1 files changed, 119 insertions, 0 deletions
diff --git a/src/shared/qrcode-util.c b/src/shared/qrcode-util.c
new file mode 100644
index 0000000..4a33c28
--- /dev/null
+++ b/src/shared/qrcode-util.c
@@ -0,0 +1,119 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "qrcode-util.h"
+
+#if HAVE_QRENCODE
+#include <qrencode.h>
+
+#include "dlfcn-util.h"
+#include "locale-util.h"
+#include "log.h"
+#include "strv.h"
+#include "terminal-util.h"
+
+#define ANSI_WHITE_ON_BLACK "\033[40;37;1m"
+#define UNICODE_FULL_BLOCK       u8"█"
+#define UNICODE_LOWER_HALF_BLOCK u8"▄"
+#define UNICODE_UPPER_HALF_BLOCK u8"▀"
+
+static void *qrcode_dl = NULL;
+
+static QRcode* (*sym_QRcode_encodeString)(const char *string, int version, QRecLevel level, QRencodeMode hint, int casesensitive) = NULL;
+static void (*sym_QRcode_free)(QRcode *qrcode) = NULL;
+
+int dlopen_qrencode(void) {
+        int r;
+
+        FOREACH_STRING(s, "libqrencode.so.4", "libqrencode.so.3") {
+                r = dlopen_many_sym_or_warn(
+                        &qrcode_dl, s, LOG_DEBUG,
+                        DLSYM_ARG(QRcode_encodeString),
+                        DLSYM_ARG(QRcode_free));
+                if (r >= 0)
+                        break;
+        }
+
+        return r;
+}
+
+static void print_border(FILE *output, unsigned width) {
+        /* Four rows of border */
+        for (unsigned y = 0; y < 4; y += 2) {
+                fputs(ANSI_WHITE_ON_BLACK, output);
+
+                for (unsigned x = 0; x < 4 + width + 4; x++)
+                        fputs(UNICODE_FULL_BLOCK, output);
+
+                fputs(ANSI_NORMAL "\n", output);
+        }
+}
+
+static void write_qrcode(FILE *output, QRcode *qr) {
+        assert(qr);
+
+        if (!output)
+                output = stdout;
+
+        print_border(output, qr->width);
+
+        for (unsigned y = 0; y < (unsigned) qr->width; y += 2) {
+                const uint8_t *row1 = qr->data + qr->width * y;
+                const uint8_t *row2 = row1 + qr->width;
+
+                fputs(ANSI_WHITE_ON_BLACK, output);
+                for (unsigned x = 0; x < 4; x++)
+                        fputs(UNICODE_FULL_BLOCK, output);
+
+                for (unsigned x = 0; x < (unsigned) qr->width; x++) {
+                        bool a, b;
+
+                        a = row1[x] & 1;
+                        b = (y+1) < (unsigned) qr->width ? (row2[x] & 1) : false;
+
+                        if (a && b)
+                                fputc(' ', output);
+                        else if (a)
+                                fputs(UNICODE_LOWER_HALF_BLOCK, output);
+                        else if (b)
+                                fputs(UNICODE_UPPER_HALF_BLOCK, output);
+                        else
+                                fputs(UNICODE_FULL_BLOCK, output);
+                }
+
+                for (unsigned x = 0; x < 4; x++)
+                        fputs(UNICODE_FULL_BLOCK, output);
+                fputs(ANSI_NORMAL "\n", output);
+        }
+
+        print_border(output, qr->width);
+        fflush(output);
+}
+
+int print_qrcode(FILE *out, const char *header, const char *string) {
+        QRcode* qr;
+        int r;
+
+        /* If this is not an UTF-8 system or ANSI colors aren't supported/disabled don't print any QR
+         * codes */
+        if (!is_locale_utf8() || !colors_enabled())
+                return -EOPNOTSUPP;
+
+        r = dlopen_qrencode();
+        if (r < 0)
+                return r;
+
+        qr = sym_QRcode_encodeString(string, 0, QR_ECLEVEL_L, QR_MODE_8, 1);
+        if (!qr)
+                return -ENOMEM;
+
+        if (header)
+                fprintf(out, "\n%s:\n\n", header);
+
+        write_qrcode(out, qr);
+
+        fputc('\n', out);
+
+        sym_QRcode_free(qr);
+        return 0;
+}
+#endif