Commit Graph

7324 Commits

Author SHA1 Message Date
Corinna Vinschen 38fd7ddb79 Allow sysconf to return CPU cache information
* include/sys/unistd.h (_SC_LEVEL*): Add cache-related variables as
        on Linux.

        * fhandler_proc.cc (format_proc_cpuinfo): Fetch cache information
        from new cache functions in sysconf.cc, get_cpu_cache_intel and
        get_cpu_cache_amd.
        * sysconf.cc (__nt_query_system): New local helper.
        (get_nproc_values): Utilize __nt_query_system on pre-Windows 7 systems.
        Use GetLogicalProcessorInformationEx otherwise to handle more than
        64 CPUs.  Only handle _SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN.
        (get_phys_pages): New helper to handle _SC_PHYS_PAGES.
        (cpuid2_cache_descriptor): New array to map Intel CPUID 2 descriptor
        values to cache type, cache size, associativity and linesize.
        (cpuid2_cache_desc_compar): Comparision function for bsearch over
        cpuid2_cache_descriptor.
        (get_cpu_cache_intel_cpuid2): New function to fetch cache info from
        Intel CPUID 2.
        (get_cpu_cache_intel_cpuid4): Ditto from Intel CPUID 4.
        (get_cpu_cache_intel): New function as CPU-specific entry point.
        (assoc): New array to map associativity values from AMD CPUID
        0x80000006.
        (get_cpu_cache_amd): New function to fetch cache info from AMD CPUIDs
        0x80000005 and 0x80000006.
        (get_cpu_cache): New function to fetch cache info.
        (sca): Call get_phys_pages if _SC_PHYS_PAGES is requested.  Call
        get_cpu_cache for new _SC_* cache requests.
        (SC_MAX): Set to _SC_LEVEL4_CACHE_LINESIZE.
        (get_phys_pages(void)): Call get_phys_pages(int).
        * include/cygwin/version.h (CYGWIN_VERSION_API_MINOR): Bump.

        * new-features.xml (ov-new2.3): Document sysconf cache addition.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-29 09:16:47 +02:00
Corinna Vinschen 35d5d87540 Implement POSIX_MADV_WILLNEED/POSIX_MADV_DONTNEED for newer OSes
* autoload.cc (DiscardVirtualMemory): Import.
        (PrefetchVirtualMemory): Import.
        * mmap.cc (posix_madvise): Actually implement POSIX_MADV_WILLNEED
        utilizing PrefetchVirtualMemory and POSIX_MADV_DONTNEED utilizing
        DiscardVirtualMemory on systems supporting them.
        * wincap.h (wincaps::has_broken_prefetchvm): New element.
        * wincap.cc: Implement above element throughout.
        (wincapc::init): Make sure has_broken_prefetchvm is only true on
        W10 under WOW64.
        * include/cygwin/version.h (CYGWIN_VERSION_DLL_MAJOR): Bump to 2003.
        (CYGWIN_VERSION_API_MINOR): Reset to 0.

        * new-features.xml (ov-new2.3): New section, document posix_madvise
        POSIX_MADV_WILLNEED/POSIX_MADV_DONTNEED change.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-27 13:34:25 +02:00
Corinna Vinschen 9074b9b8ad fhandler_proc.cc: Only request group relation information
* fhandler_proc.cc (format_proc_cpuinfo): Only fetch group relations,
        we don't need anything else.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-26 18:39:53 +02:00
Corinna Vinschen 7f3efa3b65 winsup.h: Claim Windows 10 support
* winsup.h (_WIN32_WINNT): Set to 0x0a00 for Windows 10.
        (WINVER): Ditto.  Remove outdated comment.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-25 22:23:01 +02:00
Corinna Vinschen 4b104ce070 autoload.cc: Drop using full paths for system DLLs
System DLLs are always first in the DLL search order so
	http://www.microsoft.com/technet/security/advisory/2269637.mspx
	doesn't apply for them.

        * autoload.cc (std_dll_init): Revert using full paths to system DLLs.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-25 22:17:43 +02:00
Corinna Vinschen 859c10beee autload.cc: Avoid clobbering return address in noload on i686
This fixes a long-standing problem when GetProcAddress fails
	to load a function.  The noload code calls SetLastError on
	i686 without saving the edx register.  Starting with Windows 7,
	SetLastError apparently uses $edx and the register is set to
	0x00000000 on return.  So the subsequent `jmp *$edx' in noload
	supposed to return to the caller, actually jumps to address NULL,
	which results in a SEGV.

