Add basic signing code

src/fmail.c

@@ -206,9 +206,61 @@ initialize_gpgme(void)
         errx(EXIT_FAILURE, "cannot initialize GPGME: %s",
              gpgme_strerror(gerr));
 
+    gpgme_set_armor(ctx, 1);
+
     return ctx;
 }
 
+static void
+sign_stream(gpgme_ctx_t ctx, FILE *in, FILE *out)
+{
+    gpgme_data_t gin, gout;
+    char boundary[32], buffer[512];
+    int n;
+
+    gpgme_data_new_from_stream(&gin, in);
+    gpgme_data_new(&gout);
+
+    gpgme_op_sign(ctx, gin, gout, GPGME_SIG_MODE_DETACH);
+
+    generate_boundary(boundary, sizeof(boundary));
+    fprintf(out, "Content-Type: multipart/signed;\r\n"
+                 "  boundary=\"%s\";\r\n"
+                 "  protocol=\"application/pgp-signature\";\r\n"
+                 "  micalg=pgp-sha1\r\n"
+                 "\r\n"
+                 "--%s\r\n",
+                 boundary, boundary);
+
+    fseek(in, 0, SEEK_SET);
+    while ( (n = fread(buffer, 1, sizeof(buffer), in)) > 0 )
+        fwrite(buffer, 1, n, out);
+
+    fprintf(out, "\r\n"
+                  "--%s\r\n"
+                 "Content-Type: application/pgp-signature; name=signature.asc\r\n"
+                 "\r\n",
+                 boundary);
+
+    gpgme_data_seek(gout, 0, SEEK_SET);
+    while ( (n = gpgme_data_read(gout, buffer, sizeof(buffer))) > 0 ) {
+        int i = 0;
+
+        while ( i < n ) {
+            if ( buffer[i] == '\n' )
+                fputc('\r', out);
+            fputc(buffer[i], out);
+
+            i += 1;
+        }
+    }
+
+    fprintf(out, "\r\n--%s--\r\n", boundary);
+
+    gpgme_data_release(gin);
+    gpgme_data_release(gout);
+}
+
 
 
 /* Main function. */
@@ -265,12 +317,18 @@ main(int argc, char *argv[])
     /* Write all headers. */
     fprintf(stdout, "%s", sb_get(headers));
 
-    /* Write encoded body. */
-    process_text_body(stdin, stdout);
+    if ( sign_ctx ) {
+        FILE *tmp = tmpfile();
 
-    /* Clean-up. */
-    if ( sign_ctx )
+        process_text_body(stdin, tmp);
+        fseek(tmp, 0, SEEK_SET);
+        sign_stream(sign_ctx, tmp, stdout);
+
+        fclose(tmp);
         gpgme_release(sign_ctx);
+    }
+    else
+        process_text_body(stdin, stdout);
 
     return EXIT_SUCCESS;
 }