diff options
Diffstat (limited to 'src/port/dirmod.c')
| -rw-r--r-- | src/port/dirmod.c | 407 |
1 files changed, 407 insertions, 0 deletions
diff --git a/src/port/dirmod.c b/src/port/dirmod.c new file mode 100644 index 0000000..e22a41c --- /dev/null +++ b/src/port/dirmod.c @@ -0,0 +1,407 @@ +/*------------------------------------------------------------------------- + * + * dirmod.c + * directory handling functions + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * This includes replacement versions of functions that work on + * Win32 (NT4 and newer). + * + * IDENTIFICATION + * src/port/dirmod.c + * + *------------------------------------------------------------------------- + */ + +#ifndef FRONTEND +#include "postgres.h" +#else +#include "postgres_fe.h" +#endif + +/* Don't modify declarations in system headers */ +#if defined(WIN32) || defined(__CYGWIN__) +#undef rename +#undef unlink +#endif + +#include <unistd.h> +#include <sys/stat.h> + +#if defined(WIN32) || defined(__CYGWIN__) +#ifndef __CYGWIN__ +#include <winioctl.h> +#else +#include <windows.h> +#include <w32api/winioctl.h> +#endif +#endif + +#if defined(WIN32) || defined(__CYGWIN__) + +/* + * pgrename + */ +int +pgrename(const char *from, const char *to) +{ + int loops = 0; + + /* + * We need to loop because even though PostgreSQL uses flags that allow + * rename while the file is open, other applications might have the file + * open without those flags. However, we won't wait indefinitely for + * someone else to close the file, as the caller might be holding locks + * and blocking other backends. + */ +#if defined(WIN32) && !defined(__CYGWIN__) + while (!MoveFileEx(from, to, MOVEFILE_REPLACE_EXISTING)) +#else + while (rename(from, to) < 0) +#endif + { +#if defined(WIN32) && !defined(__CYGWIN__) + DWORD err = GetLastError(); + + _dosmaperr(err); + + /* + * Modern NT-based Windows versions return ERROR_SHARING_VIOLATION if + * another process has the file open without FILE_SHARE_DELETE. + * ERROR_LOCK_VIOLATION has also been seen with some anti-virus + * software. This used to check for just ERROR_ACCESS_DENIED, so + * presumably you can get that too with some OS versions. We don't + * expect real permission errors where we currently use rename(). + */ + if (err != ERROR_ACCESS_DENIED && + err != ERROR_SHARING_VIOLATION && + err != ERROR_LOCK_VIOLATION) + return -1; +#else + if (errno != EACCES) + return -1; +#endif + + if (++loops > 100) /* time out after 10 sec */ + return -1; + pg_usleep(100000); /* us */ + } + return 0; +} + + +/* + * pgunlink + */ +int +pgunlink(const char *path) +{ + int loops = 0; + + /* + * We need to loop because even though PostgreSQL uses flags that allow + * unlink while the file is open, other applications might have the file + * open without those flags. However, we won't wait indefinitely for + * someone else to close the file, as the caller might be holding locks + * and blocking other backends. + */ + while (unlink(path)) + { + if (errno != EACCES) + return -1; + if (++loops > 100) /* time out after 10 sec */ + return -1; + pg_usleep(100000); /* us */ + } + return 0; +} + +/* We undefined these above; now redefine for possible use below */ +#define rename(from, to) pgrename(from, to) +#define unlink(path) pgunlink(path) +#endif /* defined(WIN32) || defined(__CYGWIN__) */ + + +#if