[musl] [PATCH 1/4] ldso: add option to rewrite the argv block

[rcombs <rcombs@rcombs.me>]

---
 ldso/dynlink.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/ldso/dynlink.c b/ldso/dynlink.c
index 6468f20..c378f00 100644
--- a/ldso/dynlink.c
+++ b/ldso/dynlink.c
@@ -1698,6 +1698,7 @@ void __dls3(size_t *sp, size_t *auxv)
 	char **argv = (void *)(sp+1);
 	char **argv_orig = argv;
 	char **envp = argv+argc+1;
+	int replace_argv = 0;
 
 	/* Find aux vector just past environ[] and use it to initialize
 	 * global data that may be needed before we can make syscalls. */
@@ -1771,6 +1772,8 @@ void __dls3(size_t *sp, size_t *auxv)
 				if (opt[5]=='=') replace_argv0 = opt+6;
 				else if (opt[5]) *argv = 0;
 				else if (*argv) replace_argv0 = *argv++;
+			} else if (!memcmp(opt, "replace-argv", 12)) {
+				replace_argv = 1;
 			} else {
 				argv[0] = 0;
 			}
@@ -1949,6 +1952,22 @@ void __dls3(size_t *sp, size_t *auxv)
 	debug.state = 0;
 	_dl_debug_state();
 
+	if (replace_argv) {
+		char *argv_end = argv_orig[0];
+		char *orig_ptr = argv_orig[0];
+		int i;
+		for (i = 0; i < (int)(argc - (argv-argv_orig)); i++) {
+			char *src = (i == 0 && replace_argv0) ? replace_argv0 : argv[i];
+			int len = strlen(src) + 1;
+			memmove(orig_ptr, src, len);
+			argv_end = argv[i] + strlen(argv[i]);
+			argv[i] = orig_ptr;
+			orig_ptr += len;
+		}
+		for (; orig_ptr < argv_end; orig_ptr++)
+			*orig_ptr = 0;
+	}
+
 	if (replace_argv0) argv[0] = replace_argv0;
 
 	errno = 0;
-- 
2.7.4