The Tor Browser: nsprpub/lib/libc/src/base64.c@b8a032363ba2 (annotated)

nsprpub/lib/libc/src/base64.c@b8a032363ba2 (annotated)

nsprpub/lib/libc/src/base64.c

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* 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/. */
 #include "plbase64.h"
 #include "prlog.h" /* For PR_NOT_REACHED */
 #include "prmem.h" /* for malloc / PR_MALLOC */
 #include <string.h> /* for strlen */
 static unsigned char *base = (unsigned char *)"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 static void
 encode3to4
 (
     const unsigned char    *src,
     unsigned char          *dest
 )
 {
     PRUint32 b32 = (PRUint32)0;
     PRIntn i, j = 18;
     for( i = 0; i < 3; i++ )
     {
         b32 <<= 8;
         b32 |= (PRUint32)src[i];
     }
     for( i = 0; i < 4; i++ )
     {
         dest[i] = base[ (PRUint32)((b32>>j) & 0x3F) ];
         j -= 6;
     }
     return;
 }
 static void
 encode2to4
 (
     const unsigned char    *src,
     unsigned char          *dest
 )
 {
     dest[0] = base[ (PRUint32)((src[0]>>2) & 0x3F) ];
     dest[1] = base[ (PRUint32)(((src[0] & 0x03) << 4) | ((src[1] >> 4) & 0x0F)) ];
     dest[2] = base[ (PRUint32)((src[1] & 0x0F) << 2) ];
     dest[3] = (unsigned char)'=';
     return;
 }
 static void
 encode1to4
 (
     const unsigned char    *src,
     unsigned char          *dest
 )
 {
     dest[0] = base[ (PRUint32)((src[0]>>2) & 0x3F) ];
     dest[1] = base[ (PRUint32)((src[0] & 0x03) << 4) ];
     dest[2] = (unsigned char)'=';
     dest[3] = (unsigned char)'=';
     return;
 }
 static void
 encode
 (
     const unsigned char    *src,
     PRUint32                srclen,
     unsigned char          *dest
 )
 {
     while( srclen >= 3 )
     {
         encode3to4(src, dest);
         src += 3;
         dest += 4;
         srclen -= 3;
     }
     switch( srclen )
     {
         case 2:
             encode2to4(src, dest);
             break;
         case 1:
             encode1to4(src, dest);
             break;
         case 0:
             break;
         default:
             PR_NOT_REACHED("coding error");
     }
     return;
 }
 /*
  * PL_Base64Encode
  *
  * If the destination argument is NULL, a return buffer is
  * allocated, and the data therein will be null-terminated.
  * If the destination argument is not NULL, it is assumed to
  * be of sufficient size, and the contents will not be null-
  * terminated by this routine.
  *
  * Returns null if the allocation fails.
  */
 PR_IMPLEMENT(char *)
 PL_Base64Encode
 (
     const char *src,
     PRUint32    srclen,
     char       *dest
 )
 {
     if( 0 == srclen )
     {
         size_t len = strlen(src);
         srclen = len;
         /* Detect truncation. */
         if( srclen != len )
         {
             return (char *)0;
         }
     }
     if( (char *)0 == dest )
     {
         PRUint32 destlen;
         /* Ensure all PRUint32 values stay within range. */
         if( srclen > (PR_UINT32_MAX/4) * 3 )
         {
             return (char *)0;
         }
         destlen = ((srclen + 2)/3) * 4;
         dest = (char *)PR_MALLOC(destlen + 1);
         if( (char *)0 == dest )
         {
             return (char *)0;
         }
         dest[ destlen ] = (char)0; /* null terminate */
     }
     encode((const unsigned char *)src, srclen, (unsigned char *)dest);
     return dest;
 }
 static PRInt32
 codetovalue
 (
     unsigned char c
 )
 {
     if( (c >= (unsigned char)'A') && (c <= (unsigned char)'Z') )
     {
         return (PRInt32)(c - (unsigned char)'A');
     }
     else if( (c >= (unsigned char)'a') && (c <= (unsigned char)'z') )
     {
         return ((PRInt32)(c - (unsigned char)'a') +26);
     }
     else if( (c >= (unsigned char)'0') && (c <= (unsigned char)'9') )
     {
         return ((PRInt32)(c - (unsigned char)'0') +52);
     }
     else if( (unsigned char)'+' == c )
     {
         return (PRInt32)62;
     }
     else if( (unsigned char)'/' == c )
     {
         return (PRInt32)63;
     }
     else
     {
         return -1;
     }
 }
 static PRStatus
 decode4to3
 (
     const unsigned char    *src,
     unsigned char          *dest
 )
 {
     PRUint32 b32 = (PRUint32)0;
     PRInt32 bits;
     PRIntn i;
     for( i = 0; i < 4; i++ )
     {
         bits = codetovalue(src[i]);
