libc/inet: Unbreak gethostent()

Although gethostent() is obsoleted, there is no reason to keep it broken.
Fix two problems:

* commit f65e66078b "resolver: switch to config parser" leave an extra break
  statement in case of GETHOSTENT in __read_etc_hosts_r. In result,
  output buffer wasn't initialized at all.

* gethostent static buffer has insufficient size to store aliases,
  so __read_etc_hosts_r always returns ERANGE. Restore ALIAS_DIM define.

Add test-case.

Signed-off-by: Leonid Lisovskiy <lly.dev@gmail.com>

libc/inet/resolv.c

@@ -337,6 +337,8 @@ Domain name in a message can be represented as either:
 
 #define MAX_RECURSE    5
 #define MAXALIASES  (4)
+/* 1:ip + 1:full + MAX_ALIASES:aliases + 1:NULL */
+#define ALIAS_DIM   (2 + MAXALIASES + 1)
 #define BUFSZ       (80) /* one line */
 
 #define NS_TYPE_ELT					0x40 /*%< EDNS0 extended label type */
@@ -1650,9 +1652,8 @@ int __read_etc_hosts_r(
 		result_buf->h_aliases = tok+1;
 		if (action == GETHOSTENT) {
 			/* Return whatever the next entry happens to be. */
-			break;
-		}
-		if (action == GET_HOSTS_BYADDR) {
+			;
+		} else if (action == GET_HOSTS_BYADDR) {
 			if (strcmp(name, *tok) != 0)
 				continue;
 		} else { /* GET_HOSTS_BYNAME */
@@ -2623,13 +2624,13 @@ struct hostent *gethostent(void)
 {
 	static struct hostent hoste;
 	static char *buf = NULL;
-	struct hostent *host;
+	struct hostent *host = NULL;
 #ifndef __UCLIBC_HAS_IPV6__
  #define HOSTENT_BUFSZ	(sizeof(struct in_addr) + sizeof(struct in_addr *) * 2 + \
-			BUFSZ /*namebuffer*/ + 2 /* margin */)
+			sizeof(char *)*ALIAS_DIM + BUFSZ /*namebuffer*/ + 2 /* margin */)
 #else
  #define HOSTENT_BUFSZ	(sizeof(struct in6_addr) + sizeof(struct in6_addr *) * 2 + \
-			BUFSZ /*namebuffer*/ + 2 /* margin */)
+			sizeof(char *)*ALIAS_DIM + BUFSZ /*namebuffer*/ + 2 /* margin */)
 #endif /* __UCLIBC_HAS_IPV6__ */
 
 	__INIT_GETXX_BUF(HOSTENT_BUFSZ);

test/inet/gethost.c

@@ -0,0 +1,40 @@
+#include <errno.h>
+#include <netdb.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+
+int main(void)
+{
+       in_addr_t addr = inet_addr("127.0.0.1");
+       struct hostent *hent;
+
+       hent = gethostent();
+       if (hent == NULL) {
+               printf("gethostent(%d):%s\n", errno, hstrerror(h_errno));
+               exit(1);
+       }
+
+       hent = gethostbyname("localhost");
+       if (hent == NULL) {
+               printf("gethostbyname(%d):%s\n", errno, hstrerror(h_errno));
+               exit(1);
+       }
+
+       hent = gethostbyname2("localhost", AF_INET);
+       if (hent == NULL) {
+               printf("gethostbyname2(%d):%s\n", errno, hstrerror(h_errno));
+               exit(1);
+       }
+
+       hent = gethostbyaddr(&addr, sizeof(addr), AF_INET);
+       if (hent == NULL) {
+               printf("gethostbyaddr(%d):%s\n", errno, hstrerror(h_errno));
+               exit(1);
+       }
+
+       return 0;
+}
+