Add visibility rules.

This change marks public symbols as dynamically exported. This means
that it becomes viable to build a shared library of libcrypto and libssl
with -fvisibility=hidden.

On Windows, one not only needs to mark functions for export in a
component, but also for import when using them from a different
component. Because of this we have to build with
|BORINGSSL_IMPLEMENTATION| defined when building the code. Other
components, when including our headers, won't have that defined and then
the |OPENSSL_EXPORT| tag becomes an import tag instead. See the #defines
in base.h

In the asm code, symbols are now hidden by default and those that need
to be exported are wrapped by a C function.

In order to support Chromium, a couple of libssl functions were moved to
ssl.h from ssl_locl.h: ssl_get_new_session and ssl_update_cache.

Change-Id: Ib4b76e2f1983ee066e7806c24721e8626d08a261
Reviewed-on: https://boringssl-review.googlesource.com/1350
Reviewed-by: Adam Langley <agl@google.com>

3 files changed, 33 insertions, 15 deletions

diff --git a/crypto/rc4/asm/rc4-586.pl b/crypto/rc4/asm/rc4-586.pl
index e3f3b044..fc860ae2 100644
--- a/crypto/rc4/asm/rc4-586.pl
+++ b/crypto/rc4/asm/rc4-586.pl
@@ -152,8 +152,8 @@ if ($alt=0) {
 
 &external_label("OPENSSL_ia32cap_P");
 
-# void RC4(RC4_KEY *key,size_t len,const unsigned char *inp,unsigned char *out);
-&function_begin("RC4");
+# void asm_RC4(RC4_KEY *key,size_t len,const unsigned char *inp,unsigned char *out);
+&function_begin("asm_RC4");
 	&mov	($dat,&wparam(0));	# load key schedule pointer
 	&mov	($ty, &wparam(1));	# load len
 	&mov	($inp,&wparam(2));	# load inp
@@ -293,7 +293,7 @@ if ($alt=0) {
 	&mov	(&DWP(-4,$dat),$yy);		# save key->y
 	&mov	(&BP(-8,$dat),&LB($xx));	# save key->x
 &set_label("abort");
-&function_end("RC4");
+&function_end("asm_RC4");
 
 ########################################################################
 
@@ -303,8 +303,8 @@ $idi="ebp";
 $ido="ecx";
 $idx="edx";
 
-# void RC4_set_key(RC4_KEY *key,int len,const unsigned char *data);
-&function_begin("RC4_set_key");
+# void asm_RC4_set_key(RC4_KEY *key,int len,const unsigned char *data);
+&function_begin("asm_RC4_set_key");
 	&mov	($out,&wparam(0));		# load key
 	&mov	($idi,&wparam(1));		# load len
 	&mov	($inp,&wparam(2));		# load data
@@ -382,7 +382,7 @@ $idx="edx";
 	&xor	("eax","eax");
 	&mov	(&DWP(-8,$out),"eax");		# key->x=0;
 	&mov	(&DWP(-4,$out),"eax");		# key->y=0;
-&function_end("RC4_set_key");
+&function_end("asm_RC4_set_key");
 
 # const char *RC4_options(void);
 &function_begin_B("RC4_options");
diff --git a/crypto/rc4/asm/rc4-x86_64.pl b/crypto/rc4/asm/rc4-x86_64.pl
index a5b2216a..797ae13f 100644
--- a/crypto/rc4/asm/rc4-x86_64.pl
+++ b/crypto/rc4/asm/rc4-x86_64.pl
@@ -125,10 +125,11 @@ $code=<<___;
 .text
 .extern	OPENSSL_ia32cap_P
 
-.globl	RC4
-.type	RC4,\@function,4
+.globl	asm_RC4
+.type	asm_RC4,\@function,4
 .align	16
-RC4:	or	$len,$len
+asm_RC4:
+	or	$len,$len
 	jne	.Lentry
 	ret
 .Lentry:
@@ -423,7 +424,7 @@ $code.=<<___;
 	add	\$24,%rsp
 .Lepilogue:
 	ret
-.size	RC4,.-RC4
+.size	asm_RC4,.-asm_RC4
 ___
 }
 
@@ -431,10 +432,10 @@ $idx="%r8";
 $ido="%r9";
 
 $code.=<<___;
-.globl	RC4_set_key
-.type	RC4_set_key,\@function,3
+.globl	asm_RC4_set_key
+.type	asm_RC4_set_key,\@function,3
 .align	16
-RC4_set_key:
+asm_RC4_set_key:
 	lea	8($dat),$dat
 	lea	($inp,$len),$inp
 	neg	$len
@@ -502,7 +503,7 @@ RC4_set_key:
 	mov	%eax,-8($dat)
 	mov	%eax,-4($dat)
 	ret
-.size	RC4_set_key,.-RC4_set_key
+.size	asm_RC4_set_key,.-asm_RC4_set_key
 
 .globl	RC4_options
 .type	RC4_options,\@abi-omnipotent
diff --git a/crypto/rc4/rc4.c b/crypto/rc4/rc4.c
index a93f96ed..ec3de231 100644
--- a/crypto/rc4/rc4.c
+++ b/crypto/rc4/rc4.c
@@ -345,4 +345,21 @@ void RC4_set_key(RC4_KEY *rc4key, unsigned len, const uint8_t *key) {
   }
 }
 
-#endif
+#else
+
+/* In this case several functions are provided by asm code. However, one cannot
+ * control asm symbol visibility with command line flags and such so they are
+ * always hidden and wrapped by these C functions, which can be so
+ * controlled. */
+
+void asm_RC4(RC4_KEY *key, size_t len, const uint8_t *in, uint8_t *out);
+void RC4(RC4_KEY *key, size_t len, const uint8_t *in, uint8_t *out) {
+  asm_RC4(key, len, in, out);
+}
+
+void asm_RC4_set_key(RC4_KEY *rc4key, unsigned len, const uint8_t *key);
+void RC4_set_key(RC4_KEY *rc4key, unsigned len, const uint8_t *key) {
+  RC4_set_key(rc4key, len, key);
+}
+
+#endif  /* OPENSSL_NO_ASM || (!OPENSSL_X86_64 && !OPENSSL_X86) */