split: support split -n on larger pipe input

* bootstrap.conf (gnulib_modules): Add free-posix, tmpfile.
* src/split.c (copy_to_tmpfile): New function.
(input_file_size): Use it to split larger files when sizes cannot
easily be determined via fstat or lseek.  See Bug#61386#235.
* tests/split/l-chunk.sh: Mark tests of /dev/zero as
very expensive since they exhaust /tmp.

1 files changed, 4 insertions, 2 deletions

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index f0e46b9ee..7852e9f8a 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -3409,8 +3409,10 @@ are not split even if they overlap a partition, the files written
 can be larger or smaller than the partition size, and even empty
 if a line/record is so long as to completely overlap the partition.
 
-For @samp{r} mode, the size of @var{input} is irrelevant,
-and so can be a pipe for example.
+When the input is a pipe or some other special file where the size
+cannot easily be determined, there is no trouble for @samp{r} mode
+because the size of the input is irrelevant.  For other modes, such an
+input is first copied to a temporary to determine its size.
 
 @item -a @var{length}
 @itemx --suffix-length=@var{length}