podman-top: use containers/psgo

Use github.com/containers/psgo instead of execing `ps (1)`.  The psgo
library enables a much more flexible interface with respect to which
data to be printed (e.g., capabilities, seccomp mode, PID, PCPU, etc.)
while the output can be parsed reliably.  The library does not use
ps (1) but parses /proc and /dev instead.  To list the processes of a
given container, psgo will join the mount namespace of the given
container and extract all data from there.

Notice that this commit breaks compatibility with docker-top.

Signed-off-by: Valentin Rothberg <vrothberg@suse.com>

Closes: #1113
Approved by: rhatdan

1 files changed, 30 insertions, 0 deletions

diff --git a/libpod/container_top_linux.go b/libpod/container_top_linux.go
new file mode 100644
index 000000000..450130add
--- /dev/null
+++ b/libpod/container_top_linux.go
@@ -0,0 +1,30 @@
+// +build linux
+
+package libpod
+
+import (
+	"strconv"
+	"strings"
+
+	"github.com/containers/psgo/ps"
+)
+
+// GetContainerPidInformation returns process-related data of all processes in
+// the container.  The output data can be controlled via the `descriptors`
+// argument which expects format descriptors and supports all AIXformat
+// descriptors of ps (1) plus some additional ones to for instance inspect the
+// set of effective capabilities.  Eeach element in the returned string slice
+// is a tab-separated string.
+//
+// For more details, please refer to github.com/containers/psgo.
+func (c *Container) GetContainerPidInformation(descriptors []string) ([]string, error) {
+	pid := strconv.Itoa(c.state.PID)
+	format := strings.Join(descriptors, ",")
+	return ps.JoinNamespaceAndProcessInfo(pid, format)
+}
+
+// GetContainerPidInformationDescriptors returns a string slice of all supported
+// format descriptors of GetContainerPidInformation.
+func GetContainerPidInformationDescriptors() ([]string, error) {
+	return ps.ListDescriptors(), nil
+}