more error messages

compile.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"fmt"
+	"os/exec"
+	"sync"
+)
+
+func Compile(cfg *CompileConfig, ch chan<- *CompileReport, wg *sync.WaitGroup) {
+	filename := fmt.Sprintf("%s_%s_%s%s", ProjectName, cfg.OS, cfg.Arch, cfg.FileExt)
+
+	ch <- &CompileReport{Config: cfg, State: StateCompiling}
+
+	compileCmd := exec.Command("go", "build", "-o", filename)
+	compileCmd.Dir = ModulePath
+
+	if err := compileCmd.Start(); err != nil {
+		ch <- &CompileReport{Config: cfg, State: StateCompileError}
+		wg.Done()
+		return
+	}
+	if err := compileCmd.Wait(); err != nil {
+		ch <- &CompileReport{Config: cfg, State: StateCompileError}
+		wg.Done()
+		return
+	}
+
+	Compress(filename, cfg, ch, wg)
+
+	// uncomment for independent compile and compress tasks
+	// (slightly slower in tests, most likely because of more context switches)
+	/*
+		ch <- &CompileReport{Config: cfg, State: StateWaiting}
+		go Runner.Run(func() { Compress(filename, cfg, ch, wg) })
+	*/
+}
+
+func Compress(filename string, cfg *CompileConfig, ch chan<- *CompileReport, wg *sync.WaitGroup) {
+	defer wg.Done()
+
+	ch <- &CompileReport{Config: cfg, State: StateCompressing}
+
+	if !*NoCompress && cfg.Compress {
+		compressCmd := exec.Command("upx", "--best", filename)
+		compressCmd.Dir = ModulePath
+
+		if err := compressCmd.Start(); err != nil {
+			ch <- &CompileReport{Config: cfg, State: StateCompressError}
+			return
+		}
+
+		if err := compressCmd.Wait(); err != nil {
+			ch <- &CompileReport{Config: cfg, State: StateCompressError}
+			return
+		}
+	}
+
+	ch <- &CompileReport{Config: cfg, State: StateDone}
+}

compile_report.go

@@ -27,6 +27,8 @@ var (
 	ColorError      = color.New(color.FgRed, color.Bold)
 	ColorInProgress = color.New(color.FgBlue)
 	ColorDone       = color.New(color.FgGreen, color.Bold)
+
+	ColorWarn = color.New(color.FgYellow, color.Bold)
 )
 
 func (s CompileState) String() string {

main.go

@@ -1,21 +1,29 @@
 package main
 
 import (
+	"errors"
 	"flag"
 	"fmt"
+	"os"
 	"os/exec"
 	"path/filepath"
 	"runtime"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
 	"git.milar.in/milarin/channel"
 )
 
-var ModulePath string
-var ProjectName string
+// globals
+var (
+	ModulePath  string
+	ProjectName string
+	Runner      channel.Runner
+)
 
+// command line arguments
 var (
 	OS   = flag.String("os", "", "comma-separated list of operating systems to compile for (empty for all)")
 	Arch = flag.String("arch", "", "comma-separated list of architectures to compile for (empty for all)")
@@ -25,21 +33,41 @@ var (
 	NumThreads = flag.Int("t", runtime.NumCPU(), "amount of threads (0 = infinite)")
 )
 
-var Runner channel.Runner
-
 func main() {
 	var err error
 	flag.Parse()
 