        * autoload.cc (noload): i686 only: Save and restore $edx when calling
        SetLastError to avoid clobbering return address stating with Windows 7.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-25 22:15:22 +02:00
Corinna Vinschen 70b02101ca mmap.cc: Fix some comments
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-25 22:02:35 +02:00
Corinna Vinschen a396499757 Sigproc.cc: Fix copyright.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-24 19:09:16 +02:00
Corinna Vinschen dbc1cae5c5 Fix hang stracing forking processes but not following child
* ntdll.h (PROCESSINFOCLASS): Define ProcessDebugFlags.
        * sigproc.cc (child_info::child_info): Only propagate _CI_STRACED to
        child if strace is actually tracing child processes.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-24 18:37:53 +02:00
Corinna Vinschen 986069c7e3 Bump Cygwin DLL minor number.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-24 18:35:49 +02:00
Corinna Vinschen cb2ab5fd01 Cygwin: Return port number from getservent in network byte order
* netdb.cc (parse_services_line): Convert port number to network byte
        order.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-18 13:12:07 +02:00
Corinna Vinschen f9f3d44f27 exceptions.cc: Drop including ucontext.h.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-18 11:09:25 +02:00
Corinna Vinschen 4cb24051f4 Don't call LsaLookupSids if we're not utilizing Windows account DBs
* grp.cc (internal_getgrfull): Drop asking caches.  Explain why.
        (internal_getgroups): In case we're not utilizing the Windows account
        DBs, don't call LsaLookupSids but iterate over the group SIDs in the
        token and call internal_getgrsid for each of them.  Explain why.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-17 22:45:02 +02:00
Corinna Vinschen 88dce3abd8 Try harder to avoid LDAP access for RFC2307 mapping
* fhandler_disk_file.cc (fhandler_base::fstat_by_nfs_ea): Rearrange
        to fall back to myself uid/gid in case we don't utilize Windows
        account DBs, just as prior to 1.7.34.
        * sec_helper.cc (cygpsid::get_id): Disable Samba user/group mapping per
        RFC2307 if we're not utilizing Windows account DBs.
        * security.cc (convert_samba_sd): Revert previous patch.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-17 20:24:49 +02:00
Corinna Vinschen 37b6936f8b Fix /proc/cpuinfo topology info on newer AMD CPUs
* fhandler_proc.cc (format_proc_cpuinfo): Handle AMDs providing
        extended topology info in CPUID leaf 0x8000001e.  Fix handling of
        AMD CPUs providing extended legacy core info in CPUID leaf 0x80000008.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-17 16:35:41 +02:00
Orgad Shaneh ede983934c mkglobals_h: Handle CRLF earlier.
When globals.cc has CRLF line endings, winsup.h is not removed, and
	compilation fails for duplicate definitions.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-17 11:05:43 +02:00
Corinna Vinschen 861a27db66 Support cpb and eff_freq_ro power mgmt flags in /proc/cpuinfo
* fhandler_proc.cc (format_proc_cpuinfo): Print cpb and eff_freq_ro
        power management flags.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-17 10:04:33 +02:00
Corinna Vinschen b5f56ec286 Cygwin: Improve 2.2.1 release notes
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-15 13:32:31 +02:00
Corinna Vinschen 344860a104 Cygwin: Try to fix potential data corruption in pipe write
* fhandler.cc (fhandler_base_overlapped::raw_write): When performing
        nonblocking I/O, copy user space data into own buffer.  Add longish
        comment to explain why.
        * fhandler.h (fhandler_base_overlapped::atomic_write_buf): New member.
        (fhandler_base_overlapped::fhandler_base_overlapped): Initialize
        atomic_write_buf.
        (fhandler_base_overlapped::fhandler_base_overlapped): New destructor,
        free'ing atomic_write_buf.
        (fhandler_base_overlapped::copyto): Set atomic_write_buf to NULL in
        copied fhandler.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-15 12:30:09 +02:00
Corinna Vinschen 36d500e425 Fix copy/paste error in previous patch
* security.cc (convert_samba_sd): Fix copy/paste error in previous
	patch.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-14 21:55:42 +02:00
Corinna Vinschen 5de7f2e6c3 Don't perform RFC2307 account mapping without account DB
* fhandler_disk_file.cc (fhandler_base::fstat_by_nfs_ea): Only try
        to map user and group info per RFC2307 if account info is fetched
        from Windows account DB.
        (convert_samba_sd): Ditto.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-14 21:41:37 +02:00
Corinna Vinschen c19f1b9f8e Evaluate all group perms in ACL to emulate POSIX user perms
* security,cc (get_attribute_from_acl): Merge all group perms into
        user perms if user is member of group.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-14 10:10:34 +02:00
Corinna Vinschen e0d48debed Fix /proc/cpuinfo topology and cache size info
* autoload.cc (GetLogicalProcessorInformationEx): Import.
        (SetThreadGroupAffinity): Import.
        * fhandler_proc.cc (add_size): New macro.
        (get_msb): New inline function.
        (mask_bits): Ditto.
        (format_proc_cpuinfo): Drop handling of old CPUs.  Check if we're
        running on a OS version supporting porcessor groups.  If so, use
        SetThreadGroupAffinity to set thread affinity.  Improve cache info
        to include 3rd level cache on Intel CPUs.  Improve multi core info.
        * wincap.h (wincaps::has_processor_groups): New element.
        * wincap.cc: Implement above element throughout.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-13 17:59:47 +02:00
Corinna Vinschen 1e15b46737 miscfuncs.cc: Fix comment preceeding x86_64 memset and friends.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-10 12:07:22 +02:00
Corinna Vinschen 1641a85e8f Revert to leaving $HOME alone
* uinfo.cc (cygheap_user::ontherange): Revert previous patch.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-10 12:00:12 +02:00
Corinna Vinschen 09d458b5c7 Bump Cygwin DLL minor number.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-08-03 21:46:55 +02:00
Corinna Vinschen 7666b3634b Cygwin: Fix x86_64 memcpy/memset for n > 2GB
https://cygwin.com/ml/cygwin/2015-07/msg00344.html:

