diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..1bc5169 --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +dive diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..c6ffb1a --- /dev/null +++ b/LICENSE @@ -0,0 +1,21 @@ +MIT License + +Copyright (c) 2024 Madonuko, Ultramarine Project, Fyra Labs, Et al. + +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. diff --git a/README.md b/README.md new file mode 100644 index 0000000..b472faa --- /dev/null +++ b/README.md @@ -0,0 +1,3 @@ +# dive + +A chroot utility (just like `arch-chroot`). diff --git a/dive.nimble b/dive.nimble new file mode 100644 index 0000000..7931b71 --- /dev/null +++ b/dive.nimble @@ -0,0 +1,15 @@ +# Package + +version = "0.1.0" +author = "madomado" +description = "A chroot utility" +license = "MIT" +srcDir = "src" +bin = @["dive"] + + +# Dependencies + +requires "nim >= 2.1.1" +requires "cligen" +requires "sweet" diff --git a/src/dive.nim b/src/dive.nim new file mode 100644 index 0000000..031cb5a --- /dev/null +++ b/src/dive.nim @@ -0,0 +1,96 @@ +import std/[strutils, strformat, paths, os, dirs, files, osproc] +import asyncdispatch +import cligen, sweet +import log, mounts + +let mounteds = getMounts() + +proc is_mountpoint(root: Path): bool = + for mount in mounteds: + if root == mount.mountpoint.Path: + return true + +proc mkdir(dir: Path) = + try: dir.createDir + except OSError: + error "Cannot create dir: " & dir.string + quit 1 + +proc run(cmd: string) {.async.} = + info "Running command: "&cmd + let p = startProcess("sh", args=["-c", cmd], options={poParentStreams}) + while p.running: + await sleepAsync 10 + let rc = p.waitForExit + if !!rc: + fatal "Fail to execute command: "&cmd + fatal "Command returned exit code: " & $rc + quit 1 + +proc force_mountpoint(root: Path) {.async.} = + if root.is_mountpoint: return + warn fmt"{root.string} is not a mountpoint, bind-mounting…" + await run fmt"mount --bind {root.string.quoteShell} {root.string.quoteShell}" + +proc mount(path: Path, mountargs: string) {.async.} = + if !path.is_mountpoint: + mkdir path + await run "mount "&mountargs&" "&path.string + +proc mount_dirs(root: Path) {.async.} = + await mount(root/"proc".Path, "-t proc proc") and + mount(root/"sys".Path, "-t sysfs sys") and + mount(root/"dev".Path, "-o bind /dev") and + mount(root/"dev/pts".Path, "-o bind /dev/pts") + +proc cp_resolv(root: Path) {.async.} = + if !"/etc/resolv.conf".Path.fileExists: + warn "/etc/resolv.conf does not exist" + return + let dest = root/"etc/resolv.conf".Path + if !dest.fileExists: + warn "Refusing to copy resolv.conf because it doesn't exist inside chroot" + return + await run "mount -c --bind /etc/resolv.conf "&dest.string + +proc umount(path: string) {.async.} = + try: await run fmt"umount {path}" + finally: discard + +proc umount_all(root: string) {.async.} = + await umount(fmt"{root}/proc") and + umount(fmt"{root}/sys") and + umount(fmt"{root}/dev {root}/dev/pts") and + umount(fmt"{root}/etc/resolv.conf") + +proc find_shell(root: Path): string = + if fileExists root/"bin/fish".Path: + return "/bin/fish" + if fileExists root/"bin/zsh".Path: + return "/bin/zsh" + if fileExists root/"bin/bash".Path: + return "/bin/bash" + if fileExists root/"bin/sh".Path: + return "/bin/sh" + warn "Cannot detect any shell in the chroot… falling back to /bin/sh" + "/bin/sh" + +proc dive(args: seq[string], verbosity = lvlNotice, keepresolv = false) = + ## A chroot utility + if !args.len: + fatal "You must provide an argument for the root directory" + quit 1 + let root = args[0].Path + let cp_resolv_fut = cp_resolv root + waitFor (force_mountpoint root) and (mount_dirs root) and cp_resolv_fut + waitFor cp_resolv_fut + let shell = find_shell root + let str_args = args[1..^1].join(" ") + waitFor run fmt"SHELL={shell} chroot {root.string} {str_args}" + waitFor umount_all(root.string) + + +dispatch dive, help = { + "args": " [shell command]", + "verbosity": "set the logging verbosity: {lvlAll, lvlDebug, lvlInfo, lvlNotice, lvlWarn, lvlError, lvlFatal, lvlNone}", +}, short = {"keepresolv": 'r'} diff --git a/src/log.nim b/src/log.nim new file mode 100644 index 0000000..e359f52 --- /dev/null +++ b/src/log.nim @@ -0,0 +1,6 @@ +import std/logging + +var logger = newConsoleLogger(fmtStr="mkfstab: $levelname: ", useStderr=true) +addHandler logger + +export debug, error, fatal, info, log, notice, warn, logging diff --git a/src/mounts.nim b/src/mounts.nim new file mode 100644 index 0000000..402013e --- /dev/null +++ b/src/mounts.nim @@ -0,0 +1,25 @@ +import std/[streams, strformat, strscans] +import log + +type Mount* = tuple[device: string, mountpoint: string, fstype: string, mountopts: string] + +proc notSpace(input: string, match: var string, start: int): int = + result = 0 + while input[start+result] != ' ': inc result + match = input[start..start+result-1] + + +proc getMounts*(): seq[Mount] = + var fdmounts = newFileStream("/proc/mounts") + if fdmounts == nil: + # cannot open file + return @[] + defer: fdmounts.close() + var linenum = 0 + var line, dev, mp, fstype, mountopts: string + while fdmounts.readLine line: + inc linenum + if scanf(line, "${notSpace} ${notSpace} ${notSpace} ${notSpace} 0 0$.", dev, mp, fstype, mountopts): + result.add (device: dev, mountpoint: mp, fstype: fstype, mountopts: mountopts) + else: + error fmt"Fail to parse /proc/mounts:{linenum} : {line}"