30eda1d2b8
Apart from the obvious little issues, this also works around a
(seeming) libtool/linker:
a.c defines a symbol:
int kFoo;
b.c uses it:
extern int kFoo;
int f() {
return kFoo;
}
compile them:
$ gcc -c a.c
$ gcc -c b.c
and create a dummy main in order to run it, main.c:
int f();
int main() {
return f();
}
this works as expected:
$ gcc main.c a.o b.o
but, if we make an archive:
$ ar q lib.a a.o b.o
and use that:
$ gcc main.c lib.a
Undefined symbols for architecture x86_64
"_kFoo", referenced from:
_f in lib.a(b.o)
(It doesn't matter what order the .o files are put into the .a)
Linux and Windows don't seem to have this problem.
nm on a.o shows that the symbol is of type "C", which is a "common symbol"[1].
Basically the linker will merge multiple common symbol definitions together.
If ones makes a.c read:
int kFoo = 0;
Then one gets a type "D" symbol - a "data section symbol" and everything works
just fine.
This might actually be a libtool bug instead of an ld bug: Looking at `xxd
lib.a | less`, the __.SYMDEF SORTED index at the beginning of the archive
doesn't contain an entry for kFoo unless initialised.
Change-Id: I4cdad9ba46e9919221c3cbd79637508959359427
147 lines
5.6 KiB
C
147 lines
5.6 KiB
C
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.] */
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#if !defined(__STDC_FORMAT_MACROS)
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#define __STDC_FORMAT_MACROS
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#endif
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#include <openssl/cpu.h>
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#if defined(OPENSSL_X86) || defined(OPENSSL_X86_64)
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#include <stdio.h>
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#include <inttypes.h>
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/* This value must be explicitly initialised to zero in order to work around a
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* bug in libtool or the linker on OS X.
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*
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* If not initialised then it becomes a "common symbol". When put into an
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* archive, linking on OS X will fail to resolve common symbols. By
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* initialising it to zero, it becomes a "data symbol", which isn't so
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* affected. */
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uint32_t OPENSSL_ia32cap_P[4] = {0};
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/* OPENSSL_ia32_cpuid is defined in cpu-x86_64-asm.pl. */
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extern uint64_t OPENSSL_ia32_cpuid(uint32_t*);
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#if !defined(OPENSSL_WINDOWS)
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void OPENSSL_cpuid_setup(void) __attribute__ ((constructor));
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#endif
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/* handle_cpu_env applies the value from |in| to the CPUID values in |out[0]|
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* and |out[1]|. See the comment in |OPENSSL_cpuid_setup| about this. */
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static void handle_cpu_env(uint32_t *out, const char *in) {
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const int invert = in[0] == '~';
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uint64_t v;
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if (!sscanf(in + invert, "%" PRIi64, &v)) {
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return;
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}
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if (invert) {
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out[0] &= ~v;
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out[1] &= ~(v >> 32);
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} else {
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out[0] = v;
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out[1] = v >> 32;
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}
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}
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#if defined(OPENSSL_WINDOWS)
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#pragma section(".CRT$XCU", read)
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void __cdecl OPENSSL_cpuid_setup(void);
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__declspec(allocate(".CRT$XCU")) void(*cpuid_constructor)(void) = OPENSSL_cpuid_setup;
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void __cdecl OPENSSL_cpuid_setup(void) {
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#else
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void OPENSSL_cpuid_setup(void) {
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#endif
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const char *env1, *env2;
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#if defined(OPENSSL_X86_64)
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OPENSSL_ia32_cpuid(OPENSSL_ia32cap_P);
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#else
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uint64_t vec = OPENSSL_ia32_cpuid(OPENSSL_ia32cap_P);
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/* 1<<10 sets a reserved bit to indicate that the variable
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* was already initialised. */
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OPENSSL_ia32cap_P[0] = ((uint32_t)vec) | (1 << 10);
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OPENSSL_ia32cap_P[1] = vec >> 32;
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#endif
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env1 = getenv("OPENSSL_ia32cap");
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if (env1 == NULL) {
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return;
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}
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/* OPENSSL_ia32cap can contain zero, one or two values, separated with a ':'.
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* Each value is a 64-bit, unsigned value which may start with "0x" to
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* indicate a hex value. Prior to the 64-bit value, a '~' may be given.
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*
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* If '~' isn't present, then the value is taken as the result of the CPUID.
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* Otherwise the value is inverted and ANDed with the probed CPUID result.
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*
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* The first value determines OPENSSL_ia32cap_P[0] and [1]. The second [2]
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* and [3]. */
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handle_cpu_env(&OPENSSL_ia32cap_P[0], env1);
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env2 = strchr(env1, ':');
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if (env2 != NULL) {
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handle_cpu_env(&OPENSSL_ia32cap_P[2], env2 + 1);
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}
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}
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#endif /* OPENSSL_X86 || OPENSSL_X86_64 */
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