From 207f554b11455f2b82f0562e65ad968087e427eb Mon Sep 17 00:00:00 2001
From: Daniel Roskams <rocket.penguin@riseup.net>
Date: Wed, 12 Oct 2016 20:05:40 +0800
Subject: [PATCH] Document chroot(8).

---
 utils/Makefile |  1 +
 utils/chroot.8 | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++
 utils/chroot.c | 28 +++++--------------------
 3 files changed, 61 insertions(+), 23 deletions(-)
 create mode 100644 utils/chroot.8

diff --git a/utils/Makefile b/utils/Makefile
index 3a5477bd..fb58a6e8 100644
--- a/utils/Makefile
+++ b/utils/Makefile
@@ -84,6 +84,7 @@ chroot \
 unmount \
 
 MANPAGES8=\
+chroot.8 \
 unmount.8 \
 
 all: $(BINARIES) $(SBINS)
diff --git a/utils/chroot.8 b/utils/chroot.8
new file mode 100644
index 00000000..851efe15
--- /dev/null
+++ b/utils/chroot.8
@@ -0,0 +1,55 @@
+.Dd September 29, 2016
+.Dt CHROOT 8
+.Os
+.Sh NAME
+.Nm chroot
+.Nd run command with changed root directory
+.Sh SYNOPSIS
+.Nm
+.Op Fl d
+.Ar newroot
+.Oo
+.Ar command
+.Oo
+.Ar arguments ...
+.Oc
+.Oc
+.Sh DESCRIPTION
+.Nm
+changes the root directory to
+.Ar newroot
+and runs
+.Ar command
+with the given
+.Ar arguments .
+.Ar command
+defaults to
+.Xr sh 1 .
+The working directory for
+.Ar command
+is changed to
+.Pa / .
+.Pp
+The options are as follows:
+.Bl -tag -width "12345678"
+.It Fl d, Fl \-devices
+Mount
+.Pa /dev
+from the host system into the
+.Pa /dev
+inside
+.Ar newroot .
+The mountpoint is removed when
+.Ar command
+completes.  This option is useful for running installations.
+.El
+.Sh ENVIRONMENT
+The environment is preserved.
+.Ev PATH
+is used to search for
+.Ar command .
+.Sh EXIT STATUS
+.Nm
+will exit 0 on success and non-zero otherwise.
+.Sh SEE ALSO
+.Xr chroot 2
diff --git a/utils/chroot.c b/utils/chroot.c
index f30e61b4..09d57077 100644
--- a/utils/chroot.c
+++ b/utils/chroot.c
@@ -21,6 +21,7 @@
 #include <sys/stat.h>
 #include <sys/wait.h>
 
+#include <err.h>
 #include <errno.h>
 #include <error.h>
 #include <fcntl.h>
@@ -45,16 +46,6 @@ static void compact_arguments(int* argc, char*** argv)
 	}
 }
 
-static void help(FILE* fp, const char* argv0)
-{
-	fprintf(fp, "Usage: %s [OPTION]... ROOT [CMD] [ARGUMENT...]\n", argv0);
-}
-
-static void version(FILE* fp, const char* argv0)
-{
-	fprintf(fp, "%s (Sortix) %s\n", argv0, VERSIONSTR);
-}
-
 static char* mount_point_dev;
 
 static void unmount_handler(int signum)
@@ -71,7 +62,6 @@ static void unmount_handler(int signum)
 int main(int argc, char* argv[])
 {
 	bool devices = false;
-	const char* argv0 = argv[0];
 	for ( int i = 1; i < argc; i++ )
 	{
 		const char* arg = argv[i];
@@ -87,21 +77,13 @@ int main(int argc, char* argv[])
 			{
 			case 'd': devices = true; break;
 			default:
-				fprintf(stderr, "%s: unknown option -- '%c'\n", argv0, c);
-				help(stderr, argv0);
-				exit(1);
+				errx(1, "unknown option -- '%c'", c);
 			}
 		}
-		else if ( !strcmp(arg, "--help") )
-			help(stdout, argv0), exit(0);
-		else if ( !strcmp(arg, "--version") )
-			version(stdout, argv0), exit(0);
+		else if ( !strcmp(arg, "--devices") )
+			devices = true;
 		else
-		{
-			fprintf(stderr, "%s: unknown option: %s\n", argv0, arg);
-			help(stderr, argv0);
-			exit(1);
-		}
+			errx(1, "unknown option: %s", arg);
 	}
 
 	compact_arguments(&argc, &argv);