1 files changed, 148 insertions, 0 deletions
diff --git a/src/common/wait_error.c b/src/common/wait_error.c
new file mode 100644
index 0000000..a90b745
--- /dev/null
+++ b/src/common/wait_error.c
@@ -0,0 +1,148 @@
+/*-------------------------------------------------------------------------
+ *
+ * wait_error.c
+ *		Convert a wait/waitpid(2) result code to a human-readable string
+ *
+ *
+ * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/wait_error.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include <signal.h>
+#include <sys/wait.h>
+
+/*
+ * Return a human-readable string explaining the reason a child process
+ * terminated. The argument is a return code returned by wait(2) or
+ * waitpid(2), which also applies to pclose(3) and system(3). The result is a
+ * translated, palloc'd or malloc'd string.
+ */
+char *
+wait_result_to_str(int exitstatus)
+{
+	char		str[512];
+
+	/*
+	 * To simplify using this after pclose() and system(), handle status -1
+	 * first.  In that case, there is no wait result but some error indicated
+	 * by errno.
+	 */
+	if (exitstatus == -1)
+	{
+		snprintf(str, sizeof(str), "%m");
+	}
+	else if (WIFEXITED(exitstatus))
+	{
+		/*
+		 * Give more specific error message for some common exit codes that
+		 * have a special meaning in shells.
+		 */
+		switch (WEXITSTATUS(exitstatus))
+		{
+			case 126:
+				snprintf(str, sizeof(str), _("command not executable"));
+				break;
+
+			case 127:
+				snprintf(str, sizeof(str), _("command not found"));
+				break;
+
+			default:
+				snprintf(str, sizeof(str),
+						 _("child process exited with exit code %d"),
+						 WEXITSTATUS(exitstatus));
+		}
+	}
+	else if (WIFSIGNALED(exitstatus))
+	{
+#if defined(WIN32)
+		snprintf(str, sizeof(str),
+				 _("child process was terminated by exception 0x%X"),
+				 WTERMSIG(exitstatus));
+#else
+		snprintf(str, sizeof(str),
+				 _("child process was terminated by signal %d: %s"),
+				 WTERMSIG(exitstatus), pg_strsignal(WTERMSIG(exitstatus)));
+#endif
+	}
+	else
+		snprintf(str, sizeof(str),
+				 _("child process exited with unrecognized status %d"),
+				 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;
+}
+
+/*
+ * Return the shell exit code (normally 0 to 255) that corresponds to the
+ * given wait status.  The argument is a wait status as returned by wait(2)
+ * or waitpid(2), which also applies to pclose(3) and system(3).  To support
+ * the latter two cases, we pass through "-1" unchanged.
+ */
+int
+wait_result_to_exit_code(int exit_status)
+{
+	if (exit_status == -1)
+		return -1;				/* failure of pclose() or system() */
+	if (WIFEXITED(exit_status))
+		return WEXITSTATUS(exit_status);
+	if (WIFSIGNALED(exit_status))
+		return 128 + WTERMSIG(exit_status);
+	/* On many systems, this is unreachable */
+	return -1;
+}