Support --make-file

build-root.c

@@ -63,6 +63,7 @@ usage ()
            "	--mount-proc DEST	  Mount procfs on DEST in the sandbox\n"
            "	--mount-dev DEST	  Mount new dev on DEST in the sandbox\n"
            "	--make-dir DEST		  Create dir at DEST in the sandbox\n"
+           "	--make-file FD DEST	  Copy from FD to dest DEST in the sandbox\n"
            "	--make-symlink SRC DEST	  Create symlink at DEST in the sandbox with target SRC\n"
            "	--make-passwd DEST	  Create trivial /etc/passwd file at DEST in the sandbox\n"
            "	--make-group DEST	  Create trivial /etc/group file at DEST in the sandbox\n"
@@ -296,6 +297,7 @@ typedef enum {
   SETUP_MOUNT_PROC,
   SETUP_MOUNT_DEV,
   SETUP_MAKE_DIR,
+  SETUP_MAKE_FILE,
   SETUP_MAKE_SYMLINK,
   SETUP_MAKE_PASSWD,
   SETUP_MAKE_GROUP,
@@ -307,6 +309,7 @@ struct _SetupOp {
   SetupOpType type;
   const char *source;
   const char *dest;
+  int fd;
   SetupOp *next;
 };
 
@@ -319,6 +322,7 @@ setup_op_new (SetupOpType type)
   SetupOp *op = xcalloc (sizeof (SetupOp));
 
   op->type = type;
+  op->fd = -1;
   if (last_op != NULL)
     last_op->next = op;
   else
@@ -518,6 +522,26 @@ main (int argc,
           argv += 1;
           argc -= 1;
         }
+      else if (strcmp (arg, "--make-file") == 0)
+        {
+          SetupOp *op;
+          int file_fd;
+          char *endptr;
+
+          if (argc < 3)
+            die ("--make-file takes two arguments");
+
+          file_fd = strtol (argv[1], &endptr, 10);
+          if (argv[1][0] == 0 || endptr[0] != 0 || file_fd < 0)
+            die ("Invalid fd: %s", argv[1]);
+
+          op = setup_op_new (SETUP_MAKE_FILE);
+          op->fd = file_fd;
+          op->dest = argv[2];
+
+          argv += 2;
+          argc -= 2;
+        }
       else if (strcmp (arg, "--make-symlink") == 0)
         {
           SetupOp *op;
@@ -840,6 +864,21 @@ main (int argc,
 
         break;
 
+      case SETUP_MAKE_FILE:
+        {
+          cleanup_fd int dest_fd = -1;
+
+          dest_fd = creat (dest, 0666);
+          if (dest_fd == -1)
+            die_with_error ("Can't create file %s", op->dest);
+
+          if (copy_file_data (op->fd, dest_fd) != 0)
+            die_with_error ("Can't write data to file %s", op->dest);
+
+          close (op->fd);
+        }
+        break;
+
       case SETUP_MAKE_SYMLINK:
         if (symlink (op->source, dest) != 0)
           die_with_error ("Can't make symlink at %s", op->dest);

utils.c

@@ -330,6 +330,71 @@ create_file (const char *path,
   return res;
 }
 
+#define BUFSIZE	8192
+/* Sets errno on error (!= 0), ENOSPC on short write */
+int
+copy_file_data (int     sfd,
+                int     dfd)
+{
+  char buffer[BUFSIZE];
+  ssize_t bytes_read;
+
+  while (TRUE)
+    {
+      bytes_read = read (sfd, buffer, BUFSIZE);
+      if (bytes_read == -1)
+        {
+          if (errno == EINTR)
+            continue;
+
+          return -1;
+        }
+
+      if (bytes_read == 0)
+        break;
+
+      if (write_to_fd (dfd, buffer, bytes_read) != 0)
+        return -1;
+    }
+
+  return 0;
+}
+
+/* Sets errno on error (!= 0), ENOSPC on short write */
+int
+copy_file (const char *src_path,
+           const char *dst_path,
+           mode_t      mode)
+{
+  int sfd;
+  int dfd;
+  int res;
+  int errsv;
+
+  sfd = open (src_path, O_CLOEXEC | O_RDONLY);
+  if (sfd == -1)
+    return -1;
+
+  dfd = creat (dst_path, mode);
+  if (dfd == -1)
+    {
+      errsv = errno;
+      close (sfd);
+      errno = errsv;
+      return -1;
+    }
+
+  res = copy_file_data (sfd, dfd);
+
+  errsv = errno;
+  close (sfd);
+  close (dfd);
+  errno = errsv;
+
+  return res;
+}
+
+
 /* Sets errno on error (== NULL) */
 char *
 load_file_at (int dirfd,

utils.h

@@ -81,6 +81,11 @@ int   write_file_at  (int          dirfd,
 int   write_to_fd    (int          fd,
                       const char  *content,
                       ssize_t      len);
+int   copy_file_data (int          sfd,
+                      int          dfd);
+int   copy_file      (const char  *src_path,
+                      const char  *dst_path,
+                      mode_t       mode);
 int   create_file    (const char  *path,
                       mode_t       mode,
                       const char  *content);