[Qemu-devel] [PATCH v2 03/18] cutils: Add qemu_strdup_hexlify() and qemu_strdup_unhexlify()

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Add two helpers: one to represent a binary data as a string of
hexadecimal values, and one to restore a such string into its
original binary data.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 include/qemu/cutils.h | 33 ++++++++++++++++++++++++++
 util/cutils.c         | 55 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/include/qemu/cutils.h b/include/qemu/cutils.h
index d2dad3057c..375a5508b0 100644
--- a/include/qemu/cutils.h
+++ b/include/qemu/cutils.h
@@ -171,6 +171,39 @@ bool test_buffer_is_zero_next_accel(void);
 int uleb128_encode_small(uint8_t *out, uint32_t n);
 int uleb128_decode_small(const uint8_t *in, uint32_t *n);
 
+/**
+ * qemu_strdup_hexlify:
+ *
+ * Encode a sequence of binary data into its hexadecimal stringified
+ * representation.
+ *
+ * @ptr: Buffer to hexlify
+ * @size: Length of the buffer
+ *
+ * Use qemu_strdup_unhexlify() to convert the hex string to original data.
+ *
+ * Returns: A newly allocated, zero-terminated hex encoded string representing
+ * the data. The returned string must be freed with g_free().
+ */
+gchar *qemu_strdup_hexlify(gconstpointer ptr, gsize size);
+
+/**
+ * qemu_strdup_unhexlify:
+ *
+ * Decode a sequence of hexadecimal encoded text into binary data.
+ *
+ * @hex_string: String to unhexlify
+ * @out_size: if not NULL: gsize to be written with the data length
+ *
+ * This function is the opposite of qemu_strdup_hexlify().
+ *
+ * Returns: A newly allocated buffer containing the binary data that text
+ * represents. The returned buffer must be freed with g_free().
+ * Note that the returned binary data is not necessarily zero-terminated,
+ * so it should not be used as a character string.
+ */
+gpointer qemu_strdup_unhexlify(const gchar *hex_string, gsize *out_size);
+
 /**
  * qemu_pstrcmp0:
  * @str1: a non-NULL pointer to a C string (*str1 can be NULL)
diff --git a/util/cutils.c b/util/cutils.c
index e098debdc0..bf324c0d8b 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -779,6 +779,61 @@ int uleb128_decode_small(const uint8_t *in, uint32_t *n)
     }
 }
 
+static guchar hexval(const gchar v)
+{
+    switch (v) {
+    case '0' ... '9':
+        return v - '0';
+    case 'A' ... 'F':
+        return v - 'A' + 10;
+    case 'a' ... 'f':
+        return v - 'a' + 10;
+    default:
+        return 0;
+    }
+}
+
+gchar *qemu_strdup_hexlify(gconstpointer ptr, gsize len)
+{
+    guchar *data = (guchar *)ptr;
+    gchar *hex_string;
+
+    if (!ptr || !len) {
+        return g_strdup("");
+    }
+
+    hex_string = g_malloc(2 * len + 1);
+    for (gsize i = 0; i < len; i++) {
+        g_snprintf(&hex_string[2 * i], 3, "%02x", data[i]);
+    }
+
+    return hex_string;
+}
+
+gpointer qemu_strdup_unhexlify(const gchar *hex_string, gsize *out_size)
+{
+    size_t size = 0;
+    guchar *data = NULL;
+
+    if (hex_string) {
+        size = strlen(hex_string) / 2;
+        if (size) {
+            size_t i;
+
+            data = g_new(guchar, size + 1);
+            for (i = 0; i < size; i++) {
+                data[i]  = hexval(*hex_string++) << 4;
+                data[i] |= hexval(*hex_string++);
+            }
+            data[i] = '\0';
+        }
+    }
+    if (out_size) {
+        *out_size = size;
+    }
+    return data;
+}
+
 /*
  * helper to parse debug environment variables
  */
-- 
2.20.1