I am sponsoring the following self-reviewed case for myself.
It adds a new option (-z wrap=symbol) to the Solaris link-editor (ld)
along with two synonyms: -wrap=symbol and --wrap=symbol.
I believe it qualifies for self review:
- This is a GNU familiarity case --- the GNU ld used by Linux accepts
the -wrap/--wrap options and it is used by software of importance to
Solaris (Xorg).
- We have established precedent for providing GNU ld options to ease
building of open source software on our platform. One example is:
PSARC 2008/583 add gld options to ld(1)
- There are no backward compatibility issues with the proposed syntax,
and the form of the syntax does not break new ground.
The wrap option tells the link-editor to rename function references
in a systematic way that allows the user to link "wrapper" functions
against already compiled code. The user of this feature supplies the
wrapper functions. This feature will be integrated as:
6850768 ld option to autogenerate wrappers/interposers similar to
GNU ld --wrap
Documentation for the original GNU ld feature can be found at:
http://sourceware.org/binutils/docs-2.19/ld/Options.html#index-g_t_002d_002dwrap-249
Diffs for the changes to the proposed new ld(1) manpage are shown below.
-----
Release Binding: Patch/Micro
New ld options:
-z wrap Committed
-wrap Committed
--wrap Committed
-----
*** ld.orig Mon Aug 24 14:38:24 2009
--- ld.new Tue Sep 15 13:28:59 2009
***************
*** 30,36 ****
[-z preinitarray=function] [-z redlocsym] [-z relaxreloc]
[-z rescan-now] [-z recan] [-z rescan-start ... -z rescan-end]]
[-z target=sparc|x86] [-z text | textwarn | textoff]
! [-z verbose] filename...
DESCRIPTION
--- 30,36 ----
[-z preinitarray=function] [-z redlocsym] [-z relaxreloc]
[-z rescan-now] [-z recan] [-z rescan-start ... -z rescan-end]]
[-z target=sparc|x86] [-z text | textwarn | textoff]
! [-z verbose] [-z wrap=symbol] filename...
DESCRIPTION
***************
*** 1114,1119 ****
--- 1114,1152 ----
are deemed too noisy to be generated by default.
+ -z wrap=symbol
+ -wrap=symbol
+ --wrap=symbol
+
+ Rename undefined references to symbol in order to allow wrapper
+ code to be linked into the output object without having to modify
+ source code. When -z wrap is specified, all undefined references
+ to symbol are modified to reference __wrap_symbol, and all
+ references to __real_symbol are modified to reference symbol. The
+ user is expected to provide an object containing the __wrap_symbol
+ function. This wrapper function can call __real_symbol in order to
+ reference the actual function being wrapped.
+
+ The following is an example of a wrapper for the malloc() function:
+
+ void *
+ __wrap_malloc (size_t c)
+ {
+ printf ("malloc called with %zu\n", c);
+ return __real_malloc (c);
+ }
+
+ If you link other code with this file using -z wrap=malloc to
+ compile all the objects, then all calls to malloc will call the
+ function __wrap_malloc instead. The call to __real_malloc in
+ __wrap_malloc will call the real malloc function.
+
+ The real and wrapped functions should be maintained in separate
+ source files. Otherwise, the compiler or assembler may resolve
+ the call instead of leaving that operation for the link-editor
+ to carry out, and prevent the wrap from occurring.
+
+
ENVIRONMENT VARIABLES
LD_ALTEXEC
