Re: [PATCH v4 4/4] fsmonitor: normalize FSEvents event paths to the real path

[Jeff Hostetler <git@jeffhostetler.com>]

On 8/31/22 12:09 PM, Eric DeCosta via GitGitGadget wrote:
> From: Eric DeCosta <edecosta@mathworks.com>
> 
> Consider the following network working directory that is mounted under
> /System/Volumes/Data:
> 
> /network/working/directory
> 
> The git working directory path is:
> 
> /System/Volumes/Data/network/working/directory
> 
> The paths reported by FSEvents always start with /network. fsmonitor
> expects paths to be under the working directory; therefore it
> fails to match /network/... and ignores the change.

I'm not sure I understand what's going on here.
Are you saying that FSEvents reports network mounted
directories with a path relative to the mount-point
rather than an absolute path?

In your example, is "/network/working/directory" a
valid path on your system (that also happens to be the
same directory as "/System/Volumes/...")

That is, do you have some aliasing going on where both paths
are valid -- like a pair of hard-linked directories?
Or, is there something special about a network mount point?


Did you have to "cd /System/Volumes/..." to get Git to have
the absolute path be this?  Or were you doing a "cd /network/..."?
(Sorry to ask so many questions but I don't have a pair of
systems to test any of this on right now.)

> 
> Change things such that if fsmonitor.allowRemote is true that the
> paths reported via FSEevents are normalized to the real path.
> 
> Signed-off-by: Eric DeCosta <edecosta@mathworks.com>
> ---
>   compat/fsmonitor/fsm-listen-darwin.c | 11 ++++++++---
>   1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/compat/fsmonitor/fsm-listen-darwin.c b/compat/fsmonitor/fsm-listen-darwin.c
> index 8e208e8289e..2ed828649ff 100644
> --- a/compat/fsmonitor/fsm-listen-darwin.c
> +++ b/compat/fsmonitor/fsm-listen-darwin.c
> @@ -26,6 +26,7 @@
>   #include "fsmonitor.h"
>   #include "fsm-listen.h"
>   #include "fsmonitor--daemon.h"
> +#include "fsmonitor-settings.h"
>   
>   struct fsm_listen_data
>   {
> @@ -183,7 +184,6 @@ static void my_add_path(struct fsmonitor_batch *batch, const char *path)
>   	free(composed);
>   }
>   
> -
>   static void fsevent_callback(ConstFSEventStreamRef streamRef,
>   			     void *ctx,
>   			     size_t num_of_events,
> @@ -209,7 +209,12 @@ static void fsevent_callback(ConstFSEventStreamRef streamRef,
>   		/*
>   		 * On Mac, we receive an array of absolute paths.
>   		 */
> -		path_k = paths[k];
> +		if (fsm_settings__get_allow_remote(the_repository) > 0) {
> +			strbuf_reset(&tmp);
> +			strbuf_realpath_forgiving(&tmp, paths[k], 0);
> +			path_k = tmp.buf;
> +		} else
> +			path_k = paths[k];

This feels wrong.

It is not that fsmonitor.allowRemote is true, but whether or not
this particular file system *IS* remote, right?

>   
>   		/*
>   		 * If you want to debug FSEvents, log them to GIT_TRACE_FSMONITOR.
> @@ -237,6 +242,7 @@ static void fsevent_callback(ConstFSEventStreamRef streamRef,
>   
>   			fsmonitor_force_resync(state);
>   			fsmonitor_batch__free_list(batch);
> +			batch = NULL;
>   			string_list_clear(&cookie_list, 0);
>   
>   			/*
> @@ -313,7 +319,6 @@ static void fsevent_callback(ConstFSEventStreamRef streamRef,
>   
>   		case IS_WORKDIR_PATH:
>   			/* try to queue normal pathnames */
> -
>   			if (trace_pass_fl(&trace_fsmonitor))
>   				log_flags_set(path_k, event_flags[k]);
>   
>