netdb: Add protocol and service functions from LSB

These take advantage of the musl implementation for simplicity.

Signed-off-by: Samuel Holland <samuel@sholland.org>

1 files changed, 79 insertions, 0 deletions

diff --git a/libgcompat/netdb.c b/libgcompat/netdb.c
new file mode 100644
index 0000000..ae7713a
--- /dev/null
+++ b/libgcompat/netdb.c
@@ -0,0 +1,79 @@
+#include <errno.h>  /* ENOENT */
+#include <netdb.h>  /* getproto* */
+#include <stddef.h> /* NULL, size_t */
+#include <string.h> /* memcpy */
+
+/**
+ * Retrieve information from the network protocol database by protocol name,
+ * reentrantly.
+ *
+ * LSB 5.0: LSB-Core-generic/baselib-getprotobyname-r.html
+ */
+int getprotobyname_r(const char *name, struct protoent *result_buf, char *buf,
+                     size_t buflen, struct protoent **result)
+{
+	struct protoent *prototmp = getprotobyname(name);
+
+	/* musl does not reuse static storage, so no race is possible. */
+	if (prototmp == NULL) {
+		*result = NULL;
+		return ENOENT;
+	}
+	*result = memcpy(result_buf, prototmp, sizeof(*result_buf));
+
+	return 0;
+}
+
+/**
+ * Retrieve information from the network protocol database by protocol number,
+ * reentrantly.
+ *
+ * LSB 5.0: LSB-Core-generic/baselib-getprotobynumber-r.html
+ */
+int getprotobynumber_r(int proto, struct protoent *result_buf, char *buf,
+                       size_t buflen, struct protoent **result)
+{
+	struct protoent *prototmp = getprotobynumber(proto);
+
+	/* musl does not reuse static storage, so no race is possible. */
+	if (prototmp == NULL) {
+		*result = NULL;
+		return ENOENT;
+	}
+	*result = memcpy(result_buf, prototmp, sizeof(*result_buf));
+
+	return 0;
+}
+
+/**
+ * Read the next entry of the protocol database, reentrantly.
+ *
+ * LSB 5.0: LSB-Core-generic/baselib-getprotoent-r.html
+ */
+int getprotoent_r(struct protoent *result_buf, char *buf, size_t buflen,
+                  struct protoent **result)
+{
+	struct protoent *prototmp = getprotoent();
+
+	/* musl does not reuse static storage, so no race is possible. */
+	if (prototmp == NULL) {
+		*result = NULL;
+		return ENOENT;
+	}
+	*result = memcpy(result_buf, prototmp, sizeof(*result_buf));
+
+	return 0;
+}
+
+/**
+ * Read the next entry of the network services database, reentrantly.
+ *
+ * LSB 5.0: LSB-Core-generic/baselib-getservent-r.html
+ */
+int getservent_r(struct servent *result_buf, char *buf, size_t buflen,
+                 struct servent **result)
+{
+	/* musl does not implement getservent(). */
+	*result = NULL;
+	return ENOENT;
+}