/*
$Header: d:/cvsroot/tads/TADS2/LER.H,v 1.2 1999/05/17 02:52:12 MJRoberts Exp $
*/

/* Copyright (c) 1991, 2002 Michael J. Roberts.  All Rights Reserved. */
/*
Name
  ler.h - library error handling definitions
Function
  Defines error handling mechanism
Notes
  All of the functions and macros in here are named ERRxxx because
  this file was based on the TADS err.h, which used the ERRxxx naming
  convention, and it would be a lot of trouble to change.

  This package defines a set of macros that allows code to raise and
  handle exceptions.  A macro is provided which signals an error, which
  does a non-local goto to the innermost enclosing exception handler.
  A set of macros sets up exception handling code.
  
  To catch exceptions that occur inside a block of code (i.e., in the
  code or in any subroutines called by the code), begin the block with
  ERRBEGIN.  At the end of the protected code, place the exception
  handler, which starts with ERRCATCH.  At the end of the exception
  handler, place ERREND.  If no exception occurs, execution goes
  through the protected code, then resumes at the code following
  the ERREND.
  
  The exception handler can signal another error, which will cause
  the next enclosing frame to catch the error.  Alternatively, if
  the exception handler doesn't signal an error or return, execution
  continues at the code following the ERREND.  Exceptions that are
  signalled during exception handling will be caught by the next
  enclosing frame, unless the exception handler code is itself
  protected by another ERRBEGIN-ERREND block.
  
  To signal an error, use errsig().
  
  To use a string argument in a signalled error, cover the string
  with errstr(ctx, str, len); for example:
  
     errsig1(ctx, ERR_XYZ, ERRTSTR, errstr(ctx, buf, strlen(buf)));

  This copies the string into a buffer that is unaffected by
  stack resetting during error signalling.
Modified
  10/23/97 CNebel        - fixed warnings from Metrowerks C compiler.
  12/30/92 MJRoberts     - created from TADS err.h
  09/14/92 MJRoberts     - add errlog2
  08/15/91 MJRoberts     - creation
*/

#ifndef LER_INCLUDED
#define LER_INCLUDED

#include "os.h"
#ifndef LIB_INCLUDED
#include "lib.h"
#endif
#include <setjmp.h>
#include <assert.h>

#ifdef __cplusplus
extern "C" {
#endif

/* maximum length of a facility identifier */
#define ERRFACMAX    6

union erradef
{
    int   erraint;                                      /* integer argument */
    char *errastr;                                  /* text string argument */
};
typedef union erradef erradef;

struct errdef
{
    struct errdef *errprv;                          /* previous error frame */
    int            errcode;        /* error code of exception being handled */
    char           errfac[ERRFACMAX+1];        /* facility of current error */
    erradef        erraav[10];                      /* parameters for error */
    int            erraac;                   /* count of parameters in argc */
    jmp_buf        errbuf;           /* jump buffer for current error frame */
};
typedef struct errdef errdef;

#define ERRBUFSIZ 512

/* seek location record for an error message by number */
struct errmfdef
{
    uint  errmfnum;                                         /* error number */
    ulong errmfseek;                       /* seek location of this message */
};
typedef struct errmfdef errmfdef;

struct errcxdef
{
    errdef   *errcxptr;                              /* current error frame */
    void    (*errcxlog)(void *, char *fac, int err, int argc, erradef *);
                                         /* error logging callback function */
    void     *errcxlgc;               /* context for error logging callback */
    int       errcxofs;                        /* offset in argument buffer */
    char      errcxbuf[ERRBUFSIZ];            /* space for argument strings */
    osfildef *errcxfp;                /* message file, if one is being used */
    errmfdef *errcxseek;              /* seek locations of messages in file */
    uint      errcxsksz;                         /* size of errcxseek array */
    ulong     errcxbase;   /* offset in physical file of logical error file */
    struct appctxdef *errcxappctx;              /* host application context */
};
typedef struct errcxdef errcxdef;

/* begin protected code */
#define ERRBEGIN(ctx) \
  { \
    errdef fr_; \
    if ((fr_.errcode = setjmp(fr_.errbuf)) == 0) \
    { \
      fr_.errprv = (ctx)->errcxptr; \
      (ctx)->errcxptr = &fr_;

