Re: pkg/58433: pkg_add segmentation fault

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

There are actually two issues here:

1. The failure mode for missing xbase was confusing.

   We have now addressed this by checking REQUIRES -- although the
   check is now tripping over other problems because, e.g., the gcc10
   package's REQUIRES entries are broken, PR pkg/58857: gcc10-libs
   REQUIRES libraries so it cannot be added wth new pkg_add.  So we
   might have to revert that, or weaken the check, if we can't fix
   gcc>=10 promptly.

2. pkg_add(8) proceeded to crash with SIGSEGV for reasons unrelated to
   the missing shared library.

   This turns out to be another instance of PR pkg/57179: occasional
   pkg_add core dumps, which was a bug in libfetch that is now fixed
   and pulled up to netbsd-10 to be included in the imminent 10.1
   release.

Here's the stack trace I got out of a core dump by following the steps
to reproduce on 10.0 exactly, without `-vvv' which happens to suppress
the symptoms of (2) but is more helpful for diagnosing (1), confirming
that (2) matches PR 57179:

$ gdb -batch -ex bt /usr/sbin/pkg_add /usr/pkg/pkg_add.core
[New process 26694]
Core was generated by `pkg_add'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x000076fbd35824ab in strcmp () from /usr/lib/libc.so.12
#0  0x000076fbd35824ab in strcmp () from /usr/lib/libc.so.12
#1  0x000076fbd5a097c0 in fetch_cache_put (conn=0x76fbd64bfc00, closecb=0x76fbd5a09f97 <fetch_close>) at /usr/src/external/bsd/fetch/dist/libfetch/common.c:411
#2  0x000076fbd5a046eb in http_closefn (v=0x76fbd5c70bb0) at /usr/src/external/bsd/fetch/dist/libfetch/http.c:331
#3  0x000076fbd5a0a99c in fetchIO_close (f=0x76fbd64647e0) at /usr/src/external/bsd/fetch/dist/libfetch/common.c:1032
#4  0x000000010b00e96b in fetch_archive_close (a=<optimized out>, client_data=0x76fbd5cc0dc0) at /usr/src/external/bsd/pkg_install/dist/lib/pkg_io.c:138
#5  0x000076fbd4a7e16b in client_close_proxy (self=<optimized out>) at /usr/src/external/bsd/libarchive/dist/libarchive/archive_read.c:257
#6  client_close_proxy (self=0x76fbd64a5fc0) at /usr/src/external/bsd/libarchive/dist/libarchive/archive_read.c:248
#7  0x000076fbd4a7e324 in close_filters (a=<optimized out>, a=<optimized out>) at /usr/src/external/bsd/libarchive/dist/libarchive/archive_read.c:1009
#8  0x000076fbd4a7e3af in _archive_read_close (_a=0x76fbd64e1a00) at /usr/src/external/bsd/libarchive/dist/libarchive/archive_read.c:1069
#9  0x000076fbd4a7eedb in _archive_read_free (_a=0x76fbd64e1a00) at /usr/src/external/bsd/libarchive/dist/libarchive/archive_read.c:1094
#10 _archive_read_free (_a=0x76fbd64e1a00) at /usr/src/external/bsd/libarchive/dist/libarchive/archive_read.c:1080
#11 0x000000010b006c7f in pkg_do (pkgpath=<optimized out>, mark_automatic=0, top_level=top_level@entry=1) at /usr/src/external/bsd/pkg_install/dist/add/perform.c:1602
#12 0x000000010b008354 in pkg_perform (pkgs=pkgs@entry=0x7f7fff570020) at /usr/src/external/bsd/pkg_install/dist/add/perform.c:1617
#13 0x000000010b0119fd in main (argc=<optimized out>, argv=<optimized out>) at /usr/src/external/bsd/pkg_install/dist/add/main.c:201