init commit

3sem/seminars/l7/01.c

@@ -0,0 +1,27 @@
+#include <stdio.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+int
+main(int argc, char *argv[])
+{
+    int fd = open(argv[1], O_RDWR | O_CREAT, 0666);
+
+    struct stat st;
+    lseek(fd, 0, SEEK_END);
+    stat(argv[1], &st);
+    char *addr = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+
+    for (int i = 0; i < st.st_size / 2; i++) {
+        char tmp = addr[i];
+        addr[i] = addr[st.st_size - i - 1];
+        addr[st.st_size - i - 1] = tmp;
+    }
+
+    close(fd);
+    munmap(addr, st.st_size);
+
+    return 0;
+}