Constify the BIGNUM routines a bit more. The only trouble were the
[openssl.git] / crypto / bn / bn_lib.c
index b6b0ce4..3e4965d 100644 (file)
@@ -304,42 +304,35 @@ BIGNUM *BN_new(void)
        return(ret);
        }
 
-/* This is an internal function that should not be used in applications.
- * It ensures that 'b' has enough room for a 'words' word number number.
- * It is mostly used by the various BIGNUM routines. If there is an error,
- * NULL is returned. If not, 'b' is returned. */
-
-BIGNUM *bn_expand2(BIGNUM *b, int words)
+/* This is used both by bn_expand2() and bn_dup_expand() */
+/* The caller MUST check that words > b->dmax before calling this */
+static BN_ULONG *internal_bn_expand(const BIGNUM *b, int words)
        {
-       BN_ULONG *A,*a;
+       BN_ULONG *A,*a = NULL;
        const BN_ULONG *B;
        int i;
 
-       bn_check_top(b);
-
-       if (words > b->dmax)
+       bn_check_top(b);        
+       if (BN_get_flags(b,BN_FLG_STATIC_DATA))
                {
-               bn_check_top(b);        
-               if (BN_get_flags(b,BN_FLG_STATIC_DATA))
-                       {
-                       BNerr(BN_F_BN_EXPAND2,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
-                       return(NULL);
-                       }
-               a=A=(BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG)*(words+1));
-               if (A == NULL)
-                       {
-                       BNerr(BN_F_BN_EXPAND2,ERR_R_MALLOC_FAILURE);
-                       return(NULL);
-                       }
+               BNerr(BN_F_BN_EXPAND2,BN_R_EXPAND_ON_STATIC_BIGNUM_DATA);
+               return(NULL);
+               }
+       a=A=(BN_ULONG *)OPENSSL_malloc(sizeof(BN_ULONG)*(words+1));
+       if (A == NULL)
+               {
+               BNerr(BN_F_BN_EXPAND2,ERR_R_MALLOC_FAILURE);
+               return(NULL);
+               }
 #if 1
-               B=b->d;
-               /* Check if the previous number needs to be copied */
-               if (B != NULL)
-                       {
+       B=b->d;
+       /* Check if the previous number needs to be copied */
+       if (B != NULL)
+               {
 #if 0
-                       /* This lot is an unrolled loop to copy b->top 
-                        * BN_ULONGs from B to A
-                        */
+               /* This lot is an unrolled loop to copy b->top 
+                * BN_ULONGs from B to A
+                */
 /*
  * I have nothing against unrolling but it's usually done for
  * several reasons, namely:
@@ -363,94 +356,145 @@ BIGNUM *bn_expand2(BIGNUM *b, int words)
  *
  *                                     <appro@fy.chalmers.se>
  */
-                       for (i=b->top&(~7); i>0; i-=8)
-                               {
-                               A[0]=B[0]; A[1]=B[1]; A[2]=B[2]; A[3]=B[3];
-                               A[4]=B[4]; A[5]=B[5]; A[6]=B[6]; A[7]=B[7];
-                               A+=8;
-                               B+=8;
-                               }
-                       switch (b->top&7)
-                               {
-                       case 7:
-                               A[6]=B[6];
-                       case 6:
-                               A[5]=B[5];
-                       case 5:
-                               A[4]=B[4];
-                       case 4:
-                               A[3]=B[3];
-                       case 3:
-                               A[2]=B[2];
-                       case 2:
-                               A[1]=B[1];
-                       case 1:
-                               A[0]=B[0];
-                       case 0:
-                               /* I need the 'case 0' entry for utrix cc.
-                                * If the optimizer is turned on, it does the
-                                * switch table by doing
-                                * a=top&7
-                                * a--;
-                                * goto jump_table[a];
-                                * If top is 0, this makes us jump to 0xffffffc 
-                                * which is rather bad :-(.
-                                * eric 23-Apr-1998
-                                */
-                               ;
-                               }
+               for (i=b->top&(~7); i>0; i-=8)
+                       {
+                       A[0]=B[0]; A[1]=B[1]; A[2]=B[2]; A[3]=B[3];
+                       A[4]=B[4]; A[5]=B[5]; A[6]=B[6]; A[7]=B[7];
+                       A+=8;
+                       B+=8;
+                       }
+               switch (b->top&7)
+                       {
+               case 7:
+                       A[6]=B[6];
+               case 6:
+                       A[5]=B[5];
+               case 5:
+                       A[4]=B[4];
+               case 4:
+                       A[3]=B[3];
+               case 3:
+                       A[2]=B[2];
+               case 2:
+                       A[1]=B[1];
+               case 1:
+                       A[0]=B[0];
+               case 0:
+                       /* I need the 'case 0' entry for utrix cc.
+                        * If the optimizer is turned on, it does the
+                        * switch table by doing
+                        * a=top&7
+                        * a--;
+                        * goto jump_table[a];
+                        * If top is 0, this makes us jump to 0xffffffc 
+                        * which is rather bad :-(.
+                        * eric 23-Apr-1998
+                        */
+                       ;
+                       }
 #else
-                       for (i=b->top>>2; i>0; i--,A+=4,B+=4)
-                               {
-                               /*
-                                * The fact that the loop is unrolled
-                                * 4-wise is a tribute to Intel. It's
-                                * the one that doesn't have enough
-                                * registers to accomodate more data.
-                                * I'd unroll it 8-wise otherwise:-)
-                                *
-                                *              <appro@fy.chalmers.se>
-                                */
-                               BN_ULONG a0,a1,a2,a3;
-                               a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
-                               A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
-                               }
-                       switch (b->top&3)
-                               {
-                               case 3: A[2]=B[2];
-                               case 2: A[1]=B[1];
-                               case 1: A[0]=B[0];
-                               case 0: ; /* ultrix cc workaround, see above */
-                               }
-#endif
-                       OPENSSL_free(b->d);
+               for (i=b->top>>2; i>0; i--,A+=4,B+=4)
+                       {
+                       /*
+                        * The fact that the loop is unrolled
+                        * 4-wise is a tribute to Intel. It's
+                        * the one that doesn't have enough
+                        * registers to accomodate more data.
+                        * I'd unroll it 8-wise otherwise:-)
+                        *
+                        *              <appro@fy.chalmers.se>
+                        */
+                       BN_ULONG a0,a1,a2,a3;
+                       a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
+                       A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
                        }
-
-               b->d=a;
-               b->dmax=words;
-
-               /* Now need to zero any data between b->top and b->max */
-
-               A= &(b->d[b->top]);
-               for (i=(b->dmax - b->top)>>3; i>0; i--,A+=8)
+               switch (b->top&3)
                        {
-                       A[0]=0; A[1]=0; A[2]=0; A[3]=0;
-                       A[4]=0; A[5]=0; A[6]=0; A[7]=0;
+               case 3: A[2]=B[2];
+               case 2: A[1]=B[1];
+               case 1: A[0]=B[0];
+               case 0: ; /* ultrix cc workaround, see above */
                        }
-               for (i=(b->dmax - b->top)&7; i>0; i--,A++)
-                       A[0]=0;
+#endif
+               }
+
+       /* Now need to zero any data between b->top and b->max */
+
+       A= &(a[b->top]);
+       for (i=(words - b->top)>>3; i>0; i--,A+=8)
+               {
+               A[0]=0; A[1]=0; A[2]=0; A[3]=0;
+               A[4]=0; A[5]=0; A[6]=0; A[7]=0;
+               }
+       for (i=(words - b->top)&7; i>0; i--,A++)
+               A[0]=0;
 #else
-                       memset(A,0,sizeof(BN_ULONG)*(words+1));
-                       memcpy(A,b->d,sizeof(b->d[0])*b->top);
-                       b->d=a;
-                       b->max=words;
+       memset(A,0,sizeof(BN_ULONG)*(words+1));
+       memcpy(A,b->d,sizeof(b->d[0])*b->top);
 #endif
                
