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New implementation for os.sameFile on Windows

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Hard-links on Windows are now treated just as they are on POSIX.
The new implementation is faster than the previous, but still it's quite
slower than fstat (use with caution).
This commit is contained in:
Zahary Karadjov 2011-12-07 00:53:27 +02:00
commit 0e609d2101
3 changed files with 66 additions and 25 deletions
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49
lib/pure/os.nim
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@ -567,26 +567,45 @@ proc isAbsolute*(path: string): bool {.rtl, noSideEffect, extern: "nos$1".} =
result = path[0] == '/'
proc sameFile*(path1, path2: string): bool {.rtl, extern: "nos$1".} =
## Returns True if both pathname arguments refer to the same file or
## directory (as indicated by device number and i-node number).
## Raises an exception if an stat() call on either pathname fails.
## Returns True if both pathname arguments refer to the same physical
## file or directory. Raises an exception if any of the files does not
## exist or information about it can not be obtained.
##
## This proc will return true if given two alternative hard-linked or
## sym-linked paths to the same file or directory.
when defined(Windows):
var
a, b: TWin32FindData
var resA = findfirstFileA(path1, a)
var resB = findfirstFileA(path2, b)
if resA != -1 and resB != -1:
result = $a.cFileName == $b.cFileName
else:
# work around some ``findfirstFileA`` bugs
result = cmpPaths(path1, path2) == 0
if resA != -1: findclose(resA)
if resB != -1: findclose(resB)
var success = true
template OpenHandle(path: expr): expr =
CreateFileA(path, 0'i32, FILE_SHARE_DELETE or FILE_SHARE_READ or
FILE_SHARE_WRITE, nil, OPEN_EXISTING,
FILE_FLAG_BACKUP_SEMANTICS or FILE_ATTRIBUTE_NORMAL, 0)
var f1 = OpenHandle(path1)
var f2 = OpenHandle(path2)
if f1 != INVALID_HANDLE_VALUE and f2 != INVALID_HANDLE_VALUE:
var fi1, fi2: TBY_HANDLE_FILE_INFORMATION
if GetFileInformationByHandle(f1, addr(fi1)) != 0 and
GetFileInformationByHandle(f2, addr(fi2)) != 0:
result = fi1.dwVolumeSerialNumber == fi2.dwVolumeSerialNumber and
fi1.nFileIndexHigh == fi2.nFileIndexHigh and
fi1.nFileIndexLow == fi2.nFileIndexLow
else: success = false
else: success = false
discard CloseHandle(f1)
discard CloseHandle(f2)
if not success:
OSError()
else:
var
a, b: TStat
if stat(path1, a) < 0'i32 or stat(path2, b) < 0'i32:
result = cmpPaths(path1, path2) == 0 # be consistent with Windows
OSError()
else:
result = a.st_dev == b.st_dev and a.st_ino == b.st_ino