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/**************************************************************************/
/* */
/* OCaml */
/* */
/* David Allsopp, MetaStack Solutions Ltd. */
/* */
/* Copyright 2015 MetaStack Solutions Ltd. */
/* */
/* All rights reserved. This file is distributed under the terms of */
/* the GNU Lesser General Public License version 2.1, with the */
/* special exception on linking described in the file LICENSE. */
/* */
/**************************************************************************/
#include <caml/mlvalues.h>
#include <caml/memory.h>
#include <caml/alloc.h>
#include <caml/fail.h>
#include <caml/signals.h>
#include "unixsupport.h"
#include <errno.h>
#include <winioctl.h>
CAMLprim value unix_readlink(value opath)
{
CAMLparam1(opath);
CAMLlocal1(result);
HANDLE h;
char* path = String_val(opath);
DWORD attributes;
caml_enter_blocking_section();
attributes = GetFileAttributes(path);
caml_leave_blocking_section();
if (attributes == INVALID_FILE_ATTRIBUTES) {
win32_maperr(GetLastError());
uerror("readlink", opath);
}
else if (!(attributes & FILE_ATTRIBUTE_REPARSE_POINT)) {
errno = EINVAL;
uerror("readlink", opath);
}
else {
caml_enter_blocking_section();
if ((h = CreateFile(path,
FILE_READ_ATTRIBUTES,
FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT,
NULL)) == INVALID_HANDLE_VALUE) {
caml_leave_blocking_section();
errno = ENOENT;
uerror("readlink", opath);
}
else {
char buffer[16384];
DWORD read;
REPARSE_DATA_BUFFER* point;
if (DeviceIoControl(h, FSCTL_GET_REPARSE_POINT, NULL, 0, buffer, 16384, &read, NULL)) {
caml_leave_blocking_section();
point = (REPARSE_DATA_BUFFER*)buffer;
if (point->ReparseTag == IO_REPARSE_TAG_SYMLINK) {
int cbLen = point->SymbolicLinkReparseBuffer.SubstituteNameLength / sizeof(WCHAR);
int len;
len = WideCharToMultiByte(
CP_THREAD_ACP,
0,
point->SymbolicLinkReparseBuffer.PathBuffer + point->SymbolicLinkReparseBuffer.SubstituteNameOffset / 2,
cbLen,
NULL,
0,
NULL,
NULL);
result = caml_alloc_string(len);
WideCharToMultiByte(
CP_THREAD_ACP,
0,
point->SymbolicLinkReparseBuffer.PathBuffer + point->SymbolicLinkReparseBuffer.SubstituteNameOffset / 2,
cbLen,
String_val(result),
len,
NULL,
NULL);
CloseHandle(h);
}
else {
errno = EINVAL;
CloseHandle(h);
uerror("readline", opath);
}
}
else {
caml_leave_blocking_section();
win32_maperr(GetLastError());
CloseHandle(h);
uerror("readlink", opath);
}
}
}
CAMLreturn(result);
}
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