-	if err := FillCompileConfigs(); err != nil {
-		panic(err)
-	}
-
 	ModulePath, err = filepath.Abs(flag.Arg(0))
 	if err != nil {
 		panic(err)
 	}
-	ProjectName = filepath.Base(ModulePath)
+
+	if _, err := exec.LookPath("go"); err != nil {
+		ColorError.Fprintln(os.Stderr, "go not found in PATH. compilation not possible")
+		return
+	}
+
+	if !*NoCompress {
+		if _, err := exec.LookPath("upx"); err != nil {
+			ColorWarn.Fprintln(os.Stderr, "upx not found in PATH. file compression not possible")
+			*NoCompress = true
+		}
+	}
+
+	if err := FillCompileConfigs(); err != nil {
+		ColorError.Fprintln(os.Stderr, fmt.Errorf("target architectures could not be determined: %w", err))
+		return
+	}
+
+	if _, err := os.Stat(filepath.Join(ModulePath, "go.mod")); errors.Is(err, os.ErrNotExist) {
+		ColorError.Fprintf(os.Stderr, "no Go module found at '%s'\n", ModulePath)
+		return
+	}
+
+	if err := DetermineProjectName(); err != nil {
+		ColorError.Fprintln(os.Stderr, fmt.Errorf("project name could not be determined: %w", err))
+		return
+	}
 
 	ch := make(chan *CompileReport, len(CompileConfigs))
 	wg := new(sync.WaitGroup)
@@ -65,58 +93,26 @@ func main() {
 	<-doneCh // wait for Watch
 
 	if !*Silent {
-		fmt.Printf("compilation took %s (using %s threads)\n", end.Sub(start), GetThreadCount())
+		fmt.Printf("compilation took %s (using %s threads)\n", end.Sub(start), GetThreadCountString())
 	}
 }
 
-func Compile(cfg *CompileConfig, ch chan<- *CompileReport, wg *sync.WaitGroup) {
-	filename := fmt.Sprintf("%s_%s_%s%s", ProjectName, cfg.OS, cfg.Arch, cfg.FileExt)
-
-	ch <- &CompileReport{Config: cfg, State: StateCompiling}
-
-	compileCmd := exec.Command("go", "build", "-o", filename)
-	compileCmd.Dir = ModulePath
-	if err := compileCmd.Start(); err != nil {
-		ch <- &CompileReport{Config: cfg, State: StateCompileError}
-		wg.Done()
-		return
-	}
-	if err := compileCmd.Wait(); err != nil {
-		ch <- &CompileReport{Config: cfg, State: StateCompileError}
-		wg.Done()
-		return
+func DetermineProjectName() error {
+	data, err := os.ReadFile(filepath.Join(ModulePath, "go.mod"))
+	if err != nil {
+		return err
 	}
 
-	Compress(filename, cfg, ch, wg)
-
-	// uncomment for independent compile and compress tasks
-	/*
-		ch <- &CompileReport{Config: cfg, State: StateWaiting}
-		go Runner.Run(func() { Compress(filename, cfg, ch, wg) })
-	*/
-}
-
-func Compress(filename string, cfg *CompileConfig, ch chan<- *CompileReport, wg *sync.WaitGroup) {
-	defer wg.Done()
-
-	ch <- &CompileReport{Config: cfg, State: StateCompressing}
-
-	if !*NoCompress && cfg.Compress {
-		compressCmd := exec.Command("upx", "--best", filename)
-		compressCmd.Dir = ModulePath
-
-		if err := compressCmd.Start(); err != nil {
-			ch <- &CompileReport{Config: cfg, State: StateCompressError}
-			return
-		}
-
-		if err := compressCmd.Wait(); err != nil {
-			ch <- &CompileReport{Config: cfg, State: StateCompressError}
-			return
+	for _, line := range strings.Split(string(data), "\n") {
+		if strings.HasPrefix(line, "module ") {
+			fullName := strings.TrimPrefix(line, "module ")
+			parts := strings.Split(fullName, "/")
+			ProjectName = parts[len(parts)-1]
+			return nil
 		}
 	}
 
-	ch <- &CompileReport{Config: cfg, State: StateDone}
+	return errors.New("malformed syntax in go.mod file")
 }
 
 func GetRunner() channel.Runner {
@@ -127,7 +123,7 @@ func GetRunner() channel.Runner {
 	}
 }
 
-func GetThreadCount() string {
+func GetThreadCountString() string {
 	if *NumThreads == 0 {
 		return "infinitely many"
 	}