[PATCH 0/6] posix: Do not recurse once per pattern component in glob (BZ #34453)

glob calls itself recursively once per directory component and once per
brace expression, so stack usage grows with the length of the pattern
and a few thousand components overflow a default 8 MiB stack before
glob can answer (BZ #34453).

The last patch replaces the recursion with heap-allocated state, the
same approach used for the recent ftw fix (commit 418581126ac, "io:
ftw: Use state stack instead of recursion (BZ 33882)").  The directory
components are collected into an array and matched iteratively from
left to right, and the brace expansions are walked with an explicit
stack.

The patches before it remove the alloca usage from glob.  Besides
simplifying the recursion removal, this makes glibc and gnulib run the
same code: gnulib builds this file with __libc_use_alloca defined to
false, so the alloca paths were compiled out there and only glibc ever
executed them.  The alloca accounting is also a tricky and misleading
API, it only counts the buffers explicitly allocated through
alloca_account, not the rest of each frame, and every recursive call
started again with a fresh budget, so it never bounded the actual
stack usage.

Checked on x86_64-linux-gnu, aarch64-linux-gnu, and i686-linux-gnu.
The file was also built and tested as gnulib's glob replacement.

Adhemerval Zanella (6):
  posix: Use malloc instead of alloca for the glob directory name
  posix: Move the glob home directory lookups out of __glob
  posix: Use malloc instead of alloca for the glob user name
  posix: Use malloc instead of alloca for the glob brace expansion
  posix: Remove the alloca uses from glob_in_dir
  posix: Do not recurse once per pattern component in glob [BZ #34453]

 posix/Makefile           |    1 +
 posix/glob.c             | 1043 ++++++++++++++++++++++++++------------
 posix/tst-glob-bz34453.c |  116 +++++
 posix/tst-glob-tilde.c   |   19 +
 4 files changed, 847 insertions(+), 332 deletions(-)
 create mode 100644 posix/tst-glob-bz34453.c

-- 
2.53.0