From: Vladimír Čunát <vladimir.cunat@nic.cz>
Date: Wed, 12 May 2021 11:48:00 +0000 (+0200)
Subject: lib/utils kr_fail(): don't mangle errno
X-Git-Tag: v5.4.0~18^2~7
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4b62334f290460fb2d4bebc4a74120a4cdc816ec;p=thirdparty%2Fknot-resolver.git

lib/utils kr_fail(): don't mangle errno
---

diff --git a/lib/utils.c b/lib/utils.c
index b3e9b549e..7287fcfe4 100644
--- a/lib/utils.c
+++ b/lib/utils.c
@@ -43,6 +43,7 @@ int kr_dbg_assumption_fork = DBG_ASSUMPTION_FORK;
 
 void kr_fail(bool is_fatal, const char *expr, const char *func, const char *file, int line)
 {
+	const int errno_orig = errno;
 	if (is_fatal)
 		kr_log_critical("requirement \"%s\" failed in %s@%s:%d\n", expr, func, file, line);
 	else
@@ -51,12 +52,12 @@ void kr_fail(bool is_fatal, const char *expr, const char *func, const char *file
 	if (is_fatal || (kr_dbg_assumption_abort && !kr_dbg_assumption_fork))
 		abort();
 	else if (!kr_dbg_assumption_abort || !kr_dbg_assumption_fork)
-		return;
+		goto recover;
 	// We want to fork and abort the child, unless rate-limited.
 	static uint64_t limited_until = 0;
 	const uint64_t now = kr_now();
 	if (now < limited_until)
-		return;
+		goto recover;
 	if (kr_dbg_assumption_fork > 0) {
 		// Add jitter +- 25%; in other words: 75% + uniform(0,50%).
 		// Motivation: if a persistent problem starts happening, desynchronize
@@ -66,6 +67,8 @@ void kr_fail(bool is_fatal, const char *expr, const char *func, const char *file
 	}
 	if (fork() == 0)
 		abort();
+recover:
+	errno = errno_orig;
 }
 
 /*
diff --git a/lib/utils.h b/lib/utils.h
index 82bcf66e4..e11e8b144 100644
--- a/lib/utils.h
+++ b/lib/utils.h
@@ -57,6 +57,7 @@ typedef void (*trace_log_f)(const struct kr_request *request, const char *msg);
  * If the check fails, optionally fork()+abort() to generate coredump
  * and continue running in parent process.  Return value must be handled to
  * ensure safe recovery from error.  Use kr_require() for unrecoverable checks.
+ * The errno variable is not mangled, e.g. you can: if (!kr_assume(...)) return errno;
  */
 #define kr_assume(expression) kr_assume_func((expression), #expression,       \
 					     __func__, __FILE__, __LINE__)
diff --git a/modules/dnstap/dnstap.c b/modules/dnstap/dnstap.c
index 56e101227..73e8df7dd 100644
--- a/modules/dnstap/dnstap.c
+++ b/modules/dnstap/dnstap.c
@@ -387,7 +387,7 @@ static int find_string(const JsonNode *node, char **val, size_t len) {
 		return kr_error(EINVAL);
 	*val = strndup(node->string_, len);
 	if (!kr_assume(*val != NULL))
-		return kr_error(EFAULT);
+		return kr_error(errno);
 	return kr_ok();
 }