resolver: abuse _res a little less

In the past, _res was a global variable.  Now, it's multiple function calls.
Several functions in the resolver use _res multiple times and therefore
call the function(s) far more than necessary.

Fix those callers to store the result of _res in a local variable.

Add __noinline to the definition of res_init() to avoid the code bloat
that these changes would have otherwise incurred.  Thanks to jilles
for noticing this.

Reviewed by:	jilles
MFC after:	1 week
Sponsored by:	Dell Inc.
Differential Revision:	https://reviews.freebsd.org/D3887

diff --git a/lib/libc/resolv/res_data.c b/lib/libc/resolv/res_data.c
index f02083863b03e0e3fb2849e105f051b7bf87e013..e2f905f1075ec13d57311307ad74fef87bfd4588 100644 (file)
--- a/lib/libc/resolv/res_data.c
+++ b/lib/libc/resolv/res_data.c
@@ -77,9 +77,10 @@ const char *_res_sectioncodes[] = {
 
 int  res_ourserver_p(const res_state, const struct sockaddr_in *);
 
-int
+__noinline int
 res_init(void) {
        extern int __res_vinit(res_state, int);
+       res_state statp = &_res;
 
        /*
         * These three fields used to be statically initialized.  This made
@@ -100,14 +101,14 @@ res_init(void) {
         * set in RES_DEFAULT).  Our solution is to declare such applications
         * "broken".  They could fool us by setting RES_INIT but none do (yet).
         */
-       if (!_res.retrans)
-               _res.retrans = RES_TIMEOUT;
-       if (!_res.retry)
-               _res.retry = RES_DFLRETRY;
-       if (!(_res.options & RES_INIT))
-               _res.options = RES_DEFAULT;
-
-       return (__res_vinit(&_res, 1));
+       if (!statp->retrans)
+               statp->retrans = RES_TIMEOUT;
+       if (!statp->retry)
+               statp->retry = RES_DFLRETRY;
+       if (!(statp->options & RES_INIT))
+               statp->options = RES_DEFAULT;
+
+       return (__res_vinit(statp, 1));
 }
 
 void
@@ -122,10 +123,11 @@ fp_query(const u_char *msg, FILE *file) {
 
 void
 fp_nquery(const u_char *msg, int len, FILE *file) {
-       if ((_res.options & RES_INIT) == 0U && res_init() == -1)
+       res_state statp = &_res;
+       if ((statp->options & RES_INIT) == 0U && res_init() == -1)
                return;
 
-       res_pquery(&_res, msg, len, file);
+       res_pquery(statp, msg, len, file);
 }
 
 int
@@ -138,23 +140,25 @@ res_mkquery(int op,                       /*!< opcode of query  */
            u_char *buf,                /*!< buffer to put query  */
            int buflen)                 /*!< size of buffer  */
 {
-       if ((_res.options & RES_INIT) == 0U && res_init() == -1) {
-               RES_SET_H_ERRNO(&_res, NETDB_INTERNAL);
+       res_state statp = &_res;
+       if ((statp->options & RES_INIT) == 0U && res_init() == -1) {
+               RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                return (-1);
        }
-       return (res_nmkquery(&_res, op, dname, class, type,
+       return (res_nmkquery(statp, op, dname, class, type,
                             data, datalen,
                             newrr_in, buf, buflen));
 }
 
 int
 res_mkupdate(ns_updrec *rrecp_in, u_char *buf, int buflen) {
-       if ((_res.options & RES_INIT) == 0U && res_init() == -1) {
-               RES_SET_H_ERRNO(&_res, NETDB_INTERNAL);
+       res_state statp = &_res;
+       if ((statp->options & RES_INIT) == 0U && res_init() == -1) {
+               RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                return (-1);
        }
 
-       return (res_nmkupdate(&_res, rrecp_in, buf, buflen));
+       return (res_nmkupdate(statp, rrecp_in, buf, buflen));
 }
 
 int
@@ -163,11 +167,12 @@ res_query(const char *name,       /*!< domain name  */
          u_char *answer,       /*!< buffer to put answer  */
          int anslen)           /*!< size of answer buffer  */
 {
-       if ((_res.options & RES_INIT) == 0U && res_init() == -1) {
-               RES_SET_H_ERRNO(&_res, NETDB_INTERNAL);
+       res_state statp = &_res;
+       if ((statp->options & RES_INIT) == 0U && res_init() == -1) {
+               RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                return (-1);
        }
-       return (res_nquery(&_res, name, class, type, answer, anslen));
+       return (res_nquery(statp, name, class, type, answer, anslen));
 }
 