	RtlFillMemory and RtlCopyMemory only work for size values
	up to 2GB.  Fix this problem by using NetBSD code for
	memset and memcpy.  Add entry points for memmove, wmemset,
	wmemmove, wmemcpy.  Thanks to Roman Petrovski
	<RPetrovski@illumina.com> for pointing this out.

        * miscfuncs.cc (memset): x86_64 only: Implement in assembler.
        (memmove,memcpy): x86_64 only: Ditto.
        (wmemmove,wmemcpy): x86_64 only: Ditto.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-29 22:09:34 +02:00
Corinna Vinschen d32ea61ae4 cygwin: Fix copyright dates
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-29 13:45:46 +02:00
Corinna Vinschen 6ab56bdd3f cygwin: Fix crashes under AllocationPreference=0x100000 condition
* cygtls.h: Include cygtls_padsize.h and define CYGTLS_PADSIZE there.
        * cygtls_padsize.h: New file.  Define CYGTLS_PADSIZE.
        * environ.cc (parse_options): Fix NULL pointer access.
        * init.cc (threadfunc_fe): Do not force stack align on x86_64.

        * strace.cc (main2): Rename from main.
        (main): Make room for _cygtls area on stack and just call main2.  Add
        comment to explain why.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-29 13:32:29 +02:00
Corinna Vinschen 03c8afda17 Improve cygwin 2.2.0 release text
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-23 21:19:43 +02:00
Corinna Vinschen be8183701a Fix potential buffer overflow in makecontext trampoline
glibc's tst-makecontext2 testcase uncovered a bug in
	__cont_link_context.  If the function misses to reserve
	shadow space for the calls to setcontext/cygwin_exit,
	both functions could overwrite memory beyond the stack
	configured in uc_stack.

        * exceptions.cc (__cont_link_context): x86_64: align stack and reserve
        shadow space for subsequent function calls, otherwise suffer potential
        buffer overflow.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-23 20:25:22 +02:00
Corinna Vinschen 1e80973f28 Ignore non-absolute $HOME when started from native process
* uinfo.cc (cygheap_user::ontherange): Ignore $HOME if it's not
	starting with a slash (aka, absolute POSIX Path).

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-23 17:42:07 +02:00
Corinna Vinschen 7c96ab0b43 Cygwin: Implement siglongjmp and sigsetjmp functions.
* libc/include/machine/setjmp.h (siglongjmp): Declare as function on
	Cygwin.
	(sigsetjmp): Ditto.
	(_longjmp): Mark as noreturn function on Cygwin.

