/* $Id: must2.h,v 1.4 2021/11/16 21:57:49 oj14ozun Exp $
 * further experiments with c error handling
 *
 * examples:
 * mzr stat("/etc/passwd", &buf);         -- must be zero, or return
 * mpf mem = malloc(1024);                -- must be positive or exit(failure)
 * mnb listen = accept(sock, NULL, NULL); -- must be negative or break
 */

#include <stdbool.h>

#define __must(handle, check)                                   \
     for (void *___q = 1, *___v = NULL;                             \
          (*__v || ((check(__v)) && handle)) || ___q;           \
          ___q = 0)                                                 \
          __v = &

/* handles */
#define __Rn(n)      { return n; }           /* return n */
#define __RN     __Rn(-1)                    /* return negative */
#define __R0     __Rn(0)                     /* return zero */
#define __E1     { exit(EXIT_FAILURE); };    /* exit with 1 */
#define __E0     { exit(EXIT_SUCCESS); }     /* exit with 0 */
#define __W1                                 /* warn and exit with 1 */ \
     { perror(__FILE__ ", " #__LINE__); exit(EXIT_FAILURE); }
#define __W0                                 /* warn and exit with 0 */	\
     { perror(__FILE__ ", " #__LINE__); exit(EXIT_SUCCESS); }
#define __JC     { continue; }               /* just continue */
#define __JB     { break; }                  /* just break */
#define __Gl(l)      { goto l; }             /* goto label */

/* checks */
#define __ER(no) ((x), no == errno)          /* non-negative */

/* actual macros */
#define mzr    __must(__RN, 0 ==)         /* must be zero or return negative */
#define mzf    __must(__E0, 0 ==)         /* must be zero or fail (exit 1) */
#define mze    __must(__E1, 0 ==)         /* must be zero or quit (exit 0) */
#define mzw    __must(__W1, 0 ==)         /* must be zero or warn and fail (exit 1)  */
#define mzc    __must(__JC, 0 ==)         /* must be zero or continue  */
#define mzb    __must(__JB, 0 ==)         /* must be zero or break  */
#define mzn(n) __must(__Rn(n), 0 ==)      /* must be zero or return n  */
#define mzg(l) __must(__Gl(l), 0 ==)      /* must be zero or goto l  */

#define mpr    __must(__RN, 0 <)          /* must be positive or return negative */
#define mpf    __must(__E0, 0 <)          /* must be positive or fail (exit 1) */
#define mpe    __must(__E1, 0 <)          /* must be positive or quit (exit 0) */
#define mpw    __must(__W1, 0 <)          /* must be positive or warn and fail (exit 1)  */
#define mpc    __must(__JC, 0 <)          /* must be positive or continue  */
#define mpb    __must(__JB, 0 <)          /* must be positive or break  */
#define mpn(n) __must(__Rn(n), 0 <)       /* must be positive or return n  */
#define mpg(l) __must(__Gl(l), 0 <)       /* must be positive or goto l  */

#define mnr    __must(__RN, 0 >)          /* must be negative or return negative */
#define mnf    __must(__E0, 0 >)          /* must be negative or fail (exit 1) */
#define mne    __must(__E1, 0 >)          /* must be negative or quit (exit 0) */
#define mnw    __must(__W1, 0 >)          /* must be negative or warn and fail (exit 1)  */
#define mnc    __must(__JC, 0 >)          /* must be negative or continue  */
#define mnb    __must(__JB, 0 >)          /* must be negative or break  */
#define mnn(n) __must(__Rn(n), 0 >)       /* must be negative or return n  */
#define mng(l) __must(__Gl(l), 0 >)       /* must be negative or goto l  */

#define mer    __must(__RN, __ER(0))      /* errno must be zero or return negative */
#define mef    __must(__E0, __ER(0))      /* errno must be zero or fail (exit 1) */
#define mee    __must(__E1, __ER(0))      /* errno must be zero or quit (exit 0) */
#define mew    __must(__W1, __ER(0))      /* errno must be zero or warn and fail (exit 1)  */
#define mec    __must(__JC, __ER(0))      /* errno must be zero or continue  */
#define meb    __must(__JB, __ER(0))      /* errno must be zero or break  */
#define men(n) __must(__Rn(n), __ER(0))   /* errno must be zero or return n  */
#define meg(l) __must(__Gl(l), __ER(0))   /* errno must be zero or goto l  */

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