 #ifndef _LIBC
@@ -189,12 +194,13 @@ res_isourserver(const struct sockaddr_in *inp) {
 
 int
 res_send(const u_char *buf, int buflen, u_char *ans, int anssiz) {
-       if ((_res.options & RES_INIT) == 0U && res_init() == -1) {
+       res_state statp = &_res;
+       if ((statp->options & RES_INIT) == 0U && res_init() == -1) {
                /* errno should have been set by res_init() in this case. */
                return (-1);
        }
 
-       return (res_nsend(&_res, buf, buflen, ans, anssiz));
+       return (res_nsend(statp, buf, buflen, ans, anssiz));
 }
 
 #ifndef _LIBC
@@ -202,12 +208,13 @@ int
 res_sendsigned(const u_char *buf, int buflen, ns_tsig_key *key,
               u_char *ans, int anssiz)
 {
-       if ((_res.options & RES_INIT) == 0U && res_init() == -1) {
+       res_state statp = &_res;
+       if ((statp->options & RES_INIT) == 0U && res_init() == -1) {
                /* errno should have been set by res_init() in this case. */
                return (-1);
        }
 
-       return (res_nsendsigned(&_res, buf, buflen, key, ans, anssiz));
+       return (res_nsendsigned(statp, buf, buflen, key, ans, anssiz));
 }
 #endif
 
@@ -218,12 +225,13 @@ res_close(void) {
 
 int
 res_update(ns_updrec *rrecp_in) {
-       if ((_res.options & RES_INIT) == 0U && res_init() == -1) {
-               RES_SET_H_ERRNO(&_res, NETDB_INTERNAL);
+       res_state statp = &_res;
+       if ((statp->options & RES_INIT) == 0U && res_init() == -1) {
+               RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                return (-1);
        }
 
-       return (res_nupdate(&_res, rrecp_in, NULL));
+       return (res_nupdate(statp, rrecp_in, NULL));
 }
 
 int
@@ -232,12 +240,13 @@ res_search(const char *name,      /*!< domain name  */
           u_char *answer,      /*!< buffer to put answer  */
           int anslen)          /*!< size of answer  */
 {
-       if ((_res.options & RES_INIT) == 0U && res_init() == -1) {
-               RES_SET_H_ERRNO(&_res, NETDB_INTERNAL);
+       res_state statp = &_res;
+       if ((statp->options & RES_INIT) == 0U && res_init() == -1) {
+               RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                return (-1);
        }
 
-       return (res_nsearch(&_res, name, class, type, answer, anslen));
+       return (res_nsearch(statp, name, class, type, answer, anslen));
 }
 
 int
@@ -247,24 +256,26 @@ res_querydomain(const char *name,
                u_char *answer,         /*!< buffer to put answer  */
                int anslen)             /*!< size of answer  */
 {
-       if ((_res.options & RES_INIT) == 0U && res_init() == -1) {
-               RES_SET_H_ERRNO(&_res, NETDB_INTERNAL);
+       res_state statp = &_res;
+       if ((statp->options & RES_INIT) == 0U && res_init() == -1) {
+               RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                return (-1);
        }
 
-       return (res_nquerydomain(&_res, name, domain,
+       return (res_nquerydomain(statp, name, domain,
                                 class, type,
                                 answer, anslen));
 }
 
 u_int
 res_randomid(void) {
-       if ((_res.options & RES_INIT) == 0U && res_init() == -1) {
-               RES_SET_H_ERRNO(&_res, NETDB_INTERNAL);
+       res_state statp = &_res;
+       if ((statp->options & RES_INIT) == 0U && res_init() == -1) {
+               RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
                return (-1);
        }
 
-       return (res_nrandomid(&_res));
+       return (res_nrandomid(statp));
 }
 
 int
@@ -284,13 +295,15 @@ hostalias(const char *name) {
 int
 local_hostname_length(const char *hostname) {
        int len_host, len_domain;
+       res_state statp;
 
-       if (!*_res.defdname)
+       statp = &_res;
+       if (!*statp->defdname)
                res_init();
        len_host = strlen(hostname);
-       len_domain = strlen(_res.defdname);
+       len_domain = strlen(statp->defdname);
        if (len_host > len_domain &&
-           !strcasecmp(hostname + len_host - len_domain, _res.defdname) &&
+           !strcasecmp(hostname + len_host - len_domain, statp->defdname) &&
            hostname[len_host - len_domain - 1] == '.')
                return (len_host - len_domain - 1);
        return (0);