-/*             memset(&(p[b->max]),0,((words+1)-b->max)*sizeof(BN_ULONG)); */
-/*     { int i; for (i=b->max; i<words+1; i++) p[i]=i;} */
+       return(a);
+       }
 
+/* This is an internal function that can be used instead of bn_expand2()
+ * when there is a need to copy BIGNUMs instead of only expanding the
+ * data part, while still expanding them.
+ * Especially useful when needing to expand BIGNUMs that are declared
+ * 'const' and should therefore not be changed.
+ * The reason to use this instead of a BN_dup() followed by a bn_expand2()
+ * is memory allocation overhead.  A BN_dup() followed by a bn_expand2()
+ * will allocate new memory for the BIGNUM data twice, and free it once,
+ * while bn_dup_expand() makes sure allocation is made only once.
+ */
+
+BIGNUM *bn_dup_expand(const BIGNUM *b, int words)
+       {
+       BIGNUM *r = NULL;
+
+       if (words > b->dmax)
+               {
+               BN_ULONG *a = internal_bn_expand(b, words);
+
+               if (a)
+                       {
+                       r = BN_new();
+                       r->top = b->top;
+                       r->dmax = words;
+                       r->neg = b->neg;
+                       r->d = a;
+                       }
+               /* Otherwise, there was an error in allocation in
+                  internal_bn_expand(), and NULL should be returned */
+               }
+       else
+               {
+               r = BN_dup(b);
+               }
+
+       return r;
+       }
+
+/* This is an internal function that should not be used in applications.
+ * It ensures that 'b' has enough room for a 'words' word number number.
+ * It is mostly used by the various BIGNUM routines. If there is an error,
+ * NULL is returned. If not, 'b' is returned. */
+
+BIGNUM *bn_expand2(BIGNUM *b, int words)
+       {
+       if (words > b->dmax)
+               {
+               BN_ULONG *a = internal_bn_expand(b, words);
+
+               if (a)
+                       {
+                       OPENSSL_free(b->d);
+                       b->d=a;
+                       b->dmax=words;
+                       }
+               else
+                       b = NULL;
                }
-       return(b);
+       return b;
        }
 
 BIGNUM *BN_dup(const BIGNUM *a)
@@ -513,7 +557,7 @@ void BN_clear(BIGNUM *a)
        a->neg=0;
        }
 
-BN_ULONG BN_get_word(BIGNUM *a)
+BN_ULONG BN_get_word(const BIGNUM *a)
        {
        int i,n;
        BN_ULONG ret=0;