1 files changed, 72 insertions, 0 deletions
diff --git a/src/util.c b/src/util.c
new file mode 100644
index 0000000..772dbf8
--- /dev/null
+++ b/src/util.c
@@ -0,0 +1,72 @@
+/* Copyright 2016 Luke Shumaker */
+
+#include <ctype.h> /* for isdigit */
+#include <stdlib.h>
+#include <error.h>
+#include <errno.h>
+
+#include "util.h"
+
+void *xrealloc(void *ptr, size_t size)
+{
+	void *ret = realloc(ptr, size);
+	if (ret == NULL) {
+		if (ptr==NULL)
+			error(1, errno, "Could not allocate memory");
+		else
+			error(1, errno, "Could not re-allocate memory");
+	}
+	return ret;
+}
+
+bool is_numeric(const char *str) {
+	for (size_t i = 0; str[i] != '\0'; i++)
+		if (!isdigit(str[i]))
+			return false;
+	if (str[0] == '\0')
+		return false;
+	return true;
+}	
+
+int get_fd(const char *addr) {
+	int sock;
+	if (strcmp(addr, "stdin") == 0) {
+		sock = 0;
+	} else if (strcmp(addr, "stdout") == 0) {
+		sock = 1;
+	} else if (strcmp(addr, "stderr") == 0) {
+		sock = 2;
+	} else if (strncmp(addr, "systemd", strlen("systemd")) == 0) {
+		sock = 3; /* <systemd/sd-daemon.h>:SD_LISTEN_FDS_START */
+		addr = &addr[strlen("systemd")];
+		switch (addr[0]) {
+		case '\0':
+			/* do nothing */
+			break;
+		case ':':
+			addr = &addr[1];
+			if (is_numeric(addr)) {
+				sock += atoi(addr);
+			} else {
+				const char *e = getenv("LISTEN_FDNAMES");
+				if (e == NULL)
+					return -ENOTCONN;
+				char *names = strdupa(e);
+				char *name = NULL;
+				int i = -1;
+				do {
+					name = strsep(&names, ":");
+					i++;
+				} while (name != NULL && strcmp(name, addr) != 0);
+				if (name == NULL)
+					return -ENOENT;
+				sock += i;
+			}
+		}
+	} else {
+		if (!is_numeric(addr))
+			return -EINVAL;
+		sock = atoi(addr);
+	}
+	return sock;
+}