utils

commit: c5547b30e92b23b6efba9bade55ab68019cee9ee
parent 7835f19d8a4206670491707e484afe550f2f4cdc
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date:   Fri,  4 Aug 2023 22:51:45 +0200

cmd/chroot: New command

Note: While coreutils supports options on chroot(1), BusyBox doesn't and after
a quick search on codesearch.debian.net with `\bchroot --\w` as a regex it
seems to be very rare usage.

Diffstat:
A
cmd/chroot.1
52
++++++++++++++++++++++++++++++++++++++++++++++++++++
A
cmd/chroot.c
62
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
M
coreutils.txt
2
+-

3 files changed, 115 insertions(+), 1 deletion(-)
diff --git a/cmd/chroot.1 b/cmd/chroot.1
@@ -0,0 +1,52 @@
+.\" Collection of Unix tools, comparable to coreutils
+.\" Copyright 2017-2023 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
+.\" SPDX-License-Identifier: MPL-2.0
+.Dd 2023-08-04
+.Dt CHROOT 1
+.Os
+.Sh NAME
+.Nm chroot
+.Nd run in another root directory
+.Sh SYNOPSIS
+.Nm
+.Ar newroot
+.Op Ar command Op Ar args ...
+.Sh DESCRIPTION
+.Nm
+runs
+.Ar command
+in the root directory at
+.Ar newroot .
+If no
+.Ar command
+was given,
+.Nm
+instead runs
+.Lc $SHELL -i
+with
+.Ev SHELL
+itself defaulting to
+.Pa /bin/sh .
+.Sh EXIT STATUS
+If
+.Ar command
+is invoked, the exit status of
+.Nm
+shall be the exit status of
+.Ar command ;
+Otherwise, the
+.Nm
+utility shall exit with one of the following values:
+.Bl -tag -width Ds
+.It 125
+An error occured in
+.Nm
+.It 126
+.Ar command
+was found but couldn't be invoked.
+.It 127
+.Ar command
+wasn't found.
+.El
+.Sh AUTHORS
+.An Haelwenn (lanodan) Monnier Aq Mt contact@hacktivis.me
diff --git a/cmd/chroot.c b/cmd/chroot.c
@@ -0,0 +1,62 @@
+// Collection of Unix tools, comparable to coreutils
+// SPDX-FileCopyrightText: 2017-2023 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
+// SPDX-License-Identifier: MPL-2.0
+
+#define _POSIX_C_SOURCE 200809L
+#define _DEFAULT_SOURCE // chroot
+#include <assert.h>     // assert
+#include <errno.h>      // errno
+#include <stdbool.h>    // false
+#include <stdio.h>      // fprintf, perror
+#include <stdlib.h>     // getenv
+#include <unistd.h>     // chroot, execl, execv
+
+int
+main(int argc, char *argv[])
+{
+	if(argc < 2)
+	{
+		fprintf(stderr, "chroot: Needs arguments\n");
+		fprintf(stderr, "Usage: chroot <newroot> [command [args ...]]\n");
+		return 125;
+	}
+
+	if(chroot(argv[1]) < 0)
+	{
+		perror("chroot");
+		return 125;
+	}
+
+	if(chdir("/") < 0)
+	{
+		perror("chdir");
+		return 125;
+	}
+
+	int ret = 0;
+	errno   = 0;
+	if(argc == 2)
+	{
+		char *shell = getenv("SHELL");
+		if(shell == NULL) shell = "/bin/sh";
+
+		/* flawfinder: ignore. No restrictions on commands is intended */
+		ret = execlp(shell, shell, "-i", NULL);
+	}
+	else
+	{
+		argv += 2;
+		/* flawfinder: ignore. No restrictions on commands is intended */
+		ret = execvp(argv[0], argv);
+	}
+
+	if(ret != 0)
+	{
+		perror("chroot: exec");
+		if(errno == ENOENT) return 127;
+
+		return 126;
+	}
+
+	assert(false);
+}
diff --git a/coreutils.txt b/coreutils.txt
@@ -12,7 +12,7 @@ chcon: No, SELinux-specific, wtf
 chgrp: Todo
 chmod: Todo
 chown: Todo
-chroot: Todo
+chroot: Done
 cksum: No, POSIX
 comm: Maybe, POSIX
 cp: Todo