[llvm] r203136 - [Support/FileSystem] Introduce llvm::sys::fs::create_symbolic_link().

[Reid Kleckner]

Ended up reverting this in r203143.  We can't use symlinks in any
meaningful way on Windows.


On Thu, Mar 6, 2014 at 11:04 AM, Reid Kleckner <rnk at google.com> wrote:

> Takumi's bots agree:
> http://bb.pgr.jp/builders/ninja-clang-i686-msc17-R/builds/7637
>
> Symlinks were added in Vista.  I don't believe LLVM has dropped support
> for running on XP yet, so we can't use symlinks unconditionally.  I also
> thought you had to have admin to create symlinks on Vista, so they're
> pretty hard to use anyway.
>
> http://msdn.microsoft.com/en-us/library/windows/desktop/aa363866(v=vs.85).aspx
>
>
> On Thu, Mar 6, 2014 at 10:59 AM, Reid Kleckner <rnk at google.com> wrote:
>
>> The Windows implementation doesn't compile for me:
>> d:\src\llvm\lib\support\Windows/Path.inc(193) : error C2039:
>> 'CreateSymbolicLinkW' : is not a member of '`global namespace''
>>
>>
>> On Thu, Mar 6, 2014 at 9:36 AM, Argyrios Kyrtzidis <akyrtzi at gmail.com>wrote:
>>
>>> Author: akirtzidis
>>> Date: Thu Mar  6 11:36:46 2014
>>> New Revision: 203136
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=203136&view=rev
>>> Log:
>>> [Support/FileSystem] Introduce llvm::sys::fs::create_symbolic_link().
>>>
>>> Modified:
>>>     llvm/trunk/include/llvm/Support/FileSystem.h
>>>     llvm/trunk/lib/Support/Unix/Path.inc
>>>     llvm/trunk/lib/Support/Windows/Path.inc
>>>
>>> Modified: llvm/trunk/include/llvm/Support/FileSystem.h
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/FileSystem.h?rev=203136&r1=203135&r2=203136&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/include/llvm/Support/FileSystem.h (original)
>>> +++ llvm/trunk/include/llvm/Support/FileSystem.h Thu Mar  6 11:36:46 2014
>>> @@ -293,6 +293,14 @@ error_code create_directory(const Twine
>>>  ///          , otherwise a platform specific error_code.
>>>  error_code create_hard_link(const Twine &to, const Twine &from);
>>>
>>> +/// @brief Create a symbolic link from \a from to \a to.
>>> +///
>>> +/// @param to The path to link to.
>>> +/// @param from The path to link from. This is created.
>>> +/// @returns errc::success if successful
>>> +///          , otherwise a platform specific error_code.
>>> +error_code create_symbolic_link(const Twine &to, const Twine &from);
>>> +
>>>  /// @brief Get the current path.
>>>  ///
>>>  /// @param result Holds the current path on return.
>>>
>>> Modified: llvm/trunk/lib/Support/Unix/Path.inc
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Unix/Path.inc?rev=203136&r1=203135&r2=203136&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/lib/Support/Unix/Path.inc (original)
>>> +++ llvm/trunk/lib/Support/Unix/Path.inc Thu Mar  6 11:36:46 2014
>>> @@ -285,6 +285,19 @@ error_code create_hard_link(const Twine
>>>    return error_code::success();
>>>  }
>>>
>>> +error_code create_symbolic_link(const Twine &to, const Twine &from) {
>>> +  // Get arguments.
>>> +  SmallString<128> from_storage;
>>> +  SmallString<128> to_storage;
>>> +  StringRef f = from.toNullTerminatedStringRef(from_storage);
>>> +  StringRef t = to.toNullTerminatedStringRef(to_storage);
>>> +
>>> +  if (::symlink(t.begin(), f.begin()) == -1)
>>> +    return error_code(errno, system_category());
>>> +
>>> +  return error_code::success();
>>> +}
>>> +
>>>  error_code remove(const Twine &path, bool IgnoreNonExisting) {
>>>    SmallString<128> path_storage;
>>>    StringRef p = path.toNullTerminatedStringRef(path_storage);
>>>
>>> Modified: llvm/trunk/lib/Support/Windows/Path.inc
>>> URL:
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Windows/Path.inc?rev=203136&r1=203135&r2=203136&view=diff
>>>
>>> ==============================================================================
>>> --- llvm/trunk/lib/Support/Windows/Path.inc (original)
>>> +++ llvm/trunk/lib/Support/Windows/Path.inc Thu Mar  6 11:36:46 2014
>>> @@ -177,6 +177,25 @@ error_code create_hard_link(const Twine
>>>    return error_code::success();
>>>  }
>>>
>>> +error_code create_symbolic_link(const Twine &to, const Twine &from) {
>>> +  // Get arguments.
>>> +  SmallString<128> from_storage;
>>> +  SmallString<128> to_storage;
>>> +  StringRef f = from.toStringRef(from_storage);
>>> +  StringRef t = to.toStringRef(to_storage);
>>> +
>>> +  // Convert to utf-16.
>>> +  SmallVector<wchar_t, 128> wide_from;
>>> +  SmallVector<wchar_t, 128> wide_to;
>>> +  if (error_code ec = UTF8ToUTF16(f, wide_from)) return ec;
>>> +  if (error_code ec = UTF8ToUTF16(t, wide_to)) return ec;
>>> +
>>> +  if (!::CreateSymbolicLinkW(wide_from.begin(), wide_to.begin(), NULL))
>>> +    return windows_error(::GetLastError());
>>> +
>>> +  return error_code::success();
>>> +}
>>> +
>>>  error_code remove(const Twine &path, bool IgnoreNonExisting) {
>>>    SmallString<128> path_storage;
>>>    SmallVector<wchar_t, 128> path_utf16;
>>>
>>>
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>>
>>
>
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