hello world: fuse overlay is working!

Signed-off-by: vsoch <[email protected]>

Author: vsoch

.gitignore

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+bin
+vendor

COPYRIGHT

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+Intellectual Property Notice
+----------------------------
+
+HPCIC DevTools is licensed under the MIT license (LICENSE).
+
+Copyrights and patents in this project are retained by
+contributors. No copyright assignment is required to contribute to
+HPCIC DevTools.
+
+SPDX usage
+------------
+
+Individual files contain SPDX tags instead of the full license text.
+This enables machine processing of license information based on the SPDX
+License Identifiers that are available here: https://spdx.org/licenses/

LICENSE

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+MIT License
+
+Copyright (c) 2022-2023 LLNS, LLC and other HPCIC DevTools Developers.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Makefile

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+COMMONENVVAR=GOOS=$(shell uname -s | tr A-Z a-z)
+CPP = $(shell which cpp)
+
+.PHONY: all
+all: build
+
+.PHONY: build
+build: 
+	mkdir -p ./bin
+	go build -o ./bin/clib-gen cmd/gen/gen.go
+	
+
+.PHONY: test
+test:
+	bats -t test/bats/cli.bats

NOTICE

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+This work was produced under the auspices of the U.S. Department of
+Energy by Lawrence Livermore National Laboratory under Contract
+DE-AC52-07NA27344.
+
+This work was prepared as an account of work sponsored by an agency of
+the United States Government. Neither the United States Government nor
+Lawrence Livermore National Security, LLC, nor any of their employees
+makes any warranty, expressed or implied, or assumes any legal liability
+or responsibility for the accuracy, completeness, or usefulness of any
+information, apparatus, product, or process disclosed, or represents that
+its use would not infringe privately owned rights.
+
+Reference herein to any specific commercial product, process, or service
+by trade name, trademark, manufacturer, or otherwise does not necessarily
+constitute or imply its endorsement, recommendation, or favoring by the
+United States Government or Lawrence Livermore National Security, LLC.
+
+The views and opinions of authors expressed herein do not necessarily
+state or reflect those of the United States Government or Lawrence
+Livermore National Security, LLC, and shall not be used for advertising
+or product endorsement purposes.

README.md

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+# Compat Lib
+
+This is a library that prepares artifacts that describe the libraries needed (exposed via ldd) for a specific binary.
+We are going to do several experiments here (as I learn about the space).
+
+## Compatibility Wrapper
+
+If we wrap a binary, we can:
+
+1. Parse the ELF to get sonames needed
+2. Generate a fuse overlay where everything will be found in one spot (no searching needed)
+3. Then execute the binary.
+
+We would want to see that the exercise of not needing to do the search speeds up that loading time. If it does, it would make sense to pre-package this metadata with the binary for some registry to use.
+
+
+🚧️ Under Development! 🚧️
+
+## Usage
+
+Build the binary
+
+```bash
+make
+```
+
+Test running with a binary:
+
+```bash
+./bin/clib-gen --binary /home/vanessa/Desktop/Code/spack/opt/spack/linux-ubuntu24.04-zen4/gcc-13.2.0/xz-5.4.6-klise22d77jjaoejkucrczlkvnm6f4au/bin/lzcat 
+```
+
+Work in progress! The above calls the custom open function, so now we can do a special case for the libraries.
+
+
+## License
+
+HPCIC DevTools is distributed under the terms of the MIT license.
+All new contributions must be made under this license.
+
+See [LICENSE](https://github.com/converged-computing/cloud-select/blob/main/LICENSE),
+[COPYRIGHT](https://github.com/converged-computing/cloud-select/blob/main/COPYRIGHT), and
+[NOTICE](https://github.com/converged-computing/cloud-select/blob/main/NOTICE) for details.
+
+SPDX-License-Identifier: (MIT)
+
+LLNL-CODE- 842614

