[gmime] Improved g_mime_content_encoding_from_string()

[Rico Tzschichholz <ricotz src gnome org>]

commit 036d72b841e7b47265c705079775c4ec4794bf3b
Author: Jeffrey Stedfast <jestedfa microsoft com>
Date:   Sun Nov 25 10:13:09 2018 -0500

    Improved g_mime_content_encoding_from_string()
    
    GMimePart internally was copying the Content-Transfer-Encoding
    header value to a temporary buffer in order to strip leading/trailing
    whitespace characters.
    
    With the new and improved version of g_mime_content_encoding_from_string(),
    this is no longer necessary.

 gmime/gmime-encodings.c | 31 +++++++++++++++++++++----------
 gmime/gmime-part.c      | 20 +-------------------
 2 files changed, 22 insertions(+), 29 deletions(-)
---
diff --git a/gmime/gmime-encodings.c b/gmime/gmime-encodings.c
index 0138253e..1a90f5be 100644
--- a/gmime/gmime-encodings.c
+++ b/gmime/gmime-encodings.c
@@ -100,6 +100,14 @@ static unsigned char tohex[16] = {
 };
 
 
+static gboolean
+is (const char *str, const char *value, size_t n)
+{
+       return g_ascii_strncasecmp (str, value, n) == 0 &&
+               (str[n] == '\0' || is_lwsp (str[n]);
+}
+
+
 /**
  * g_mime_content_encoding_from_string:
  * @str: a string representing a Content-Transfer-Encoding value
@@ -113,25 +121,28 @@ static unsigned char tohex[16] = {
 GMimeContentEncoding
 g_mime_content_encoding_from_string (const char *str)
 {
-       if (!g_ascii_strcasecmp (str, "7bit"))
+       while (is_lwsp (*str))
+               str++;
+       
+       if (is (str, "7bit", 4))
                return GMIME_CONTENT_ENCODING_7BIT;
-       else if (!g_ascii_strcasecmp (str, "8bit"))
+       else if (is (str, "8bit", 4))
                return GMIME_CONTENT_ENCODING_8BIT;
-       else if (!g_ascii_strcasecmp (str, "7-bit"))
+       else if (is (str, "7-bit", 5))
                return GMIME_CONTENT_ENCODING_7BIT;
-       else if (!g_ascii_strcasecmp (str, "8-bit"))
+       else if (is (str, "8-bit", 5))
                return GMIME_CONTENT_ENCODING_8BIT;
-       else if (!g_ascii_strcasecmp (str, "binary"))
+       else if (is (str, "binary", 6))
                return GMIME_CONTENT_ENCODING_BINARY;
-       else if (!g_ascii_strcasecmp (str, "base64"))
+       else if (is (str, "base64", 6))
                return GMIME_CONTENT_ENCODING_BASE64;
-       else if (!g_ascii_strcasecmp (str, "quoted-printable"))
+       else if (is (str, "quoted-printable", 16))
                return GMIME_CONTENT_ENCODING_QUOTEDPRINTABLE;
-       else if (!g_ascii_strcasecmp (str, "uuencode"))
+       else if (is (str, "uuencode", 8))
                return GMIME_CONTENT_ENCODING_UUENCODE;
-       else if (!g_ascii_strcasecmp (str, "x-uuencode"))
+       else if (is (str, "x-uuencode", 10))
                return GMIME_CONTENT_ENCODING_UUENCODE;
-       else if (!g_ascii_strcasecmp (str, "x-uue"))
+       else if (is (str, "x-uue", 5))
                return GMIME_CONTENT_ENCODING_UUENCODE;
        else
                return GMIME_CONTENT_ENCODING_DEFAULT;
diff --git a/gmime/gmime-part.c b/gmime/gmime-part.c
index 7c4ff75c..e31473d6 100644
--- a/gmime/gmime-part.c
+++ b/gmime/gmime-part.c
@@ -165,28 +165,11 @@ static const char *content_headers[] = {
 };
 
 
-static void
-copy_atom (const char *src, char *dest, size_t n)
-{
-       register const char *inptr = src;
-       register char *outptr = dest;
-       char *outend = dest + n;
-       
-       while (is_lwsp (*inptr))
-               inptr++;
-       
-       while (is_atom (*inptr) && outptr < outend)
-               *outptr++ = *inptr++;
-       
-       *outptr = '\0';
-}
-
 static gboolean
 process_header (GMimeObject *object, GMimeHeader *header)
 {
        GMimePart *mime_part = (GMimePart *) object;
        const char *name, *value;
-       char encoding[32];
        guint i;
        
        name = g_mime_header_get_name (header);
@@ -202,8 +185,7 @@ process_header (GMimeObject *object, GMimeHeader *header)
        switch (i) {
        case HEADER_CONTENT_TRANSFER_ENCODING:
                value = g_mime_header_get_value (header);
-               copy_atom (value, encoding, sizeof (encoding) - 1);
-               mime_part->encoding = g_mime_content_encoding_from_string (encoding);
+               mime_part->encoding = g_mime_content_encoding_from_string (value);
                break;
        case HEADER_CONTENT_DESCRIPTION:
                value = g_mime_header_get_value (header);