	* common.din (siglongjmp): Export.
	(sigsetjmp): Export.
	* gendef: Change formatting of some comments.
	(sigsetjmp): Implement.
	(siglongjmp): Implement.
	(__setjmpex): x86_64 only: Drop entry point.
	(setjmp): x86_64 only: Store tls stackptr in Frame now, store MXCSR
	and FPUCW registers in Spare, as MSVCRT does.
	(longjmp): x86_64 only: Restore tls stackptr from Frame now, restore
	MXCSR and FPUCW registers from Spare.
	* include/cygwin/version.h (CYGWIN_VERSION_API_MINOR): Bump.

	* new-features.xml (ov-new2.2): Document sigsetjmp, siglongjmp.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-21 17:31:02 +02:00
Corinna Vinschen b723ec272e Add previous ldd fix to release file
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-20 18:43:16 +02:00
Corinna Vinschen e437a7d826 Lower Cygwin's MINSIGSTKSZ and SIGSTKSZ
* include/cygwin/signal.h (MINSIGSTKSZ): Define as 8K, unconditionally.
        (SIGSTKSZ): Define as 32K, unconditionally.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-19 22:40:29 +02:00
Corinna Vinschen 4889f730c1 Reduce stack pressure throughout Cygwin
* dcrt0.cc (initial_env): Reduce size of local path buffers to
        PATH_MAX.  Allocate debugger_command from process heap.
        (init_windows_system_directory): Very early initialize new global
        variable global_progname.
        * dll_init.cc (dll_list::alloc): Make path buffer static.  Explain why.
        (dll_list::populate_deps): Use tmp_pathbuf for local path buffer.
        * exceptions.cc (debugger_command): Convert to PWCHAR.
        (error_start_init): Allocate debugger_command and fill with wide char
        strings.  Only allocate if NULL.
        (try_to_debug): Just check if debugger_command is a NULL pointer to
        return.  Drop conversion from char to WCHAR and drop local variable
        dbg_cmd.
        * globals.cc (global_progname): New global variable to store Windows
        application path.
        * pinfo.cc (pinfo_basic::pinfo_basic): Just copy progname over from
        global_progname.
        (pinfo::status_exit): Let path_conv create the POSIX path to
        avoid local buffer.
        * pseudo_reloc.cc (__report_error): Utilize global_progname, drop local
        buffer.
        * smallprint.cc (__small_vsprintf): Just utilize global_progname for
        %P format specifier.
        (__small_vswprintf): Ditto.
        * strace.cc (PROTECT): Change to reflect x being a pointer.  Reformat.
        (CHECK): Ditto.  Reformat.
        (strace::activate): Utilize global_progname, drop local buffer.
        Fix formatting.
        (strace::vsprntf): Reduce size of local progname buffer to NAME_MAX.
        Copy and, if necessary, convert only the last path component to
        progname.
        (strace_buf_guard): New muto.
        (buf): New static pointer.
        (strace::vprntf): Use buf under strace_buf_guard lock only.  Allocate
        buffer space for buf on Windows heap.
        * wow64.cc (wow64_respawn_process): Utilize global_progname, drop
        local path buffer.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-19 22:38:30 +02:00
Corinna Vinschen 93a8435f82 Remove x86_64 __sjfault/__ljfault
* gendef: Remove unused 64 bit versions of __sjfault and __ljfault.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-18 14:48:32 +02:00
Corinna Vinschen 877b02be08 Rearrange makecontext and add lots of comments
* exceptions.cc (makecontext): Rearrange order of initialization and
        document at great length.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-18 12:35:23 +02:00
Corinna Vinschen b2df1577c7 Fix ucontext creation in call_signal handler
* exceptions.cc (__unwind_single_frame): Define empty macro on i686.
        (_cygtls::call_signal_handler): Try to make sure signal context makes
        sense in case we're generating context here.  Add comment to explain.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-17 18:29:52 +02:00
Corinna Vinschen 16d2d9f131 Comment fixup
* exceptions.cc (getcontext/x86_64): Drop comment on RtlCaptureContext.
        (swapcontext/x86_64): Fix comment yet again.
        (getcontext/i686): Move comment from x86_64 getcontext, slightly
        rearranged, to preceeding comment.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-17 16:47:14 +02:00
Corinna Vinschen b3ccf998cc Reuse __unwind_single_frame where appropriate
* exceptions.cc (__unwind_single_frame): Move up in file to be
        accessible from other places.  Move comment to getcontext.
        (stack_info::walk): Call __unwind_single_frame in 64 bit case.  Fix
        preceeding comment.
        (myfault_altstack_handler): Call __unwind_single_frame.
        (getcontext): Give comment from __unwind_single_frame a new home.
        (swapcontext): Fix comment.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-17 16:29:41 +02:00
Corinna Vinschen 1020bb292a Implement getcontext, setcontext, makecontext, swapcontext
* common.din (getcontext): Export.
        (makecontext): Export.
        (setcontext): Export.
        (swapcontext): Export.
        * exceptions.cc (__unwind_single_frame): New static functions, 64 bit
        only.
        (setcontext): New function.
        (getcontext): New function.
        (swapcontext): New function.
        (__cont_link_context): New function.
        (makecontext): New function.
        * include/cygwin/version.h (CYGWIN_VERSION_DLL_MAJOR): Bump to 2002.
        (CYGWIN_VERSION_API_MINOR): Bump.
        * include/ucontext.h (getcontext): Add prototype.
        (setcontext): Ditto.
        (swapcontext): Ditto.
        (makecontext): Ditto.
        * ntdll.h (NtContinue): Ditto.

