Merge pull request #31297 from AdrianVovk/sha256-util-lib

basic: Add some sha256 helper functions

src/basic/meson.build

@@ -79,6 +79,7 @@ basic_sources = files(
         'replace-var.c',
         'rlimit-util.c',
         'runtime-scope.c',
+        'sha256.c',
         'sigbus.c',
         'signal-util.c',
         'siphash24.c',

src/basic/sha256.c

@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <unistd.h>
+
+#include "hexdecoct.h"
+#include "macro.h"
+#include "sha256.h"
+
+int sha256_fd(int fd, uint64_t max_size, uint8_t ret[static SHA256_DIGEST_SIZE]) {
+        struct sha256_ctx ctx;
+        uint64_t total_size = 0;
+
+        sha256_init_ctx(&ctx);
+
+        for (;;) {
+                uint8_t buffer[64 * 1024];
+                ssize_t n;
+
+                n = read(fd, buffer, sizeof(buffer));
+                if (n < 0)
+                        return -errno;
+                if (n == 0)
+                        break;
+
+                if (!INC_SAFE(&total_size, n) || total_size > max_size)
+                        return -EFBIG;
+
+                sha256_process_bytes(buffer, n, &ctx);
+        }
+
+        sha256_finish_ctx(&ctx, ret);
+        return 0;
+}
+
+int parse_sha256(const char *s, uint8_t ret[static SHA256_DIGEST_SIZE]) {
+        _cleanup_free_ uint8_t *data = NULL;
+        size_t size = 0;
+        int r;
+
+        if (!sha256_is_valid(s))
+                return -EINVAL;
+
+        r = unhexmem_full(s, SHA256_DIGEST_SIZE * 2, false, (void**) &data, &size);
+        if (r < 0)
+                return r;
+        assert(size == SHA256_DIGEST_SIZE);
+
+        memcpy(ret, data, size);
+        return 0;
+}

src/basic/sha256.h

@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#pragma once
+
+#include <stdint.h>
+
+#include "sha256-fundamental.h"
+#include "string-util.h"
+
+int sha256_fd(int fd, uint64_t max_size, uint8_t ret[static SHA256_DIGEST_SIZE]);
+
+int parse_sha256(const char *s, uint8_t res[static SHA256_DIGEST_SIZE]);
+
+static inline bool sha256_is_valid(const char *s) {
+        return s && in_charset(s, HEXDIGITS) && (strlen(s) == SHA256_DIGEST_SIZE * 2);
+}