GLib-2.0 ▶ GLib ▶ file_set_contents_fullSince 2.66

Writes all of contents to a file named filename, with good error checking. If a file called filename already exists it will be overwritten.

flags control the properties of the write operation: whether it’s atomic, and what the tradeoff is between returning quickly or being resilient to system crashes.

As this function performs file I/O, it is recommended to not call it anywhere where blocking would cause problems, such as in the main loop of a graphical application. In particular, if flags has any value other than GLib.FileSetContentsFlags.NONE then this function may call fsync().

If GLib.FileSetContentsFlags.CONSISTENT is set in flags, the operation is atomic in the sense that it is first written to a temporary file which is then renamed to the final name.

Notes:

• On UNIX, if filename already exists hard links to filename will break. Also since the file is recreated, existing permissions, access control lists, metadata etc. may be lost. If filename is a symbolic link, the link itself will be replaced, not the linked file.

• On UNIX, if filename already exists and is non-empty, and if the system supports it (via a journalling filesystem or equivalent), and if GLib.FileSetContentsFlags.CONSISTENT is set in flags, the fsync() call (or equivalent) will be used to ensure atomic replacement: filename will contain either its old contents or contents, even in the face of system power loss, the disk being unsafely removed, etc.

• On UNIX, if filename does not already exist or is empty, there is a possibility that system power loss etc. after calling this function will leave filename empty or full of NUL bytes, depending on the underlying filesystem, unless GLib.FileSetContentsFlags.DURABLE and GLib.FileSetContentsFlags.CONSISTENT are set in flags.

• On Windows renaming a file will not remove an existing file with the new name, so on Windows there is a race condition between the existing file being removed and the temporary file being renamed.

• On Windows there is no way to remove a file that is open to some process, or mapped into memory. Thus, this function will fail if filename already exists and is open.

If the call was successful, it returns true. If the call was not successful, it returns false and sets error. The error domain is G_FILE_ERROR. Possible error codes are those in the GLib.FileError enumeration.

Note that the name for the temporary file is constructed by appending up to 7 characters to filename.

If the file didn’t exist before and is created, it will be given the permissions from mode. Otherwise, the permissions of the existing file will remain unchanged.