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tar: don't assume O_NONBLOCK is benign on regular files

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On Data Migration Facility (DMF), High Peformance Storage System (HPSS),
and presumably other file systems based on hierarchical storage, opening
a regular file with O_NONBLOCK can cause later reads to fail with
errno == EAGAIN.  We need the O_NONBLOCK to avoid some security races.
Work around the problem by using fcntl to clear the O_NONBLOCK
flag if I/O fails with that errno value.
Problem reported by Vitezslav Cizek in
<http://lists.gnu.org/archive/html/bug-tar/2012-01/msg00000.html>.
* src/common.h (blocking_read, blocking_write): New decls.
* src/misc.c (blocking_read, blocking_write): New functions.
* src/compare.c (process_rawdata):
* src/create.c (dump_regular_file):
* src/extract.c (extract_file):
* src/sparse.c (sparse_scan_file, sparse_extract_region):
This commit is contained in:
Paul Eggert
2012-01-06 12:38:55 -08:00
parent 7a5a3708cb
commit 03858cf583
6 changed files with 64 additions and 10 deletions
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6
src/sparse.c
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@@ -230,7 +230,7 @@ sparse_scan_file (struct tar_sparse_file *file)
if (!tar_sparse_scan (file, scan_begin, NULL))
return false;
while ((count = safe_read (fd, buffer, sizeof buffer)) != 0
while ((count = blocking_read (fd, buffer, sizeof buffer)) != 0
&& count != SAFE_READ_ERROR)
{
/* Analyze the block. */
@@ -360,7 +360,7 @@ sparse_extract_region (struct tar_sparse_file *file, size_t i)
return false;
}
set_next_block_after (blk);
count = full_write (file->fd, blk->buffer, wrbytes);
count = blocking_write (file->fd, blk->buffer, wrbytes);
write_size -= count;
file->dumped_size += count;
mv_size_left (file->stat_info->archive_file_size - file->dumped_size);
@@ -991,7 +991,7 @@ pax_dump_header_1 (struct tar_sparse_file *file)
off_t size = 0;
struct sp_array *map = file->stat_info->sparse_map;
char *save_file_name = file->stat_info->file_name;
#define COPY_STRING(b,dst,src) do \
{ \
char *endp = b->buffer + BLOCKSIZE; \