__getcwd is called from dcigettext.o (brought in by various ISO C
functionality), but calls rewinddir, which is not an ISO C function.
This patch makes __getcwd call __rewinddir instead and makes rewinddir
a weak alias for __rewinddir.
Since getcwd.c is shared with gnulib (albeit not merged in either
direction for a long time, and omitted from gnulib's
config/srclist.txt list of shared files) I put in a #ifndef _LIBC
define of __rewinddir to rewinddir, although a future merged version
of getcwd could end up looking significantly different.
Tested for x86_64 (testsuite, and that disassembly of installed shared
libraries is unchanged by this patch).
[BZ #17584]
* dirent/rewinddir.c (rewinddir): Rename to __rewinddir and define
as weak alias of __rewinddir. Don't use libc_hidden_def.
(__rewinddir): Use libc_hidden_def.
* sysdeps/mach/hurd/rewinddir.c: Rename to __rewinddir and define
as weak alias of __rewinddir. Don't use libc_hidden_def.
(__rewinddir): Use libc_hidden_def.
* sysdeps/posix/rewinddir.c: Rename to __rewinddir and define as
weak alias of __rewinddir. Don't use libc_hidden_def.
(__rewinddir): Use libc_hidden_def.
* include/dirent.h (rewinddir): Don't use libc_hidden_proto.
(__rewinddir): Use libc_hidden_proto.
* sysdeps/posix/getcwd.c [!_LIBC] (__rewinddir): Define to
rewinddir.
(__getcwd): Use __rewinddir instead of rewinddir.
The getcwd syscall (so far?) can only handle path up to one page
in size. There is no limit about directory hierarchy depth, though,
and the POSIX getcwd is supposed to handle this. In that case fall
back to the generic getcwd.
Additionally, optimize the generic getcwd to use openat when possible
to change the asymptotic performance from O(N^2) to O(n).
