Fix bundled git running other git as a child on Windows

1 files changed, 26 insertions, 1 deletions

diff --git a/bpkg/fetch-git.cxx b/bpkg/fetch-git.cxx
index 00b925b..afb7a26 100644
--- a/bpkg/fetch-git.cxx
+++ b/bpkg/fetch-git.cxx
@@ -211,13 +211,38 @@ namespace bpkg
         }
       }
 
+      // On startup git prepends the PATH environment variable value with the
+      // computed directory path where its sub-programs are supposedly located
+      // (--exec-path option, GIT_EXEC_PATH environment variable, etc; see
+      // cmd_main() in git's git.c for details).
+      //
+      // Then, when git needs to run itself or one of its components as a
+      // child process, it resolves the full executable path searching in
+      // directories listed in PATH (see locate_in_PATH() in git's
+      // run-command.c for details).
+      //
+      // On Windows we install git and its components into a place where it is
+      // not expected to be, which results in the wrong path in PATH as set by
+      // git (for example, c:/build2/libexec/git-core) which in turn may lead
+      // to running some other git that appear in the PATH variable. To
+      // prevent this we pass the git's exec directory via the --exec-path
+      // option explicitly.
+      //
+      string ep;
+      process_path pp (process::path_search (co.git (), true /* init */));
+
+#ifdef _WIN32
+      ep = "--exec-path=" + pp.effect.directory ().string ();
+#endif
+
       return process_start_callback ([] (const char* const args[], size_t n)
                                      {
                                        if (verb >= 2)
                                          print_process (args, n);
                                      },
                                      0 /* stdin */, out, err,
-                                     process_env (co.git (), *unset_vars),
+                                     process_env (pp, *unset_vars),
+                                     !ep.empty () ? ep.c_str () : nullptr,
                                      forward<A> (args)...);
     }
     catch (const process_error& e)