aktualizr-lite: Fix logic for finding latest version

You can't assume the targets will be ordered latest->oldest. This
creates a version comparison helper that tries its best to compare
things.

Signed-off-by: Andy Doan <andy@foundries.io>

src/aktualizr_lite/CMakeLists.txt

@@ -1,5 +1,6 @@
 if(BUILD_OSTREE)
-add_executable(aktualizr-lite main.cc)
+set(SOURCES main.cc version.h)
+add_executable(aktualizr-lite ${SOURCES})
 target_link_libraries(aktualizr-lite aktualizr_static_lib ${AKTUALIZR_EXTERNAL_LIBS})
 
 install(TARGETS aktualizr-lite RUNTIME DESTINATION bin COMPONENT aktualizr-lite)
@@ -18,5 +19,5 @@ add_test(test_aktualizr-lite
 
 endif(BUILD_OSTREE)
 
-aktualizr_source_file_checks(main.cc)
+aktualizr_source_file_checks(${SOURCES})
 # vim: set tabstop=4 shiftwidth=4 expandtab:

src/aktualizr_lite/main.cc

@@ -10,6 +10,7 @@
 #include "config/config.h"
 #include "package_manager/ostreemanager.h"
 #include "primary/sotauptaneclient.h"
+#include "version.h"
 
 namespace bpo = boost::program_options;
 
@@ -111,15 +112,25 @@ static std::unique_ptr<Uptane::Target> find_target(const std::shared_ptr<SotaUpt
       throw std::runtime_error("Unable to find update");
     }
   }
+
+  bool find_latest = (version == "latest");
+  std::unique_ptr<Uptane::Target> latest = nullptr;
   for (auto &t : client->allTargets()) {
     for (auto const &it : t.hardwareIds()) {
       if (it == hwid) {
-        if (version == "latest" || version == t.filename() || version == t.custom_version()) {
+        if (find_latest) {
+          if (latest == nullptr || Version(latest->custom_version()) < Version(t.custom_version())) {
+            latest = std_::make_unique<Uptane::Target>(t);
+          }
+        } else if (version == t.filename() || version == t.custom_version()) {
           return std_::make_unique<Uptane::Target>(t);
         }
       }
     }
   }
+  if (find_latest) {
+    return latest;
+  }
   throw std::runtime_error("Unable to find update");
 }
 

src/aktualizr_lite/test_lite.sh

@@ -34,6 +34,7 @@ add_target() {
     fi
     cat >$custom_json <<EOF
 {
+  "version": "$1",
   "hardwareIds": ["hwid-for-test"],
   "targetFormat": "OSTREE"
 }
@@ -95,10 +96,12 @@ fi
 
 ## Check that we can do the update command
 update=$(ostree admin status | head -n 1)
-name=$(echo $update | cut -d\  -f1)
+name="zlast"  # give a name that will cause the custom version to be the latest
 sha=$(echo $update | cut -d\  -f2 | sed 's/\.0$//')
 echo "Adding new target: $name / $sha"
 add_target $name $sha
 
 $valgrind $aklite --loglevel 1 -c $sota_dir/sota.toml update --update-name $name
 ostree admin status
+
+$valgrind $aklite --loglevel 1 -c $sota_dir/sota.toml update | grep "Updating to: Target(zlast"

src/aktualizr_lite/version.h

@@ -0,0 +1,29 @@
+#include <iostream>
+
+struct Version {
+  int major = 0, minor = 0, revision = 0, build = 0;
+  std::string raw_ver;
+
+  Version(const std::string& version) {
+    if (!std::sscanf(version.c_str(), "%d.%d.%d.%d", &major, &minor, &revision, &build)) {
+      raw_ver = version;
+    }
+  }
+
+  bool operator<(const Version& other) {
+    if (!raw_ver.empty() || !other.raw_ver.empty()) {
+      // if either one isn't a version number, then the best we can do is
+      // compare them alphabetically
+      return raw_ver < other.raw_ver;
+    }
+    if (major < other.major) return true;
+    if (minor < other.minor) return true;
+    if (revision < other.revision) return true;
+    if (build < other.build) return true;
+    return false;
+  }
+
+  bool operator==(const Version& other) {
+    return major == other.major && minor == other.minor && revision == other.revision && build == other.build;
+  }
+};