Fix solink and add a postsolink hook (use the hook for android strip)

build/toolchain/gcc_toolchain.gni

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This template defines a GCC toolchain.
 #
 # It requires the following variables specifying the executables to run:
 #  - cc
 #  - cxx
 #  - ar
@@ skipping 62 matching lines @@
       depfile = "\$out.d"
       deps = "gcc"
     }
     tool("alink") {
       command = "rm -f \$out && $ar rcs \$out @\$rspfile"
       description = "AR \$out"
       rspfile = "\$out.rsp"
       rspfile_content = "\$in"
     }
     tool("solink") {
-      command = "if [ ! -e \$lib -o ! -e \${lib}.TOC ]; then $ld -shared \$ldflags -o \$lib -Wl,-soname=\$soname @\$rspfile && { readelf -d \${lib} | grep SONAME ; nm -gD -f p \${lib} | cut -f1-2 -d' '; } > \${lib}.TOC; else $ld -shared \$ldflags -o \$lib -Wl,-soname=\$soname -Wl,--whole-archive \$in \$solibs -Wl,--no-whole-archive $libs_section_prefix \$libs $libs_section_postfix && { readelf -d \${lib} | grep SONAME ; nm -gD -f p \${lib} | cut -f1-2 -d' '; } > \${lib}.tmp && if ! cmp -s \${lib}.tmp \${lib}.TOC; then mv \${lib}.tmp \${lib}.TOC ; fi; fi"
+      rspfile = "\$out.rsp"
+      rspfile_content = "-Wl,--whole-archive \$in \$solibs -Wl,--no-whole-archive $libs_section_prefix \$libs $libs_section_postfix"
+
+      # TODO(cjhopman): There needs to be a way for gn to correctly figure out
+      # the outputs of a solink command.

[cjhopman, 2014/07/07 23:00:50]

Currently, it looks like gn doesn't know about the .TOC output at all. I don't
know what the plan for that is. That is more complicated then just specifying it
as an output of these actions, though, since it should actually be used as the
inputs to other libraries (instead of the .so file).

Still, if there is no way for this "tool" to specify its outputs, then there's
no good way for the postsolink hook below to add outputs (or rather, there's no
way for ninja to know about such added outputs).

[brettw, 2014/07/08 22:06:54]

I don't know the plan for this either, something we need to figure out.
Currently the outputs and such are hardcoded.

+
+      link_command = "$ld -shared \$ldflags -o \$lib -Wl,-soname=\$soname $rspfile_content"
+      toc_command = "{ readelf -d \${lib} | grep SONAME ; nm -gD -f p \${lib} | cut -f1-2 -d' '; } > \${lib}.tmp"
+      replace_command = "if ! cmp -s \${lib}.tmp \${lib}.TOC; then mv \${lib}.tmp \${lib}.TOC; fi"
+      command = "$link_command && $toc_command && $replace_command"

[cjhopman, 2014/07/07 23:00:50]

This is slightly different from the previous version. That one would be
something like:

$if_not_exists; then $link_command && $toc_command > \${lib}.TOC; else
$link_command && $toc_command > \${lib}.tmp && replace_command; fi

Afaict, `cmp` will fail if a file doesn't exist and so there isn't really a need
for the if/else.

It's possible that there is some platform where this doesn't do what I expect,
though (mac maybe?).

+
+      if (defined(invoker.postsolink)) {

[brettw, 2014/07/08 22:06:54]

Can you add the extra stuff you added to the optional parameters documentation
above?

+        command += " && " + invoker.postsolink
+      }
+
       description = "SOLINK \$lib"
-      rspfile = "\$out.rsp"
-      rspfile_content = "-Wl,--whole-archive \$in \$solibs -Wl,--no-whole-archive \$libs"
       #pool = "link_pool"
       restat = "1"
     }
     tool("link") {
       command = "$ld \$ldflags -o \$out -Wl,--start-group @\$rspfile \$solibs -Wl,--end-group $libs_section_prefix \$libs $libs_section_postfix"
       description = "LINK \$out"
       rspfile = "\$out.rsp"
       rspfile_content = "\$in"
       #pool = "link_pool"
     }
@@ skipping 11 matching lines @@
     toolchain_args() {
       cpu_arch = invoker.toolchain_cpu_arch
       os = invoker.toolchain_os
     }
 
     if (defined(invoker.deps)) {
       deps = invoker.deps
     }
   }
 }