feat: Add AIX support for system/filesystem

CHANGELOG.md

@@ -7,6 +7,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Added
 
+- Add AIX support for system/filesystem #58
+
 ### Changed
 
 ### Deprecated

metric/system/filesystem/filesystem.go

@@ -15,8 +15,8 @@
 // specific language governing permissions and limitations
 // under the License.
 
-//go:build darwin || freebsd || linux || openbsd || windows
-// +build darwin freebsd linux openbsd windows
+//go:build darwin || freebsd || linux || openbsd || windows || aix
+// +build darwin freebsd linux openbsd windows aix
 
 package filesystem
 

metric/system/filesystem/filesystem_aix.go

@@ -0,0 +1,152 @@
+// Licensed to Elasticsearch B.V. under one or more contributor
+// license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright
+// ownership. Elasticsearch B.V. licenses this file to you under
+// the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+//go:build aix
+// +build aix
+
+package filesystem
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+/*
+#include <sys/types.h>
+#include <sys/mntctl.h>
+#include <sys/vmount.h>
+*/
+import "C"
+
+// get the list of mounts on aix
+func parseMounts(_ string, filter func(FSStat) bool) ([]FSStat, error) {
+	buf, ret, err := aixVmount()
+	if err != nil {
+		return nil, fmt.Errorf("error fetching mounts: %w", err)
+	}
+
+	fsList := []FSStat{}
+
+	// iterate through every vmount struct contained in buf
+	var nextBufIdx uint
+	for i := 0; i < int(ret); i++ {
+		vmt := (*C.struct_vmount)(unsafe.Pointer(&buf[nextBufIdx]))
+		nextBufIdx += uint(vmt.vmt_length)
+
+		// Parse fields
+		vmt_object := vmtDataToString(vmt, vmt.vmt_data[C.VMT_OBJECT])
+		vmt_stub := vmtDataToString(vmt, vmt.vmt_data[C.VMT_STUB])
+		vmt_hostname := vmtDataToString(vmt, vmt.vmt_data[C.VMT_HOSTNAME])
+		vmt_args := vmtDataToString(vmt, vmt.vmt_data[C.VMT_ARGS])
+
+		device := vmt_object
+		if vmt_hostname != "-" && vmt_hostname != "" {
+			device = device + vmt_hostname
+		}
+
+		fs := FSStat{
+			Device:    device,
+			Directory: vmt_stub,
+			Type:      aixGetFsName(int(vmt.vmt_gfstype)),
+			Options:   vmt_args,
+		}
+
+		if filter(fs) {
+			fsList = append(fsList, fs)
+		}
+	}
+
+	return fsList, nil
+}
+
+// aixVmount calls the vmount MCTL_QUERY function and returns the buffer
+// with the number of vmount structs.
+func aixVmount() ([]C.char, int, error) {
+	bufSize := 8 * 1024 // sane initial buffer size
+	buf := make([]C.char, bufSize)
+
+	// First call to vmount
+	ret, errno := C.mntctl(C.MCTL_QUERY, (C.ulong)(bufSize), &buf[0])
+	if ret == -1 {
+		return nil, 0, fmt.Errorf("mntctl failed with errno %d", errno)
+	}
+
+	// Check if our buffer was to small
+	if ret == 0 {
+		// Now use the proposed buffer size, which is stored as a word (4 bytes) in our previous buffer.
+		bufSize := int(*((*C.uint)(unsafe.Pointer(&buf[0]))))
+		if bufSize < 4 {
+			return nil, 0, fmt.Errorf("something is wrong, the proposed buffer of %d bytes can't even store a new proposal", bufSize)
+		}
+
+		// Create a new buffer with the proposed size and try again
+		buf = make([]C.char, bufSize)
+
+		ret, errno = C.mntctl(C.MCTL_QUERY, (C.ulong)(bufSize), &buf[0])
+		if ret == -1 {
+			return nil, 0, fmt.Errorf("second call to mntctl failed with errno %d", errno)
+		}
+
+		if ret == 0 {
+			return nil, 0, fmt.Errorf("second call to mntctl with buffer size %d bytes failed and proposed again a new buffer size", bufSize)
+		}
+	}
+
+	return buf, int(ret), nil
+}
+
+// vmtDataToString decodes the vmt_data structures of vmount as Go string
+func vmtDataToString(vmt *C.struct_vmount, data C.struct_vmt_data) string {
+	ptr := unsafe.Pointer(vmt)
+	ptr = unsafe.Add(ptr, data.vmt_off)
+	return C.GoString((*C.char)(ptr))
+}
+
+// aixGetFsName maps the gfs_type to the string values as described in vmount.h
+func aixGetFsName(gfstype int) string {
+	fsmap := map[int]string{
+		C.MNT_J2:      "jfs2",
+		C.MNT_NAMEFS:  "namefs",
+		C.MNT_NFS:     "nfs",
+		C.MNT_JFS:     "jfs",
+		C.MNT_CDROM:   "cdrom",
+		C.MNT_PROCFS:  "procfs",
+		C.MNT_SFS:     "sfs",
+		C.MNT_CACHEFS: "cachefs",
+		C.MNT_NFS3:    "nfs3",
+		C.MNT_AUTOFS:  "autofs",
+		C.MNT_POOLFS:  "poolfs",
+		C.MNT_VXFS:    "vxfs",
+		C.MNT_VXODM:   "vxodm",
+		C.MNT_UDF:     "udf",
+		C.MNT_NFS4:    "nfs4",
+		C.MNT_RFS4:    "rfs4",
+		C.MNT_CIFS:    "cifs",
+		C.MNT_PMEMFS:  "pmemfs",
+		C.MNT_AHAFS:   "ahafs",
+		C.MNT_STNFS:   "stnfs",
+		C.MNT_ASMFS:   "asmfs",
+		C.MNT_SMBC:    "smb",
+	}
+
+	fsname, ok := fsmap[gfstype]
+	if !ok {
+		return "unknown"
+	}
+
+	return fsname
+}