cvs commit: src/include string.h src/lib/libc/string
Makefile.inc memchr.3 memrchr.c src/sys/sys param.h
kabaev at gmail.com
Wed May 28 13:17:57 UTC 2008
On Tue, 27 May 2008 20:04:28 +0000 (UTC)
Xin LI <delphij at FreeBSD.org> wrote:
> delphij 2008-05-27 20:04:27 UTC
> FreeBSD src repository
> Modified files: (Branch: RELENG_6)
> include string.h
> lib/libc/string Makefile.inc memchr.3
> sys/sys param.h
> Added files: (Branch: RELENG_6)
> lib/libc/string memrchr.c
> MFC: Add memrchr(3).
> Obtained from: OpenBSD
> Revision Changes Path
> 22.214.171.124 +1 -0 src/include/string.h
> 126.96.36.199 +2 -1 src/lib/libc/string/Makefile.inc
> 188.8.131.52 +28 -3 src/lib/libc/string/memchr.3
> 184.108.40.206 +40 -0 src/lib/libc/string/memrchr.c (new)
> 220.127.116.11 +1 -1 src/sys/sys/param.h
There are two levels of symbol versions checking:
1. Up-front checking of version name.
When binary starts, rtld checks that all versions it was compiled
against are provided by the dynamically loaded libraries. I.e. if
libc.so.7:FBSD_1.1 is recorded as a requirement in binary and given
libc.so.7 does not have that version, the binary execution is
terminated right on the spot.
The assumption here is that if version FOO is claimed to be provided by
the library then _all_ symbols at FOO binary might need are present. This
is the level of symbol versions checking Solaris provides. Linux goes a
2. Per-symbol versions.
In addition to the above, ld encodes required version of each undefined
symbol in a binary and uses (name, version) pair to resolve undefined
references as opposed to using only the symbol name. This allows for
several versions of the same symbol to exist within the binary, i.e.
something like read at FOO1 and read at FOO2 are now possible.
Your changes broke assumption in 1. To do it 100% correctly, we probably
need to introduce a side version for memchr, something like
memrchr@@FBSD_1.0a in stable branch and provide a compatibility
alias memrchr at FBSD_1.0a for it in -current at the same time.
libc.so.7 from RELENG_7 will have:
libc.so.7 from -current then will have:
memrchr at FBSD_1.0a -> memrchr@@FBSD_1.1
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