libpod: Add support for 'podman top' on FreeBSD

This simply runs ps(1) on the host and filters for processes inside the
container.

[NO NEW TESTS NEEDED]

Signed-off-by: Doug Rabson <dfr@rabson.org>

libpod/container_top_freebsd.go

@@ -0,0 +1,131 @@
+//go:build freebsd
+// +build freebsd
+
+package libpod
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"os/exec"
+	"strings"
+	"sync"
+
+	"github.com/containers/podman/v4/libpod/define"
+	"github.com/containers/podman/v4/pkg/util"
+	"github.com/google/shlex"
+	"github.com/sirupsen/logrus"
+)
+
+var isDescriptor = map[string]bool{}
+
+func init() {
+	allDescriptors, err := util.GetContainerPidInformationDescriptors()
+	if err != nil {
+		// Should never happen
+		logrus.Debugf("failed call to util.GetContainerPidInformationDescriptors()")
+		return
+	}
+	for _, d := range allDescriptors {
+		isDescriptor[d] = true
+	}
+}
+
+// Top gathers statistics about the running processes in a container. It returns a
+// []string for output
+func (c *Container) Top(descriptors []string) ([]string, error) {
+	conStat, err := c.State()
+	if err != nil {
+		return nil, fmt.Errorf("unable to look up state for %s: %w", c.ID(), err)
+	}
+	if conStat != define.ContainerStateRunning {
+		return nil, errors.New("top can only be used on running containers")
+	}
+
+	// Default to 'ps -ef' compatible descriptors
+	if len(descriptors) == 0 {
+		descriptors = []string{"user", "pid", "ppid", "pcpu", "etime", "tty", "time", "args"}
+	}
+
+	// If everything in descriptors is a supported AIX format
+	// descriptor, we use 'ps -ao <descriptors>', otherwise we pass
+	// everything straight through to ps.
+	supportedDescriptors := true
+	for _, d := range descriptors {
+		if _, ok := isDescriptor[d]; !ok {
+			supportedDescriptors = false
+			break
+		}
+	}
+	if supportedDescriptors {
+		descriptors = []string{"-ao", strings.Join(descriptors, ",")}
+	}
+
+	// Note that the descriptors to ps(1) must be shlexed (see #12452).
+	psDescriptors := []string{}
+	for _, d := range descriptors {
+		shSplit, err := shlex.Split(d)
+		if err != nil {
+			return nil, fmt.Errorf("parsing ps args: %w", err)
+		}
+		for _, s := range shSplit {
+			if s != "" {
+				psDescriptors = append(psDescriptors, s)
+			}
+		}
+	}
+
+	args := []string{
+		"-J",
+		c.jailName(),
+	}
+	args = append(args, psDescriptors...)
+
+	output, err := c.execPS(args)
+	if err != nil {
+		return nil, fmt.Errorf("executing ps(1): %w", err)
+	}
+
+	return output, nil
+}
+
+func (c *Container) execPS(args []string) ([]string, error) {
+	cmd := exec.Command("ps", args...)
+	stdoutPipe, err := cmd.StdoutPipe()
+	if err != nil {
+		return nil, err
+	}
+	stderrPipe, err := cmd.StderrPipe()
+	if err != nil {
+		return nil, err
+	}
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	stdout := []string{}
+	go func() {
+		scanner := bufio.NewScanner(stdoutPipe)
+		for scanner.Scan() {
+			stdout = append(stdout, scanner.Text())
+		}
+		wg.Done()
+	}()
+	stderr := []string{}
+	go func() {
+		scanner := bufio.NewScanner(stderrPipe)
+		for scanner.Scan() {
+			stderr = append(stderr, scanner.Text())
+		}
+		wg.Done()
+	}()
+
+	if err := cmd.Start(); err != nil {
+		return nil, err
+	}
+	wg.Wait()
+	if err := cmd.Wait(); err != nil {
+		return nil, fmt.Errorf("ps(1) command failed: %w, output: %s", err, strings.Join(stderr, " "))
+	}
+
+	return stdout, nil
+}

libpod/container_top_unsupported.go

@@ -1,5 +1,5 @@
-//go:build !linux
-// +build !linux
+//go:build !linux && !freebsd
+// +build !linux,!freebsd
 
 package libpod