75 lines
2.8 KiB
Go
75 lines
2.8 KiB
Go
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// Package terminal encapsulates some platform-specific logic for detecting
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// if we're running in a terminal and, if so, properly configuring that
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// terminal to meet the assumptions that the rest of Terraform makes.
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//
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// Specifically, Terraform requires a Terminal which supports virtual terminal
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// sequences and which accepts UTF-8-encoded text.
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//
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// This is an abstraction only over the platform-specific detection of and
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// possibly initialization of terminals. It's not intended to provide
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// higher-level abstractions of the sort provided by packages like termcap or
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// curses; ultimately we just assume that terminals are "standard" VT100-like
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// terminals and use a subset of control codes that works across the various
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// platforms we support. Our approximate target is "xterm-compatible"
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// virtual terminals.
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package terminal
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import (
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"os"
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)
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// Streams represents a collection of three streams that each may or may not
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// be connected to a terminal.
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//
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// If a stream is connected to a terminal then there are more possibilities
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// available, such as detecting the current terminal width. If we're connected
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// to something else, such as a pipe or a file on disk, the stream will
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// typically provide placeholder values or do-nothing stubs for
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// terminal-requiring operatons.
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//
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// Note that it's possible for only a subset of the streams to be connected
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// to a terminal. For example, this happens if the user runs Terraform with
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// I/O redirection where Stdout might refer to a regular disk file while Stderr
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// refers to a terminal, or various other similar combinations.
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type Streams struct {
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Stdout *OutputStream
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Stderr *OutputStream
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Stdin *InputStream
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}
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// Init tries to initialize a terminal, if Terraform is running in one, and
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// returns an object describing what it was able to set up.
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//
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// An error for this function indicates that the current execution context
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// can't meet Terraform's assumptions. For example, on Windows Init will return
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// an error if Terraform is running in a Windows Console that refuses to
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// activate UTF-8 mode, which can happen if we're running on an unsupported old
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// version of Windows.
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//
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// Note that the success of this function doesn't mean that we're actually
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// running in a terminal. It could also represent successfully detecting that
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// one or more of the input/output streams is not a terminal.
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func Init() (*Streams, error) {
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// These configure* functions are platform-specific functions in other
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// files that use //+build constraints to vary based on target OS.
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stderr, err := configureOutputHandle(os.Stderr)
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if err != nil {
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return nil, err
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}
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stdout, err := configureOutputHandle(os.Stdout)
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if err != nil {
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return nil, err
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}
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stdin, err := configureInputHandle(os.Stdin)
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if err != nil {
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return nil, err
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}
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return &Streams{
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Stdout: stdout,
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Stderr: stderr,
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Stdin: stdin,
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}, nil
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}
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