RPATH: Add option for using $ORIGIN in build tree

This makes binaries independent of the build directory by not embedding
the build directory via RPATH.  The tests are partially based on the
existing RuntimePath test, but with the check moved into a POST_BUILD
command such that it can be skipped when the platform lacks support.

Fixes: #18413

2 files changed, 27 insertions, 3 deletions

diff --git a/Source/cmComputeLinkInformation.cxx b/Source/cmComputeLinkInformation.cxx
index 0e48ca8..27b8599 100644
--- a/Source/cmComputeLinkInformation.cxx
+++ b/Source/cmComputeLinkInformation.cxx
@@ -421,7 +421,8 @@ std::string cmComputeLinkInformation::GetRPathLinkString() const
     return "";
   }
 
-  // Construct the linker runtime search path.
+  // Construct the linker runtime search path. These MUST NOT contain tokens
+  // such as $ORIGIN, see https://sourceware.org/bugzilla/show_bug.cgi?id=16936
   return cmJoin(this->OrderDependentRPath->GetOrderedDirectories(), ":");
 }
 
@@ -1702,6 +1703,14 @@ void cmComputeLinkInformation::GetRPath(std::vector<std::string>& runtimeDirs,
     !this->Makefile->IsOn("CMAKE_SKIP_INSTALL_RPATH") &&
     this->Target->GetPropertyAsBool("INSTALL_RPATH_USE_LINK_PATH");
 
+  // Select whether to use $ORIGIN in RPATHs for artifacts in the build tree.
+  std::string const& originToken = this->Makefile->GetSafeDefinition(
+    "CMAKE_SHARED_LIBRARY_RPATH_ORIGIN_TOKEN");
+  std::string targetOutputDir = this->Target->GetDirectory(this->Config);
+  bool use_relative_build_rpath =
+    this->Target->GetPropertyAsBool("BUILD_RPATH_USE_ORIGIN") &&
+    !originToken.empty() && !targetOutputDir.empty();
+
   // Construct the RPATH.
   std::set<std::string> emitted;
   if (use_install_rpath) {
@@ -1711,6 +1720,8 @@ void cmComputeLinkInformation::GetRPath(std::vector<std::string>& runtimeDirs,
   if (use_build_rpath) {
     // Add directories explicitly specified by user
     if (const char* build_rpath = this->Target->GetProperty("BUILD_RPATH")) {
+      // This will not resolve entries to use $ORIGIN, the user is expected to
+      // do that if necessary.
       cmCLI_ExpandListUnique(build_rpath, runtimeDirs, emitted);
     }
   }
@@ -1728,6 +1739,8 @@ void cmComputeLinkInformation::GetRPath(std::vector<std::string>& runtimeDirs,
       this->Makefile->GetSafeDefinition("CMAKE_INSTALL_PREFIX");
     cmSystemTools::ConvertToUnixSlashes(rootPath);
     std::vector<std::string> const& rdirs = this->GetRuntimeSearchPath();
+    std::string const& topBinaryDir =
+      this->CMakeInstance->GetHomeOutputDirectory();
     for (std::string const& ri : rdirs) {
       // Put this directory in the rpath if using build-tree rpath
       // support or if using the link path as an rpath.
@@ -1741,6 +1754,18 @@ void cmComputeLinkInformation::GetRPath(std::vector<std::string>& runtimeDirs,
           d += "/";
           d += suffix;
           cmSystemTools::ConvertToUnixSlashes(d);
+        } else if (use_relative_build_rpath) {
+          // If expansion of the $ORIGIN token is supported and permitted per
+          // policy, use relative paths in the RPATH.
+          if (cmSystemTools::ComparePath(d, topBinaryDir) ||
+              cmSystemTools::IsSubDirectory(d, topBinaryDir)) {
+            d = cmSystemTools::RelativePath(targetOutputDir, d);
+            if (!d.empty()) {
+              d = originToken + "/" + d;
+            } else {
+              d = originToken;
+            }
+          }
         }
         if (emitted.insert(d).second) {
           runtimeDirs.push_back(std::move(d));
@@ -1749,8 +1774,6 @@ void cmComputeLinkInformation::GetRPath(std::vector<std::string>& runtimeDirs,
         // Do not add any path inside the source or build tree.
         std::string const& topSourceDir =
           this->CMakeInstance->GetHomeDirectory();
-        std::string const& topBinaryDir =
-          this->CMakeInstance->GetHomeOutputDirectory();
         if (!cmSystemTools::ComparePath(ri, topSourceDir) &&
             !cmSystemTools::ComparePath(ri, topBinaryDir) &&
             !cmSystemTools::IsSubDirectory(ri, topSourceDir) &&
diff --git a/Source/cmTarget.cxx b/Source/cmTarget.cxx
index 1458f01..987bdb3 100644
--- a/Source/cmTarget.cxx
+++ b/Source/cmTarget.cxx
@@ -218,6 +218,7 @@ cmTarget::cmTarget(std::string const& name, cmStateEnums::TargetType type,
     this->SetPropertyDefault("ANDROID_ASSETS_DIRECTORIES", nullptr);
     this->SetPropertyDefault("ANDROID_ANT_ADDITIONAL_OPTIONS", nullptr);
     this->SetPropertyDefault("BUILD_RPATH", nullptr);
+    this->SetPropertyDefault("BUILD_RPATH_USE_ORIGIN", nullptr);
     this->SetPropertyDefault("INSTALL_NAME_DIR", nullptr);
     this->SetPropertyDefault("INSTALL_RPATH", "");
     this->SetPropertyDefault("INSTALL_RPATH_USE_LINK_PATH", "OFF");