hygiene, clarify clit_bit handling in differ(), close expfd only when open()ed

Signed-off-by: Sebastian Freundt <hroptatyr@fresse.org>
hygiene, resize buffers in bufexp() so that \nul terminators fit in as well

Signed-off-by: Sebastian Freundt <hroptatyr@fresse.org>
hygiene, only close fds when they're non-negative

Signed-off-by: Sebastian Freundt <hroptatyr@fresse.org>
hygiene, clarify (through comments) why there are 1U offsets in prepend_path()

Signed-off-by: Sebastian Freundt <hroptatyr@fresse.org>
hygiene, mind cert's ENV34-C and strdup() getenv()'d data right away

Signed-off-by: Sebastian Freundt <hroptatyr@fresse.org>
Merge branch 'code/hygiene'

* code/hygiene:
  hygiene, mind cert's ENV34-C and strdup() getenv()'d data right away
  hygiene, clarify (through comments) why there are 1U offsets in prepend_path()
  hygiene, only close fds when they're non-negative
  hygiene, resize buffers in bufexp() so that \nul terminators fit in as well
  hygiene, clarify clit_bit handling in differ(), close expfd only when open()ed