From c40606cf686962aff1fdecadbf393907160c6eb0 Mon Sep 17 00:00:00 2001
From: mbays <mbays@sdf.org>
Date: Sat, 6 Mar 2021 00:00:00 +0000
Subject: [PATCH] play with child

---
 main.c | 81 +++++++++++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 56 insertions(+), 25 deletions(-)

diff --git a/main.c b/main.c
index 4dada4f..f731430 100644
--- a/main.c
+++ b/main.c
@@ -1,3 +1,5 @@
+#include <poll.h>
+#include <signal.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -75,6 +77,30 @@ bool write_all(int fd, const char* buf, int n)
     return true;
 }
 
+/* Write anything written timelily on `in` to `out`, converting \n to \r\n.
+ * Return false on read error, else true. */
+static bool stream_text(int in, int out) {
+    char buf[256];
+    struct pollfd pfd = { in, POLLIN , 0 };
+
+    poll(&pfd, 1, 5000);
+    while (pfd.revents & POLLIN) {
+        const int r = read(in, buf, 256 - 1);
+        if (r < 0) return false;
+        buf[r] = 0;
+
+        const char *b = buf;
+        while (*b) {
+            if (*b == '\n') write(out, "\r\n", 2);
+            else write(out, b, 1);
+            ++b;
+        }
+
+        poll(&pfd, 1, 200);
+    }
+    return true;
+}
+
 void respond(void *object, const Request_Info *request_info, int socket)
 {
     State *state = (State *)object;
@@ -87,6 +113,7 @@ void respond(void *object, const Request_Info *request_info, int socket)
     }
 
     Child *child = NULL, *slot = NULL;
+    bool spawned = false;
 
     /* Find child with this cert hash, or spawn new.
      * For simplicity, we use a static array of children rather than 
@@ -107,7 +134,7 @@ void respond(void *object, const Request_Info *request_info, int socket)
     if (child == NULL) {
         if (slot == NULL) {
             if (state->num_children == MAX_CHILDREN) {
-                put("40 Too many children!");
+                put("40 Too many children!\r\n");
                 // TODO: consider infanticide at this point?
                 return;
             }
@@ -116,44 +143,48 @@ void respond(void *object, const Request_Info *request_info, int socket)
         child = slot;
 
         if (!spawn(state->command, state->args, child, socket)) {
-            put("40 Spawn failure.");
+            put("40 Spawn failure.\r\n");
             return;
         }
 
         child->exists = true;
         strncpy(child->owner, request_info->tls_client_hash, 32);
+
+        spawned = true;
     }
 
-    // TODO: process magic escape codes in query
+    const char *q = request_info->query_string_decoded;
+    if (*q == '!') {
+        ++q;
+        if (*q == '?') {
+            put("10\r\n");
+            return;
+        } else if (*q != '!') {
+            put("40 Unknown gemrepl meta-command (use '!!' for a literal '!')\r\n");
+        }
+    }
 
-    const int qlen = strlen(request_info->query_string_decoded);
-    if (qlen > 0) {
-        // FIXME: handle sigpipe
-        if (write(child->in, request_info->query_string_decoded, qlen) < 0
-                || write(child->in, "\n", 1) < 0) {
-            put("40 Error when writing to child");
+    const int qlen = strlen(q);
+    if (!spawned || qlen > 0) {
+        signal(SIGPIPE, SIG_IGN);
+        bool err = (write(child->in, q, qlen) < 0
+                || write(child->in, "\n", 1) < 0);
+        signal(SIGPIPE, SIG_DFL);
+        if (err) {
+            put("40 Error when writing to child\r\n");
+            // TODO: probably this means the child died.
+            // Should we already respawn?
             return;
         }
-        // TODO: when to write a bare newline?
     }
 
     put("20 text/gemini\r\n");
-    char buf[1024];
-    const int r = read(child->out, buf, 1024 - 1);
-    if (r < 0) {
-        put("40 Error reading from child");
-        return;
+
+    if (!stream_text(child->out, socket)) {
+        put("[gemrepl: error when reading from child]\r\n");
     }
-    buf[r] = 0;
-    put(buf);
-    put("\r\n");
-
-    // TODO:
-    // read for while, streaming response
-    //  be a bit clever about when to close;
-    //  maybe: give it 5s to start producing output,
-    //  read until it's blocked for 0.2s, or has been going for more than 2s.
-    //  use poll() or select() to implement timeouts, I guess.
+
+    put("=> ?!? Input command");
 }
 
 int main(int argc, char **argv)
-- 
2.11.4.GIT