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Adds support for symlinks in Windows.

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This commit is contained in:
Andrea Mazzoleni 2013-02-21 19:12:59 +01:00
parent 470dc9d47e
commit 2f42aadf38
3 changed files with 191 additions and 12 deletions
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175
mingw.c
View file

@ -41,8 +41,6 @@ typedef struct _FILE_ATTRIBUTE_TAG_INFO {
#define IO_REPARSE_TAG_SYMLINK (0xA000000C)
#endif
BOOL WINAPI CreateHardLinkW(LPCWSTR lpFileName, LPCWSTR lpExistingFileName, LPSECURITY_ATTRIBUTES lpSecurityAttributes);
/**
* Number of conversion buffers.
*/
@ -91,7 +89,7 @@ static char* u16tou8(const wchar_t* src)
conv_utf8 = 0;
ret = WideCharToMultiByte(CP_UTF8, 0, src, -1, conv_utf8_buffer[conv_utf8], sizeof(conv_utf8_buffer[0]), 0, 0);
if (ret < 0) {
if (ret <= 0) {
fwprintf(stderr, L"Error converting name %s from UTF-16 to UTF-8\n", src);
exit(EXIT_FAILURE);
}
@ -99,9 +97,32 @@ static char* u16tou8(const wchar_t* src)
return conv_utf8_buffer[conv_utf8];
}
/**
* Converts a generic string from UTF16 to UTF8.
*/
static char* u16tou8n(const wchar_t* src, size_t number_of_wchar, size_t* result_length_without_terminator)
{
int ret;
if (++conv_utf8 == CONV_ROLL)
conv_utf8 = 0;
ret = WideCharToMultiByte(CP_UTF8, 0, src, number_of_wchar, conv_utf8_buffer[conv_utf8], sizeof(conv_utf8_buffer[0]), 0, 0);
if (ret <= 0) {
fwprintf(stderr, L"Error converting from UTF-16 to UTF-8\n");
exit(EXIT_FAILURE);
}
*result_length_without_terminator = ret;
return conv_utf8_buffer[conv_utf8];
}
/**
* Converts a path to the Windows format.
*
* If only_is_required is 1, the extended-length format is used only if required.
*
* The exact operation done is:
* - If it's a '\\?\' path, convert any '/' to '\'.
* - If it's a disk designator path, like 'D:\' or 'D:/', it prepends '\\?\' to the path and convert any '/' to '\'.
@ -112,7 +133,7 @@ static char* u16tou8(const wchar_t* src)
* Naming Files, Paths, and Namespaces
* http://msdn.microsoft.com/en-us/library/windows/desktop/aa365247%28v=vs.85%29.aspx#maxpath
*/
static wchar_t* convert(const char* src)
static wchar_t* convert_arg(const char* src, int only_if_required)
{
int ret;
wchar_t* dst;
@ -123,7 +144,13 @@ static wchar_t* convert(const char* src)
dst = conv_utf16_buffer[conv_utf16];
if (src[0] == '\\' && src[1] == '\\' && src[2] == '?' && src[3] == '\\') {
if (only_if_required && strlen(src) < 260 - 12) {
/* it's a short path */
/* 260 is the MAX_PATH, note that it includes the space for the terminating NUL */
/* 12 is an additional space for filename, required when creating directory */
/* do nothing */
} else if (src[0] == '\\' && src[1] == '\\' && src[2] == '?' && src[3] == '\\') {
/* if it's already a '\\?\' path */
/* do nothing */
@ -175,6 +202,9 @@ static wchar_t* convert(const char* src)
return conv_utf16_buffer[conv_utf16];
}
#define convert(a) convert_arg(a, 0)
#define convert_if_required(a) convert_arg(a, 1)
/**
* Portable implementation of GetFileInformationByHandleEx.
* This function is not available in Windows XP.
@ -253,7 +283,7 @@ static void windows_info2stat(const BY_HANDLE_FILE_INFORMATION* info, const FILE
st->st_desc = "reparse-point-nfs";
break;
case IO_REPARSE_TAG_SYMLINK :
st->st_mode = S_IFCHR;
st->st_mode = S_IFLNK;
st->st_desc = "reparse-point-symlink";
break;
default:
@ -341,7 +371,7 @@ static void windows_finddata2stat(const WIN32_FIND_DATAW* info, struct windows_s
st->st_desc = "reparse-point-nfs";
break;
case IO_REPARSE_TAG_SYMLINK :
st->st_mode = S_IFCHR;
st->st_mode = S_IFLNK;
st->st_desc = "reparse-point-symlink";
break;
default:
@ -429,6 +459,12 @@ static void windows_errno(DWORD error)
case ERROR_NOT_ENOUGH_MEMORY :
errno = ENOMEM;
break;
case ERROR_NOT_SUPPORTED : /* when calling CreateSymlinkW if not present in kernel32 */
errno = ENOSYS;
break;
