[balsa] gmime-part-rfc2440: use g_str_has_prefix()

[Peter Bloomfield <peterb src gnome org>]

commit d161ee225a5e416d38f73eaaae82b0bd684f0a33
Author: Peter Bloomfield <PeterBloomfield bellsouth net>
Date:   Wed Jul 17 22:47:02 2019 -0400

    gmime-part-rfc2440: use g_str_has_prefix()
    
    * libbalsa/gmime-part-rfc2440.c (g_mime_part_check_rfc2440): use
      g_str_has_prefix() instead of strncmp().

 ChangeLog                     |  5 +++++
 libbalsa/gmime-part-rfc2440.c | 31 ++++++++++++++++++-------------
 2 files changed, 23 insertions(+), 13 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index d036bb180..3b3236855 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2019-07-17  Peter Bloomfield  <pbloomfield bellsouth net>
+
+       * libbalsa/gmime-part-rfc2440.c (g_mime_part_check_rfc2440): use
+       g_str_has_prefix() instead of strncmp().
+
 2019-07-16  Peter Bloomfield  <pbloomfield bellsouth net>
 
        mime-stream-shared: Use modern macros to declare and define.
diff --git a/libbalsa/gmime-part-rfc2440.c b/libbalsa/gmime-part-rfc2440.c
index 199dfe04a..85bad0c7c 100644
--- a/libbalsa/gmime-part-rfc2440.c
+++ b/libbalsa/gmime-part-rfc2440.c
@@ -56,6 +56,11 @@ g_mime_part_check_rfc2440(GMimePart * part)
     ssize_t slen;
     gchar buf[RFC2440_BUF_LEN];
     GMimePartRfc2440Mode retval = GMIME_PART_RFC2440_NONE;
+    static const char begin_pgp_message[]        = "-----BEGIN PGP MESSAGE-----";
+    static const char end_pgp_message[]          = "-----END PGP MESSAGE-----";
+    static const char begin_pgp_signed_message[] = "-----BEGIN PGP SIGNED MESSAGE-----";
+    static const char begin_pgp_signature[]      = "-----BEGIN PGP SIGNATURE-----";
+    static const char end_pgp_signature[]        = "-----END PGP SIGNATURE-----";
 
     /* try to get the content stream */
     wrapper = g_mime_part_get_content_object(part);
@@ -72,35 +77,35 @@ g_mime_part_check_rfc2440(GMimePart * part)
        g_mime_stream_read(stream, buf, slen);
        buf[slen] = '\0';
 
-       if (!strncmp(buf, "-----BEGIN PGP MESSAGE-----", 27) &&
-           strstr(buf, "-----END PGP MESSAGE-----"))
+       if (g_str_has_prefix(buf, begin_pgp_message) &&
+           strstr(buf, end_pgp_message) != NULL) {
            retval = GMIME_PART_RFC2440_ENCRYPTED;
-       else if (!strncmp(buf, "-----BEGIN PGP SIGNED MESSAGE-----", 34)) {
+        } else if (g_str_has_prefix(buf, begin_pgp_signed_message)) {
            gchar *p1, *p2;
 
-           p1 = strstr(buf, "-----BEGIN PGP SIGNATURE-----");
-           p2 = strstr(buf, "-----END PGP SIGNATURE-----");
-           if (p1 && p2 && p2 > p1)
+           p1 = strstr(buf, begin_pgp_signature);
+           p2 = strstr(buf, end_pgp_signature);
+           if (p1 != NULL && p2 != NULL && p2 > p1)
                retval = GMIME_PART_RFC2440_SIGNED;
        }
     } else {
        /* check if the beginning of the stream matches */
-       g_mime_stream_read(stream, buf, 34);
+       g_mime_stream_read(stream, buf, strlen(begin_pgp_signed_message));
        g_mime_stream_seek(stream, 1 - RFC2440_BUF_LEN,
                           GMIME_STREAM_SEEK_END);
-       if (!strncmp(buf, "-----BEGIN PGP MESSAGE-----", 27)) {
+       if (g_str_has_prefix(buf, begin_pgp_message)) {
            g_mime_stream_read(stream, buf, RFC2440_BUF_LEN - 1);
            buf[RFC2440_BUF_LEN - 1] = '\0';
-           if (strstr(buf, "-----END PGP MESSAGE-----"))
+           if (strstr(buf, end_pgp_message) != NULL)
                retval = GMIME_PART_RFC2440_ENCRYPTED;
-       } else if (!strncmp(buf, "-----BEGIN PGP SIGNED MESSAGE-----", 34)) {
+       } else if (g_str_has_prefix(buf, begin_pgp_signed_message)) {
            gchar *p1, *p2;
 
            g_mime_stream_read(stream, buf, RFC2440_BUF_LEN - 1);
            buf[RFC2440_BUF_LEN - 1] = '\0';
-           p1 = strstr(buf, "-----BEGIN PGP SIGNATURE-----");
-           p2 = strstr(buf, "-----END PGP SIGNATURE-----");
-           if (p1 && p2 && p2 > p1)
+           p1 = strstr(buf, begin_pgp_signature);
+           p2 = strstr(buf, end_pgp_signature);
+           if (p1 != NULL && p2 != NULL && p2 > p1)
                retval = GMIME_PART_RFC2440_SIGNED;
        }
     }