/* end protected code, begin error handler */
#define ERRCATCH(ctx, e) \
      assert(1==1 && (ctx)->errcxptr != fr_.errprv); \
      (ctx)->errcxptr = fr_.errprv; \
    } \
    else \
    { \
      assert(2==2 && (ctx)->errcxptr != fr_.errprv); \
      (e) = fr_.errcode; \
      (ctx)->errcxptr = fr_.errprv;
        
/* retrieve argument (int, string) in current error frame */
#define errargint(argnum) (fr_.erraav[argnum].erraint)
#define errargstr(argnum) (fr_.erraav[argnum].errastr)

    
#define ERREND(ctx) \
    } \
  }

/* end protected code, begin cleanup (no handling; just cleaning up) */
#define ERRCLEAN(ctx) \
      assert((ctx)->errcxptr != fr_.errprv); \
      (ctx)->errcxptr = fr_.errprv; \
    } \
    else \
    { \
      assert((ctx)->errcxptr != fr_.errprv); \
      (ctx)->errcxptr = fr_.errprv;

#define ERRENDCLN(ctx) \
      errrse(ctx); \
    } \
  }



/* argument types for errors with arguments */
#define ERRTINT  erraint
#define ERRTSTR  errastr

/* set argument count in error frame */
#define errargc(ctx,cnt) ((ctx)->errcxptr->erraac=(cnt))

/* enter string argument; returns pointer to argument used in errargv */
#ifdef ERR_NO_MACRO
char *errstr(errcxdef *ctx, const char *str, int len);
#else /* ERR_NO_MACRO */
  
#define errstr(ctx,str,len) \
  ((memcpy(&(ctx)->errcxbuf[(ctx)->errcxofs],str,(size_t)len), \
   (ctx)->errcxofs += (len), \
   (ctx)->errcxbuf[(ctx)->errcxofs++] = '\0'), \
   &(ctx)->errcxbuf[(ctx)->errcxofs-(len)-1])

#endif /* ERR_NO_MACRO */

/* set argument in error frame argument vector */
#define errargv(ctx,index,typ,arg) \
  ((ctx)->errcxptr->erraav[index].typ=(arg))

/* signal an error with argument count already set */
#ifdef ERR_NO_MACRO
void errsign(errcxdef *ctx, int e, char *facility);
#else /* ERR_NO_MACRO */
# ifdef DEBUG
void errjmp(jmp_buf buf, int e);
#  define errsign(ctx, e, fac) \
   (strncpy((ctx)->errcxptr->errfac, fac, ERRFACMAX),\
    (ctx)->errcxptr->errfac[ERRFACMAX]='\0',\
    (ctx)->errcxofs=0, errjmp((ctx)->errcxptr->errbuf, e))
# else /* DEBUG */
#  define errsign(ctx, e, fac) \
   (strncpy((ctx)->errcxptr->errfac, fac, ERRFACMAX),\
    (ctx)->errcxptr->errfac[ERRFACMAX]='\0',\
    (ctx)->errcxofs=0, longjmp((ctx)->errcxptr->errbuf, e))
# endif /* DEBUG */
#endif /* ERR_NO_MACRO */


/* signal an error with no arguments */
#ifdef ERR_NO_MACRO
void errsigf(errcxdef *ctx, char *facility, int err);
#else /* ERR_NO_MACRO */
#define errsigf(ctx, fac, e) (errargc(ctx,0),errsign(ctx,e,fac))
#endif /* ERR_NO_MACRO */
  
/* signal an error with one argument */
#define errsigf1(ctx, fac, e, typ1, arg1) \
  (errargv(ctx,0,typ1,arg1),errargc(ctx,1),errsign(ctx,e,fac))

/* signal an error with two arguments */
#define errsigf2(ctx, fac, e, typ1, arg1, typ2, arg2) \
  (errargv(ctx,0,typ1,arg1), errargv(ctx,1,typ2,arg2), \
   errargc(ctx,2), errsign(ctx,e,fac))

/* resignal the current error - only usable within exception handlers */
#ifdef ERR_NO_MACRO
void errrse1(errcxdef *ctx, errdef *fr);
# define errrse(ctx) errrse1(ctx, &fr_)
#else /* ERR_NO_MACRO */

