image: Allow custom paths for qemu-static binaries

This allows one to use i.e. /opt/qemu/bin or /usr/gxemul/bin for the
qemu static binaries used to generate foreign-architecture images.

2 files changed, 22 insertions, 5 deletions

diff --git a/image/creator.1 b/image/creator.1
index 5673f75..2de51a1 100644
--- a/image/creator.1
+++ b/image/creator.1
@@ -1,4 +1,4 @@
-.Dd May 16, 2020
+.Dd October 28, 2023
 .Dt HSCRIPT-IMAGE 1
 .Os "Adélie Linux"
 .Sh NAME
@@ -6,6 +6,7 @@
 .Nd create an image based on a HorizonScript for later deployment
 .Sh SYNOPSIS
 .Nm
+.Op Fl e Ar DIRECTORY
 .Op Fl h
 .Op Fl i Ar DIRECTORY
 .Op Fl n
@@ -80,6 +81,13 @@ as the argument to
 .Fl t .
 .It Fl v
 Displays the version information for this utility, and then exits.
+.It Fl e Ar DIRECTORY
+Sets the qemu-static binary directory to
+.Ar DIRECTORY .
+This must be equivalent to the configuration of binfmt-misc on the host.
+The default is
+.Pa /usr/bin ,
+and typically should not be changed unless you have a very good reason.
 .It Ar INSTALLFILE
 Specifies the location of the HorizonScript to use for configuring the image.
 You may specify
diff --git a/image/creator.cc b/image/creator.cc
index 0d97ff1..ce2c537 100644
--- a/image/creator.cc
+++ b/image/creator.cc
@@ -49,7 +49,7 @@ int main(int argc, char *argv[]) {
     bool needs_help{}, disable_pretty{}, version_only{};
     int exit_code = EXIT_SUCCESS;
     std::string if_path{"/etc/horizon/installfile"}, ir_dir{"/tmp/horizon-image"},
-                output_path{"image.tar"}, type_code{"tar"};
+                output_path{"image.tar"}, type_code{"tar"}, emul_dir{"/usr/bin"};
     BasicBackend *backend = nullptr;
     std::map<std::string, std::string> backend_opts;
     Horizon::ScriptOptions opts;
@@ -66,6 +66,7 @@ int main(int argc, char *argv[]) {
     target.add_options()
             ("output,o", value<std::string>()->default_value("image.tar"), "Desired filename for the output file.")
             ("ir-dir,i", value<std::string>()->default_value("/tmp/horizon-image"), "Where to store intermediate files.")
+            ("emul-dir,e", value<std::string>()->default_value("/usr/bin"), "Where qemu-static binaries are stored.")
             ;
     options_description backconfig{"Backend configuration options"};
     backconfig.add_options()
@@ -134,6 +135,14 @@ int main(int argc, char *argv[]) {
         ir_dir = fs::absolute(ir_dir).string();
     }
 
+    if(!vm["emul-dir"].empty()) {
+        emul_dir = vm["emul-dir"].as<std::string>();
+    }
+
+    if(fs::path(emul_dir).is_relative()) {
+        emul_dir = fs::absolute(emul_dir).string();
+    }
+
     if(!vm["output"].empty()) {
         output_path = vm["output"].as<std::string>();
     }
@@ -222,11 +231,11 @@ int main(int argc, char *argv[]) {
         if(archkey) {
             const Horizon::Keys::Arch *arch =
                     dynamic_cast<const Horizon::Keys::Arch *>(archkey);
-            qpath = "/usr/bin/qemu-" + arch_xlate(arch->value());
+            qpath = emul_dir + "/qemu-" + arch_xlate(arch->value());
             error_code ec;
             if(fs::exists(qpath, ec)) {
-                fs::create_directories(ir_dir + "/target/usr/bin", ec);
-                if(!ec) fs::copy_file(qpath, ir_dir + "/target/" + qpath, ec);
+                fs::create_directories(ir_dir + "/target" + emul_dir, ec);
+                if(!ec) fs::copy_file(qpath, ir_dir + "/target" + qpath, ec);
             }
         }