Make a simple sleep clone

exercises/coreutils/sleep/Makefile

@@ -0,0 +1,19 @@
+CC      := gcc
+CFLAGS  := -Wall -Wextra -pedantic -std=c11 -pthread -g
+TARGET  := sleep
+SRC     := main.c
+OBJS    := $(SRC:.c=.o)
+
+.PHONY: all clean
+
+all: $(TARGET)
+
+$(TARGET): $(OBJS)
+	$(CC) $(CFLAGS) -o $@ $^
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+clean:
+	rm -f $(TARGET) $(OBJS)
+

exercises/coreutils/sleep/main.c

@@ -0,0 +1,58 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <unistd.h>
+
+static void alarm_handler(int, siginfo_t *, void *);
+
+int main(int argc, char *argv[])
+{
+  struct sigaction act, old_act;
+  sigset_t newmask, oldmask, suspmask;
+  
+  if (argc < 2) {
+    fprintf(stderr, "Usage: %s SECONDS", argv[0]);
+    return EXIT_FAILURE;
+  }
+
+  unsigned int timeout = (unsigned int)strtol(argv[1], (char **)NULL, 10);
+
+  sigemptyset(&act.sa_mask);
+  act.sa_flags = 0;
+  act.sa_sigaction = alarm_handler;
+  
+  if (sigaction(SIGALRM, &act, &old_act) < 0) {
+    perror("sigaction");
+    return EXIT_FAILURE;
+  }
+
+  sigemptyset(&newmask);
+  sigaddset(&newmask, SIGALRM);
+  if (sigprocmask(SIG_BLOCK, &newmask, &oldmask) < 0) {
+    perror("sigprocmask");
+    return EXIT_FAILURE;
+  }
+
+  alarm(timeout);
+
+  suspmask = oldmask;
+  sigdelset(&suspmask, SIGALRM);
+  sigsuspend(&suspmask);
+
+  alarm(0);
+
+  if (sigaction(SIGALRM, &old_act, NULL) == -1) {
+    perror("sigaction restore");
+  }
+
+  if (sigprocmask(SIG_SETMASK, &oldmask, NULL) < 0) {
+    perror("sigprocmask restore");
+  }
+  
+  return EXIT_SUCCESS;
+}
+
+static void alarm_handler(int signo, siginfo_t *info, void *context)
+{
+  //printf("Catch signal %d from %u\n", signo, info->si_pid);
+}