tar: cry murder and bail out if file shrinks under us while we tar it up
diff --git a/archival/tar.c b/archival/tar.c
index 6aaa422..99c4adb 100644
--- a/archival/tar.c
+++ b/archival/tar.c
@@ -59,7 +59,7 @@
typedef struct TarHeader TarHeader;
/*
-** writeTarFile(), writeFileToTarball(), and writeTarHeader() are
+** writeTarFile(), writeFileToTarball(), and writeTarHeader() are
** the only functions that deal with the HardLinkInfo structure.
** Even these functions use the xxxHardLinkInfo() functions.
*/
@@ -397,7 +397,17 @@
off_t readSize = 0;
/* write the file to the archive */
- readSize = bb_copyfd_eof(inputFileFd, tbInfo->tarFd);
+ readSize = bb_copyfd_size(inputFileFd, tbInfo->tarFd, statbuf->st_size);
+ if (readSize != statbuf->st_size) {
+ /* Deadly. We record size into header first, */
+ /* and then write out file. If file shrinks in between, */
+ /* tar will be corrupted. So bail out. */
+ /* NB: GNU tar 1.16 warns and pads with zeroes */
+ /* or even seeks back and updates header */
+ bb_error_msg_and_die("short read from %s", fileName);
+ }
+ /* Check that file did not grow in between? */
+ /* if (safe_read(inputFileFd,1) == 1) warn but continue? */
close(inputFileFd);
/* Pad the file up to the tar block size */