Add some more necessary locks

libc/dns/freeaddrinfo.c

@@ -21,6 +21,7 @@
 
 /**
  * Frees addresses returned by getaddrinfo().
+ * @threadsafe
  */
 int freeaddrinfo(struct addrinfo *ai) {
   struct addrinfo *next;

libc/dns/getaddrinfo.c

@@ -41,6 +41,7 @@
  * @param res receives a pointer that must be freed with freeaddrinfo(),
  *     and won't be modified if -1 is returned
  * @return 0 on success or EAI_xxx value
+ * @threadsafe
  */
 int getaddrinfo(const char *name, const char *service,
                 const struct addrinfo *hints, struct addrinfo **res) {

libc/dns/gethoststxt.c

@@ -23,6 +23,7 @@
 #include "libc/dce.h"
 #include "libc/dns/hoststxt.h"
 #include "libc/fmt/fmt.h"
+#include "libc/intrin/pthread.h"
 #include "libc/macros.internal.h"
 #include "libc/nt/systeminfo.h"
 #include "libc/runtime/runtime.h"
@@ -32,6 +33,7 @@
 static struct HostsTxt *g_hoststxt;
 static struct HostsTxtInitialStaticMemory {
   struct HostsTxt ht;
+  pthread_mutex_t lock;
   struct HostsTxtEntry entries[8];
   char strings[64];
 } g_hoststxt_init;
@@ -53,6 +55,7 @@ static textwindows dontinline char *GetNtHostsTxtPath(char *pathbuf,
  * Returns hosts.txt map.
  *
  * @note yoinking realloc() ensures there's no size limits
+ * @threadsafe
  */
 const struct HostsTxt *GetHostsTxt(void) {
   FILE *f;
@@ -60,6 +63,7 @@ const struct HostsTxt *GetHostsTxt(void) {
   char pathbuf[PATH_MAX];
   struct HostsTxtInitialStaticMemory *init;
   init = &g_hoststxt_init;
+  pthread_mutex_lock(&init->lock);
   if (!g_hoststxt) {
     g_hoststxt = &init->ht;
     init->ht.entries.n = pushpop(ARRAYLEN(init->entries));
@@ -78,5 +82,6 @@ const struct HostsTxt *GetHostsTxt(void) {
       fclose(f);
     }
   }
+  pthread_mutex_unlock(&init->lock);
   return g_hoststxt;
 }

libc/dns/getresolvconf.c

@@ -20,6 +20,7 @@
 #include "libc/dce.h"
 #include "libc/dns/resolvconf.h"
 #include "libc/fmt/fmt.h"
+#include "libc/intrin/pthread.h"
 #include "libc/macros.internal.h"
 #include "libc/runtime/runtime.h"
 #include "libc/sock/sock.h"
@@ -28,17 +29,20 @@
 static struct ResolvConf *g_resolvconf;
 static struct ResolvConfInitialStaticMemory {
   struct ResolvConf rv;
+  pthread_mutex_t lock;
   struct sockaddr_in nameservers[3];
 } g_resolvconf_init;
 
 /**
  * Returns singleton with DNS server address.
+ * @threadsafe
  */
 const struct ResolvConf *GetResolvConf(void) {
   int rc;
   FILE *f;
   struct ResolvConfInitialStaticMemory *init;
   init = &g_resolvconf_init;
+  pthread_mutex_lock(&init->lock);
   if (!g_resolvconf) {
     g_resolvconf = &init->rv;
     pushmov(&init->rv.nameservers.n, ARRAYLEN(init->nameservers));
@@ -58,5 +62,6 @@ const struct ResolvConf *GetResolvConf(void) {
       /* TODO(jart): Elevate robustness. */
     }
   }
+  pthread_mutex_unlock(&init->lock);
   return g_resolvconf;
 }

libc/dns/lookupservicesbyname.c

@@ -47,6 +47,7 @@
  * @return -1 on error, or positive port number
  * @note aliases are read from file for comparison, but not returned.
  * @see LookupServicesByPort
+ * @threadsafe
  */
 int LookupServicesByName(const char *servname, char *servproto,
                          size_t servprotolen, char *buf, size_t bufsize,