Fix invalid pointer arithmetic.

[nmh] / sbr / base64.c

diff --git a/sbr/base64.c b/sbr/base64.c
index a1e54c92fc0cf6371e6fbc0f06e54ff792a86888..cbd225dee062c60fa42ebb8415350bc17cb4f835 100644 (file)
--- a/sbr/base64.c
+++ b/sbr/base64.c
@@ -1,5 +1,4 @@
-/*
- * base64.c -- routines for converting to base64
+/* base64.c -- routines for converting to base64
  *
  * This code is Copyright (c) 2012, by the authors of nmh.  See the
  * COPYRIGHT file in the root directory of the nmh distribution for
@@ -14,6 +13,17 @@
 static const char nib2b64[0x40+1] =
        "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 
+/*
+ * Copy data from one file to another, converting to base64-encoding.
+ *
+ * Arguments include:
+ *
+ * in          - Input filehandle (unencoded data)
+ * out         - Output filename (base64-encoded data)
+ * crlf                - If set, output encoded CRLF for every LF on input.
+ *
+ * Returns OK on success, NOTOK otherwise.
+ */
 int
 writeBase64aux (FILE *in, FILE *out, int crlf)
 {
@@ -124,17 +134,16 @@ writeBase64 (const unsigned char *in, size_t length, unsigned char *out)
        for (cc = 0; length > 0 && cc < 3; ++cc, --length)
           /* empty */ ;
 
-       if (cc == 0) {
+       if (cc == 0)
            break;
-       } else {
-           bits = (in[0] & 0xff) << 16;
-           if (cc > 1) {
-               bits |= (in[1] & 0xff) << 8;
-               if (cc > 2) {
-                   bits |= in[2] & 0xff;
-               }
-           }
-       }
+
+        bits = (in[0] & 0xff) << 16;
+        if (cc > 1) {
+            bits |= (in[1] & 0xff) << 8;
+            if (cc > 2) {
+                bits |= in[2] & 0xff;
+            }
+        }
 
        for (bp = out + 4; bp > out; bits >>= 6)
            *--bp = nib2b64[bits & 0x3f];
@@ -177,17 +186,16 @@ writeBase64raw (const unsigned char *in, size_t length, unsigned char *out)
        for (cc = 0; length > 0 && cc < 3; ++cc, --length)
           /* empty */ ;
 
-       if (cc == 0) {
+       if (cc == 0)
            break;
-       } else {
-           bits = (in[0] & 0xff) << 16;
-           if (cc > 1) {
-               bits |= (in[1] & 0xff) << 8;
-               if (cc > 2) {
-                   bits |= in[2] & 0xff;
-               }
-           }
-       }
+
+        bits = (in[0] & 0xff) << 16;
+        if (cc > 1) {
+            bits |= (in[1] & 0xff) << 8;
+            if (cc > 2) {
+                bits |= in[2] & 0xff;
+            }
+        }
 
        for (bp = out + 4; bp > out; bits >>= 6)
            *--bp = nib2b64[bits & 0x3f];
@@ -230,7 +238,13 @@ static const unsigned char b642nib[0x80] = {
 
 /*
  * Decode a base64 string.  The result, decoded, must be freed by the caller.
- * See description of arguments with declaration in h/prototypes.h.
+ *
+ * encoded      - the string to be decoded
+ * decoded      - the decoded bytes
+ * len          - number of decoded bytes
+ * skip-crs     - non-zero for text content, and for which CR's should be
+ *                skipped
+ * digest       - for an MD5 digest, it can be null
  */
 int
 decodeBase64 (const char *encoded, unsigned char **decoded, size_t *len,
@@ -260,7 +274,8 @@ decodeBase64 (const char *encoded, unsigned char **decoded, size_t *len,
                 }
                 if (skip  ||  (((unsigned char) *cp) & 0x80)  ||
                     (value = b642nib[((unsigned char) *cp) & 0x7f]) > 0x3f) {
-                    advise (NULL, "invalid BASE64 encoding in %s", cp);
+                    inform("invalid base64 byte %#x: %.42s",
+                        *(unsigned char *)cp, cp);
                     charstring_free (decoded_c);
                     *decoded = NULL;
 
@@ -301,22 +316,17 @@ test_end:
                 break;
 
             case '=':
-                if (++skip > 3) {
-                    self_delimiting = 1;
-                    break;
-                } else {
+                if (++skip <= 3)
                     goto test_end;
-                }
+                self_delimiting = 1;
+                break;
         }
     }
 
     if (! self_delimiting  &&  bitno != 18) {
-        int i;
-
         /* Show some context for the error. */
-        for (i = 0; i < 20  &&  cp > encoded; ++i, --cp) {}
-        advise (NULL, "premature ending (bitno %d) near %s", bitno,
-                cp ? cp : encoded);
+        cp -= min(cp - encoded, 20);
+        inform("premature ending (bitno %d) near %s", bitno, cp);
         charstring_free (decoded_c);
         *decoded = NULL;
 
@@ -355,7 +365,7 @@ hexify (const unsigned char *input, size_t len, char **output) {
             const int num = snprintf(s, sizeof s, "[0x%02x]", *cp);
 
             if (num <= 0  ||  (unsigned int) num >= sizeof s) {
-                advise (NULL, "hexify failed to write nonprintable character, needed %d bytes", num + 1);
+                inform("hexify failed to write nonprintable character, needed %d bytes", num + 1);
             } else {
                 charstring_append_cstring (tmp, s);
             }