[gcc r12-7705] c++tools: Work around a BSD bug in getaddrinfo().

[gcc r12-7705] c++tools: Work around a BSD bug in getaddrinfo().

[Iain D Sandoe]

https://gcc.gnu.org/g:41f01c97153d403fb34eefac245bab8ba472beea

commit r12-7705-g41f01c97153d403fb34eefac245bab8ba472beea
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Sun Mar 13 16:34:54 2022 +0000

    c++tools: Work around a BSD bug in getaddrinfo().
    
    Some versions of the BSD getaddrinfo() call do not work with the specific
    input of "0" for the servname entry (a segv results).  Since we are making
    the call with a dummy port number, the value is actually no important, other
    than it should be in range.  Work around the BSD bug by using "1" instead.
    
    Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
    
    c++tools/ChangeLog:
    
            * server.cc (accept_from): Use "1" as the dummy port number.

Diff:
---
 c++tools/server.cc | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/c++tools/server.cc b/c++tools/server.cc
index 8c6ad314886..00154a05925 100644
--- a/c++tools/server.cc
+++ b/c++tools/server.cc
@@ -360,7 +360,11 @@ accept_from (char *arg ATTRIBUTE_UNUSED)
   hints.ai_next = NULL;
 
   struct addrinfo *addrs = NULL;
-  if (int e = getaddrinfo (slash == arg ? NULL : arg, "0", &hints, &addrs))
+  /* getaddrinfo requires either hostname or servname to be non-null, so that we must
+     set a port number (to cover the case that the string passed contains just /NN).
+     Use an arbitrary in-range port number, but avoiding "0" which triggers a bug on
+     some BSD variants.  */
+  if (int e = getaddrinfo (slash == arg ? NULL : arg, "1", &hints, &addrs))
     {
       noisy ("cannot resolve '%s': %s", arg, gai_strerror (e));
       ok = false;