tree-wide: Set argv0 = bootc when doing a re-exec

We have multiple places which are re-executing the current
binary; one of those writes a temp file. Ensure that `argv0`
in the new binary is `bootc` which means it should be used
as e.g. a syslog identifier.

Signed-off-by: Colin Walters <walters@verbum.org>

Author: cgwalters

crates/lib/src/cli.rs

@@ -1215,9 +1215,8 @@ async fn usroverlay() -> Result<()> {
 pub fn global_init() -> Result<()> {
     // In some cases we re-exec with a temporary binary,
     // so ensure that the syslog identifier is set.
-    let name = "bootc";
-    ostree::glib::set_prgname(name.into());
-    if let Err(e) = rustix::thread::set_name(&CString::new(name).unwrap()) {
+    ostree::glib::set_prgname(bootc_utils::NAME.into());
+    if let Err(e) = rustix::thread::set_name(&CString::new(bootc_utils::NAME).unwrap()) {
         // This shouldn't ever happen
         eprintln!("failed to set name: {e}");
     }

crates/lib/src/install.rs

@@ -918,7 +918,7 @@ pub(crate) fn exec_in_host_mountns(args: &[std::ffi::OsString]) -> Result<()> {
         tracing::debug!("Using supermin workaround");
         rustix::process::chroot("/root").context("chroot")?;
     }
-    Err(Command::new(cmd).args(args).exec()).context("exec")?
+    Err(Command::new(cmd).args(args).arg0(bootc_utils::NAME).exec()).context("exec")?
 }
 
 pub(crate) struct RootSetup {

crates/lib/src/lsm.rs

@@ -110,6 +110,7 @@ pub(crate) fn selinux_ensure_install() -> Result<bool> {
     cmd.env(guardenv, tmpf);
     cmd.env(bootc_utils::reexec::ORIG, srcpath);
     cmd.args(std::env::args_os().skip(1));
+    cmd.arg0(bootc_utils::NAME);
     cmd.log_debug();
     Err(anyhow::Error::msg(cmd.exec()).context("execve"))
 }

crates/utils/src/lib.rs

@@ -17,6 +17,9 @@ pub mod reexec;
 mod result_ext;
 pub use result_ext::*;
 
+/// The name of our binary
+pub const NAME: &str = "bootc";
+
 /// Intended for use in `main`, calls an inner function and
 /// handles errors by printing them.
 pub fn run_main<F>(f: F)

crates/utils/src/reexec.rs

@@ -36,6 +36,7 @@ pub fn reexec_with_guardenv(k: &str, prefix_args: &[&str]) -> Result<()> {
     };
     cmd.env(k, "1");
     cmd.args(std::env::args_os().skip(1));
+    cmd.arg0(crate::NAME);
     tracing::debug!("Re-executing current process for {k}");
     Err(cmd.exec().into())
 }