Merge pull request containers#916 from cgwalters/dispatch-ostree-cont…

…ainer-argv0

 cli: Add interception for ostree extension verbs

Makefile

@@ -26,6 +26,14 @@ install:
 	  done
 	install -D -m 0644 -t $(DESTDIR)/$(prefix)/lib/systemd/system systemd/*.service systemd/*.timer
 
+# Run this to also take over the functionality of `ostree container` for example.
+# Only needed for OS/distros that have callers invoking `ostree container` and not bootc.
+install-ostree-hooks:
+	install -d $(DESTDIR)$(prefix)/libexec/libostree/ext
+	for x in ostree-container ostree-ima-sign ostree-provisional-repair; do \
+	  ln -sf ../../../bin/bootc $(DESTDIR)$(prefix)/libexec/libostree/ext/$$x; \
+	done
+
 install-with-tests: install
 	install -D -m 0755 target/release/tests-integration $(DESTDIR)$(prefix)/bin/bootc-integration-tests 
 

lib/src/cli.rs

@@ -2,8 +2,7 @@
 //!
 //! Command line tool to manage bootable ostree-based containers.
 
-use std::ffi::CString;
-use std::ffi::OsString;
+use std::ffi::{CString, OsStr, OsString};
 use std::io::Seek;
 use std::os::unix::process::CommandExt;
 use std::process::Command;
@@ -879,6 +878,18 @@ where
     run_from_opt(Opt::parse_including_static(args)).await
 }
 
+/// Find the base binary name from argv0 (without a full path). The empty string
+/// is never returned; instead a fallback string is used. If the input is not valid
+/// UTF-8, a default is used.
+fn callname_from_argv0(argv0: &OsStr) -> &str {
+    let default = "bootc";
+    std::path::Path::new(argv0)
+        .file_name()
+        .and_then(|s| s.to_str())
+        .filter(|s| !s.is_empty())
+        .unwrap_or(default)
+}
+
 impl Opt {
     /// In some cases (e.g. systemd generator) we dispatch specifically on argv0.  This
     /// requires some special handling in clap.
@@ -890,12 +901,19 @@ impl Opt {
         let mut args = args.into_iter();
         let first = if let Some(first) = args.next() {
             let first: OsString = first.into();
-            let argv0 = first.to_str().and_then(|s| s.rsplit_once('/')).map(|s| s.1);
+            let argv0 = callname_from_argv0(&first);
             tracing::debug!("argv0={argv0:?}");
-            if matches!(argv0, Some(InternalsOpts::GENERATOR_BIN)) {
-                let base_args = ["bootc", "internals", "systemd-generator"]
-                    .into_iter()
-                    .map(OsString::from);
+            let mapped = match argv0 {
+                InternalsOpts::GENERATOR_BIN => {
+                    Some(["bootc", "internals", "systemd-generator"].as_slice())
+                }
+                "ostree-container" | "ostree-ima-sign" | "ostree-provisional-repair" => {
+                    Some(["bootc", "internals", "ostree-ext"].as_slice())
+                }
+                _ => None,
+            };
+            if let Some(base_args) = mapped {
+                let base_args = base_args.into_iter().map(OsString::from);
                 return Opt::parse_from(base_args.chain(args.map(|i| i.into())));
             }
             Some(first)
@@ -1022,6 +1040,41 @@ async fn run_from_opt(opt: Opt) -> Result<()> {
     }
 }
 
+#[test]
+fn test_callname() {
+    use std::os::unix::ffi::OsStrExt;
+
+    // Cases that change
+    let mapped_cases = [
+        ("", "bootc"),
+        ("/foo/bar", "bar"),
+        ("/foo/bar/", "bar"),
+        ("foo/bar", "bar"),
+        ("../foo/bar", "bar"),
+        ("usr/bin/ostree-container", "ostree-container"),
+    ];
+    for (input, output) in mapped_cases {
+        assert_eq!(
+            output,
+            callname_from_argv0(OsStr::new(input)),
+            "Handling mapped case {input}"
+        );
+    }
+
+    // Invalid UTF-8
+    assert_eq!("bootc", callname_from_argv0(OsStr::from_bytes(b"foo\x80")));
+
+    // Cases that are identical
+    let ident_cases = ["foo", "bootc"];
+    for case in ident_cases {
+        assert_eq!(
+            case,
+            callname_from_argv0(OsStr::new(case)),
+            "Handling ident case {case}"
+        );
+    }
+}
+
 #[test]
 fn test_parse_install_args() {
     // Verify we still process the legacy --target-no-signature-verification
@@ -1073,7 +1126,7 @@ fn test_parse_generator() {
             "/usr/lib/systemd/system/bootc-systemd-generator",
             "/run/systemd/system"
         ]),
-        Opt::Internals(InternalsOpts::SystemdGenerator { .. })
+        Opt::Internals(InternalsOpts::SystemdGenerator { normal_dir, .. }) if normal_dir == "/run/systemd/system"
     ));
 }
 
@@ -1083,4 +1136,31 @@ fn test_parse_ostree_ext() {
         Opt::parse_including_static(["bootc", "internals", "ostree-container"]),
         Opt::Internals(InternalsOpts::OstreeContainer { .. })
     ));
+
+    fn peel(o: Opt) -> Vec<OsString> {
+        match o {
+            Opt::Internals(InternalsOpts::OstreeExt { args }) => args,
+            o => panic!("unexpected {o:?}"),
+        }
+    }
+    let args = peel(Opt::parse_including_static([
+        "/usr/libexec/libostree/ext/ostree-ima-sign",
+        "ima-sign",
+        "--repo=foo",
+        "foo",
+        "bar",
+        "baz",
+    ]));
+    assert_eq!(
+        args.as_slice(),
+        ["ima-sign", "--repo=foo", "foo", "bar", "baz"]
+    );
+
+    let args = peel(Opt::parse_including_static([
+        "/usr/libexec/libostree/ext/ostree-container",
+        "container",
+        "image",
+        "pull",
+    ]));
+    assert_eq!(args.as_slice(), ["container", "image", "pull"]);
 }