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m4/check-libc.m4: improve getentropy check

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- according to man.openbsd.org getentropy() is in unistd.h

- according to macOS sierra's man it's in sys/random.h

- since sys/random.h is does not exist for iOS and for linux, do
  not attempt to include it, rather redeclare the prototype

- make sure that `./configure`:

    - uses getentropy() on macOS sierra

    - does not use getentropy() if compiling for 10.11

    - does not use getentropy() if compiling for ios armv7
This commit is contained in:
Simone Basso 2016-12-09 13:21:37 +01:00
parent f8a9c71e79
commit 6fa2d21ba5
1 changed files with 23 additions and 17 deletions
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40
m4/check-libc.m4
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@ -52,10 +52,27 @@ AC_CHECK_FUNCS([explicit_bzero getauxval])
AC_CACHE_CHECK([for getentropy], ac_cv_func_getentropy, [
AC_LINK_IFELSE([AC_LANG_PROGRAM([[
#include <sys/types.h>
#include <sys/random.h>
#include <unistd.h>
#ifdef __APPLE__
# include <AvailabilityMacros.h>
# include <TargetConditionals.h>
# if (TARGET_OS_IPHONE || TARGET_OS_SIMULATOR)
/*
* As of iOS 10.1, getentropy() as a system call is defined but is not
* declared in sys/random.h and submitting an App that links to getentropy()
* leads to the App store rejecting the App because:
*
* > The app references non-public symbols in $appname: _getentropy
*
* Disabling the check for getentropy() and thus enabling libressl own
* emulation of that fixes the issue.
*/
# error "As far as we know, getentropy() is not usable on iOS"
# else
/*
* Before macOS 10.12 getentropy() was not available. In 10.12 however it
@ -78,24 +95,13 @@ AC_CACHE_CHECK([for getentropy], ac_cv_func_getentropy, [
# error "Running on Mac OSX 10.11 or earlier"
# endif
# endif
#endif
/*
* As of iOS 10.1, getentropy() as a system call is defined but is not
* declared in sys/random.h and submitting an App that links to getentropy()
* leads to the App store rejecting the App because:
*
* > The app references non-public symbols in $appname: _getentropy
*
* Disabling the check for getentropy() and thus enabling libressl own
* emulation of that fixes the issue.
*/
#if (defined TARGET_IPHONE_OS || defined TARGET_IPHONE_SIMULATOR)
# error "As far as we know, getentropy() is not usable on iOS"
#endif
# endif
#endif /* __APPLE__ */
]], [[
char buffer[1024];
(void)getentropy(buffer, sizeof (buffer));
extern int getentropy(void *, size_t);
char buffer;
(void)getentropy(&buffer, sizeof (buffer));
]])],
[ ac_cv_func_getentropy="yes" ],
[ ac_cv_func_getentropy="no"