[PATCH iproute2 0/3] hexstring truncation fixes

[Stephen Hemminger <stephen@networkplumber.org>]

This is an alternative to Gris Ge's "Fix netdevsim switch_id display
truncation", which bumped SPRINT_BSIZE from 64 to 128.

hexstring_n2a() writes into a caller buffer and silently truncates when
it is too small: the loop stops once fewer than three bytes remain and
returns the partial string. A 32-byte netdevsim switch id needs 65
bytes but SPRINT_BUF is 64, so "ip -d link show" printed only 62 of the
64 hex characters. Bumping SPRINT_BSIZE hides this one case but leaves
the truncation in place for the next key wider than the buffer, and
enlarges every unrelated SPRINT_BUF on the stack.

Fix the class of bug instead. Add hexstring_alloc(), which sizes the
output to the input, and print_hexstring(), a wrapper over print_string()
that formats and prints a binary attribute with no caller buffer. Move
the print-and-truncate sites onto it, and rebuild the ct label strings,
which open-coded pointer math into a fixed buffer, with hexstring_alloc()
and asprintf().

Stephen Hemminger (3):
  utils: add hexstring_alloc and print_hexstring helpers
  ip, tc: print hex attributes with print_hexstring
  tc: build ct label strings with hexstring_alloc

 include/json_print.h |  3 +++
 include/utils.h      |  1 +
 ip/ipaddress.c       | 19 ++++++-------------
 ip/ipmacsec.c        |  7 ++-----
 lib/bpf_legacy.c     |  6 ++----
 lib/json_print.c     | 12 ++++++++++++
 lib/utils.c          | 21 +++++++++++++++++++++
 tc/f_bpf.c           |  8 +++-----
 tc/f_flower.c        | 25 ++++++++++++++-----------
 tc/m_action.c        |  9 +++------
 tc/m_bpf.c           |  9 +++------
 tc/m_ct.c            | 24 ++++++++++++++----------
 12 files changed, 84 insertions(+), 60 deletions(-)

-- 
2.53.0