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// SPDX-License-Identifier: MPL-2.0
/*
* libpathrs: safe path resolution on Linux
* Copyright (C) 2019-2025 Aleksa Sarai <cyphar@cyphar.com>
* Copyright (C) 2019-2025 SUSE LLC
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at https://mozilla.org/MPL/2.0/.
*/
package main
import (
"context"
"fmt"
"os"
"strconv"
"strings"
"github.com/urfave/cli/v3"
"golang.org/x/sys/unix"
"cyphar.com/go-pathrs/procfs"
)
type procfsOpenFunc func(path string, flags int) (*os.File, error)
var procfsCmd = &cli.Command{
Name: "procfs",
Usage: "ProcfsHandle::* operations",
Flags: []cli.Flag{
&cli.BoolFlag{
Name: "unmasked",
Usage: "use unmasked procfs handle",
},
&cli.StringFlag{
Name: "base",
Usage: "base path for procfs operations (root, pid=<n>, self, thread-self)",
Value: "root",
},
},
Commands: []*cli.Command{
procfsOpenCmd,
procfsReadlinkCmd,
},
Before: func(ctx context.Context, cmd *cli.Command) (_ context.Context, Err error) {
var opts []procfs.OpenOption
if cmd.Bool("unmasked") {
opts = append(opts, procfs.UnmaskedProcRoot)
}
proc, err := procfs.Open(opts...)
if err != nil {
return nil, err
}
ctx = context.WithValue(ctx, "procfs", proc)
defer func() {
if Err != nil {
_ = proc.Close()
}
}()
return ctx, nil
},
After: func(ctx context.Context, cmd *cli.Command) error {
if proc, ok := ctx.Value("procfs").(*procfs.Handle); ok {
_ = proc.Close()
}
return nil
},
}
var procfsOpenCmd = cmdWithOptions(&cli.Command{
Name: "open",
Usage: "open a path in procfs",
Flags: []cli.Flag{
&cli.BoolWithInverseFlag{
Name: "follow",
Usage: "follow trailing symlinks",
Value: true,
},
},
Arguments: []cli.Argument{
&cli.StringArg{
Name: "subpath",
},
},
Action: func(ctx context.Context, cmd *cli.Command) error {
proc := ctx.Value("procfs").(*procfs.Handle)
follow := cmd.Bool("follow")
subpath := cmd.StringArg("subpath")
oflags := unix.O_RDONLY
if val := ctx.Value("oflags"); val != nil {
oflags = val.(int)
}
if !follow {
oflags |= unix.O_NOFOLLOW
}
var (
f *os.File
err error
)
baseStr := cmd.String("base")
if pidStr, ok := strings.CutPrefix(baseStr, "pid="); ok {
var pid int
pid, err = strconv.Atoi(pidStr)
if err != nil {
return fmt.Errorf("failed to parse --base=%q: %w", pidStr, err)
}
f, err = proc.OpenPid(pid, subpath, oflags)
} else {
switch baseStr {
case "root":
f, err = proc.OpenRoot(subpath, oflags)
case "self":
f, err = proc.OpenSelf(subpath, oflags)
case "thread-self":
var closer procfs.ThreadCloser
f, closer, err = proc.OpenThreadSelf(subpath, oflags)
if closer != nil {
defer closer()
}
default:
return fmt.Errorf("invalid --base value %q", baseStr)
}
}
if err != nil {
return err
}
defer f.Close()
fmt.Println("FILE-PATH", f.Name())
// TODO: Input/output file data.
return nil
},
}, oflags("oflags", "O_* flags to use when opening the file", unix.O_RDONLY))
var procfsReadlinkCmd = &cli.Command{
Name: "readlink",
Usage: "read the target path of a symbolic link in procfs",
Arguments: []cli.Argument{
&cli.StringArg{
Name: "subpath",
},
},
Action: func(ctx context.Context, cmd *cli.Command) error {
proc := ctx.Value("procfs").(*procfs.Handle)
subpath := cmd.StringArg("subpath")
var base procfs.ProcBase
baseStr := cmd.String("base")
if pidStr, ok := strings.CutPrefix(baseStr, "pid="); ok {
pid, err := strconv.Atoi(pidStr)
if err != nil {
return fmt.Errorf("failed to parse --base=%q: %w", pidStr, err)
}
base = procfs.ProcPid(pid)
} else {
switch baseStr {
case "root":
base = procfs.ProcRoot
case "self":
base = procfs.ProcSelf
case "thread-self":
base = procfs.ProcThreadSelf
default:
return fmt.Errorf("invalid --base value %q", baseStr)
}
}
target, err := proc.Readlink(base, subpath)
if err != nil {
return err
}
fmt.Println("LINK-TARGET", target)
return nil
},
}
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