+#define MAX_DIGEST_SIZE 20
+
+typedef struct _gc_hash_ctx
+{
+ Gc_hash alg;
+ Gc_hash_mode mode;
+ char hash[MAX_DIGEST_SIZE];
+#ifdef GNULIB_GC_MD2
+ struct md2_ctx md2Context;
+#endif
+#ifdef GNULIB_GC_MD4
+ struct md4_ctx md4Context;
+#endif
+#ifdef GNULIB_GC_MD5
+ struct md5_ctx md5Context;
+#endif
+#ifdef GNULIB_GC_SHA1
+ struct sha1_ctx sha1Context;
+#endif
+} _gc_hash_ctx;
+
+Gc_rc
+gc_hash_open (Gc_hash hash, Gc_hash_mode mode, gc_hash_handle * outhandle)
+{
+ _gc_hash_ctx *ctx;
+ Gc_rc rc = GC_OK;
+
+ ctx = calloc (sizeof (*ctx), 1);
+ if (!ctx)
+ return GC_MALLOC_ERROR;
+
+ ctx->alg = hash;
+ ctx->mode = mode;
+
+ switch (hash)
+ {
+#ifdef GNULIB_GC_MD2
+ case GC_MD2:
+ md2_init_ctx (&ctx->md2Context);
+ break;
+#endif
+
+#ifdef GNULIB_GC_MD4
+ case GC_MD4:
+ md4_init_ctx (&ctx->md4Context);
+ break;
+#endif
+
+#ifdef GNULIB_GC_MD5
+ case GC_MD5:
+ md5_init_ctx (&ctx->md5Context);
+ break;
+#endif
+
+#ifdef GNULIB_GC_SHA1
+ case GC_SHA1:
+ sha1_init_ctx (&ctx->sha1Context);
+ break;
+#endif
+
+ default:
+ rc = GC_INVALID_HASH;
+ break;
+ }
+
+ switch (mode)
+ {
+ case 0:
+ break;
+
+ default:
+ rc = GC_INVALID_HASH;
+ break;
+ }
+
+ if (rc == GC_OK)
+ *outhandle = ctx;
+ else
+ free (ctx);
+
+ return rc;
+}
+
+Gc_rc
+gc_hash_clone (gc_hash_handle handle, gc_hash_handle * outhandle)
+{
+ _gc_hash_ctx *in = handle;
+ _gc_hash_ctx *out;
+
+ *outhandle = out = calloc (sizeof (*out), 1);
+ if (!out)
+ return GC_MALLOC_ERROR;
+
+ memcpy (out, in, sizeof (*out));
+
+ return GC_OK;
+}
+
+size_t
+gc_hash_digest_length (Gc_hash hash)
+{
+ size_t len;
+
+ switch (hash)
+ {
+ case GC_MD2:
+ len = GC_MD2_DIGEST_SIZE;
+ break;
+
+ case GC_MD4:
+ len = GC_MD4_DIGEST_SIZE;
+ break;
+
+ case GC_MD5:
+ len = GC_MD5_DIGEST_SIZE;
+ break;
+
+ case GC_RMD160:
+ len = GC_RMD160_DIGEST_SIZE;
+ break;
+
+ case GC_SHA1:
+ len = GC_SHA1_DIGEST_SIZE;
+ break;
+
+ default:
+ return 0;
+ }
+
+ return len;
+}
+
+void
+gc_hash_write (gc_hash_handle handle, size_t len, const char *data)
+{
+ _gc_hash_ctx *ctx = handle;
+
+ switch (ctx->alg)
+ {
+#ifdef GNULIB_GC_MD2
+ case GC_MD2:
+ md2_process_bytes (data, len, &ctx->md2Context);
+ break;
+#endif
+
+#ifdef GNULIB_GC_MD4
+ case GC_MD4:
+ md4_process_bytes (data, len, &ctx->md4Context);
+ break;
+#endif
+
+#ifdef GNULIB_GC_MD5
+ case GC_MD5:
+ md5_process_bytes (data, len, &ctx->md5Context);
+ break;
+#endif
+
+#ifdef GNULIB_GC_SHA1
+ case GC_SHA1:
+ sha1_process_bytes (data, len, &ctx->sha1Context);
+ break;
+#endif
+
+ default:
+ break;
+ }
+}
+
+const char *
+gc_hash_read (gc_hash_handle handle)
+{
+ _gc_hash_ctx *ctx = handle;
+ const char *ret = NULL;
+
+ switch (ctx->alg)
+ {
+#ifdef GNULIB_GC_MD2
+ case GC_MD2:
+ md2_finish_ctx (&ctx->md2Context, ctx->hash);
+ ret = ctx->hash;
+ break;
+#endif
+
+#ifdef GNULIB_GC_MD4
+ case GC_MD4:
+ md4_finish_ctx (&ctx->md4Context, ctx->hash);
+ ret = ctx->hash;
+ break;
+#endif
+
+#ifdef GNULIB_GC_MD5
+ case GC_MD5:
+ md5_finish_ctx (&ctx->md5Context, ctx->hash);
+ ret = ctx->hash;
+ break;
+#endif
+
+#ifdef GNULIB_GC_SHA1
+ case GC_SHA1:
+ sha1_finish_ctx (&ctx->sha1Context, ctx->hash);
+ ret = ctx->hash;
+ break;
+#endif
+
+ default:
+ return NULL;
+ }
+
+ return ret;
+}
+
+void
+gc_hash_close (gc_hash_handle handle)
+{
+ _gc_hash_ctx *ctx = handle;
+
+ free (ctx);
+}
+