diff options
Diffstat (limited to 'src/port/open.c')
| -rw-r--r-- | src/port/open.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/src/port/open.c b/src/port/open.c new file mode 100644 index 0000000..14c6deb --- /dev/null +++ b/src/port/open.c @@ -0,0 +1,216 @@ +/*------------------------------------------------------------------------- + * + * open.c + * Win32 open() replacement + * + * + * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group + * + * src/port/open.c + * + *------------------------------------------------------------------------- + */ + +#ifdef WIN32 + +#ifndef FRONTEND +#include "postgres.h" +#else +#include "postgres_fe.h" +#endif + +#include <fcntl.h> +#include <assert.h> +#include <sys/stat.h> + + +static int +openFlagsToCreateFileFlags(int openFlags) +{ + switch (openFlags & (O_CREAT | O_TRUNC | O_EXCL)) + { + /* O_EXCL is meaningless without O_CREAT */ + case 0: + case O_EXCL: + return OPEN_EXISTING; + + case O_CREAT: + return OPEN_ALWAYS; + + /* O_EXCL is meaningless without O_CREAT */ + case O_TRUNC: + case O_TRUNC | O_EXCL: + return TRUNCATE_EXISTING; + + case O_CREAT | O_TRUNC: + return CREATE_ALWAYS; + + /* O_TRUNC is meaningless with O_CREAT */ + case O_CREAT | O_EXCL: + case O_CREAT | O_TRUNC | O_EXCL: + return CREATE_NEW; + } + + /* will never get here */ + return 0; +} + +/* + * - file attribute setting, based on fileMode? + */ +int +pgwin32_open(const char *fileName, int fileFlags,...) +{ + int fd; + HANDLE h = INVALID_HANDLE_VALUE; + SECURITY_ATTRIBUTES sa; + int loops = 0; + + /* Check that we can handle the request */ + assert((fileFlags & ((O_RDONLY | O_WRONLY | O_RDWR) | O_APPEND | + (O_RANDOM | O_SEQUENTIAL | O_TEMPORARY) | + _O_SHORT_LIVED | O_DSYNC | O_DIRECT | + (O_CREAT | O_TRUNC | O_EXCL) | (O_TEXT | O_BINARY))) == fileFlags); +#ifndef FRONTEND + Assert(pgwin32_signal_event != NULL); /* small chance of pg_usleep() */ +#endif + +#ifdef FRONTEND + + /* + * Since PostgreSQL 12, those concurrent-safe versions of open() and + * fopen() can be used by frontends, having as side-effect to switch the + * file-translation mode from O_TEXT to O_BINARY if none is specified. + * Caller may want to enforce the binary or text mode, but if nothing is + * defined make sure that the default mode maps with what versions older + * than 12 have been doing. + */ + if ((fileFlags & O_BINARY) == 0) + fileFlags |= O_TEXT; +#endif + + sa.nLength = sizeof(sa); + sa.bInheritHandle = TRUE; + sa.lpSecurityDescriptor = NULL; + + while ((h = CreateFile(fileName, + /* cannot use O_RDONLY, as it == 0 */ + (fileFlags & O_RDWR) ? (GENERIC_WRITE | GENERIC_READ) : + ((fileFlags & O_WRONLY) ? GENERIC_WRITE : GENERIC_READ), + /* These flags allow concurrent rename/unlink */ + (FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE), + &sa, + openFlagsToCreateFileFlags(fileFlags), + FILE_ATTRIBUTE_NORMAL | + ((fileFlags & O_RANDOM) ? FILE_FLAG_RANDOM_ACCESS : 0) | + ((fileFlags & O_SEQUENTIAL) ? FILE_FLAG_SEQUENTIAL_SCAN : 0) | + ((fileFlags & _O_SHORT_LIVED) ? FILE_ATTRIBUTE_TEMPORARY : 0) | + ((fileFlags & O_TEMPORARY) ? FILE_FLAG_DELETE_ON_CLOSE : 0) | + ((fileFlags & O_DIRECT) ? FILE_FLAG_NO_BUFFERING : 0) | + ((fileFlags & O_DSYNC) ? FILE_FLAG_WRITE_THROUGH : 0), + NULL)) == INVALID_HANDLE_VALUE) + { + /* + * Sharing violation or locking error can indicate antivirus, backup + * or similar software that's locking the file. Wait a bit and try + * again, giving up after 30 seconds. + */ + DWORD err = GetLastError(); + + if (err == ERROR_SHARING_VIOLATION || + err == ERROR_LOCK_VIOLATION) + { +#ifndef FRONTEND + if (loops == 50) + ereport(LOG, + (errmsg("could not open file \"%s\": %s", fileName, + (err == ERROR_SHARING_VIOLATION) ? _("sharing violation") : _("lock violation")), + errdetail("Continuing to retry for 30 seconds."), + errhint("You might have antivirus, backup, or similar software interfering with the database system."))); +#endif + + if (loops < 300) + { + pg_usleep(100000); + loops++; + continue; + } + } + + /* + * ERROR_ACCESS_DENIED is returned if the file is deleted but not yet + * gone (Windows NT status code is STATUS_DELETE_PENDING). In that + * case we want to wait a bit and try again, giving up after 1 second + * (since this condition should never persist very long). However, + * there are other commonly-hit cases that return ERROR_ACCESS_DENIED, + * so care is needed. In particular that happens if we try to open a + * directory, or of course if there's an actual file-permissions + * problem. To distinguish these cases, try a stat(). In the + * delete-pending case, it will either also get STATUS_DELETE_PENDING, + * or it will see the file as gone and fail with ENOENT. In other + * cases it will usually succeed. The only somewhat-likely case where + * this coding will uselessly wait is if there's a permissions problem + * with a containing directory, which we hope will never happen in any + * performance-critical code paths. + */ + if (err == ERROR_ACCESS_DENIED) + { + if (loops < 10) + { + struct stat st; + + if (stat(fileName, &st) != 0) + { + pg_usleep(100000); + loops++; + continue; + } + } + } + + _dosmaperr(err); + return -1; + } + + /* _open_osfhandle will, on error, set errno accordingly */ + if ((fd = _open_osfhandle((intptr_t) h, fileFlags & O_APPEND)) < 0) + CloseHandle(h); /* will not affect errno */ + else if (fileFlags & (O_TEXT | O_BINARY) && + _setmode(fd, fileFlags & (O_TEXT | O_BINARY)) < 0) + { + _close(fd); + return -1; + } + + return fd; +} + +FILE * +pgwin32_fopen(const char *fileName, const char *mode) +{ + int openmode = 0; + int fd; + + if (strstr(mode, "r+")) + openmode |= O_RDWR; + else if (strchr(mode, 'r')) + openmode |= O_RDONLY; + if (strstr(mode, "w+")) + openmode |= O_RDWR | O_CREAT | O_TRUNC; + else if (strchr(mode, 'w')) + openmode |= O_WRONLY | O_CREAT | O_TRUNC; + if (strchr(mode, 'a')) + openmode |= O_WRONLY | O_CREAT | O_APPEND; + + if (strchr(mode, 'b')) + openmode |= O_BINARY; + if (strchr(mode, 't')) + openmode |= O_TEXT; + + fd = pgwin32_open(fileName, openmode); + if (fd == -1) + return NULL; + return _fdopen(fd, mode); +} + +#endif |