PMEM2_SOURCE_FROM_FD(3)

NAME

pmem2_source_from_fd(), pmem2_source_from_handle(), pmem2_source_delete() - creates or deletes an instance of persistent memory data source

SYNOPSIS

    #include <libpmem2.h>
    int pmem2_source_from_fd(struct pmem2_source *src, int fd);
    int pmem2_source_from_handle(struct pmem2_source *src, HANDLE handle); /* Windows only */
    int pmem2_source_delete(struct pmem2_source **src);

DESCRIPTION

On Linux the pmem2_source_from_fd() function validates the file descriptor and instantiates a new *struct pmem2_source** object describing the data source.

On Windows the pmem2_source_from_fd() function converts a file descriptor to a file handle (using **_get_osfhandle()), and passes it to pmem2_source_from_handle(). By default _get_osfhandle() calls abort() in case of invalid file descriptor, but this behavior can be suppressed by _set_abort_behavior() and SetErrorMode**() functions. Please check MSDN documentation for more information about Windows CRT error handling.

fd must be opened with O_RDONLY or O_RDWR mode, but on Windows it is not validated.

If fd is invalid, then the function fails.

The pmem2_source_from_handle() function validates the handle and instantiates a new *struct pmem2_source object describing the data source. If handle is INVALID_HANDLE_VALUE, then the function fails. The handle has to be created with an access mode of GENERIC_READ or (GENERIC_READ | GENERIC_WRITE). For details please see the CreateFile**() documentation.

The pmem2_source_delete() function frees *src returned by pmem2_source_from_fd() or pmem2_source_from_handle() and sets *src to NULL. If *src is NULL, no operation is performed.

RETURN VALUE

The pmem2_source_from_fd() and pmem2_source_from_handle() functions return 0 on success or a negative error code on failure.

The pmem2_source_delete() function always returns 0.

ERRORS

The pmem2_source_from_fd()/pmem2_source_from_handle() functions can fail with the following errors:

•   PMEM2_E_INVALID_FILE_HANDLE - fd is not an open and valid file descriptor. On Windows the function can abort() on this failure based on CRT's abort() behavior.

•   PMEM2_E_INVALID_FILE_HANDLE - fd is opened in O_WRONLY mode.

On Linux:

•   PMEM2_E_INVALID_FILE_TYPE - fd points to a directory, block device, pipe, or socket.

•   PMEM2_E_INVALID_FILE_TYPE - fd points to a character device other than Device DAX.

On Windows:

•   PMEM2_E_INVALID_FILE_TYPE - handle points to a resource that is not a regular file.

On Windows pmem2_source_from_fd() can return all errors from the underlying pmem2_source_from_handle() function.

The pmem2_source_from_handle() can return the following errors:

•   PMEM2_E_INVALID_FILE_HANDLE - handle points to a resource that is not a file.

•   PMEM2_E_INVALID_FILE_TYPE - handle points to a directory.

The pmem2_source_from_fd() and pmem2_source_from_handle() functions can also return -ENOMEM in case of insufficient memory to allocate an instance of struct pmem2_source.

CAVEATS

On non-DAX Windows volumes, fd/handle must remain open while the mapping is in use.

SEE ALSO

errno(3), pmem2_map_new(3), libpmem2(7) and <https://pmem.io>