From: Corinna Vinschen Date: Fri, 3 Apr 2020 19:40:01 +0000 (+0200) Subject: Cygwin: symlinks: create WSL symlinks on supporting filesystems X-Git-Tag: cygwin-3_1_5-release~92 X-Git-Url: https://sourceware.org/git/?a=commitdiff_plain;h=44da5e4b8c89bfcee79eb83fd3b7142720489940;p=newlib-cygwin.git Cygwin: symlinks: create WSL symlinks on supporting filesystems WSL symlinks are reparse points containing a POSIX path in UTF-8. On filesystems supporting reparse points, use this symlink type. On other filesystems, or in case of error, fall back to the good old plain SYSTEM file. Signed-off-by: Corinna Vinschen --- diff --git a/winsup/cygwin/path.cc b/winsup/cygwin/path.cc index 7d9d61fcd..e6dc03ffa 100644 --- a/winsup/cygwin/path.cc +++ b/winsup/cygwin/path.cc @@ -1845,6 +1845,97 @@ symlink_native (const char *oldpath, path_conv &win32_newpath) return 0; } +#ifndef IO_REPARSE_TAG_LX_SYMLINK +#define IO_REPARSE_TAG_LX_SYMLINK (0xa000001d) +#endif + +typedef struct _REPARSE_LX_SYMLINK_BUFFER +{ + DWORD ReparseTag; + WORD ReparseDataLength; + WORD Reserved; + struct { + DWORD FileType; /* Take member name with a grain of salt. Value is + apparently always 2 for symlinks. */ + char PathBuffer[1];/* POSIX path as given to symlink(2). + Path is not \0 terminated. + Length is ReparseDataLength - sizeof (FileType). + Always UTF-8. + Chars given in incompatible codesets, e. g. umlauts + in ISO-8859-x, are converted to the Unicode + REPLACEMENT CHARACTER 0xfffd == \xef\xbf\bd */ + } LxSymlinkReparseBuffer; +} REPARSE_LX_SYMLINK_BUFFER,*PREPARSE_LX_SYMLINK_BUFFER; + +static int +symlink_wsl (const char *oldpath, path_conv &win32_newpath) +{ + tmp_pathbuf tp; + PREPARSE_LX_SYMLINK_BUFFER rpl = (PREPARSE_LX_SYMLINK_BUFFER) tp.c_get (); + char *path_buf = rpl->LxSymlinkReparseBuffer.PathBuffer; + const int max_pathlen = MAXIMUM_REPARSE_DATA_BUFFER_SIZE + - offsetof (REPARSE_LX_SYMLINK_BUFFER, + LxSymlinkReparseBuffer.PathBuffer); + PWCHAR utf16 = tp.w_get (); + NTSTATUS status; + IO_STATUS_BLOCK io; + OBJECT_ATTRIBUTES attr; + HANDLE fh; + int len; + + rpl->ReparseTag = IO_REPARSE_TAG_LX_SYMLINK; + rpl->Reserved = 0; + rpl->LxSymlinkReparseBuffer.FileType = 2; + /* Convert cygdrive prefix to "/mnt" for WSL compatibility. */ + if (path_prefix_p (mount_table->cygdrive, oldpath, + mount_table->cygdrive_len, false)) + stpcpy (stpcpy (path_buf, "/mnt"), + oldpath + mount_table->cygdrive_len - 1); + else + *stpncpy (path_buf, oldpath, max_pathlen) = '\0'; + /* Convert target path to UTF-16 and then back to UTF-8 to make sure the + WSL symlink is in UTF-8, independet of the current Cygwin codeset. */ + sys_mbstowcs (utf16, NT_MAX_PATH, path_buf); + len = WideCharToMultiByte (CP_UTF8, 0, utf16, -1, path_buf, max_pathlen, + NULL, NULL); + /* Length is omitting trailing \0. */ + rpl->ReparseDataLength = sizeof (DWORD) + len - 1; + /* Create reparse point. */ + status = NtCreateFile (&fh, DELETE | FILE_GENERIC_WRITE + | READ_CONTROL | WRITE_DAC, + win32_newpath.get_object_attr (attr, sec_none_nih), + &io, NULL, FILE_ATTRIBUTE_NORMAL, + FILE_SHARE_VALID_FLAGS, FILE_CREATE, + FILE_SYNCHRONOUS_IO_NONALERT + | FILE_NON_DIRECTORY_FILE + | FILE_OPEN_FOR_BACKUP_INTENT + | FILE_OPEN_REPARSE_POINT, + NULL, 0); + if (!NT_SUCCESS (status)) + { + SetLastError (RtlNtStatusToDosError (status)); + return -1; + } + set_created_file_access (fh, win32_newpath, S_IFLNK | STD_RBITS | STD_WBITS); + status = NtFsControlFile (fh, NULL, NULL, NULL, &io, FSCTL_SET_REPARSE_POINT, + (LPVOID) rpl, REPARSE_DATA_BUFFER_HEADER_SIZE + + rpl->ReparseDataLength, + NULL, 0); + if (!NT_SUCCESS (status)) + { + SetLastError (RtlNtStatusToDosError (status)); + FILE_DISPOSITION_INFORMATION fdi = { TRUE }; + status = NtSetInformationFile (fh, &io, &fdi, sizeof fdi, + FileDispositionInformation); + NtClose (fh); + if (!NT_SUCCESS (status)) + debug_printf ("Setting delete dispostion failed, status = %y", status); + return -1; + } + NtClose (fh); + return 0; +} + int symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice) { @@ -1908,7 +1999,7 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice) __leave; } - /* Handle NFS and native symlinks in their own functions. */ + /* Handle NFS, native symlinks and WSL symlinks in their own functions. */ switch (wsym_type) { case WSYM_nfs: @@ -1928,6 +2019,17 @@ symlink_worker (const char *oldpath, path_conv &win32_newpath, bool isdevice) } /* Otherwise, fall back to default symlink type. */ wsym_type = WSYM_sysfile; + /*FALLTHRU*/ + case WSYM_sysfile: + if (win32_newpath.fs_flags () & FILE_SUPPORTS_REPARSE_POINTS) + { + res = symlink_wsl (oldpath, win32_newpath); + if (!res) + __leave; + } + /* On FSes not supporting reparse points, or in case of an error + creating the WSL symlink, fall back to creating the plain old + SYSTEM file symlink. */ break; default: break; @@ -2360,29 +2462,6 @@ check_reparse_point_string (PUNICODE_STRING subst) return false; } -#ifndef IO_REPARSE_TAG_LX_SYMLINK -#define IO_REPARSE_TAG_LX_SYMLINK (0xa000001d) -#endif - -typedef struct _REPARSE_LX_SYMLINK_BUFFER -{ - DWORD ReparseTag; - WORD ReparseDataLength; - WORD Reserved; - struct { - DWORD FileType; /* Take member name with a grain of salt. Value is - apparently always 2 for symlinks. */ - char PathBuffer[1];/* POSIX path as given to symlink(2). - Path is not \0 terminated. - Length is ReparseDataLength - sizeof (FileType). - Always UTF-8. - Chars given in incompatible codesets, e. g. umlauts - in ISO-8859-x, are converted to the Unicode - REPLACEMENT CHARACTER 0xfffd == \xef\xbf\bd */ - } LxSymlinkReparseBuffer; -} REPARSE_LX_SYMLINK_BUFFER,*PREPARSE_LX_SYMLINK_BUFFER; - - /* Return values: <0: Negative errno. 0: No symlink. diff --git a/winsup/cygwin/release/3.1.5 b/winsup/cygwin/release/3.1.5 index 6f16aad93..c1d1cd89d 100644 --- a/winsup/cygwin/release/3.1.5 +++ b/winsup/cygwin/release/3.1.5 @@ -1,7 +1,7 @@ What changed: ------------- -- Support WSL symlinks. +- Support WSL symlinks. Create those by default now. Bug Fixes: diff --git a/winsup/doc/new-features.xml b/winsup/doc/new-features.xml index a200300f2..60ae60de4 100644 --- a/winsup/doc/new-features.xml +++ b/winsup/doc/new-features.xml @@ -83,7 +83,7 @@ https://gitlab.freedesktop.org/terminal-wg/specifications/issues/9. -Support WSL symlinks. +Support WSL symlinks. Create those by default now.