         if( bits < 0 )
         {
             return PR_FAILURE;
         }
         b32 <<= 6;
         b32 |= bits;
     }
     dest[0] = (unsigned char)((b32 >> 16) & 0xFF);
     dest[1] = (unsigned char)((b32 >>  8) & 0xFF);
     dest[2] = (unsigned char)((b32      ) & 0xFF);
     return PR_SUCCESS;
 }
 static PRStatus
 decode3to2
 (
     const unsigned char    *src,
     unsigned char          *dest
 )
 {
     PRUint32 b32 = (PRUint32)0;
     PRInt32 bits;
     PRUint32 ubits;
     bits = codetovalue(src[0]);
     if( bits < 0 )
     {
         return PR_FAILURE;
     }
     b32 = (PRUint32)bits;
     b32 <<= 6;
     bits = codetovalue(src[1]);
     if( bits < 0 )
     {
         return PR_FAILURE;
     }
     b32 |= (PRUint32)bits;
     b32 <<= 4;
     bits = codetovalue(src[2]);
     if( bits < 0 )
     {
         return PR_FAILURE;
     }
     ubits = (PRUint32)bits;
     b32 |= (ubits >> 2);
     dest[0] = (unsigned char)((b32 >> 8) & 0xFF);
     dest[1] = (unsigned char)((b32     ) & 0xFF);
     return PR_SUCCESS;
 }
 static PRStatus
 decode2to1
 (
     const unsigned char    *src,
     unsigned char          *dest
 )
 {
     PRUint32 b32;
     PRUint32 ubits;
     PRInt32 bits;
     bits = codetovalue(src[0]);
     if( bits < 0 )
     {
         return PR_FAILURE;
     }
     ubits = (PRUint32)bits;
     b32 = (ubits << 2);
     bits = codetovalue(src[1]);
     if( bits < 0 )
     {
         return PR_FAILURE;
     }
     ubits = (PRUint32)bits;
     b32 |= (ubits >> 4);
     dest[0] = (unsigned char)b32;
     return PR_SUCCESS;
 }
 static PRStatus
 decode
 (
     const unsigned char    *src,
     PRUint32                srclen,
     unsigned char          *dest
 )
 {
     PRStatus rv;
     while( srclen >= 4 )
     {
         rv = decode4to3(src, dest);
         if( PR_SUCCESS != rv )
         {
             return PR_FAILURE;
         }
         src += 4;
         dest += 3;
         srclen -= 4;
     }
     switch( srclen )
     {
         case 3:
             rv = decode3to2(src, dest);
             break;
         case 2:
             rv = decode2to1(src, dest);
             break;
         case 1:
             rv = PR_FAILURE;
             break;
         case 0:
             rv = PR_SUCCESS;
             break;
         default:
             PR_NOT_REACHED("coding error");
     }
     return rv;
 }
 /*
  * PL_Base64Decode
  *
  * If the destination argument is NULL, a return buffer is
  * allocated and the data therein will be null-terminated.
  * If the destination argument is not null, it is assumed
  * to be of sufficient size, and the data will not be null-
  * terminated by this routine.
  *
  * Returns null if the allocation fails, or if the source string is
  * not well-formed.
  */
 PR_IMPLEMENT(char *)
 PL_Base64Decode
 (
     const char *src,
     PRUint32    srclen,
     char       *dest
 )
 {
     PRStatus status;
     PRBool allocated = PR_FALSE;
     if( (char *)0 == src )
     {
         return (char *)0;
     }
     if( 0 == srclen )
     {
         size_t len = strlen(src);
         srclen = len;
         /* Detect truncation. */
         if( srclen != len )
         {
             return (char *)0;
         }
     }
     if( srclen && (0 == (srclen & 3)) )
     {
         if( (char)'=' == src[ srclen-1 ] )
         {
             if( (char)'=' == src[ srclen-2 ] )
             {
                 srclen -= 2;
             }
             else
             {
                 srclen -= 1;
             }
         }
     }
     if( (char *)0 == dest )
     {
         /* The following computes ((srclen * 3) / 4) without overflow. */
         PRUint32 destlen = (srclen / 4) * 3 + ((srclen % 4) * 3) / 4;
         dest = (char *)PR_MALLOC(destlen + 1);
         if( (char *)0 == dest )
         {
             return (char *)0;
         }
         dest[ destlen ] = (char)0; /* null terminate */
         allocated = PR_TRUE;
     }
     status = decode((const unsigned char *)src, srclen, (unsigned char *)dest);
     if( PR_SUCCESS != status )
     {
         if( PR_TRUE == allocated )
         {
             PR_DELETE(dest);
         }
         return (char *)0;
     }
     return dest;
 }

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nsprpub/lib/libc/src/base64.c@b8a032363ba2 (annotated)

nsprpub/lib/libc/src/base64.c