From 7e22bd716fe6bc27542182828c1aee41d6e42d0b Mon Sep 17 00:00:00 2001
From: Igor Kolokolnikov <igor@kolokolnikov.dev>
Date: Tue, 15 Sep 2026 20:37:35 -0700
Subject: [PATCH] Initial commit.

---
 Makefile   |  92 +++++++++++++++++++++++++++++++++++++++++
 caffeine.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 211 insertions(+)
 create mode 100644 Makefile
 create mode 100644 caffeine.c

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..374072b
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,92 @@
+UNAME_M := $(shell uname -m)
+
+ifeq ($(UNAME_M),x86_64)
+	ARCH := ARCHITECTURE_X64
+else ifneq ($(filter $(UNAME_M),i686,i386),)
+	ARCH := ARCHITECTURE_X86
+else ifneq ($(filter $(UNAME_M),aarch64 arm64),)
+	ARCH := ARCHITECTURE_ARM64
+else ifneq ($(filter $(UNAME_M),armv7l armv6l),)
+	ARCH := ARCHITECTURE_ARM32
+endif
+
+UNAME_E := $(shell [ $$(printf '\01\00' | od -An -tu2) -eq 1 ] && \
+		   echo "little" || echo "big")
+
+ifeq ($(UNAME_E),little)
+	ENDIANESS := LITTLE_ENDIAN
+else ifeq ($(UNAME_E),little)
+	ENDIANESS := BIG_ENDIAN
+endif
+
+UNAME_S := $(shell uname -s)
+
+ifeq ($(UNAME_S),Darwin)
+	OS := OS_MACOS
+else ifeq ($(UNAME_S),Linux)
+	OS := OS_LINUX
+endif
+
+CC = gcc
+
+ifeq ($(CC),clang)
+	COMP := COMPILER_CLANG
+else ifeq ($(CC),gcc)
+	COMP := COMPILER_GCC
+endif
+
+# -ansi -pedantic -pedantic-errors
+CFLAGS = -Wno-long-long -Wall -Wextra \
+		 -Wincompatible-pointer-types \
+		 -Wint-conversion -Wformat \
+		 -Wno-strict-prototypes -Wno-missing-field-initializers \
+		 -Wno-unused-function -Wno-unused-parameter -Wno-unused-variable \
+		 -Wno-unused-but-set-variable \
+		 -fno-show-column
+
+ifeq ($(COMP),COMPILER_CLANG)
+	CFLAGS += -fno-caret-diagnostics
+else ifeq ($(COMP),COMPILER_GCC)
+	CFLAGS += -fno-diagnostics-show-caret
+endif 
+
+ifeq ($(OS),OS_MACOS)
+	FLAGS = -glldb
+	INCLUDE = 
+	LIBS = 
+	FRAMEWORKS = 
+else ifeq ($(OS),OS_LINUX)
+	FLAGS = -O3 # -ggdb -DDEBUG=1 -DINTERNAL=1
+	INCLUDE = 
+	LIBS = 
+	FRAMEWORKS = -lX11 -lXss
+endif
+
+EXE = caffeine
+
+default: $(EXE)
+
+$(EXE): $(EXE).c
+	$(CC) $(CFLAGS) $(FLAGS) \
+		-D$(ARCH)=1 -D$(ENDIANESS)=1 -D$(OS)=1 -D$(COMP)=1 \
+		-D_DEFAULT_SOURCE -DHAVE_SHADOW_H \
+		$(INCLUDE) $^ $(LIBS) \
+		$(FRAMEWORKS) -o $@ $(ifneq $(filter $(OS), OS_MACOS OS_LINUX), \
+		/link /FORCE:MULTIPLE)
+
+watch:
+	@ while true; do \
+		inotifywait -q -q -e 'modify' . && clear && make -B; \
+	done
+
+perf:
+	perf record --call-graph dwarf ./$(EXE)
+
+run:
+	@ clear; ./$(EXE)
+
+install:
+	mv ./$(EXE) /usr/local/bin
+
+clean:
+	@ rm -rf $(EXE) $(EXE).dSYM
diff --git a/caffeine.c b/caffeine.c
new file mode 100644
index 0000000..145555c
--- /dev/null
+++ b/caffeine.c
@@ -0,0 +1,119 @@
+#include <unistd.h> /* access */
+#include <stdlib.h> /* exit */
+#include <syslog.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <errno.h>
+
+#include <X11/extensions/scrnsaver.h>
+
+#define TEMP_FILE "/tmp/caffeine"
+
+char file_exists(const char *filename)
+{
+    return access(filename, F_OK) != -1;
+}
+
+void daemonize()
+{
+    close(0);
+    close(1);
+    close(2);
+    open("/dev/null", O_RDONLY); /* stdin */
+    open("/dev/null", O_WRONLY); /* stdout */
+    open("/dev/null", O_WRONLY); /* stderr */
+    chdir("/");
+    int pid = fork();
+    if(pid > 0)
+        exit(0);
+    setsid();
+    pid = fork();
+    if(pid > 0)
+        exit(0);
+}
+
+#if 1
+static volatile sig_atomic_t n = 0;
+
+void usr1hdl(int sig)
+{
+    int save_errno = errno;
+    signal(SIGUSR1, usr1hdl);
+    n = 1;
+    errno = save_errno;
+}
+
+void termhdl(int sig)
+{
+    int save_errno = errno;
+    signal(SIGTERM, termhdl);
+    n = 2;
+    errno = save_errno;
+}
+#endif
+
+int main(int argc, char *argv[])
+{
+    Display *dpy;
+    int event_base, error_base, major, minor;
+    int is_on;
+
+    /*daemonize();*/
+
+    signal(SIGUSR1, usr1hdl);
+    signal(SIGTERM, termhdl);
+
+    openlog("caffeine", 0, LOG_USER);
+    syslog(LOG_INFO, "Daemon started, pid == %d", getpid());
+
+    dpy = XOpenDisplay(0);
+    if(!dpy) {
+        syslog(LOG_ERR, "Failed to open display.");
+        return 1;
+    }
+
+    if(!XScreenSaverQueryExtension(dpy, &event_base, &error_base)) {
+        syslog(LOG_ERR, "XScreenSaver extension does not exist.");
+        return 2;
+    }
+
+    XScreenSaverQueryVersion(dpy, &major, &minor);
+    if(!(major > 1 || (major == 1 && minor >= 1))) {
+        syslog(LOG_ERR, "XScreenSaver extension is too old, need >=1.1.");
+        return 3;
+    }
+
+    is_on = 0;
+    for(;;) {
+        pause();
+        if(n == 0) {
+            /* do nothing */
+        } else if(n == 1) {
+            is_on = !is_on;
+            if(is_on) {
+                syslog(LOG_INFO, "Enabling...");
+                creat(TEMP_FILE, 0644);
+                XScreenSaverSuspend(dpy, True);
+            } else {
+                syslog(LOG_INFO, "Disabling...");
+                unlink(TEMP_FILE);
+                XScreenSaverSuspend(dpy, False);
+            }
+            XSync(dpy, False);
+        } else if(n == 2) {
+            syslog(LOG_INFO, "Shutting down...");
+            unlink(TEMP_FILE);
+            XScreenSaverSuspend(dpy, False);
+            XSync(dpy, False);
+            break;
+        } else {
+            /* unknown state */
+        }
+
+        n = 0;
+    }
+
+    closelog();
+
+    return 0;
+}