From 8b08da73cf3d72439c4f750c96ed2f088ef1bbec Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mark@klomp.org>
Date: Tue, 12 Nov 2024 13:34:09 +0100
Subject: [PATCH 03/11] vgdb.c (fork_and_exec_valgrind): Fix another off-by-one
error write
commit 646978d9adc5 ("vgdb: Handle EINTR and EAGAIN more
consistently") introduced another off-by-one issue trying to write
back the error from child to parent.
Instead of +1 it should have been +written (which initially is zero).
This is when the child needs to do a chdir and that chdir fails. If
that happens the parent would have gotten the wrong error code.
(cherry picked from commit 747ca4eb5fed5dd58a14391a997bb9e658e3b1c8)
---
coregrind/vgdb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/coregrind/vgdb.c b/coregrind/vgdb.c
index 112f23fe6ba1..cc945c8dfafa 100644
--- a/coregrind/vgdb.c
+++ b/coregrind/vgdb.c
@@ -1289,7 +1289,7 @@ int fork_and_exec_valgrind (int argc, char **argv, const char *working_dir,
// We try to write the result to the parent, but always exit.
size_t written = 0;
while (written < sizeof (int)) {
- int nrw = write (pipefd[1], ((char *)&err) + 1,
+ int nrw = write (pipefd[1], ((char *)&err) + written,
sizeof (int) - written);
if (nrw == -1) {
if (errno == EINTR || errno == EAGAIN)
--
2.47.0