add option to update cache in a background process

the cli flag is undocumented for now, since it's experimental.

Closes: https://codeberg.org/nsxiv/nsxiv/issues/416
Closes: https://codeberg.org/nsxiv/nsxiv/pulls/425
Co-authored-by: explosion-mental <explosion0mental@gmail.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/main.c b/main.c
index a050aa8..e0ff5b3 100644
--- a/main.c
+++ b/main.c
@@ -936,6 +936,23 @@ int main(int argc, char *argv[])
 	filecnt = fileidx;
 	fileidx = options->startnum < filecnt ? options->startnum : 0;
 
+	if (options->background_cache && !options->private_mode) {
+		pid_t ppid = getpid(); /* to check if parent is still alive or not */
+		switch (fork()) {
+		case 0:
+			tns_init(&tns, files, &filecnt, &fileidx, NULL);
+			while (filecnt > 0 && getppid() == ppid) {
+				tns_load(&tns, filecnt - 1, false, true);
+				remove_file(filecnt - 1, true);
+			}
+			exit(0);
+			break;
+		case -1:
+			error(0, errno, "fork failed");
+			break;
+		}
+	}
+
 	win_init(&win);
 	img_init(&img, &win);
 	arl_init(&arl);