5 files changed, 55 insertions, 23 deletions

diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 90b150c7a8b..7825cfe532e 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -59,7 +59,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char	   *endp;
 	const char *sp;
 	int			rc;
-	bool		signaled;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
 	XLogRecPtr	restartRedoPtr;
@@ -288,17 +287,12 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	 * will perform an immediate shutdown when it sees us exiting
 	 * unexpectedly.
 	 *
-	 * Per the Single Unix Spec, shells report exit status > 128 when a called
-	 * command died on a signal.  Also, 126 and 127 are used to report
-	 * problems such as an unfindable command; treat those as fatal errors
-	 * too.
+	 * We treat hard shell errors such as "command not found" as fatal, too.
 	 */
-	if (WIFSIGNALED(rc) && WTERMSIG(rc) == SIGTERM)
+	if (wait_result_is_signal(rc, SIGTERM))
 		proc_exit(1);
 
-	signaled = WIFSIGNALED(rc) || WEXITSTATUS(rc) > 125;
-
-	ereport(signaled ? FATAL : DEBUG2,
+	ereport(wait_result_is_any_signal(rc, true) ? FATAL : DEBUG2,
 			(errmsg("could not restore file \"%s\" from archive: %s",
 					xlogfname, wait_result_to_str(rc))));
 
@@ -334,7 +328,6 @@ ExecuteRecoveryCommand(char *command, char *commandName, bool failOnSignal)
 	char	   *endp;
 	const char *sp;
 	int			rc;
-	bool		signaled;
 	XLogSegNo	restartSegNo;
 	XLogRecPtr	restartRedoPtr;
 	TimeLineID	restartTli;
@@ -401,12 +394,9 @@ ExecuteRecoveryCommand(char *command, char *commandName, bool failOnSignal)
 	{
 		/*
 		 * If the failure was due to any sort of signal, it's best to punt and
-		 * abort recovery. See also detailed comments on signals in
-		 * RestoreArchivedFile().
+		 * abort recovery.  See comments in RestoreArchivedFile().
 		 */
-		signaled = WIFSIGNALED(rc) || WEXITSTATUS(rc) > 125;
-
-		ereport((signaled && failOnSignal) ? FATAL : WARNING,
+		ereport((failOnSignal && wait_result_is_any_signal(rc, true)) ? FATAL : WARNING,
 		/*------
 		   translator: First %s represents a recovery.conf parameter name like
 		  "recovery_end_command", the 2nd is the value of that parameter, the
diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 1a7d4f99ee8..226d2ef3dac 100644
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -17,7 +17,6 @@
 #include <ctype.h>
 #include <unistd.h>
 #include <sys/stat.h>
-#include <sys/wait.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 
@@ -1713,7 +1712,7 @@ ClosePipeToProgram(CopyState cstate)
 		 * problem.
 		 */
 		if (cstate->is_copy_from && !cstate->reached_eof &&
-			WIFSIGNALED(pclose_rc) && WTERMSIG(pclose_rc) == SIGPIPE)
+			wait_result_is_signal(pclose_rc, SIGPIPE))
 			return;
 
 		ereport(ERROR,
diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index ddf9d698e04..60e153ee2c9 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -573,13 +573,11 @@ pgarch_archiveXlog(char *xlog)
 		 * If either the shell itself, or a called command, died on a signal,
 		 * abort the archiver.  We do this because system() ignores SIGINT and
 		 * SIGQUIT while waiting; so a signal is very likely something that
-		 * should have interrupted us too.  If we overreact it's no big deal,
-		 * the postmaster will just start the archiver again.
-		 *
-		 * Per the Single Unix Spec, shells report exit status > 128 when a
-		 * called command died on a signal.
+		 * should have interrupted us too.  Also die if the shell got a hard
+		 * "command not found" type of error.  If we overreact it's no big
+		 * deal, the postmaster will just start the archiver again.
 		 */
-		int			lev = (WIFSIGNALED(rc) || WEXITSTATUS(rc) > 128) ? FATAL : LOG;
+		int			lev = wait_result_is_any_signal(rc, true) ? FATAL : LOG;
 
 		if (WIFEXITED(rc))
 		{
diff --git a/src/common/wait_error.c b/src/common/wait_error.c
index f824a5f2af3..4fb5276961d 100644
--- a/src/common/wait_error.c
+++ b/src/common/wait_error.c
@@ -82,3 +82,46 @@ wait_result_to_str(int exitstatus)
 
 	return pstrdup(str);
 }
+
+/*
+ * Return true if a wait(2) result indicates that the child process
+ * died due to the specified signal.
+ *
+ * The reason this is worth having a wrapper function for is that
+ * there are two cases: the signal might have been received by our
+ * immediate child process, or there might've been a shell process
+ * between us and the child that died.  The shell will, per POSIX,
+ * report the child death using exit code 128 + signal number.
+ *
+ * If there is no possibility of an intermediate shell, this function
+ * need not (and probably should not) be used.
+ */
+bool
+wait_result_is_signal(int exit_status, int signum)
+{
+	if (WIFSIGNALED(exit_status) && WTERMSIG(exit_status) == signum)
+		return true;
+	if (WIFEXITED(exit_status) && WEXITSTATUS(exit_status) == 128 + signum)
+		return true;
+	return false;
+}
+
+/*
+ * Return true if a wait(2) result indicates that the child process
+ * died due to any signal.  We consider either direct child death
+ * or a shell report of child process death as matching the condition.
+ *
+ * If include_command_not_found is true, also return true for shell
+ * exit codes indicating "command not found" and the like
+ * (specifically, exit codes 126 and 127; see above).
+ */
+bool
+wait_result_is_any_signal(int exit_status, bool include_command_not_found)
+{
+	if (WIFSIGNALED(exit_status))
+		return true;
+	if (WIFEXITED(exit_status) &&
+		WEXITSTATUS(exit_status) > (include_command_not_found ? 125 : 128))
+		return true;
+	return false;
+}
diff --git a/src/include/port.h b/src/include/port.h
index b1ba645655f..0feddcdcaea 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -483,5 +483,7 @@ extern char *escape_single_quotes_ascii(const char *src);
 
 /* port/wait_error.c */
 extern char *wait_result_to_str(int exit_status);
+extern bool wait_result_is_signal(int exit_status, int signum);
+extern bool wait_result_is_any_signal(int exit_status, bool include_command_not_found);
 
 #endif							/* PG_PORT_H */