114 lines
3.3 KiB
Diff
114 lines
3.3 KiB
Diff
From 062c1a54b295b4ff387ebdff84a6a957fccbefd4 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?=C4=90o=C3=A0n=20Tr=E1=BA=A7n=20C=C3=B4ng=20Danh?=
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<congdanhqx@gmail.com>
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Date: Sun, 17 May 2020 22:44:25 +0700
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Subject: [PATCH 5/7] libevent: use compile time sizeof check
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Taken from https://github.com/scons/scons/wiki/AutoconfRecipes#ac_check_sizeof
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---
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src/libevent/SConscript | 81 +++++++++++++++++++++++++++++++++++++----
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1 file changed, 73 insertions(+), 8 deletions(-)
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diff --git src/libevent/SConscript src/libevent/SConscript
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index 1197b8d3..ab1f72ad 100644
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--- src/libevent/SConscript
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+++ src/libevent/SConscript
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@@ -18,22 +18,87 @@ conf.AddTest('CheckSYS_TIMERFD_H', CheckSYS_TIMERFD_H)
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# sizeof
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+# https://github.com/scons/scons/wiki/AutoconfRecipes#ac_check_sizeof
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+# Sensible default for common types on common platforms.
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+_DEFAULTS_SIZEOF = {
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+ 'short' : [2],
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+ 'int' : [4, 2],
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+ 'long' : [4, 8],
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+ 'long long' : [8, 4],
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+ 'unsigned short' : [2],
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+ 'unsigned int' : [4, 2],
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+ 'unsigned long' : [4, 8],
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+ 'unsigned long long' : [8, 4],
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+ 'float' : [4],
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+ 'double' : [8],
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+ 'long double' : [12],
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+ 'size_t' : [4, 8],
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+}
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+
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def CheckSizeOf(ctx, type, includes = None):
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+ """This check can be used to get the size of a given type,
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+ or to check whether the type is of expected size.
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+
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+ Arguments:
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+ - type : str
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+ the type to check
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+ - includes : sequence
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+ list of headers to include in the test code before testing the type
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+ Returns:
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+ status : int
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+ 0 if the check failed, or the found size of the type
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+ if the check succeeded."""
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+ minsz = 0
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+ maxsz = 16
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+
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src = '''
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#include <sys/types.h>
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#include <stdlib.h>
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#include <stdio.h>
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- int main() {printf("%d", (int)sizeof(''' + type + ''')); return 0;}
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+ #include <stdint.h>
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'''
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+ if includes:
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+ src += "\n".join("#include <%s>\n" % i for i in includes)
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- if includes is not None:
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- for inc in includes:
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- src = '#include <%s>\n%s' % (inc, src)
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+ ext = '.c'
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+ # test code taken from autoconf: this is a pretty clever hack to find that
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+ # a type is of a given size using only compilation. This speeds things up
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+ # quite a bit compared to straightforward code using TryRun
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+ src += r"""
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+typedef %s scons_check_type;
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- ctx.Message('Checking size of ' + type + '... ')
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- ret = ctx.TryRun(src + '\n', '.c')
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- ctx.Result(ret[0])
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- return ret[1]
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+int main()
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+{
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+ static int test_array[1 - 2 * ((long int) sizeof(scons_check_type) > %d)];
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+ test_array[0] = 0;
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+
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+ return 0;
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+}
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+"""
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+
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+ # Only check if the given size is the right one
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+ ctx.Message('Checking size of %s ... ' % type)
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+
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+ # Try sensible defaults first
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+ try:
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+ szrange = _DEFAULTS_SIZEOF[type]
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+ except KeyError:
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+ szrange = []
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+ szrange.extend(range(minsz, maxsz))
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+ st = 0
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+
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+ # Actual test
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+ for sz in szrange:
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+ st = ctx.TryCompile(src % (type, sz), ext)
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+ if st:
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+ break
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+
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+ if st:
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+ ctx.Result('%d' % sz)
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+ return sz
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+ else:
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+ ctx.Result('Failed !')
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+ return 0
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conf.AddTest('CheckSizeOf', CheckSizeOf)
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--
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2.27.0.rc1.5.gae92ac8ae3
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