From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Mon, 15 Aug 2022 16:03:57 +0000 (+0100)
Subject: prefork-interp: break out protocol_exchange (nfc)
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=commitdiff_plain;h=c7215e9f5ae0b5df0fe4bf04e0d2433d6063b7da;p=chiark-utils.git

prefork-interp: break out protocol_exchange (nfc)

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---

diff --git a/cprogs/prefork-interp.c b/cprogs/prefork-interp.c
index 22cdc7d..3ebcf01 100644
--- a/cprogs/prefork-interp.c
+++ b/cprogs/prefork-interp.c
@@ -280,6 +280,22 @@ static bool was_eof(FILE *call_sock) {
   return feof(call_sock) || errno==ECONNRESET;
 }
 
+// Does protocol exchange.  Returns 0 if OK, -1 if peer was garbage.
+static int protocol_exchange(FILE *call_sock) {
+  char ack;
+  size_t sr = fread(&ack, sizeof(ack), 1, call_sock);
+  if (sr != 1) {
+    if (was_eof(call_sock)) return -1;
+    diee("read() ack byte");
+  }
+  if (ack != '\n') die("got ack byte 0x%02x, not '\n'", ack);
+
+  // We're committed now, send the request (or bail out)
+  send_request(call_sock);
+
+  return 0;
+}
+
 // Returns: call(client-end), or 0 to mean "is garbage"
 // find_socket_path must have been called
 static FILE *connect_existing(void) {
@@ -300,16 +316,8 @@ static FILE *connect_existing(void) {
   call_sock = call_sock_from_fd(fd);
   fd = -1;
 
-  char ack;
-  size_t sr = fread(&ack, sizeof(ack), 1, call_sock);
-  if (sr != 1) {
-    if (was_eof(call_sock)) goto x_garbage;
-    diee("read() ack byte");
-  }
-  if (ack != '\n') die("got ack byte 0x%02x, not '\n'", ack);
-
-  // We're committed now, send the request (or bail out)
-  send_request(call_sock);
+  if (protocol_exchange(call_sock) < 0)
+    goto x_garbage;
 
   return call_sock;