src/basic/errno-util.h

/* SPDX-License-Identifier: LGPL-2.1+ */
#pragma once

#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;
}

/* 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 */
#define ERRNO_IS_DISCONNECT(r)                                          \
        IN_SET(abs(r),                                                  \
               ENOTCONN, ECONNRESET, ECONNREFUSED, ECONNABORTED, EPIPE, \
               ENETUNREACH, EHOSTUNREACH, ENOPROTOOPT, EHOSTDOWN,       \
               ENONET, ESHUTDOWN)

/* Resource exhaustion, could be our fault or general system trouble */
#define ERRNO_IS_RESOURCE(r) \
        IN_SET(abs(r), ENOMEM, EMFILE, ENFILE)