memexec.go

Documentation: github.com/amenzhinsky/go-memexec

     1  package memexec
     2  
     3  import (
     4  	"context"
     5  	"os"
     6  	"os/exec"
     7  )
     8  
     9  type Option func(e *Exec)
    10  
    11  // Exec is an in-memory executable code unit.
    12  type Exec struct {
    13  	f     *os.File
    14  	opts  []func(cmd *exec.Cmd)
    15  	clean func() error
    16  }
    17  
    18  // WithPrepare configures cmd with default values such as Env, Dir, etc.
    19  func WithPrepare(fn func(cmd *exec.Cmd)) Option {
    20  	return func(e *Exec) {
    21  		e.opts = append(e.opts, fn)
    22  	}
    23  }
    24  
    25  // WithCleanup is executed right after Exec.Close.
    26  func WithCleanup(fn func() error) Option {
    27  	return func(e *Exec) {
    28  		e.clean = fn
    29  	}
    30  }
    31  
    32  // New creates new memory execution object that can be
    33  // used for executing commands on a memory based binary.
    34  func New(b []byte, opts ...Option) (*Exec, error) {
    35  	f, err := open(b)
    36  	if err != nil {
    37  		return nil, err
    38  	}
    39  	e := &Exec{f: f}
    40  	for _, opt := range opts {
    41  		opt(e)
    42  	}
    43  	return e, nil
    44  }
    45  
    46  // Command is an equivalent of `exec.Command`,
    47  // except that the path to the executable is being omitted.
    48  func (m *Exec) Command(args ...string) *exec.Cmd {
    49  	return m.CommandContext(context.Background(), args...)
    50  }
    51  
    52  // CommandContext is an equivalent of `exec.CommandContext`,
    53  // except that the path to the executable is being omitted.
    54  func (m *Exec) CommandContext(ctx context.Context, args ...string) *exec.Cmd {
    55  	exe := exec.CommandContext(ctx, m.f.Name(), args...)
    56  	for _, opt := range m.opts {
    57  		opt(exe)
    58  	}
    59  	return exe
    60  }
    61  
    62  // Close closes Exec object.
    63  //
    64  // Any further command will fail, it's client's responsibility
    65  // to control the flow by using synchronization algorithms.
    66  func (m *Exec) Close() error {
    67  	if err := clean(m.f); err != nil {
    68  		if m.clean != nil {
    69  			_ = m.clean()
    70  		}
    71  		return err
    72  	}
    73  	if m.clean == nil {
    74  		return nil
    75  	}
    76  	return m.clean()
    77  }
    78
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