gamemode: Add common helpers to build gamemode

gamemode-zig/c/common/common-helpers.h

@@ -0,0 +1,103 @@
+/*
+
+Copyright (c) 2017-2019, Feral Interactive
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice,
+   this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+ * Neither the name of Feral Interactive nor the names of its contributors
+   may be used to endorse or promote products derived from this software
+   without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGE.
+
+ */
+
+#pragma once
+
+#include <stdlib.h>
+#include <string.h>
+#include <sys/param.h>
+#include <unistd.h>
+
+/**
+ * Value clamping helper, works like MIN/MAX but constraints a value within the range.
+ */
+#define CLAMP(l, u, value) MAX(MIN(l, u), MIN(MAX(l, u), value))
+
+/**
+ * Little helper to safely print into a buffer, returns a pointer into the buffer
+ */
+#define buffered_snprintf(b, s, ...)                                                               \
+	(snprintf(b, sizeof(b), s, __VA_ARGS__) < (ssize_t)sizeof(b) ? b : NULL)
+
+/**
+ * Little helper to safely print into a buffer, returns a newly allocated string
+ */
+#define safe_snprintf(b, s, ...)                                                                   \
+	(snprintf(b, sizeof(b), s, __VA_ARGS__) < (ssize_t)sizeof(b) ? strndup(b, sizeof(b)) : NULL)
+
+/**
+ * Helper function: Test, if haystack ends with needle.
+ */
+static inline const char *strtail(const char *haystack, const char *needle)
+{
+	char *pos = strstr(haystack, needle);
+	if (pos && (strlen(pos) == strlen(needle)))
+		return pos;
+	return NULL;
+}
+
+/**
+ * Helper function for autoclosing file-descriptors. Does nothing if the argument
+ * is NULL or the referenced integer < 0.
+ */
+inline void cleanup_close(int *fd_ptr)
+{
+	if (fd_ptr == NULL || *fd_ptr < 0)
+		return;
+
+	(void)close(*fd_ptr);
+}
+
+/**
+ * Helper macro for autoclosing file-descriptors: use by prefixing the variable,
+ * like "autoclose_fd int fd = -1;".
+ */
+#define autoclose_fd __attribute__((cleanup(cleanup_close)))
+
+/**
+ * Helper function for auto-freeing dynamically allocated memory. Does nothing
+ * if *ptr is NULL (ptr must not be NULL).
+ */
+inline void cleanup_free(void *ptr)
+{
+	/* The function is defined to work with 'void *' because
+	 * that will make sure it compiles without warning also
+	 * for all types; what we are getting passed into is a
+	 * pointer to a pointer though, so we need to cast */
+	void *target = *(void **)ptr;
+	free(target); /* free can deal with NULL */
+}
+
+/**
+ * Helper macro for auto-freeing dynamically allocated memory: use by
+ * prefixing the variable, like "autofree char *data = NULL;".
+ */
+#define autofree __attribute__((cleanup(cleanup_free)))