        * new-features.xml (ov-new2.2): Add new section.  Document getcontext,
        setcontext, makecontext, swapcontext.
        * posix.xml (std-deprec): Add getcontext, setcontext, makecontext,
        swapcontext.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-17 14:31:12 +02:00
Corinna Vinschen 9a69aac0ed Document the fact that we forgot to bump for sigaltstack and sethostname
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-17 14:02:43 +02:00
Corinna Vinschen 211cd495c4 exceptions.cc: Reenable code only disabled for debug purposes
* exceptions.cc (exception::handle): Reenable code only disabled for
	debug purposes.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-13 16:08:29 +02:00
Corinna Vinschen b90a91a618 tzset: Check timezone and country case-insensitive
* tzset.c (main): Check timezone and country case-insensitive.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-08 10:25:49 +02:00
Corinna Vinschen e6b882b957 Add accidentally missing ChangeLog entry for previous patch
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-07 20:49:02 +02:00
Corinna Vinschen 60f10c64aa x86_64: Handle myfault exceptions when running on alternate signal stack
x86_64 only:
        * cygtls.cc (san::leave): Restore _my_tls.andreas.
        * cygtls.h (class san):  Add _clemente as in 32 bit case.  Add ret and
        frame members.
        (san::san): Handle _my_tls.andreas as on 32 bit.  Take parameter and
        write it to new member ret.  Store current stack pointer in frame.
        (san::~san): New destructor to restore _my_tls.andreas.
        (__try): Use __l_except address as parameter to san::san.
        * dcrt0.cc (dll_crt0_0): Add myfault_altstack_handler as vectored
        continuation handler.
        * exception.h (myfault_altstack_handler): Declare.
        * exceptions.cc (myfault_altstack_handler): New function.  Explain what
        it's good for.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-07 20:45:06 +02:00
Corinna Vinschen 29a1263227 Simplify stack allocation code in child after fork
* child_info.h (CURR_CHILD_INFO_MAGIC): Update.
        (child_info_fork::alloc_stack_hard_way): Drop declaration.
        * dcrt0.cc (child_info_fork::alloc_stack_hard_way): Fold into
        child_info_fork::alloc_stack.
        (getstack): Remove.
        (child_info_fork::alloc_stack): Simplify check for application-provided
        stack in "hard way" code.  Don't call getstack for each page, just
        reallocate stack immediately as required.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-07 17:24:49 +02:00
Corinna Vinschen 606013bcf1 Simplify fork code setting up child stack info
* fork.cc (frok::parent): Simplify code propagating stack setup to
        child process.  Tweak comments.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2015-07-07 17:05:20 +02:00
Yaakov Selkowitz c9b3716279 winsup/cygwin: rework basename redefinition handling in path.cc
This fixes the compile after commit 79e419de62.

* path.cc: Rework basename redefinition handling.  Explain why.
2015-07-06 15:18:09 -05:00