Function tarCreateHeader

src/port/tar.c:113–206

* Fill in the buffer pointed to by h with a tar format header. This buffer * must always have space for 512 characters, which is a requirement of * the tar format. */

 * the tar format.
 */
enum tarError
tarCreateHeader(char *h, const char *filename, const char *linktarget,
				pgoff_t size, mode_t mode, uid_t uid, gid_t gid, time_t mtime)
{
	if (strlen(filename) > 99)
		return TAR_NAME_TOO_LONG;

	if (linktarget && strlen(linktarget) > 99)
		return TAR_SYMLINK_TOO_LONG;

	memset(h, 0, 512);			/* assume tar header size */

	/* Name 100 */
	strlcpy(&h[0], filename, 100);
	if (linktarget != NULL || S_ISDIR(mode))
	{
		/*
		 * We only support symbolic links to directories, and this is
		 * indicated in the tar format by adding a slash at the end of the
		 * name, the same as for regular directories.
		 */
		int			flen = strlen(filename);

		flen = Min(flen, 99);
		h[flen] = '/';
		h[flen + 1] = '\0';
	}

	/* Mode 8 - this doesn't include the file type bits (S_IFMT)  */
	print_tar_number(&h[100], 8, (mode & 07777));

	/* User ID 8 */
	print_tar_number(&h[108], 8, uid);

	/* Group 8 */
	print_tar_number(&h[116], 8, gid);

	/* File size 12 */
	if (linktarget != NULL || S_ISDIR(mode))
		/* Symbolic link or directory has size zero */
		print_tar_number(&h[124], 12, 0);
	else
		print_tar_number(&h[124], 12, size);

	/* Mod Time 12 */
	print_tar_number(&h[136], 12, mtime);

	/* Checksum 8 cannot be calculated until we've filled all other fields */

	if (linktarget != NULL)
	{
		/* Type - Symbolic link */
		h[156] = '2';
		/* Link Name 100 */
		strlcpy(&h[157], linktarget, 100);
	}
	else if (S_ISDIR(mode))
	{