update

PACKAGE DOCUMENTATION

package update
    import "github.com/inconshreveable/go-update"

    Package update allows a program to "self-update", replacing its
    executable file with new bytes.

    Package update provides the facility to create user experiences like
    auto-updating or user-approved updates which manifest as user prompts in
    commercial applications with copy similar to "Restart to being using the
    new version of X".

    Updating your program to a new version is as easy as:

	err := update.FromUrl("http://release.example.com/2.0/myprogram")
	if err != nil {
		fmt.Printf("Update failed: %v", err)
	}

    The most low-level API is FromStream() which updates the current
    executable with the bytes read from an io.Reader.

    Additional APIs are provided for common update strategies which include
    updating from a file with FromFile() and updating from the internet with
    FromUrl().

    Using the more advaced Download.UpdateFromUrl() API gives you the
    ability to resume an interrupted download to enable large updates to
    complete even over intermittent or slow connections. This API also
    enables more fine-grained control over how the update is downloaded from
    the internet as well as access to download progress,


VARIABLES

var (
    // Returned when the remote server indicates that no download is available
    UpdateUnavailable error
)


FUNCTIONS

func FromFile(filepath string) (err error)
    FromFile reads the contents of the given file and uses them to update
    the current program's executable file by calling FromStream().

func FromStream(newBinary io.Reader) (err error)
    FromStream reads the contents of the supplied io.Reader newBinary and
    uses them to update the current program's executable file.

    FromStream performs the following actions to ensure a cross-platform
    safe update:

    - Renames the current program's executable file from
    /path/to/program-name to /path/to/.program-name.old

    - Opens the now-empty path /path/to/program-name with mode 0755 and
    copies the contents of newBinary into the file.

    - If the copy is successful, it erases /path/to/.program.old. If this
    operation fails, no error is reported.

    - If the copy is unsuccessful, it attempts to rename
    /path/to/.program-name.old back to /path/to/program-name. If this
    operation fails, the error is not reported in order to not mask the
    error that caused the rename recovery attempt.

func FromUrl(url string) error
    FromUrl downloads the contents of the given url and uses them to update
    the current program's executable file. It is a convenience function
    which is equivalent to

	NewDownload().UpdateFromUrl(url)

    See Download.UpdateFromUrl for more details.


TYPES

type Download struct {
    // net/http.Client to use when downloading the update.
    // If nil, a default http.Client is used
    HttpClient *http.Client

    // Path on the file system to dowload the update to
    // If empty, a temporary file is used.
    // After the download begins, this path will be set
    // so that the client can use it to resume aborted
    // downloads
    Path string

    // Progress returns the percentage of the download
    // completed as an integer between 0 and 100
    Progress chan (int)

    // HTTP Method to use in the download request. Default is "GET"
    Method string
}
    Type Download encapsulates the necessary parameters and state needed to
    download an update from the internet. Create an instance with the
    NewDownload() factory function.


func NewDownload() *Download
    NewDownload initializes a new Download object


func (d *Download) UpdateFromUrl(url string) (err error)
    UpdateFromUrl downloads the given url from the internet to a file on
    disk and then calls FromStream() to update the current program's
    executable file with the contents of that file.

    If the update is successful, the downloaded file will be erased from
    disk. Otherwise, it will remain in d.Path to allow the download to
    resume later or be skipped entirely.

    Only HTTP/1.1 servers that implement the Range header are supported.

    UpdateFromUrl() uses HTTP status codes to determine what action to take.

    - The HTTP server should return 200 or 206 for the update to be
    downloaded.

    - The HTTP server should return 204 if no update is available at this
    time. This will cause UpdateFromUrl to return the error
    UpdateUnavailable.

    - If the HTTP server returns a 3XX redirect, it will be followed
    according to d.HttpClient's redirect policy.

    - Any other HTTP status code will cause UpdateFromUrl to return an
    error.