/* void errrse(errcxdef *ctx); */
# define errrse(ctx) \
  (errargc(ctx, fr_.erraac),\
   memcpy((ctx)->errcxptr->erraav, fr_.erraav, \
    (size_t)(fr_.erraac*sizeof(erradef))),\
   errsign(ctx, fr_.errcode, fr_.errfac))

#endif /* ERR_NO_MACRO */

/*
 *   For use in an error handler (ERRCATCH..ERREND) only: Copy the
 *   parameters from the error currently being handled to the enclosing
 *   frame.  This is useful when "keeping" an error being handled - i.e.,
 *   the arguments will continue to be used outside of the
 *   ERRCATCH..ERREND code. 
 */
/* void errkeepargs(errcxdef *ctx); */
#define errkeepargs(ctx) errcopyargs(ctx, &fr_)

/* 
 *   copy the parameters for an error from another frame into the current
 *   frame - this can be used when we want to be able to display an error
 *   that occurred in an inner frame within code that is protected by a
 *   new enclosing error frame 
 */
/* void errcopyargs(errcxdef *ctx, errdef *fr); */
#define errcopyargs(ctx, fr) \
   (errargc((ctx), (fr)->erraac), \
    memcpy((ctx)->errcxptr->erraav, (fr)->erraav, \
           (size_t)((fr)->erraac*sizeof(erradef))))

/* log error that's been caught, using arguments already caught */
#define errclog(ctx) \
 ((*(ctx)->errcxlog)((ctx)->errcxlgc,fr_.errfac,fr_.errcode,\
  fr_.erraac,fr_.erraav))

/* log an error that's been set up but not signalled yet */
#define errprelog(ctx, err) \
 ((*(ctx)->errcxlog)((ctx)->errcxlgc,(ctx)->errcxptr->errfac,\
   err,(ctx)->errcxptr->erraac,\
   (ctx)->errcxptr->erraav))

/* log an error (no signalling, just reporting) */
#ifdef ERR_NO_MACRO
void errlogn(errcxdef *ctx, int err, char *facility);
#else /* ERR_NO_MACRO */

#define errlogn(ctx,err,fac) \
 ((ctx)->errcxofs=0,\
  (*(ctx)->errcxlog)((ctx)->errcxlgc,fac,err,(ctx)->errcxptr->erraac,\
  (ctx)->errcxptr->erraav))

#endif /* ERR_NO_MACRO */

/* log an error with no arguments */
#ifdef ERR_NO_MACRO
void errlogf(errcxdef *ctx, char *facility, int err);
#else /* ERR_NO_MACRO */

/* void errlogf(errcxdef *ctx, char *facility, int err); */
#define errlogf(ctx,fac,err) (errargc(ctx,0),errlogn(ctx,err,fac))

#endif /* ERR_NO_MACRO */

/* log an error with one argument */
#define errlogf1(ctx, fac, e, typ1, arg1) \
 (errargv(ctx,0,typ1,arg1),errargc(ctx,1),errlogn(ctx,e,fac))
  
/* log an error with two arguments */
#define errlogf2(ctx, fac, e, typ1, arg1, typ2, arg2) \
 (errargv(ctx,0,typ1,arg1),errargv(ctx,1,typ2,arg2),\
  errargc(ctx,2),errlogn(ctx,e,fac))


/*
 *   Format an error message, sprintf-style, using arguments in an
 *   erradef array (which is passed to the error-logging callback).
 *   Returns the length of the output string, even if the actual
 *   output string was truncated because the outbuf was too short.
 *   (If called with outbufl == 0, nothing will be written out, but
 *   the size of the buffer needed, minus the terminating null byte,
 *   will be computed and returned.)
 */
int errfmt(char *outbuf, int outbufl, char *fmt, int argc,
           erradef *argv);
  
/* get the text of an error */
void errmsg(errcxdef *ctx, char *outbuf, uint outbufl, uint err);
  
/* initialize error subsystem, opening error message file if necessary */
void errini(errcxdef *ctx, osfildef *fp);

/* allocate and initialize error context, free error context */
errcxdef *lerini();
void      lerfre(errcxdef *ctx);

/* error message structure - number + text */
typedef struct errmdef errmdef;
struct errmdef
{
    uint   errmerr;                                         /* error number */
    char  *errmtxt;                                /* text of error message */
};

#ifdef __cplusplus
}
#endif

#endif /* ERR_INCLUDED */
