Android bionic patch to log /etc/hosts lookup times, see https://github.com/sufficientlysecure/ad-away/issues/491

bionic-libc-lookup-times.diff

diff --git a/libc/dns/net/getaddrinfo.c b/libc/dns/net/getaddrinfo.c
index 2612d6a..277afb0 100644
--- a/libc/dns/net/getaddrinfo.c
+++ b/libc/dns/net/getaddrinfo.c
@@ -80,6 +80,7 @@
 #include <fcntl.h>
 #include <sys/cdefs.h>
 #include <sys/types.h>
+#include <time.h>
 #include <sys/stat.h>
 #include <sys/param.h>
 #include <sys/socket.h>
@@ -103,6 +104,7 @@
 #include <string.h>
 #include <strings.h>
 #include <unistd.h>
+#include <private/libc_logging.h>
 
 #include <syslog.h>
 #include <stdarg.h>
@@ -2042,15 +2044,18 @@ _gethtent(FILE **hostf, const char *name, const struct addrinfo *pai)
 	const char *addr;
 	char hostbuf[8*1024];
 
+	clock_t start = clock();
+	void *retval = NULL;
+
 //	fprintf(stderr, "_gethtent() name = '%s'\n", name);
 	assert(name != NULL);
 	assert(pai != NULL);
 
 	if (!*hostf && !(*hostf = fopen(_PATH_HOSTS, "r" )))
-		return (NULL);
+		goto ret;
  again:
 	if (!(p = fgets(hostbuf, sizeof hostbuf, *hostf)))
-		return (NULL);
+		goto ret;
 	if (*p == '#')
 		goto again;
 	if (!(cp = strpbrk(p, "#\n")))
@@ -2095,7 +2100,16 @@ found:
 			}
 		}
 	}
-	return res0;
+	retval = res0;
+	clock_t endt;
+ret:
+	endt = clock();
+	unsigned int mstime = (endt - start) * 1000 / CLOCKS_PER_SEC;
+	
+	__libc_format_log(ANDROID_LOG_WARN, "libc", "Lookup of `%s' took %u ms\n", name, mstime);
+
+
+	return retval;
 }
 
 /*ARGSUSED*/