Move computation of absolute paths from Makefile to runtime (in preparation for RUNTIME_PREFIX)

This commit prepares the Makefile for relocatable binaries (called
RUNTIME_PREFIX).  Such binaries will be able to be moved together
with the system configuration files to a different directory,
requiring to compute the prefix at runtime.

In a first step, we make all paths relative in the Makefile and
teach system_path() to add the prefix instead.  We used to compute
absolute paths in the Makefile and passed them to C as defines.  We
now pass relative paths to C and call system_path() to add the
prefix at runtime.

Signed-off-by: Steffen Prohaska <prohaska@zib.de>
Acked-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 8 insertions, 5 deletions

diff --git a/exec_cmd.c b/exec_cmd.c
index cdd35f919..114d6389e 100644
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -9,11 +9,14 @@ static const char *argv0_path;
 
 const char *system_path(const char *path)
 {
-	if (!is_absolute_path(path) && argv0_path) {
-		struct strbuf d = STRBUF_INIT;
-		strbuf_addf(&d, "%s/%s", argv0_path, path);
-		path = strbuf_detach(&d, NULL);
-	}
+	static const char *prefix = PREFIX;
+	struct strbuf d = STRBUF_INIT;
+
+	if (is_absolute_path(path))
+		return path;
+
+	strbuf_addf(&d, "%s/%s", prefix, path);
+	path = strbuf_detach(&d, NULL);
 	return path;
 }