added bpc_fileDigest.c

bpc_fileDigest.c

@@ -0,0 +1,49 @@
+/*
+ * Library routines
+ *
+ * Copyright (C) 2020 Craig Barratt.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, visit the http://fsf.org website.
+ */
+
+#include "backuppc.h"
+
+/*
+ * Compute the md5 digest of a file. Returns 0 on success
+ */
+int bpc_fileDigest(char *fileName, int compress, bpc_digest *digest)
+{
+    md_context md5;
+    bpc_fileZIO_fd fd;
+    ssize_t nRead;
+    uchar buffer[1 << 20];
+
+    digest->len = 0;
+    md5_begin(&md5);
+    if ( bpc_fileZIO_open(&fd, fileName, 0, compress) ) {
+	bpc_logErrf("bpc_fileDigest: can't open %s for reading\n", fileName);
+	return -1;
+    }
+    while ( (nRead = bpc_fileZIO_read(&fd, buffer, sizeof(buffer))) > 0 ) {
+	md5_update(&md5, buffer, nRead);
+    }
+    bpc_fileZIO_close(&fd);
+    if ( nRead < 0 ) {
+	bpc_logErrf("bpc_fileDigest: failed to read %s\n", fileName);
+	return -1;
+    }
+    md5_result(&md5, digest->digest);
+    digest->len = MD5_DIGEST_LEN;
+    return 0;
+}