Make a simple echo clone

exercises/coreutils/echo/Makefile

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

exercises/coreutils/echo/main.c

@@ -0,0 +1,50 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+int main(int argc, char *argv[])
+{
+  if (argc == 1) {
+    write(STDOUT_FILENO, "\n", 1);
+    return EXIT_SUCCESS;
+  }
+
+  size_t argl[argc-1];
+  size_t bytes_count = 0;
+  for (int i = 1; i < argc; i++) {
+    size_t len = strlen(argv[i]);
+    bytes_count += len;
+    argl[i-1] = len;
+  }
+  bytes_count += argc - 2; // whitespaces
+  bytes_count += 1;        // newline
+
+  char *str = malloc(bytes_count + 1);
+  if (str == NULL) {
+    perror("malloc");
+    return EXIT_FAILURE;
+  }
+
+  size_t pos = 0;
+  for (int i = 1; i < argc; i++) {
+    memcpy(str + pos, argv[i], argl[i-1]);
+    pos += argl[i-1];
+    if (i < argc - 1) {
+      str[pos++] = ' ';
+    }
+  }
+  str[pos++] = '\n';
+  str[pos] = '\0';
+
+  if (write(STDOUT_FILENO, str, pos) == -1) {
+     perror("write");
+     free(str);
+     return EXIT_FAILURE;
+  }
+
+  free(str);
+  str = NULL;
+
+  return EXIT_SUCCESS;
+}