On 4/1/2021 11:40 AM, Jeff Hostetler via GitGitGadget wrote:
> From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
...
> +#define FSMONITOR_COOKIE_PREFIX ".fsmonitor-daemon-"
> +
> +enum fsmonitor_path_type fsmonitor_classify_path_workdir_relative(
> + const char *rel)
> +{
> + if (fspathncmp(rel, ".git", 4))
> + return IS_WORKDIR_PATH;
> + rel += 4;
> +
> + if (!*rel)
> + return IS_DOT_GIT;
> + if (*rel != '/')
> + return IS_WORKDIR_PATH; /* e.g. .gitignore */
> + rel++;
> +
> + if (!fspathncmp(rel, FSMONITOR_COOKIE_PREFIX,
> + strlen(FSMONITOR_COOKIE_PREFIX)))
Seems like this strlen() could be abstracted out. Is it
something the compiler can compute and set for us? Or,
should we create a macro for this constant?
> + return IS_INSIDE_DOT_GIT_WITH_COOKIE_PREFIX;
> +
> + return IS_INSIDE_DOT_GIT;
> +}
Here is the reasoning I was missing for why we watch the .git
directory.
> +enum fsmonitor_path_type fsmonitor_classify_path_gitdir_relative(
> + const char *rel)
> +{
> + if (!fspathncmp(rel, FSMONITOR_COOKIE_PREFIX,
> + strlen(FSMONITOR_COOKIE_PREFIX)))
> + return IS_INSIDE_GITDIR_WITH_COOKIE_PREFIX;
> +
> + return IS_INSIDE_GITDIR;
> +}
And I was about to ask "what happens if we are watching the .git
directory of a worktree?" but here we have a different classifier.
> +static enum fsmonitor_path_type try_classify_workdir_abs_path(
> + struct fsmonitor_daemon_state *state,
> + const char *path)
> +{
> + const char *rel;
> +
> + if (fspathncmp(path, state->path_worktree_watch.buf,
> + state->path_worktree_watch.len))
> + return IS_OUTSIDE_CONE;
> +
> + rel = path + state->path_worktree_watch.len;
> +
> + if (!*rel)
> + return IS_WORKDIR_PATH; /* it is the root dir exactly */
> + if (*rel != '/')
> + return IS_OUTSIDE_CONE;
> + rel++;
> +
> + return fsmonitor_classify_path_workdir_relative(rel);
> +}
> +
> +enum fsmonitor_path_type fsmonitor_classify_path_absolute(
> + struct fsmonitor_daemon_state *state,
> + const char *path)
> +{
> + const char *rel;
> + enum fsmonitor_path_type t;
> +
> + t = try_classify_workdir_abs_path(state, path);
> + if (state->nr_paths_watching == 1)
> + return t;
> + if (t != IS_OUTSIDE_CONE)
> + return t;
> +
> + if (fspathncmp(path, state->path_gitdir_watch.buf,
> + state->path_gitdir_watch.len))
> + return IS_OUTSIDE_CONE;
> +
> + rel = path + state->path_gitdir_watch.len;
> +
> + if (!*rel)
> + return IS_GITDIR; /* it is the <gitdir> exactly */
> + if (*rel != '/')
> + return IS_OUTSIDE_CONE;
> + rel++;
> +
> + return fsmonitor_classify_path_gitdir_relative(rel);
> +}
And here is where you differentiate the event across the two
cases. OK.
> +/*
> + * Pathname classifications.
> + *
> + * The daemon classifies the pathnames that it receives from file
> + * system notification events into the following categories and uses
> + * that to decide whether clients are told about them. (And to watch
> + * for file system synchronization events.)
> + *
> + * The client should only care about paths within the working
> + * directory proper (inside the working directory and not ".git" nor
> + * inside of ".git/"). That is, the client has read the index and is
> + * asking for a list of any paths in the working directory that have
> + * been modified since the last token. The client does not care about
> + * file system changes within the .git directory (such as new loose
> + * objects or packfiles). So the client will only receive paths that
> + * are classified as IS_WORKDIR_PATH.
> + *
> + * The daemon uses the IS_DOT_GIT and IS_GITDIR internally to mean the
> + * exact ".git" directory or GITDIR. If the daemon receives a delete
> + * event for either of these directories, it will automatically
> + * shutdown, for example.
> + *
> + * Note that the daemon DOES NOT explicitly watch nor special case the
> + * ".git/index" file. The daemon does not read the index and does not
> + * have any internal index-relative state. The daemon only collects
> + * the set of modified paths within the working directory.
> + */
> +enum fsmonitor_path_type {
> + IS_WORKDIR_PATH = 0,
> +
> + IS_DOT_GIT,
> + IS_INSIDE_DOT_GIT,
> + IS_INSIDE_DOT_GIT_WITH_COOKIE_PREFIX,
> +
> + IS_GITDIR,
> + IS_INSIDE_GITDIR,
> + IS_INSIDE_GITDIR_WITH_COOKIE_PREFIX,
> +
> + IS_OUTSIDE_CONE,
> +};
> +
> +/*
> + * Classify a pathname relative to the root of the working directory.
> + */
> +enum fsmonitor_path_type fsmonitor_classify_path_workdir_relative(
> + const char *relative_path);
> +
> +/*
> + * Classify a pathname relative to a <gitdir> that is external to the
> + * worktree directory.
> + */
> +enum fsmonitor_path_type fsmonitor_classify_path_gitdir_relative(
> + const char *relative_path);
> +
> +/*
> + * Classify an absolute pathname received from a filesystem event.
> + */
> +enum fsmonitor_path_type fsmonitor_classify_path_absolute(
> + struct fsmonitor_daemon_state *state,
> + const char *path);
> +
> #endif /* HAVE_FSMONITOR_DAEMON_BACKEND */
> #endif /* FSMONITOR_DAEMON_H */
Had I looked ahead and read these comments beforehand, then I would
have had an easier time determining the intended behavior from the
implementations. Oops.
Thanks,
-Stolee
