From 79d18ab6560ac4b164a731919a26469b2d447643 Mon Sep 17 00:00:00 2001
From: Sylvestre Ledru <sylvestre@debian.org>
Date: Sat, 4 Mar 2023 18:23:33 +0100
Subject: [PATCH] generate manpages

---
 Cargo.lock           | 17 +++++++++++++++++
 Cargo.toml           |  4 +++-
 GNUmakefile          |  2 ++
 src/bin/coreutils.rs | 39 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 61 insertions(+), 1 deletion(-)

diff --git a/Cargo.lock b/Cargo.lock
index 89d67bf81..e4f489eae 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -267,6 +267,16 @@ dependencies = [
  "os_str_bytes",
 ]
 
+[[package]]
+name = "clap_mangen"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb0f09a0ca8f0dd8ac92c546b426f466ef19828185c6d504c80c48c9c2768ed9"
+dependencies = [
+ "clap",
+ "roff",
+]
+
 [[package]]
 name = "codespan-reporting"
 version = "0.11.1"
@@ -324,6 +334,7 @@ dependencies = [
  "chrono",
  "clap",
  "clap_complete",
+ "clap_mangen",
  "conv",
  "filetime",
  "glob",
@@ -1874,6 +1885,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "roff"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b833d8d034ea094b1ea68aa6d5c740e0d04bad9d16568d08ba6f76823a114316"
+
 [[package]]
 name = "rstest"
 version = "0.16.0"
diff --git a/Cargo.toml b/Cargo.toml
index 61a461deb..d8d43b252 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 # coreutils (uutils)
 # * see the repository LICENSE, README, and CONTRIBUTING files for more information
 
-# spell-checker:ignore (libs) libselinux gethostid procfs bigdecimal kqueue fundu
+# spell-checker:ignore (libs) libselinux gethostid procfs bigdecimal kqueue fundu mangen
 
 [package]
 name = "coreutils"
@@ -271,6 +271,7 @@ byteorder = "1.3.2"
 chrono = { version="^0.4.23", default-features=false, features=["std", "alloc", "clock"]}
 clap = { version = "4.0", features = ["wrap_help", "cargo"] }
 clap_complete = "4.0"
+clap_mangen = "0.2"
 compare = "0.1.0"
 coz = { version = "0.1.3" }
 crossterm = ">=0.19"
@@ -352,6 +353,7 @@ clap = { workspace=true }
 once_cell = { workspace=true }
 uucore = { workspace=true }
 clap_complete = { workspace=true }
+clap_mangen = { workspace=true }
 phf = { workspace=true }
 selinux = { workspace=true, optional = true }
 textwrap = { workspace=true }
diff --git a/GNUmakefile b/GNUmakefile
index b242bc8ce..81b90d32f 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -349,10 +349,12 @@ endif
 	mkdir -p $(DESTDIR)$(DATAROOTDIR)/zsh/site-functions
 	mkdir -p $(DESTDIR)$(DATAROOTDIR)/bash-completion/completions
 	mkdir -p $(DESTDIR)$(DATAROOTDIR)/fish/vendor_completions.d
+	mkdir -p $(DESTDIR)$(DATAROOTDIR)/man/man1
 	$(foreach prog, $(INSTALLEES), \
 		$(BUILDDIR)/coreutils completion $(prog) zsh > $(DESTDIR)$(DATAROOTDIR)/zsh/site-functions/_$(PROG_PREFIX)$(prog); \
 		$(BUILDDIR)/coreutils completion $(prog) bash > $(DESTDIR)$(DATAROOTDIR)/bash-completion/completions/$(PROG_PREFIX)$(prog); \
 		$(BUILDDIR)/coreutils completion $(prog) fish > $(DESTDIR)$(DATAROOTDIR)/fish/vendor_completions.d/$(PROG_PREFIX)$(prog).fish; \
+		$(BUILDDIR)/coreutils manpage $(prog) > $(DESTDIR)$(DATAROOTDIR)/man/man1/$(PROG_PREFIX)$(prog).1; \
 	)
 
 uninstall:
diff --git a/src/bin/coreutils.rs b/src/bin/coreutils.rs
index 08c0774ba..ac9750f93 100644
--- a/src/bin/coreutils.rs
+++ b/src/bin/coreutils.rs
@@ -5,6 +5,8 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 
+// spell-checker:ignore manpages mangen
+
 use clap::{Arg, Command};
 use clap_complete::Shell;
 use std::cmp;
@@ -90,6 +92,10 @@ fn main() {
             gen_completions(args, &utils);
         }
 
+        if util == "manpage" {
+            gen_manpage(args, &utils);
+        }
+
         match utils.get(util) {
             Some(&(uumain, _)) => {
                 process::exit(uumain((vec![util_os].into_iter()).chain(args)));
@@ -167,6 +173,39 @@ fn gen_completions<T: uucore::Args>(
     process::exit(0);
 }
 
+/// Generate the manpage for the utility in the first parameter
+fn gen_manpage<T: uucore::Args>(
+    args: impl Iterator<Item = OsString>,
+    util_map: &UtilityMap<T>,
+) -> ! {
+    let all_utilities: Vec<_> = std::iter::once("coreutils")
+        .chain(util_map.keys().copied())
+        .collect();
+
+    let matches = Command::new("manpage")
+        .about("Prints manpage to stdout")
+        .arg(
+            Arg::new("utility")
+                .value_parser(clap::builder::PossibleValuesParser::new(all_utilities))
+                .required(true),
+        )
+        .get_matches_from(std::iter::once(OsString::from("manpage")).chain(args));
+
+    let utility = matches.get_one::<String>("utility").unwrap();
+
+    let command = if utility == "coreutils" {
+        gen_coreutils_app(util_map)
+    } else {
+        util_map.get(utility).unwrap().1()
+    };
+
+    let man = clap_mangen::Man::new(command);
+    man.render(&mut io::stdout())
+        .expect("Man page generation failed");
+    io::stdout().flush().unwrap();
+    process::exit(0);
+}
+
 fn gen_coreutils_app<T: uucore::Args>(util_map: &UtilityMap<T>) -> Command {
     let mut command = Command::new("coreutils");
     for (_, (_, sub_app)) in util_map {