case ERROR_PRIVILEGE_NOT_HELD : /* when calling CreateSymlinkW if no SeCreateSymbolicLinkPrivilige permission */
errno = EPERM;
break;
default:
fprintf(stderr, "Unexpected Windows error %d.\n", (int)error);
errno = EIO;
@ -468,6 +504,7 @@ int windows_lstat(const char* file, struct windows_stat* st)
HANDLE h;
WIN32_FIND_DATAW data;
/* FindFirstFileW by default gets information of symbolic links and not of their targets */
h = FindFirstFileW(convert(file), &data);
if (h == INVALID_HANDLE_VALUE) {
windows_errno(GetLastError());
@ -499,6 +536,11 @@ int windows_mkdir(const char* file)
return _wmkdir(convert(file));
}
int windows_rmdir(const char* file)
{
return _wrmdir(convert(file));
}
int lstat_ex(const char* file, struct windows_stat* st)
{
BY_HANDLE_FILE_INFORMATION info;
@ -811,5 +853,124 @@ int windows_link(const char* existing, const char* file)
return 0;
}
/**
* Portable implementation of CreateSymbolicLinkW.
* This function is not available in Windows XP.
*/
static int flag_CreateSymbolicLinkW = 0;
static BOOLEAN (WINAPI* ptr_CreateSymbolicLinkW)(LPWSTR, LPWSTR, DWORD);
int windows_symlink(const char* existing, const char* file)
{
/* if not yet initialized, do it now */
if (!flag_CreateSymbolicLinkW) {
HMODULE h = GetModuleHandleA("KERNEL32.DLL");
if (h) {
ptr_CreateSymbolicLinkW = (void*)GetProcAddress(h, "CreateSymbolicLinkW");
}
flag_CreateSymbolicLinkW = 1;
}
if (!ptr_CreateSymbolicLinkW) {
windows_errno(ERROR_NOT_SUPPORTED);
return -1;
}
/* We must convert to the extended-length \\?\ format if the path is too long */
/* otherwise the link creation fails. */
/* But we don't want to always convert it, to avoid to recreate */
/* user symlinks different than they were before */
if (!ptr_CreateSymbolicLinkW(convert(file), convert_if_required(existing), 0)) {
windows_errno(GetLastError());
return -1;
}
return 0;
}
/* Adds missing defition in MingW winnt.h */
#ifndef FSCTL_GET_REPARSE_POINT
#define FSCTL_GET_REPARSE_POINT 0x000900a8
#endif
#ifndef REPARSE_DATA_BUFFER_HEADER_SIZE
typedef struct _REPARSE_DATA_BUFFER {
DWORD ReparseTag;
WORD ReparseDataLength;
WORD Reserved;
_ANONYMOUS_UNION union {
struct {
WORD SubstituteNameOffset;
WORD SubstituteNameLength;
WORD PrintNameOffset;
WORD PrintNameLength;
ULONG Flags;
WCHAR PathBuffer[1];
} SymbolicLinkReparseBuffer;
struct {
WORD SubstituteNameOffset;
WORD SubstituteNameLength;
WORD PrintNameOffset;
WORD PrintNameLength;
WCHAR PathBuffer[1];
} MountPointReparseBuffer;
struct {
BYTE DataBuffer[1];
} GenericReparseBuffer;
} DUMMYUNIONNAME;
} REPARSE_DATA_BUFFER, *PREPARSE_DATA_BUFFER;
#endif
int windows_readlink(const char* file, char* buffer, size_t size)
{
HANDLE h;
const char* name;
size_t len;
unsigned char rdb_buffer[MAXIMUM_REPARSE_DATA_BUFFER_SIZE];
REPARSE_DATA_BUFFER* rdb = (REPARSE_DATA_BUFFER*)rdb_buffer;
DWORD ret;
DWORD n;
/*
* Open the handle of the file.
*
* Use FILE_FLAG_BACKUP_SEMANTICS to open directories and to override the file security checks.
* Use FILE_FLAG_OPEN_REPARSE_POINT to open symbolic links and not the their target.
*/
h = CreateFileW(convert(file), 0, FILE_SHARE_READ | FILE_SHARE_WRITE, 0, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OPEN_REPARSE_POINT, 0);
if (h == INVALID_HANDLE_VALUE) {
windows_errno(GetLastError());
return -1;
}
/* read the reparse point */
ret = DeviceIoControl(h, FSCTL_GET_REPARSE_POINT, 0, 0, rdb_buffer, sizeof(rdb_buffer), &n, 0);
if (ret == 0) {
windows_errno(GetLastError());
CloseHandle(h);
return -1;
}
CloseHandle(h);
/* check if it's really a symbolic link */
if (rdb->ReparseTag != IO_REPARSE_TAG_SYMLINK) {
errno = EINVAL;
return -1;
}
/* convert the name to UTF-8 */
name = u16tou8n(rdb->SymbolicLinkReparseBuffer.PathBuffer + rdb->SymbolicLinkReparseBuffer.PrintNameOffset,
rdb->SymbolicLinkReparseBuffer.PrintNameLength / 2, &len);
/* check for overflow */
if (len > size) {
len = size;
}
memcpy(buffer, name, len);
return len;
}
#endif

