tor-browser

error.c (7714B)

---

/* 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 */

#if defined(__MINGW32__)
#include <windows.h>
#endif

#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;
static const PRCallOnceType error_call_again;

/*
* error_once_function
*
* This is the once-called callback.
*/
static PRStatus
error_once_function(void)
{

/*
* This #ifdef function is redundant. It performs the same thing as the
* else case.
*
* However, the MinGW version looks up the function from nss3's export
* table, and on MinGW _that_ behaves differently than passing a
* function pointer in a different module because MinGW has
* -mnop-fun-dllimport specified, which generates function thunks for
* cross-module calls. And when a module (like nssckbi) gets unloaded,
* and you try to call into that thunk (which is now missing) you'll
* crash. So we do this bit of ugly to avoid that crash. Fortunately
* this is the only place we've had to do this.
*/
#if defined(__MINGW32__)
   HMODULE nss3 = GetModuleHandleW(L"nss3");
   if (nss3) {
       PRThreadPrivateDTOR freePtr = (PRThreadPrivateDTOR)GetProcAddress(nss3, "PR_Free");
       if (freePtr) {
           return PR_NewThreadPrivateIndex(&error_stack_index, freePtr);
       }
   }
   return PR_NewThreadPrivateIndex(&error_stack_index, PR_Free);
#else
   return PR_NewThreadPrivateIndex(&error_stack_index, PR_Free);
#endif
}

/*
* 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);
       error_stack_index = INVALID_TPD_INDEX;
       error_call_once = error_call_again; /* allow to init again */
   }
   return;
}