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#ifndef ERROR_H

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#define ERROR_H

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/*

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 * Error-handling functions

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 */

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#include <errno.h>

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/*

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 * Type used for error codes is an explicitly *unsigned* int, meaning that error codes themselves are positive.

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 * Negative error codes also exist in some places, and they are just a negative err_t.

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 */

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typedef unsigned int err_t;

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/*

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 * List of defined error codes, organized mostly by function name

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 */

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enum error_code {

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    ERR_CALLOC                  = 0x000100,

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    // network resolver errors

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    ERR_GETADDRINFO             = 0x000200,

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    ERR_GETADDRINFO_EMPTY       = 0x000201,     /* No valid results */

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    // low-level network errors

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    ERR_SOCKET                  = 0x000301,

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    ERR_CONNECT                 = 0x000302,

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    // low-level IO errors

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    ERR_READ                    = 0x000401,

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    ERR_WRITE                   = 0x000402,

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};

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/*

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 * An error code and associated extra infos

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 */

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struct error_info {

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    /* The base error code */

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    err_t code;

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    /* Additional detail info, usually some third-part error code */

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    unsigned int extra;

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};

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/** No error, evaulates as logical false */

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#define SUCCESS (0)

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/* Evaulates to error_info.code as lvalue */

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#define ERROR_CODE(err_info) ((err_info).code)

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/* Evaulates to error_info.extra as lvalue */

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#define ERROR_EXTRA(err_info) ((err_info).extra)

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/* Set error_info.code to SUCCESS, evaulates as zero */

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#define RESET_ERROR(err_info) ((err_info).code = SUCCESS)

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/* Compare error_info.code != 0 */

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#define IS_ERROR(err_info) (!!(err_info).code)

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/* Set error_info.code, but leave err_extra as-is. Evaluates to err_code */

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#define SET_ERROR(err_info, err_code) ((err_info).code = (err_code))

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/* Set error_info.code/extra. XXX: should evaluate to err_code */

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#define _SET_ERROR_EXTRA(err_info, err_code, err_extra) (err_info).code = (err_code); err_info.extra = (err_extra)

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#define SET_ERROR_EXTRA(err_info, err_code, err_extra) do { _SET_ERROR_EXTRA(err_info, err_code, err_extra); } while (0)

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/* Set error.info.code to err_code, and .extra to errno. XXX: should evaulate to err_code */

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#define _SET_ERROR_ERRNO(err_info, err_code) _SET_ERROR_EXTRA(err_info, err_code, errno);

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#define SET_ERROR_ERRNO(err_info, err_code) SET_ERROR_EXTRA(err_info, err_code, errno);

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/* Ss above, but also return err_code from func. XXX: use 'return SET_ERROR...' instead */

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#define RETURN_SET_ERROR(err_info, err_code) do { _SET_ERROR(err_info, err_code); return (err_code); } while (0)

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#define RETURN_SET_ERROR_EXTRA(err_info, err_code, err_extra) do { _SET_ERROR_EXTRA(err_info, err_code, err_extra); return (err_code); } while (0)

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#define RETURN_SET_ERROR_ERRNO(err_info, err_code) do { _SET_ERROR_ERRNO(err_info, err_code); return (err_code); } while (0)

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#endif