Set $fifo variable when ctpv is started

clear.sh

@@ -1,3 +1,3 @@
-setup_fifo "$1" 1
+setup_fifo 1
 
 printf '{"action": "remove", "identifier": "preview"}\n' > "$fifo"

end.sh

@@ -1,4 +1,4 @@
-setup_fifo "$1" 1
+setup_fifo 1
 
 # tell ctpv server to exit
 printf '\0' > "$fifo"

helpers.sh

@@ -1,3 +1,7 @@
+echo_err() {
+	echo "$@" >&2
+}
+
 fifo_open() {
 	# https://unix.stackexchange.com/a/522940/183147
 	dd oflag=nonblock conv=notrunc,nocreat count=0 of="$1" \
@@ -5,8 +9,12 @@ fifo_open() {
 }
 
 setup_fifo() {
-	fifo="$(printf '/tmp/ctpvfifo.%s' "${1:-$id}")"
-	exit_code="${2:-127}"
+	if [ -z "$fifo" ]; then
+		echo_err '$fifo is empty!'
+		exit 1
+	fi
+
+	exit_code="${1:-127}"
 	[ -e "$fifo" ] || exit "$exit_code"
 	fifo_open "$fifo" || exit "$exit_code"
 }

preview.c

@@ -4,6 +4,7 @@
 #include "utils.h"
 #include "error.h"
 #include "shell.h"
+#include "server.h"
 #include "preview.h"
 
 #define FAILED_PREVIEW_EC NOTEXIST_EC
@@ -157,6 +158,9 @@ static int run(Preview *p, int *exitcode)
 
 int run_preview(const char *ext, const char *mimetype, PreviewArgs *pa)
 {
+    if (pa->id || (pa->id = getenv("id")))
+        ERRCHK_RET_OK(server_set_fifo_var(pa->id));
+
     SET_PENV("ctpv", pa->ctpv);
     SET_PENV("f", pa->f);
     SET_PENV("w", pa->w);

server.c

@@ -11,6 +11,8 @@
 #include "shell.h"
 #include "gen/server.h"
 
+#define FIFO_FILENAME_SIZE 256
+
 static pid_t ueberzug_pid;
 
 static void kill_ueberzug(void)
@@ -99,6 +101,11 @@ static int check_ueberzug(int *exitcode)
     return spawn(args, NULL, exitcode, NULL, NULL);
 }
 
+static void get_fifo_name(char *buf, size_t len, const char *id_s)
+{
+    snprintf(buf, len-1, "/tmp/ctpvfifo.%s", id_s);
+}
+
 int server_listen(char const *id_s)
 {
     int ret = OK;
@@ -111,8 +118,8 @@ int server_listen(char const *id_s)
         goto exit;
     }
 
-    char fifo[256];
-    snprintf(fifo, LEN(fifo)-1, "/tmp/ctpvfifo.%s", id_s);
+    char fifo[FIFO_FILENAME_SIZE];
+    get_fifo_name(fifo, LEN(fifo), id_s);
 
     ERRCHK_GOTO(mkfifo(fifo, 0600) == -1 && errno != EEXIST, ret, exit,
                 FUNCFAILED("mkfifo"), ERRNOS);
@@ -148,12 +155,25 @@ cleanup:
     return ret;
 }
 
+int server_set_fifo_var(const char *id_s)
+{
+    char fifo[FIFO_FILENAME_SIZE];
+    get_fifo_name(fifo, LEN(fifo), id_s);
+    ERRCHK_RET(setenv("fifo", fifo, 1) != 0, FUNCFAILED("setenv"), ERRNOS);
+
+    return OK;
+}
+
 int server_clear(const char *id_s)
 {
+    ERRCHK_RET_OK(server_set_fifo_var(id_s));
+
     return run_script(scr_clear_sh, LEN(scr_clear_sh)-1, (char *)id_s);
 }
 
 int server_end(const char *id_s)
 {
+    ERRCHK_RET_OK(server_set_fifo_var(id_s));
+
     return run_script(scr_end_sh, LEN(scr_end_sh)-1, (char *)id_s);
 }

server.h

@@ -2,6 +2,7 @@
 #define SERVER_H
 
 int server_listen(char const *id_s);
+int server_set_fifo_var(const char *id_s);
 int server_clear(const char *id_s);
 int server_end(const char *id_s);