From 13ff8745c9dafcff23e549b5cf6505ebe9a6855e Mon Sep 17 00:00:00 2001
From: Paul Kulchenko <paul@kulchenko.com>
Date: Tue, 1 Mar 2022 19:32:03 -0800
Subject: [PATCH] Update OpenExecutable to check for result from open with RDWR
 access

---
 libc/runtime/openexecutable.S | 12 ++++++++++++
 tool/net/redbean.c            |  4 ++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/libc/runtime/openexecutable.S b/libc/runtime/openexecutable.S
index c76f03139..7efdcd9c3 100644
--- a/libc/runtime/openexecutable.S
+++ b/libc/runtime/openexecutable.S
@@ -41,6 +41,7 @@ OpenExecutable:
 	pushq	MAP_PRIVATE(%rip)		# -0x30(%rbp)
 	pushq	MAP_FIXED(%rip)			# -0x38(%rbp)
 	pushq	__NR_mprotect(%rip)		# -0x40(%rbp)
+	pushq	O_RDONLY(%rip)			# -0x48(%rbp)
 	push	%rbx				# code buffer
 	push	%r12				# data buffer
 	push	%r14				# filename
@@ -122,6 +123,17 @@ OpenExecutable:
 	mov	-0x20(%rbp),%esi		# O_RDWR
 	syscall
 	mov	%eax,%r15d
+	mov	$-1,%eax			# check if successful
+	cmp	%eax,%r15d
+	jne	0f
+
+//	Open executable in read-only mode.
+	mov	-0x08(%rbp),%eax		# __NR_open
+	mov	%r14,%rdi
+	mov	-0x48(%rbp),%esi		# O_RDONLY
+	syscall
+	mov	%eax,%r15d
+0:
 
 //	Map code segment.
 	mov	-0x10(%rbp),%eax		# __NR_mmap
diff --git a/tool/net/redbean.c b/tool/net/redbean.c
index a929286f9..40ed300ad 100644
--- a/tool/net/redbean.c
+++ b/tool/net/redbean.c
@@ -6854,8 +6854,8 @@ static void RestoreApe(void) {
   if (endswith(zpath, ".com.dbg")) return;
   if ((a = GetAssetZip("/.ape", 5)) && (p = LoadAsset(a, &n))) {
     close(zfd);
-    zfd = OpenExecutable();
-    write(zfd, p, n);
+    if ((zfd = OpenExecutable()) == -1 || write(zfd, p, n) == -1)
+      WARNF("(srvr) can't restore .ape");
     free(p);
   } else {
     WARNF("(srvr) /.ape not found");