25
mingw.h
View file

@ -45,6 +45,7 @@
#define rename windows_rename
#define remove windows_remove
#define mkdir(a, b) windows_mkdir(a)
#define rmdir windows_rmdir
#define dirent windows_dirent
#define DIR windows_dir
#define opendir windows_opendir
@ -58,10 +59,10 @@
#define dirent_lstat windows_dirent_lstat
#define stat_desc windows_stat_desc
#define sleep windows_sleep
/* In Windows symbolic links are not supported */
#define S_ISLNK(mode) 0
#define readlink(a,b,c) -1
#define symlink(a,b) -1
#define S_IFLNK 0x7000 /* 4==DIR, 8==REG */
#define S_ISLNK(m) (((m) & _S_IFMT) == S_IFLNK)
#define readlink windows_readlink
#define symlink windows_symlink
#define link windows_link
/**
@ -121,6 +122,11 @@ int windows_access(const char* file, int mode);
*/
int windows_mkdir(const char* file);
/**
* Like rmdir().
*/
int windows_rmdir(const char* file);
/**
* Like the C lstat() including the inode/device information.
* It doesn't work for all kind of files and directories. For example "\System Volume Information" cannot be opened.
@ -226,6 +232,17 @@ const char* windows_stat_desc(struct stat* st);
*/
void windows_sleep(unsigned seconds);
/**
* Like readlink().
*/
int windows_readlink(const char* file, char* buffer, size_t size);
/**
* Like symlink().
* Return ENOSYS if symlinks are not supported.
*/
int windows_symlink(const char* existing, const char* file);
/**
* Like link().
*/

3
portable.h
View file

@ -26,7 +26,8 @@
/* Config */
#ifdef __MINGW32__ /* Specific for MINGW */
#define __MSVCRT_VERSION__ 0x0601 /* Define the MSVCRT version required */
#define __MSVCRT_VERSION__ 0x0601 /* Define the MSVCRT version targetting Windows XP */
#define _WIN32_WINNT 0x501 /* Include Windows XP CreateHardLinkW */
#include <windows.h>
#endif