cmd/gen/gen.go

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+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/compspec/compat-lib/pkg/fs"
+	"github.com/compspec/compat-lib/pkg/generate"
+)
+
+func main() {
+	fmt.Println("⭐️ Compatibility Library Generator (clib-gen)")
+	binary := flag.String("binary", "", "Binary to trace")
+
+	flag.Parse()
+	path := *binary
+
+	fmt.Printf("Preparing to find shared libraries needed for %s\n", path)
+	paths, err := generate.FindSharedLibs(path)
+	if err != nil {
+		log.Panicf("Error finding shared libraries for %s: %x", path, err)
+	}
+	for _, path := range paths {
+		fmt.Println(path)
+	}
+
+	// Generate the fusefs server
+	compatFS, err := fs.NewCompatFS()
+	if err != nil {
+		log.Panicf("Cannot generate fuse server: %x", err)
+	}
+
+	// Removes mount point directory when done
+	defer compatFS.Cleanup()
+
+	c := make(chan os.Signal)
+	signal.Notify(c, os.Interrupt, syscall.SIGTERM)
+	go func() {
+		<-c
+		compatFS.Server.Unmount()
+	}()
+	compatFS.Server.Wait()
+
+}

go.mod

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+module github.com/compspec/compat-lib
+
+go 1.22
+
+require (
+	github.com/hanwen/go-fuse/v2 v2.6.1
+	github.com/u-root/u-root v0.14.0
+)
+
+require golang.org/x/sys v0.17.0 // indirect

go.sum

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+github.com/hanwen/go-fuse/v2 v2.6.1 h1:F3RUMbAuRhVTi3fvgf8HjMPvOm9xEv5wjuy/AXJtEwI=
+github.com/hanwen/go-fuse/v2 v2.6.1/go.mod h1:ugNaD/iv5JYyS1Rcvi57Wz7/vrLQJo10mmketmoef48=
+github.com/kylelemons/godebug v0.0.0-20170820004349-d65d576e9348 h1:MtvEpTB6LX3vkb4ax0b5D2DHbNAUsen0Gx5wZoq3lV4=
+github.com/kylelemons/godebug v0.0.0-20170820004349-d65d576e9348/go.mod h1:B69LEHPfb2qLo0BaaOLcbitczOKLWTsrBG9LczfCD4k=
+github.com/moby/sys/mountinfo v0.6.2 h1:BzJjoreD5BMFNmD9Rus6gdd1pLuecOFPt8wC+Vygl78=
+github.com/moby/sys/mountinfo v0.6.2/go.mod h1:IJb6JQeOklcdMU9F5xQ8ZALD+CUr5VlGpwtX+VE0rpI=
+github.com/u-root/u-root v0.14.0 h1:Ka4T10EEML7dQ5XDvO9c3MBN8z4nuSnGjcd1jmU2ivg=
+github.com/u-root/u-root v0.14.0/go.mod h1:hAyZorapJe4qzbLWlAkmSVCJGbfoU9Pu4jpJ1WMluqE=
+golang.org/x/sys v0.17.0 h1:25cE3gD+tdBA7lp7QfhuV+rJiE9YXTcS3VG1SqssI/Y=
+golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=

