On Tue, May 26, 2020 at 09:40:27PM +0100, David CARLIER wrote:
> From b24a6702beb2a4e2a9c1c03b69c6d1dd07d4cf08 Mon Sep 17 00:00:00 2001
> From: David Carlier <devne...@gmail.com>
> Date: Tue, 26 May 2020 21:35:27 +0100
> Subject: [PATCH] util/oslib: current process full path resolution on MacOS
>
> Using existing libproc to fill the path.
>
> Signed-off-by: David Carlier <devne...@gmail.com>
> ---
> util/oslib-posix.c | 13 +++++++++++++
> 1 file changed, 13 insertions(+)
>
> diff --git a/util/oslib-posix.c b/util/oslib-posix.c
> index 062236a1ab..96f0405ee6 100644
> --- a/util/oslib-posix.c
> +++ b/util/oslib-posix.c
> @@ -55,6 +55,10 @@
> #include <sys/sysctl.h>
> #endif
>
> +#ifdef __APPLE__
> +#include <libproc.h>
> +#endif
> +
> #include "qemu/mmap-alloc.h"
>
> #ifdef CONFIG_DEBUG_STACK_USAGE
> @@ -366,6 +370,15 @@ void qemu_init_exec_dir(const char *argv0)
> p = buf;
> }
> }
> +#elif defined(__APPLE__)
> + {
> + uint32_t len;
> + len = proc_pidpath(getpid(), buf, sizeof(buf) - 1);
Hi David,
proc_pidpath handler in the xnu kernel is indirectly calling
build_path_with_parent [1] and it includes NULL terminator into
buffersize, i.e. the patch seems to limit path length to one less
character than OS allows.
> + if (len > 0) {
> + buf[len] = 0;
> + p = buf;
> + }
> + }
> #endif
> /* If we don't have any way of figuring out the actual executable
> location then try argv[0]. */
> --
> 2.26.2
>
The change looks okay but it's not clear why it is needed [2].
Also, libproc.h [3] has this comment:
/*
* This header file contains private interfaces to obtain process information.
* These interfaces are subject to change in future releases.
*/
But iTerm2 [4] an Chromium [5] are using it. An alternative (if it works
and IMO less appealing) would be to retrieve process path using AppKit [6].
1.
https://opensource.apple.com/source/xnu/xnu-6153.81.5/bsd/vfs/vfs_cache.c.auto.html
2.
https://wiki.qemu.org/Contribute/SubmitAPatch#Write_a_meaningful_commit_message
3.
https://opensource.apple.com/source/xnu/xnu-6153.81.5/libsyscall/wrappers/libproc/libproc.h.auto.html
4.
https://gitlab.com/gnachman/iterm2/blob/872e3d63fbcaf7b4235c4f3b7273e09a7ba4c1d1/sources/iTermLSOF.m#L31
5.
https://github.com/chromium/chromium/blob/2ca8c5037021c9d2ecc00b787d58a31ed8fc8bcb/base/process/process_handle_mac.cc#L31
6. https://developer.apple.com/documentation/appkit/nsworkspace?language=objc
Regards,
Roman
