[Valgrind-developers] [valgrind] sys_statx: support for statx(fd, NULL, AT_EMPTY_PATH)

[Mark W. <ma...@so...>]

https://sourceware.org/git/gitweb.cgi?p=valgrind.git;h=de408f75bf28d76a0016325b75f14be45631472a

commit de408f75bf28d76a0016325b75f14be45631472a
Author: Miao Wang <sha...@gm...>
Date:   Mon Aug 26 22:08:43 2024 +0800

    sys_statx: support for statx(fd, NULL, AT_EMPTY_PATH)
    
    statx(fd, NULL, AT_EMPTY_PATH) is supported since Linux 6.11 and this
    patch adds the support to valgrind, so that it won't complain when
    NULL is used as |filename| and |flags| includes AT_EMPTY_PATH.
    
    Ref: commit 0ef625bba6fb ("vfs: support statx(..., NULL, AT_EMPTY_PATH, ...)")
    
    Signed-off-by: Miao Wang <sha...@gm...>

Diff:
---
 coregrind/m_syswrap/syswrap-linux.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/coregrind/m_syswrap/syswrap-linux.c b/coregrind/m_syswrap/syswrap-linux.c
index 9f3c51c179..4533855998 100644
--- a/coregrind/m_syswrap/syswrap-linux.c
+++ b/coregrind/m_syswrap/syswrap-linux.c
@@ -4209,8 +4209,12 @@ PRE(sys_statx)
    // in which it passes NULL for both filename and buf, and then looks at the
    // return value, so as to determine whether or not this syscall is supported.
    Bool both_filename_and_buf_are_null = ARG2 == 0 && ARG5 == 0;
+   Bool statx_null_path = (ARG2 == 0) && (ARG3 & VKI_AT_EMPTY_PATH);
    if (!both_filename_and_buf_are_null) {
-      PRE_MEM_RASCIIZ( "statx(filename)", ARG2 );
+      // Since Linux 6.11, the kernel allows passing a NULL filename when
+      // the AT_EMPTY_PATH flag is set.
+      if (!statx_null_path)
+         PRE_MEM_RASCIIZ( "statx(filename)", ARG2 );
       PRE_MEM_WRITE( "statx(buf)", ARG5, sizeof(struct vki_statx) );
    }
 }