app: add code for macOS and Windows apps under 'app' (#12933)

* app: add code for macOS and Windows apps under 'app'

* app: add readme

* app: windows and linux only for now

* ci: fix ui CI validation

---------

Co-authored-by: jmorganca <jmorganca@gmail.com>

app/server/server_unix.go

@@ -0,0 +1,104 @@
+//go:build darwin
+
+package server
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log/slog"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"syscall"
+)
+
+var (
+	pidFile       = filepath.Join(os.Getenv("HOME"), "Library", "Application Support", "Ollama", "ollama.pid")
+	serverLogPath = filepath.Join(os.Getenv("HOME"), ".ollama", "logs", "server.log")
+)
+
+func commandContext(ctx context.Context, name string, arg ...string) *exec.Cmd {
+	return exec.CommandContext(ctx, name, arg...)
+}
+
+func terminate(proc *os.Process) error {
+	return proc.Signal(os.Interrupt)
+}
+
+func terminated(pid int) (bool, error) {
+	proc, err := os.FindProcess(pid)
+	if err != nil {
+		return false, fmt.Errorf("failed to find process: %v", err)
+	}
+
+	err = proc.Signal(syscall.Signal(0))
+	if err != nil {
+		if errors.Is(err, os.ErrProcessDone) || errors.Is(err, syscall.ESRCH) {
+			return true, nil
+		}
+
+		return false, fmt.Errorf("error signaling process: %v", err)
+	}
+
+	return false, nil
+}
+
+// reapServers kills all ollama processes except our own
+func reapServers() error {
+	// Get our own PID to avoid killing ourselves
+	currentPID := os.Getpid()
+
+	// Use pkill to kill ollama processes
+	// -x matches the whole command name exactly
+	// We'll get the list first, then kill selectively
+	cmd := exec.Command("pgrep", "-x", "ollama")
+	output, err := cmd.Output()
+	if err != nil {
+		// No ollama processes found
+		slog.Debug("no ollama processes found")
+		return nil //nolint:nilerr
+	}
+
+	pidsStr := strings.TrimSpace(string(output))
+	if pidsStr == "" {
+		return nil
+	}
+
+	pids := strings.Split(pidsStr, "\n")
+	for _, pidStr := range pids {
+		pidStr = strings.TrimSpace(pidStr)
+		if pidStr == "" {
+			continue
+		}
+
+		pid, err := strconv.Atoi(pidStr)
+		if err != nil {
+			slog.Debug("failed to parse PID", "pidStr", pidStr, "err", err)
+			continue
+		}
+		if pid == currentPID {
+			continue
+		}
+
+		proc, err := os.FindProcess(pid)
+		if err != nil {
+			slog.Debug("failed to find process", "pid", pid, "err", err)
+			continue
+		}
+
+		if err := proc.Signal(syscall.SIGTERM); err != nil {
+			// Try SIGKILL if SIGTERM fails
+			if err := proc.Signal(syscall.SIGKILL); err != nil {
+				slog.Warn("failed to stop external ollama process", "pid", pid, "err", err)
+				continue
+			}
+		}
+
+		slog.Info("stopped external ollama process", "pid", pid)
+	}
+
+	return nil
+}