memory: Add basic Solaris VirtualMemory() support

This commit adds support for VirtualMemory() in package mem. The support
only extends to total memory capcity, since that is all that is required
in Nomad. It does take into account global versus non-global zones, and
does not use cgo.

This has been tested inside a zone in the Joyent public cloud for a
non-global zone, and in the global zone of a SmartOS virtual machine.

mem/mem_fallback.go

@@ -1,4 +1,4 @@
-// +build !darwin,!linux,!freebsd,!openbsd,!windows
+// +build !darwin,!linux,!freebsd,!openbsd,!solaris,!windows
 
 package mem
 

mem/mem_solaris.go

@@ -0,0 +1,109 @@
+package mem
+
+import (
+	"errors"
+	"fmt"
+	"os/exec"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/shirou/gopsutil/internal/common"
+)
+
+// VirtualMemory for Solaris is a minimal implementation which only returns
+// what Nomad needs. It does take into account global vs zone, however.
+func VirtualMemory() (*VirtualMemoryStat, error) {
+	result := &VirtualMemoryStat{}
+
+	zoneName, err := zoneName()
+	if err != nil {
+		return nil, err
+	}
+
+	if zoneName == "global" {
+		cap, err := globalZoneMemoryCapacity()
+		if err != nil {
+			return nil, err
+		}
+		result.Total = cap
+	} else {
+		cap, err := nonGlobalZoneMemoryCapacity()
+		if err != nil {
+			return nil, err
+		}
+		result.Total = cap
+	}
+
+	return result, nil
+}
+
+func SwapMemory() (*SwapMemoryStat, error) {
+	return nil, common.ErrNotImplementedError
+}
+
+func zoneName() (string, error) {
+	zonename, err := exec.LookPath("/usr/bin/zonename")
+	if err != nil {
+		return "", err
+	}
+
+	out, err := invoke.Command(zonename)
+	if err != nil {
+		return "", err
+	}
+
+	return strings.TrimSpace(string(out)), nil
+}
+
+var globalZoneMemoryCapacityMatch = regexp.MustCompile(`Memory size: ([\d]+) Megabytes`)
+
+func globalZoneMemoryCapacity() (uint64, error) {
+	prtconf, err := exec.LookPath("/usr/sbin/prtconf")
+	if err != nil {
+		return 0, err
+	}
+
+	out, err := invoke.Command(prtconf)
+	if err != nil {
+		return 0, err
+	}
+
+	match := globalZoneMemoryCapacityMatch.FindAllStringSubmatch(string(out), -1)
+	if len(match) != 1 {
+		return 0, errors.New("Memory size not contained in output of /usr/sbin/prtconf")
+	}
+
+	totalMB, err := strconv.ParseUint(match[0][1], 10, 64)
+	if err != nil {
+		return 0, err
+	}
+
+	return totalMB * 1024 * 1024, nil
+}
+
+var kstatMatch = regexp.MustCompile(`([^\s]+)[\s]+([^\s]*)`)
+
+func nonGlobalZoneMemoryCapacity() (uint64, error) {
+	kstat, err := exec.LookPath("/usr/bin/kstat")
+	if err != nil {
+		return 0, err
+	}
+
+	out, err := invoke.Command(kstat, "-p", "-c", "zone_memory_cap", "memory_cap:*:*:physcap")
+	if err != nil {
+		return 0, err
+	}
+
+	kstats := kstatMatch.FindAllStringSubmatch(string(out), -1)
+	if len(kstats) != 1 {
+		return 0, fmt.Errorf("Expected 1 kstat, found %d", len(kstats))
+	}
+
+	memSizeBytes, err := strconv.ParseUint(kstats[0][2], 10, 64)
+	if err != nil {
+		return 0, err
+	}
+
+	return memSizeBytes, nil
+}