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 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 /*

  * error.c

  *

  * This file contains the code implementing the per-thread error 

  * stacks upon which most NSS routines report their errors.

  */

 #ifndef BASE_H

 #include "base.h"

 #endif /* BASE_H */

 #include <limits.h> /* for UINT_MAX */

 #include <string.h> /* for memmove */

 #define NSS_MAX_ERROR_STACK_COUNT 16 /* error codes */

 /*

  * The stack itself has a header, and a sequence of integers.

  * The header records the amount of space (as measured in stack

  * slots) already allocated for the stack, and the count of the

  * number of records currently being used.

  */

 struct stack_header_str {

   PRUint16 space;

   PRUint16 count;

 };

 struct error_stack_str {

   struct stack_header_str header;

   PRInt32 stack[1];

 };

 typedef struct error_stack_str error_stack;

 /*

  * error_stack_index

  *

  * Thread-private data must be indexed.  This is that index.

  * See PR_NewThreadPrivateIndex for more information.

  *

  * Thread-private data indexes are in the range [0, 127].

  */

 #define INVALID_TPD_INDEX UINT_MAX

 static PRUintn error_stack_index = INVALID_TPD_INDEX;

 /*

  * call_once

  *

  * The thread-private index must be obtained (once!) at runtime.

  * This block is used for that one-time call.

  */

 static PRCallOnceType error_call_once;

 /*

  * error_once_function

  *

  * This is the once-called callback.

  */

 static PRStatus

 error_once_function ( void)

 {

   return PR_NewThreadPrivateIndex(&error_stack_index, PR_Free);

 }

 /*

  * error_get_my_stack

  *

  * This routine returns the calling thread's error stack, creating

  * it if necessary.  It may return NULL upon error, which implicitly

  * means that it ran out of memory.

  */

 static error_stack *

 error_get_my_stack ( void)

 {

   PRStatus st;

   error_stack *rv;

   PRUintn new_size;

   PRUint32 new_bytes;

   error_stack *new_stack;

   if( INVALID_TPD_INDEX == error_stack_index ) {

     st = PR_CallOnce(&error_call_once, error_once_function);

     if( PR_SUCCESS != st ) {

       return (error_stack *)NULL;

     }

   }

   rv = (error_stack *)PR_GetThreadPrivate(error_stack_index);

   if( (error_stack *)NULL == rv ) {

     /* Doesn't exist; create one */

     new_size = 16;

   } else if( rv->header.count == rv->header.space  &&

              rv->header.count  < NSS_MAX_ERROR_STACK_COUNT ) {

     /* Too small, expand it */

     new_size = PR_MIN( rv->header.space * 2, NSS_MAX_ERROR_STACK_COUNT);

   } else {

     /* Okay, return it */

     return rv;

   }

   new_bytes = (new_size * sizeof(PRInt32)) + sizeof(error_stack);

   /* Use NSPR's calloc/realloc, not NSS's, to avoid loops! */

   new_stack = PR_Calloc(1, new_bytes);

   if( (error_stack *)NULL != new_stack ) {

     if( (error_stack *)NULL != rv ) {

 	(void)nsslibc_memcpy(new_stack,rv,rv->header.space);

     }

     new_stack->header.space = new_size;

   }

   /* Set the value, whether or not the allocation worked */

   PR_SetThreadPrivate(error_stack_index, new_stack);

   return new_stack;

 }

 /*

  * The error stack

  *

  * The public methods relating to the error stack are:

  *

  *  NSS_GetError

  *  NSS_GetErrorStack

  *

  * The nonpublic methods relating to the error stack are:

  *

  *  nss_SetError

  *  nss_ClearErrorStack

  *

  */

 /*

  * NSS_GetError

  *

  * This routine returns the highest-level (most general) error set

  * by the most recent NSS library routine called by the same thread

  * calling this routine.

  *

  * This routine cannot fail.  However, it may return zero, which

  * indicates that the previous NSS library call did not set an error.

  *

  * Return value:

  *  0 if no error has been set

  *  A nonzero error number

  */

 NSS_IMPLEMENT PRInt32

 NSS_GetError ( void)

 {

   error_stack *es = error_get_my_stack();

   if( (error_stack *)NULL == es ) {

     return NSS_ERROR_NO_MEMORY; /* Good guess! */

   }

   if( 0 == es->header.count ) {

     return 0;

   }

   return es->stack[ es->header.count-1 ];

 }

 /*

  * NSS_GetErrorStack

  *

  * This routine returns a pointer to an array of integers, containing

  * the entire sequence or "stack" of errors set by the most recent NSS

  * library routine called by the same thread calling this routine.

  * NOTE: the caller DOES NOT OWN the memory pointed to by the return

  * value.  The pointer will remain valid until the calling thread

  * calls another NSS routine.  The lowest-level (most specific) error 

  * is first in the array, and the highest-level is last.  The array is

  * zero-terminated.  This routine may return NULL upon error; this

  * indicates a low-memory situation.

  *

  * Return value:

  *  NULL upon error, which is an implied NSS_ERROR_NO_MEMORY

  *  A NON-caller-owned pointer to an array of integers

  */

 NSS_IMPLEMENT PRInt32 *

 NSS_GetErrorStack ( void)

 {

   error_stack *es = error_get_my_stack();

   if( (error_stack *)NULL == es ) {

     return (PRInt32 *)NULL;

   }

   /* Make sure it's terminated */

   es->stack[ es->header.count ] = 0;

   return es->stack;

 }

 /*

  * nss_SetError

  *

  * This routine places a new error code on the top of the calling 

  * thread's error stack.  Calling this routine wiht an error code

  * of zero will clear the error stack.

  */

 NSS_IMPLEMENT void

 nss_SetError ( PRUint32 error)

 {

   error_stack *es;

   if( 0 == error ) {

     nss_ClearErrorStack();

     return;

   }

   es = error_get_my_stack();

   if( (error_stack *)NULL == es ) {

     /* Oh, well. */

     return;

   }

   if (es->header.count < es->header.space) {

     es->stack[ es->header.count++ ] = error;

   } else {

     memmove(es->stack, es->stack + 1, 

 		(es->header.space - 1) * (sizeof es->stack[0]));

     es->stack[ es->header.space - 1 ] = error;

   }

   return;

 }

 /*

  * nss_ClearErrorStack

  *

  * This routine clears the calling thread's error stack.

  */

 NSS_IMPLEMENT void

 nss_ClearErrorStack ( void)

 {

   error_stack *es = error_get_my_stack();

   if( (error_stack *)NULL == es ) {

     /* Oh, well. */

     return;

   }

   es->header.count = 0;

   es->stack[0] = 0;

   return;

 }

 /*

  * nss_DestroyErrorStack

  *

  * This routine frees the calling thread's error stack.

  */

 NSS_IMPLEMENT void

 nss_DestroyErrorStack ( void)

 {

   if( INVALID_TPD_INDEX != error_stack_index ) {

     PR_SetThreadPrivate(error_stack_index, NULL);

   }

   return;

 }