/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2018 Red Hat, Inc.
 */

#ifndef __NM_ERRNO_H__
#define __NM_ERRNO_H__

#include <errno.h>

/*****************************************************************************/

enum _NMErrno {
    _NM_ERRNO_MININT         = G_MININT,
    _NM_ERRNO_MAXINT         = G_MAXINT,
    _NM_ERRNO_RESERVED_FIRST = 100000,

    /* when we cannot represent a number as positive number, we resort to this
     * number. Basically, the values G_MININT, -NME_ERRNO_SUCCESS, NME_ERRNO_SUCCESS
     * and G_MAXINT all map to the same value. */
    NME_ERRNO_OUT_OF_RANGE = G_MAXINT,

    /* Indicate that the original errno was zero. Zero denotes *no error*, but we know something
     * went wrong and we want to report some error. This is a placeholder to mean, something
     * was wrong, but errno was zero. */
    NME_ERRNO_SUCCESS = G_MAXINT - 1,

    /* an unspecified error. */
    NME_UNSPEC = _NM_ERRNO_RESERVED_FIRST,

    /* A bug, for example when an assertion failed.
     * Should never happen. */
    NME_BUG,

    /* a native error number (from <errno.h>) cannot be mapped as
     * an nm-error, because it is in the range [_NM_ERRNO_RESERVED_FIRST,
     * _NM_ERRNO_RESERVED_LAST]. */
    NME_NATIVE_ERRNO,

    /* netlink errors. */
    NME_NL_SEQ_MISMATCH,
    NME_NL_MSG_TRUNC,
    NME_NL_MSG_TOOSHORT,
    NME_NL_DUMP_INTR,
    NME_NL_ATTRSIZE,
    NME_NL_BAD_SOCK,
    NME_NL_NOADDR,
    NME_NL_MSG_OVERFLOW,

    /* platform errors. */
    NME_PL_NOT_FOUND,
    NME_PL_EXISTS,
    NME_PL_WRONG_TYPE,
    NME_PL_NOT_SLAVE,
    NME_PL_NO_FIRMWARE,
    NME_PL_OPNOTSUPP,
    NME_PL_NETLINK,
    NME_PL_CANT_SET_MTU,

    _NM_ERRNO_RESERVED_LAST_PLUS_1,
    _NM_ERRNO_RESERVED_LAST = _NM_ERRNO_RESERVED_LAST_PLUS_1 - 1,
};

/*****************************************************************************/

/* When we receive an errno from a system function, we can safely assume
 * that the error number is not negative. We rely on that, and possibly just
 * "return -errsv;" to signal an error. We also rely on that, because libc
 * is our trusted base: meaning, if it cannot even succeed at setting errno
 * according to specification, all bets are off.
 *
 * This macro returns the input argument, and asserts that the error variable
 * is positive.
 *
 * In a sense, the macro is related to nm_errno_native() function, but the difference
 * is that this macro asserts that @errsv is positive, while nm_errno_native() coerces
 * negative values to be non-negative. */
#define NM_ERRNO_NATIVE(errsv)        \
    ({                                \
        const int _errsv_x = (errsv); \
                                      \
        nm_assert(_errsv_x > 0);      \
        _errsv_x;                     \
    })

/* Normalize native errno.
 *
 * Our API may return native error codes (<errno.h>) as negative values. This function
 * takes such an errno, and normalizes it to their positive value.
 *
 * The special values G_MININT and zero are coerced to NME_ERRNO_OUT_OF_RANGE and NME_ERRNO_SUCCESS
 * respectively.
 * Other values are coerced to their inverse.
 * Other positive values are returned unchanged.
 *
 * Basically, this normalizes errsv to be positive (taking care of two pathological cases).
 */
static inline int
nm_errno_native(int errsv)
{
    switch (errsv) {
    case 0:
        return NME_ERRNO_SUCCESS;
    case G_MININT:
        return NME_ERRNO_OUT_OF_RANGE;
    default:
        return errsv >= 0 ? errsv : -errsv;
    }
}

/* Normalizes an nm-error to be positive.
 *
 * Various API returns negative error codes, and this function converts the negative
 * value to its positive.
 *
 * Note that @nmerr is on the domain of NetworkManager specific error numbers,
 * which is not the same as the native error numbers (errsv from <errno.h>). But
 * as far as normalizing goes, nm_errno() does exactly the same remapping as
 * nm_errno_native(). */
static inline int
nm_errno(int nmerr)
{
    return nm_errno_native(nmerr);
}

/* this maps a native errno to a (always non-negative) nm-error number.
 *
 * Note that nm-error numbers are embedded into the range of regular
 * errno. The only difference is, that nm-error numbers reserve a
 * range (_NM_ERRNO_RESERVED_FIRST, _NM_ERRNO_RESERVED_LAST) for their
 * own purpose.
 *
 * That means, converting an errno to nm-error number means in
 * most cases just returning itself.
 * Only pathological cases need special handling:
 *
 *  - 0 is mapped to NME_ERRNO_SUCCESS;
 *  - G_MININT is mapped to NME_ERRNO_OUT_OF_RANGE;
 *  - values in the range of (+/-) [_NM_ERRNO_RESERVED_FIRST, _NM_ERRNO_RESERVED_LAST]
 *    are mapped to NME_NATIVE_ERRNO
 *  - all other values are their (positive) absolute value.
 */
static inline int
nm_errno_from_native(int errsv)
{
    switch (errsv) {
    case 0:
        return NME_ERRNO_SUCCESS;
    case G_MININT:
        return NME_ERRNO_OUT_OF_RANGE;
    default:
        if (errsv < 0)
            errsv = -errsv;
        return G_UNLIKELY(errsv >= _NM_ERRNO_RESERVED_FIRST && errsv <= _NM_ERRNO_RESERVED_LAST)
                   ? NME_NATIVE_ERRNO
                   : errsv;
    }
}

const char *nm_strerror(int nmerr);

/*****************************************************************************/

#define NM_STRERROR_BUFSIZE 1024

const char *nm_strerror_native_r(int errsv, char *buf, gsize buf_size);
const char *nm_strerror_native(int errsv);

/*****************************************************************************/

#endif /* __NM_ERRNO_H__ */