MFC r289837

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.

Sponsored by:   Dell Inc.

1 files changed, 52 insertions, 39 deletions

diff --git a/lib/libc/resolv/res_data.c b/lib/libc/resolv/res_data.c
index f020838..e2f905f 100644
--- 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);