From d4408a3d8b6317acad39ad3d34259789bb4d00df Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Mon, 29 May 2017 06:39:41 +0000
Subject: [PATCH] ruby-runner.c: replace argv[0]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58950 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ruby-runner.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/ruby-runner.c b/ruby-runner.c
index c16e7c6829..f44a02bcc7 100644
--- a/ruby-runner.c
+++ b/ruby-runner.c
@@ -12,6 +12,11 @@ int
 main(int argc, char **argv)
 {
     static const char builddir[] = BUILDDIR;
+    static const char rubypath[] = BUILDDIR"/"STRINGIZE(RUBY_INSTALL_NAME);
+    const size_t dirsize = sizeof(builddir);
+    const size_t namesize = sizeof(rubypath) - dirsize;
+    const char *rubyname = rubypath + dirsize;
+    char *arg0 = argv[0], *p;
     const char *libpath = getenv(LIBPATHENV);
     char c = 0;
 
@@ -20,16 +25,27 @@ main(int argc, char **argv)
     }
     if (c) {
 	size_t n = strlen(libpath);
-	char *e = malloc(sizeof(builddir)+n+1);
-	memcpy(e, builddir, sizeof(builddir)-1);
-	e[sizeof(builddir)-1] = PATH_SEP;
-	memcpy(e+sizeof(builddir), libpath, n+1);
+	char *e = malloc(dirsize+n+1);
+	memcpy(e, builddir, dirsize-1);
+	e[dirsize-1] = PATH_SEP;
+	memcpy(e+dirsize, libpath, n+1);
 	libpath = e;
     }
     else {
 	libpath = builddir;
     }
     setenv(LIBPATHENV, libpath, 1);
-    execv(BUILDDIR"/"STRINGIZE(RUBY_INSTALL_NAME), argv);
+
+    if (!(p = strrchr(arg0, '/'))) p = arg0; else p++;
+    if (strlen(p) < namesize - 1) {
+	argv[0] = malloc(p - arg0 + namesize);
+	memcpy(argv[0], arg0, p - arg0);
+	memcpy(argv[0] + (p - arg0), rubypath + dirsize, namesize);
+    }
+    else {
+	memcpy(p, rubyname, namesize);
+    }
+
+    execv(rubypath, argv);
     return -1;
 }