misc/hash: add mp_hash_to_bstr function

This util function uses the generic libavutil hash API to hash any data
with the specified algorithm to a bstr. It deduplicates multiple hash
routines used in mpv.

meson.build

@@ -138,6 +138,7 @@ sources = files(
     'misc/charset_conv.c',
     'misc/codepoint_width.c',
     'misc/dispatch.c',
+    'misc/hash.c',
     'misc/io_utils.c',
     'misc/json.c',
     'misc/language.c',

misc/hash.c

@@ -0,0 +1,41 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * mpv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+
+#include <libavutil/hash.h>
+
+#include "common/common.h"
+#include "misc/hash.h"
+
+bstr mp_hash_to_bstr(void *talloc_ctx, const uint8_t *data, size_t len, const char *algorithm)
+{
+    struct AVHashContext *ctx = NULL;
+    mp_require(av_hash_alloc(&ctx, algorithm) == 0);
+    int size = av_hash_get_size(ctx);
+    uint8_t hash[AV_HASH_MAX_SIZE] = {0};
+
+    av_hash_init(ctx);
+    av_hash_update(ctx, data, len);
+    av_hash_final(ctx, hash);
+    av_hash_freep(&ctx);
+
+    bstr ret = {0};
+    for (int n = 0; n < size; n++)
+        bstr_xappend_asprintf(talloc_ctx, &ret, "%02X", hash[n]);
+    return ret;
+}

misc/hash.h

@@ -0,0 +1,26 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * mpv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include "misc/bstr.h"
+
+/*
+ * Return the hashed data as a hex string with upper case letters.
+ * The list of available algorithms is available at libavutil/hash.c.
+ */
+bstr mp_hash_to_bstr(void *talloc_ctx, const uint8_t *data, size_t len, const char *algorithm);