1 files changed, 49 insertions, 0 deletions
diff --git a/libkeccak_generalised_sum_fd.c b/libkeccak_generalised_sum_fd.c
new file mode 100644
index 0000000..133ffa9
--- /dev/null
+++ b/libkeccak_generalised_sum_fd.c
@@ -0,0 +1,49 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+/**
+ * Calculate a Keccak-family hashsum of a file,
+ * the content of the file is assumed non-sensitive
+ * 
+ * @param   fd       The file descriptor of the file to hash
+ * @param   state    The hashing state, should not be initialised (memory leak otherwise)
+ * @param   spec     Specifications for the hashing algorithm
+ * @param   suffix   The data suffix, see `libkeccak_digest`
+ * @param   hashsum  Output array for the hashsum, have an allocation size of
+ *                   at least `((spec->output + 7) / 8) * sizeof(char)`, may be `NULL`
+ * @return           Zero on success, -1 on error
+ */
+int
+libkeccak_generalised_sum_fd(int fd, libkeccak_state_t *restrict state, const libkeccak_spec_t *restrict spec,
+                             const char *restrict suffix, void *restrict hashsum)
+{
+	ssize_t got;
+	struct stat attr;
+	size_t blksize = 4096;
+	char *restrict chunk;
+
+	if (libkeccak_state_initialise(state, spec) < 0)
+		return -1;
+
+	if (fstat(fd, &attr) == 0)
+		if (attr.st_blksize > 0)
+			blksize = (size_t)(attr.st_blksize);
+  
+	chunk = alloca(blksize);
+
+	for (;;) {
+		got = read(fd, chunk, blksize);
+		if (got < 0) {
+			if (errno == EINTR)
+				continue;
+			return -1;
+		}
+		if (got == 0)
+			break;
+		if (libkeccak_fast_update(state, chunk, (size_t)got) < 0)
+			return -1;
+	}
+
+	return libkeccak_fast_digest(state, NULL, 0, 0, suffix, hashsum);
+}