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-rw-r--r--src/basic/errno-util.h119
1 files changed, 119 insertions, 0 deletions
diff --git a/src/basic/errno-util.h b/src/basic/errno-util.h
new file mode 100644
index 0000000..5609820
--- /dev/null
+++ b/src/basic/errno-util.h
@@ -0,0 +1,119 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "macro.h"
+
+static inline void _reset_errno_(int *saved_errno) {
+ if (*saved_errno < 0) /* Invalidated by UNPROTECT_ERRNO? */
+ return;
+
+ errno = *saved_errno;
+}
+
+#define PROTECT_ERRNO \
+ _cleanup_(_reset_errno_) _unused_ int _saved_errno_ = errno
+
+#define UNPROTECT_ERRNO \
+ do { \
+ errno = _saved_errno_; \
+ _saved_errno_ = -1; \
+ } while (false)
+
+static inline int negative_errno(void) {
+ /* This helper should be used to shut up gcc if you know 'errno' is
+ * negative. Instead of "return -errno;", use "return negative_errno();"
+ * It will suppress bogus gcc warnings in case it assumes 'errno' might
+ * be 0 and thus the caller's error-handling might not be triggered. */
+ assert_return(errno > 0, -EINVAL);
+ return -errno;
+}
+
+static inline const char *strerror_safe(int error) {
+ /* 'safe' here does NOT mean thread safety. */
+ return strerror(abs(error));
+}
+
+static inline int errno_or_else(int fallback) {
+ /* To be used when invoking library calls where errno handling is not defined clearly: we return
+ * errno if it is set, and the specified error otherwise. The idea is that the caller initializes
+ * errno to zero before doing an API call, and then uses this helper to retrieve a somewhat useful
+ * error code */
+ if (errno > 0)
+ return -errno;
+
+ return -abs(fallback);
+}
+
+/* Hint #1: ENETUNREACH happens if we try to connect to "non-existing" special IP addresses, such as ::5.
+ *
+ * Hint #2: The kernel sends e.g., EHOSTUNREACH or ENONET to userspace in some ICMP error cases. See the
+ * icmp_err_convert[] in net/ipv4/icmp.c in the kernel sources.
+ *
+ * Hint #3: When asynchronous connect() on TCP fails because the host never acknowledges a single packet,
+ * kernel tells us that with ETIMEDOUT, see tcp(7). */
+static inline bool ERRNO_IS_DISCONNECT(int r) {
+ return IN_SET(abs(r),
+ ECONNABORTED,
+ ECONNREFUSED,
+ ECONNRESET,
+ EHOSTDOWN,
+ EHOSTUNREACH,
+ ENETDOWN,
+ ENETRESET,
+ ENETUNREACH,
+ ENONET,
+ ENOPROTOOPT,
+ ENOTCONN,
+ EPIPE,
+ EPROTO,
+ ESHUTDOWN,
+ ETIMEDOUT);
+}
+
+/* Transient errors we might get on accept() that we should ignore. As per error handling comment in
+ * the accept(2) man page. */
+static inline bool ERRNO_IS_ACCEPT_AGAIN(int r) {
+ return ERRNO_IS_DISCONNECT(r) ||
+ IN_SET(abs(r),
+ EAGAIN,
+ EINTR,
+ EOPNOTSUPP);
+}
+
+/* Resource exhaustion, could be our fault or general system trouble */
+static inline bool ERRNO_IS_RESOURCE(int r) {
+ return IN_SET(abs(r),
+ EMFILE,
+ ENFILE,
+ ENOMEM);
+}
+
+/* Seven different errors for "operation/system call/ioctl/socket feature not supported" */
+static inline bool ERRNO_IS_NOT_SUPPORTED(int r) {
+ return IN_SET(abs(r),
+ EOPNOTSUPP,
+ ENOTTY,
+ ENOSYS,
+ EAFNOSUPPORT,
+ EPFNOSUPPORT,
+ EPROTONOSUPPORT,
+ ESOCKTNOSUPPORT);
+}
+
+/* Two different errors for access problems */
+static inline bool ERRNO_IS_PRIVILEGE(int r) {
+ return IN_SET(abs(r),
+ EACCES,
+ EPERM);
+}
+
+/* Three difference errors for "not enough disk space" */
+static inline bool ERRNO_IS_DISK_SPACE(int r) {
+ return IN_SET(abs(r),
+ ENOSPC,
+ EDQUOT,
+ EFBIG);
+}