defined(WIN32) && !defined(__CYGWIN__) /* Cygwin has its own symlinks */ + +/* + * pgsymlink support: + * + * This struct is a replacement for REPARSE_DATA_BUFFER which is defined in VC6 winnt.h + * but omitted in later SDK functions. + * We only need the SymbolicLinkReparseBuffer part of the original struct's union. + */ +typedef struct +{ + DWORD ReparseTag; + WORD ReparseDataLength; + WORD Reserved; + /* SymbolicLinkReparseBuffer */ + WORD SubstituteNameOffset; + WORD SubstituteNameLength; + WORD PrintNameOffset; + WORD PrintNameLength; + WCHAR PathBuffer[FLEXIBLE_ARRAY_MEMBER]; +} REPARSE_JUNCTION_DATA_BUFFER; + +#define REPARSE_JUNCTION_DATA_BUFFER_HEADER_SIZE \ + FIELD_OFFSET(REPARSE_JUNCTION_DATA_BUFFER, SubstituteNameOffset) + + +/* + * pgsymlink - uses Win32 junction points + * + * For reference: http://www.codeproject.com/KB/winsdk/junctionpoints.aspx + */ +int +pgsymlink(const char *oldpath, const char *newpath) +{ + HANDLE dirhandle; + DWORD len; + char buffer[MAX_PATH * sizeof(WCHAR) + offsetof(REPARSE_JUNCTION_DATA_BUFFER, PathBuffer)]; + char nativeTarget[MAX_PATH]; + char *p = nativeTarget; + REPARSE_JUNCTION_DATA_BUFFER *reparseBuf = (REPARSE_JUNCTION_DATA_BUFFER *) buffer; + + CreateDirectory(newpath, 0); + dirhandle = CreateFile(newpath, GENERIC_READ | GENERIC_WRITE, + 0, 0, OPEN_EXISTING, + FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, 0); + + if (dirhandle == INVALID_HANDLE_VALUE) + return -1; + + /* make sure we have an unparsed native win32 path */ + if (memcmp("\\??\\", oldpath, 4) != 0) + snprintf(nativeTarget, sizeof(nativeTarget), "\\??\\%s", oldpath); + else + strlcpy(nativeTarget, oldpath, sizeof(nativeTarget)); + + while ((p = strchr(p, '/')) != NULL) + *p++ = '\\'; + + len = strlen(nativeTarget) * sizeof(WCHAR); + reparseBuf->ReparseTag = IO_REPARSE_TAG_MOUNT_POINT; + reparseBuf->ReparseDataLength = len + 12; + reparseBuf->Reserved = 0; + reparseBuf->SubstituteNameOffset = 0; + reparseBuf->SubstituteNameLength = len; + reparseBuf->PrintNameOffset = len + sizeof(WCHAR); + reparseBuf->PrintNameLength = 0; + MultiByteToWideChar(CP_ACP, 0, nativeTarget, -1, + reparseBuf->PathBuffer, MAX_PATH); + + /* + * FSCTL_SET_REPARSE_POINT is coded differently depending on SDK version; + * we use our own definition + */ + if (!DeviceIoControl(dirhandle, + CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 41, METHOD_BUFFERED, FILE_ANY_ACCESS), + reparseBuf, + reparseBuf->ReparseDataLength + REPARSE_JUNCTION_DATA_BUFFER_HEADER_SIZE, + 0, 0, &len, 0)) + { + LPSTR msg; + + errno = 0; + FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | + FORMAT_MESSAGE_IGNORE_INSERTS | + FORMAT_MESSAGE_FROM_SYSTEM, + NULL, GetLastError(), + MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT), + (LPSTR) &msg, 0, NULL); +#ifndef FRONTEND + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not set junction for \"%s\": %s", + nativeTarget, msg))); +#else + fprintf(stderr, _("could not set junction for \"%s\": %s\n"), + nativeTarget, msg); +#endif + LocalFree(msg); + + CloseHandle(dirhandle); + RemoveDirectory(newpath); + return -1; + } + + CloseHandle(dirhandle); + + return 0; +} + +/* + * pgreadlink - uses Win32 junction points + */ +int +pgreadlink(const char *path, char *buf, size_t size) +{ + DWORD attr; + HANDLE h; + char buffer[MAX_PATH * sizeof(WCHAR) + offsetof(REPARSE_JUNCTION_DATA_BUFFER, PathBuffer)]; + REPARSE_JUNCTION_DATA_BUFFER *reparseBuf = (REPARSE_JUNCTION_DATA_BUFFER *) buffer; + DWORD len; + int r; + + attr = GetFileAttributes(path); + if (attr == INVALID_FILE_ATTRIBUTES) + { + _dosmaperr(GetLastError()); + return -1; + } + if ((attr & FILE_ATTRIBUTE_REPARSE_POINT) == 0) + { + errno = EINVAL; + return -1; + } + + h = CreateFile(path, + GENERIC_READ, + FILE_SHARE_READ | FILE_SHARE_WRITE, + NULL, + OPEN_EXISTING, + FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS, + 0); + if (h == INVALID_HANDLE_VALUE) + { + _dosmaperr(GetLastError()); + return -1; + } + + if (!DeviceIoControl(h, + FSCTL_GET_REPARSE_POINT, + NULL, + 0, + (LPVOID) reparseBuf, + sizeof(buffer), + &len, + NULL)) + { + LPSTR msg; + + errno = 0; + FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | + FORMAT_MESSAGE_IGNORE_INSERTS | + FORMAT_MESSAGE_FROM_SYSTEM, + NULL, GetLastError(), + MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT), + (LPSTR) &msg, 0, NULL); +#ifndef FRONTEND + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not get junction for \"%s\": %s", + path, msg))); +#else + fprintf(stderr, _("could not get junction for \"%s\": %s\n"), + path, msg); +#endif + LocalFree(msg); + CloseHandle(h); + errno = EINVAL; + return -1; + } + CloseHandle(h); + + /* Got it, let's get some results from this */ + if (reparseBuf->ReparseTag != IO_REPARSE_TAG_MOUNT_POINT) + { + errno = EINVAL; + return -1; + } + + r = WideCharToMultiByte(CP_ACP, 0, + reparseBuf->PathBuffer, -1, + buf, + size, + NULL, NULL); + + if (r <= 0) + { + errno = EINVAL; + return -1; + } + + /* + * If the path starts with "\??\", which it will do in most (all?) cases, + * strip those out. + */ + if (r > 4 && strncmp(buf, "\\??\\", 4) == 0) + { + memmove(buf, buf + 4, strlen(buf + 4) + 1); + r -= 4; + } + return r; +} + +/* + * Assumes the file exists, so will return false if it doesn't + * (since a nonexistent file is not a junction) + */ +bool +pgwin32_is_junction(const char *path) +{ + DWORD attr = GetFileAttributes(path); + + if (attr == INVALID_FILE_ATTRIBUTES) + { + _dosmaperr(GetLastError()); + return false; + } + return ((attr & FILE_ATTRIBUTE_REPARSE_POINT) == FILE_ATTRIBUTE_REPARSE_POINT); +} +#endif /* defined(WIN32) && !defined(__CYGWIN__) */ + + +#if defined(WIN32) && !defined(__CYGWIN__) + +#undef stat + +/* + * The stat() function in win32 is not guaranteed to update the st_size + * field when run. So we define our own version that uses the Win32 API + * to update this field. + */ +int +pgwin32_safestat(const char *path, struct stat *buf) +{ + int r; + WIN32_FILE_ATTRIBUTE_DATA attr; + + r = stat(path, buf); + if (r < 0) + { + if (GetLastError() == ERROR_DELETE_PENDING) + { + /* + * File has been deleted, but is not gone from the filesystem yet. + * This can happen when some process with FILE_SHARE_DELETE has it + * open and it will be fully removed once that handle is closed. + * Meanwhile, we can't open it, so indicate that the file just + * doesn't exist. + */ + errno = ENOENT; + return -1; + } + + return r; + } + + if (!GetFileAttributesEx(path, GetFileExInfoStandard, &attr)) + { + _dosmaperr(GetLastError()); + return -1; + } + + /* + * XXX no support for large files here, but we don't do that in general on + * Win32 yet. + */ + buf->st_size = attr.nFileSizeLow; + + return 0; +} + +#endif |