1 files changed, 55 insertions, 0 deletions
diff --git a/unix/utils/nonblock.c b/unix/utils/nonblock.c
new file mode 100644
index 00000000..cece206c
--- /dev/null
+++ b/unix/utils/nonblock.c
@@ -0,0 +1,55 @@
+/*
+ * Set and clear the O_NONBLOCK fcntl option on an open file.
+ *
+ * We don't realistically expect these operations to fail (the most
+ * plausible error condition is EBADF, but we always believe ourselves
+ * to be passing a valid fd so even that's an assertion-fail sort of
+ * response), so we don't make any effort to return sensible error
+ * codes to the caller - we just log to standard error and die
+ * unceremoniously.
+ *
+ * Returns the previous state of O_NONBLOCK.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#include <fcntl.h>
+
+#include "putty.h"
+
+bool nonblock(int fd)
+{
+    int fdflags;
+
+    fdflags = fcntl(fd, F_GETFL);
+    if (fdflags < 0) {
+        fprintf(stderr, "%d: fcntl(F_GETFL): %s\n", fd, strerror(errno));
+        exit(1);
+    }
+    if (fcntl(fd, F_SETFL, fdflags | O_NONBLOCK) < 0) {
+        fprintf(stderr, "%d: fcntl(F_SETFL): %s\n", fd, strerror(errno));
+        exit(1);
+    }
+
+    return fdflags & O_NONBLOCK;
+}
+
+bool no_nonblock(int fd)
+{
+    int fdflags;
+
+    fdflags = fcntl(fd, F_GETFL);
+    if (fdflags < 0) {
+        fprintf(stderr, "%d: fcntl(F_GETFL): %s\n", fd, strerror(errno));
+        exit(1);
+    }
+    if (fcntl(fd, F_SETFL, fdflags & ~O_NONBLOCK) < 0) {
+        fprintf(stderr, "%d: fcntl(F_SETFL): %s\n", fd, strerror(errno));
+        exit(1);
+    }
+
+    return fdflags & O_NONBLOCK;
+}