hash verification

1 files changed, 71 insertions, 0 deletions

diff --git a/src/hash.c b/src/hash.c
new file mode 100644
index 0000000..2cb0851
--- /dev/null
+++ b/src/hash.c
@@ -0,0 +1,71 @@
+#include "hash.h"
+
+#include <blake2.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int pow_check_blake2b_hash(char *path, char *target_hash) {
+  FILE *fp = fopen(path, "rb");
+
+  if (!fp) {
+    printf("failed to open file to check hash\n");
+
+    return 1;
+  }
+
+  fseek(fp, 0, SEEK_END);
+  long fsize = ftell(fp);
+  fseek(fp, 0, SEEK_SET);
+
+  if (fsize < 0) {
+    printf("error: ftell\n");
+
+    fclose(fp);
+
+    return 1;
+  }
+
+  char *buf = NULL;
+
+  if (fsize > 0) {
+    buf = malloc((size_t)fsize);
+
+    if (!buf) {
+      fprintf(stderr, "out of memory\n");
+      fclose(fp);
+      return 1;
+    }
+
+    if (fread(buf, 1, (size_t)fsize, fp) != (size_t)fsize) {
+      fprintf(stderr, "read error\n");
+      free(buf);
+      fclose(fp);
+      return 1;
+    }
+  }
+
+  fclose(fp);
+
+  uint8_t digest[BLAKE2B_OUTBYTES];
+  if (blake2b(digest, buf, NULL, BLAKE2B_OUTBYTES, (size_t)fsize, 0) != 0) {
+    fprintf(stderr, "blake2b failed\n");
+    free(buf);
+    return 1;
+  }
+
+  free(buf);
+
+  char hex[BLAKE2B_OUTBYTES * 2 + 1];
+  for (size_t i = 0; i < BLAKE2B_OUTBYTES; i++) {
+    snprintf(&hex[i * 2], 3, "%02x", digest[i]);
+  }
+  hex[BLAKE2B_OUTBYTES * 2] = '\0';
+
+  if (!target_hash || strcmp(hex, target_hash) != 0) {
+    return 1;
+  }
+
+  return 0;
+}