#51: FILE: include/qemu/osdep.h:174:
+ ? (t)-1 \
^
total: 2 errors, 0 warnings, 36 lines checked
Your patch has style problems, please review. If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.
=== OUTPUT END ===
Test command exited with code: 1
---
Email generated automatically by Patchew [http://patchew.org/].
Please send your feedback to patchew-devel@freelists.org
On 23/11/2017 16:56, Peter Maydell wrote: > In our various supported host OSes, the time_t type may be either 32 > or 64 bit, and could in theory also be either signed or unsigned. > Notably, in OpenBSD time_t is a 64 bit type even if 'long' is 32 > bits, so using LONG_MAX for TIME_MAX is incorrect. > > Use an approach suggested by Paolo Bonzini which calculates > the maximum value of the type rather than hardcoding it; > to do this we use the TYPE_MAXIMUM macro from Gnulib. > > Suggested-by: Paolo Bonzini <pbonzini@redhat.com> > Signed-off-by: Peter Maydell <peter.maydell@linaro.org> > --- > include/qemu/osdep.h | 29 ++++++++++++++++++++++++++++- > 1 file changed, 28 insertions(+), 1 deletion(-) > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > index 281782d..e8568a0 100644 > --- a/include/qemu/osdep.h > +++ b/include/qemu/osdep.h > @@ -147,8 +147,35 @@ extern int daemon(int, int); > #if !defined(ESHUTDOWN) > #define ESHUTDOWN 4099 > #endif > + > +/* time_t may be either 32 or 64 bits depending on the host OS, and > + * can be either signed or unsigned, so we can't just hardcode a > + * specific maximum value. This is not a C preprocessor constant, > + * so you can't use TIME_MAX in an #ifdef, but for our purposes > + * this isn't a problem. > + */ > + > +/* The macros TYPE_SIGNED, TYPE_WIDTH, and TYPE_MAXIMUM are from > + * Gnulib, and are under the LGPL v2.1 or (at your option) any > + * later version. > + */ > + > +/* True if the real type T is signed. */ > +#define TYPE_SIGNED(t) (!((t)0 < (t)-1)) > + > +/* The width in bits of the integer type or expression T. > + * Padding bits are not supported. > + */ > +#define TYPE_WIDTH(t) (sizeof(t) * CHAR_BIT) > + > +/* The maximum and minimum values for the integer type T. */ > +#define TYPE_MAXIMUM(t) \ > + ((t) (!TYPE_SIGNED(t) \ > + ? (t)-1 \ > + : ((((t)1 << (TYPE_WIDTH(t) - 2)) - 1) * 2 + 1))) > + > #ifndef TIME_MAX > -#define TIME_MAX LONG_MAX > +#define TIME_MAX TYPE_MAXIMUM(time_t) > #endif > > /* HOST_LONG_BITS is the size of a native pointer in bits. */ > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
On 23 November 2017 at 16:00, Paolo Bonzini <pbonzini@redhat.com> wrote: > On 23/11/2017 16:56, Peter Maydell wrote: >> In our various supported host OSes, the time_t type may be either 32 >> or 64 bit, and could in theory also be either signed or unsigned. >> Notably, in OpenBSD time_t is a 64 bit type even if 'long' is 32 >> bits, so using LONG_MAX for TIME_MAX is incorrect. >> >> Use an approach suggested by Paolo Bonzini which calculates >> the maximum value of the type rather than hardcoding it; >> to do this we use the TYPE_MAXIMUM macro from Gnulib. >> >> Suggested-by: Paolo Bonzini <pbonzini@redhat.com> >> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> >> --- > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Thanks; applied to master. -- PMM
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