Merge branch 'jk/ident-ai-canonname-could-be-null' into maint

In the codepath that comes up with the hostname to be used in an
e-mail when the user didn't tell us, we looked at ai_canonname
field in struct addrinfo without making sure it is not NULL first.

* jk/ident-ai-canonname-could-be-null:
ident: handle NULL ai_canonname

diff --combined ident.c
index e20a772dde4230b0871ffe85a5204919402aaf94,28bc85491872704162c33fa7ac09460bc5b35a11..d17b5bd341eccd604c849201fb1f13153be9736e
--- 1/ident.c
--- 2/ident.c
+++ b/ident.c
@@@ -75,12 -75,14 +75,12 @@@ static int add_mailname_host(struct str
        mailname = fopen("/etc/mailname", "r");
        if (!mailname) {
                if (errno != ENOENT)
 -                      warning("cannot open /etc/mailname: %s",
 -                              strerror(errno));
 +                      warning_errno("cannot open /etc/mailname");
                return -1;
        }
        if (strbuf_getline(&mailnamebuf, mailname) == EOF) {
                if (ferror(mailname))
 -                      warning("cannot read /etc/mailname: %s",
 -                              strerror(errno));
 +                      warning_errno("cannot read /etc/mailname");
                strbuf_release(&mailnamebuf);
                fclose(mailname);
                return -1;
@@@ -101,7 -103,7 +101,7 @@@ static int canonical_name(const char *h
        memset (&hints, '\0', sizeof (hints));
        hints.ai_flags = AI_CANONNAME;
        if (!getaddrinfo(host, NULL, &hints, &ai)) {
-               if (ai && strchr(ai->ai_canonname, '.')) {
+               if (ai && ai->ai_canonname && strchr(ai->ai_canonname, '.')) {
                        strbuf_addstr(out, ai->ai_canonname);
                        status = 0;
                }
@@@ -123,7 -125,7 +123,7 @@@ static void add_domainname(struct strbu
        char buf[1024];
  
        if (gethostname(buf, sizeof(buf))) {
 -              warning("cannot get host name: %s", strerror(errno));
 +              warning_errno("cannot get host name");
                strbuf_addstr(out, "(none)");
                *is_bogus = 1;
                return;
@@@ -184,11 -186,6 +184,11 @@@ static const char *ident_default_date(v
        return git_default_date.buf;
  }
  
 +void reset_ident_date(void)
 +{
 +      strbuf_reset(&git_default_date);
 +}
 +
  static int crud(unsigned char c)
  {
        return  c <= 32  ||