pkg/fs/fs.go

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+package fs
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/hanwen/go-fuse/v2/fuse"
+)
+
+// Keep these constants for now
+const (
+	debug = true
+
+	// mount with -o allowother
+	other = false
+
+	// Try to use "mount" syscall instead of fusermount
+	directMount = false
+
+	// Allow to fall back to fusermount (probably doesn't matter given directMount false)
+	directMountStrict = false
+
+	// original FS is for the loopback root
+	originalFS = "/"
+)
+
+type CompatFS struct {
+	Server     *fuse.Server
+	MountPoint string
+}
+
+// Cleanup removes the mountpoint directory
+func (c *CompatFS) Cleanup() {
+
+	// Clean up mount point directory
+	fmt.Printf("Cleaning up %s...\n", c.MountPoint)
+	os.RemoveAll(c.MountPoint)
+}
+
+// NewCompatFS returns a new wrapper to a fuse.Server
+// We mount a fusefs to a temporary directory
+// The server returned (if not nil) needs to be
+// correctly handled - see how it is used here in the library
+func NewCompatFS() (*CompatFS, error) {
+
+	// Create a Compat Filesystem with defaults
+	compat := CompatFS{}
+
+	// TODO keep track of cpu and memory profiles
+
+	mountPoint, err := os.MkdirTemp("", "compat-lib")
+	if err != nil {
+		return nil, err
+	}
+	fmt.Printf("Mount directory %s\n", mountPoint)
+	compat.MountPoint = mountPoint
+
+	// TODO add cpu / memory monitor
+	//    fname := filepath.Join(dname, "file1")
+	//  err = os.WriteFile(fname, []byte{1, 2}, 0666)
+	//  check(err)
+	server, err := NewLoopbackRoot(originalFS, mountPoint)
+	if err != nil {
+		return nil, err
+	}
+	compat.Server = server
+	return &compat, nil
+}

pkg/fs/loopback.go

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+package fs
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+	"syscall"
+	"time"
+
+	"github.com/hanwen/go-fuse/v2/fs"
+	"github.com/hanwen/go-fuse/v2/fuse"
+)
+
+// We need to implement a custom LoopbackNode Open function
+var _ = (fs.NodeOpener)((*CompatLoopbackNode)(nil))
+
+type CompatLoopbackNode struct {
+	fs.LoopbackNode
+}
+
+func (n *CompatLoopbackNode) Open(ctx context.Context, flags uint32) (fs.FileHandle, uint32, syscall.Errno) {
+	fmt.Println("CUSTOM OPEN FOR %s with flags %s\n", ctx, flags)
+	fh, flags, errno := n.LoopbackNode.Open(ctx, flags)
+	return fh, flags, errno
+}
+
+func (n *CompatLoopbackNode) Create(ctx context.Context, name string, flags uint32, mode uint32, out *fuse.EntryOut) (*fs.Inode, fs.FileHandle, uint32, syscall.Errno) {
+	fmt.Println("CUSTOM CREATE FOR %s with flags %s\n", name, flags)
+	inode, fh, flags, errno := n.LoopbackNode.Create(ctx, name, flags, mode, out)
+	return inode, fh, flags, errno
+}
+
+func newNode(rootData *fs.LoopbackRoot, parent *fs.Inode, name string, st *syscall.Stat_t) fs.InodeEmbedder {
+	n := &CompatLoopbackNode{
+		LoopbackNode: fs.LoopbackNode{
+			RootData: rootData,
+		},
+	}
+	return n
+}
+
+func NewLoopbackRoot(rootPath, mountPoint string) (*fuse.Server, error) {
+
+	rootData := &fs.LoopbackRoot{
+		NewNode: newNode,
+		Path:    rootPath,
+	}
+
+	// one second is compatible with libfuse defaults
+	// https://man7.org/linux/man-pages/man8/mount.fuse3.8.html
+	oneSecond := time.Second
+
+	// https://github.com/hanwen/go-fuse/blob/master/fs/api.go
+	options := &fs.Options{
+		AttrTimeout:  &oneSecond,
+		EntryTimeout: &oneSecond,
+		// Leave file permissions on "000" files
+		NullPermissions: true,
+		MountOptions: fuse.MountOptions{
+			AllowOther:        other,
+			Debug:             debug,
+			DirectMount:       directMount,
+			DirectMountStrict: directMountStrict,
+
+			// First column in "df -T": original dir
+			FsName: originalFS,
+
+			// Second column in "df -T" will be shown as "fuse." + Name
+			Name: "loopback",
+
+			// "read only"
+			Options: []string{"ro"},
+			Logger:  log.New(os.Stderr, "", 0),
+		},
+	}
+
+	server, err := fs.Mount(mountPoint, newNode(rootData, nil, "", nil), options)
+	if err != nil {
+		return nil, err
+	}
+	return server, nil
+}