From 2a25221eaf63f8dbe30bf56dc14dd32fc0a06fc2 Mon Sep 17 00:00:00 2001
From: Andrew Wood <andrew.wood@ivarch.com>
Date: Mon, 27 Apr 2026 21:27:20 +0100
Subject: [PATCH] Suppress the error message about a signal interrupt in cursor
 mode in all but the first instance in a pipeline (#187).

---
 src/pv/cursor.c | 28 +++++++++++++++++++++++++++-
 src/pv/loop.c   |  7 ++++---
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/src/pv/cursor.c b/src/pv/cursor.c
index 0a8ed91..f05b3a5 100644
--- a/src/pv/cursor.c
+++ b/src/pv/cursor.c
@@ -43,6 +43,13 @@
 #endif
 
 
+/*
+ * Flag to allow reporting of "interrupted by signal" errors - cleared in
+ * secondary instances in a pipeline, so that only one will report them.
+ */
+static bool pv__allow_signal_interrupt_reporting = true;
+
+
 /*
  * Create a per-euid, per-tty, lock file in ${TMPDIR:-${TMP:-/tmp}} for the
  * tty on the given file descriptor.
@@ -360,6 +367,14 @@ static int pv_crs_ipcinit(pvcursorstate_t cursor, readonly_pvcontrol_t control,
 		cursor->shared->tty_tostop_added = false;
 		cursor->y_lastread = cursor->y_start;
 		debug("%s", "we are the first to attach");
+	} else {
+		/*
+		 * Another process was first, so prevent the current
+		 * instance from reporting "interrupted by signal" errors
+		 * since the first one will do that.
+		 */
+		debug("%s", "not the first to attach - clearing pv__allow_signal_interrupt_reporting");
+		pv__allow_signal_interrupt_reporting = false;
 	}
 
 	cursor->y_offset = cursor->pvcount - 1;
@@ -440,7 +455,7 @@ void pv_crs_init(pvcursorstate_t cursor, readonly_pvcontrol_t control, pvtransie
 
 #ifdef ECHOCTL
 	/*
-	 * If the terminal ECHCTL attribute was already cleared by this
+	 * If the terminal ECHOCTL attribute was already cleared by this
 	 * process, set the flag in shared memory to let the other instances
 	 * know.
 	 */
@@ -750,3 +765,14 @@ void pv_crs_fini(pvcursorstate_t cursor, readonly_pvcontrol_t control, pvtransie
 		}
 	}
 }
+
+
+/*
+ * Report a signal interrupt, unless the flag allowing it has been cleared
+ * due to another instance already taking responsibility.
+ */
+void pv_report_signal_interrupt(void)
+{
+	if (pv__allow_signal_interrupt_reporting)
+		pv_error("%s", _("interrupted by signal"));
+}
diff --git a/src/pv/loop.c b/src/pv/loop.c
index d1d91a9..c037568 100644
--- a/src/pv/loop.c
+++ b/src/pv/loop.c
@@ -31,6 +31,7 @@
 
 int pv_remote_transferstate_fetch(pvstate_t, pid_t, /*@null@ */ off_t *, bool);
 void pv_end_display(void);
+void pv_report_signal_interrupt(void);
 
 
 #if HAVE_SQRTL
@@ -777,7 +778,7 @@ int pv_main_loop(pvstate_t state)
 
 	if (1 == state->flags.trigger_exit) {
 		state->status.exit_status |= PV_ERROREXIT_SIGNAL;
-		pv_error("%s", _("interrupted by signal"));
+		pv_report_signal_interrupt();
 	}
 
 	return state->status.exit_status;
@@ -1324,7 +1325,7 @@ int pv_watchfd_loop(pvstate_t state)
 	 */
 	if (1 == state->flags.trigger_exit) {
 		state->status.exit_status |= PV_ERROREXIT_SIGNAL;
-		pv_error("%s", _("interrupted by signal"));
+		pv_report_signal_interrupt();
 	}
 
 	/* Free all allocated sub-structures. */
@@ -1468,7 +1469,7 @@ int pv_query_loop(pvstate_t state, pid_t query)
 
 	if (1 == state->flags.trigger_exit) {
 		state->status.exit_status |= PV_ERROREXIT_SIGNAL;
-		pv_error("%s", _("interrupted by signal"));
+		pv_report_signal_interrupt();
 	}
 
 	return state->status.exit_status;