X-Git-Url: https://diplodocus.org/git/nmh/blobdiff_plain/15c89585836a98f6340619a58a1ec0e7e1d83dfc..94187a80bd60baab4b9c4b949ad820d730578123:/sbr/base64.c

diff --git a/sbr/base64.c b/sbr/base64.c
index 79d7aa94..cbd225de 100644
--- 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
@@ -11,9 +10,20 @@
 #include <h/md5.h>
 #include <inttypes.h>
 
-static char nib2b64[0x40+1] =
+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];
@@ -209,7 +217,7 @@ writeBase64raw (const unsigned char *in, size_t length, unsigned char *out)
 }
 
 
-static unsigned char b642nib[0x80] = {
+static const unsigned char b642nib[0x80] = {
     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
@@ -230,7 +238,13 @@ static 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,
@@ -243,7 +257,8 @@ decodeBase64 (const char *encoded, unsigned char **decoded, size_t *len,
     charstring_t decoded_c = charstring_create (strlen (encoded));
     MD5_CTX mdContext;
 
-    if (digest) { MD5Init (&mdContext); }
+    if (digest)
+        MD5Init (&mdContext);
 
     bitno = 18;
     bits = 0L;
@@ -259,7 +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", encoded);
+                    inform("invalid base64 byte %#x: %.42s",
+                        *(unsigned char *)cp, cp);
                     charstring_free (decoded_c);
                     *decoded = NULL;
 
@@ -274,19 +290,22 @@ test_end:
                     if (! skip_crs  ||  b != '\r') {
                         charstring_push_back (decoded_c, b);
                     }
-                    if (digest) { MD5Update (&mdContext, (unsigned char *) &b, 1); }
+                    if (digest)
+                        MD5Update (&mdContext, (unsigned char *) &b, 1);
                     if (skip < 2) {
                         b = (bits >> 8) & 0xff;
                         if (! skip_crs  ||  b != '\r') {
                             charstring_push_back (decoded_c, b);
                         }
-                        if (digest) { MD5Update (&mdContext, (unsigned char *) &b, 1); }
+                        if (digest)
+                            MD5Update (&mdContext, (unsigned char *) &b, 1);
                         if (skip < 1) {
                             b = bits & 0xff;
                             if (! skip_crs  ||  b != '\r') {
                                 charstring_push_back (decoded_c, b);
                             }
-                            if (digest) { MD5Update (&mdContext, (unsigned char *) &b, 1); }
+                            if (digest)
+                                MD5Update (&mdContext, (unsigned char *) &b, 1);
                         }
                     }
 
@@ -297,17 +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) {
-        advise (NULL, "premature ending (bitno %d) in %s", bitno, encoded);
+        /* Show some context for the error. */
+        cp -= min(cp - encoded, 20);
+        inform("premature ending (bitno %d) near %s", bitno, cp);
         charstring_free (decoded_c);
         *decoded = NULL;
 
@@ -346,7 +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);
             }