1 files changed, 54 insertions, 0 deletions
diff --git a/src/backup_streamer.c b/src/backup_streamer.c
new file mode 100644
index 0000000..3b5929b
--- /dev/null
+++ b/src/backup_streamer.c
@@ -0,0 +1,54 @@
+#include <unistd.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <assert.h>
+#include <string.h>
+
+#include "lib.h"
+
+struct backup_streamer backup_streamer_init(char *cwd) {
+  struct backup_streamer output;
+  output.cwd_length = strnlen(cwd, PATH_MAX);
+  char *end = stpncpy(output.to_prefix, cwd, PATH_MAX - 3);
+  *(end++) = '.';
+  *(end++) = 'b';
+  *(end++) = 'k';
+  *(end++) = 0;
+  return output;
+}
+
+void get_backup_destination(struct backup_streamer *streamer, char* from) {
+  char *cursor = stpncpy(streamer->cursor, streamer->to_prefix, PATH_MAX);
+  from += streamer->cwd_length;
+  int n = (cursor - streamer->cursor) - 2;
+  strncpy(cursor, from, PATH_MAX - n);
+}
+
+int is_dir(char *path) {
+  struct stat info;
+  if (stat(path, &info) != 0) return -1;
+  return S_ISDIR(info.st_mode);
+}
+
+void backup_file(char *from, char *to) {
+  ensure_parents_exist(to);
+  pid_t pid;
+  if ((pid = fork()) == 0) {
+    char *argv[] = {"/usr/bin/cp", from, to, NULL};
+    execv(argv[0], argv);
+  }
+  assert(waitpid(pid, NULL, 0) != -1);
+}
+
+void ensure_parents_exist(char *path) {
+  int n = strnlen(path, PATH_MAX);
+  for (int i = 1; i < n; i++) {
+    if (path[i] != '/') continue;
+    path[i] = 0;
+    if (is_dir(path) == -1) {
+      debugf("mkdir %s\n", path);
+      assert(mkdir(path, 0755) != -1);
+    }
+    path[i] = '/';
+  }
+}