From c7f5b86a804ae16ab3a4bcda9593a49bce81791c Mon Sep 17 00:00:00 2001
From: Laurent Bercot <ska-skaware@skarnet.org>
Date: Thu, 9 Feb 2023 15:45:54 +0000
Subject:  Autodetect socket endpoints in s6-ioconnect, deprecate -0167

Signed-off-by: Laurent Bercot <ska@appnovation.com>
---
 doc/s6-ioconnect.html         | 22 +++++++--------------
 src/conn-tools/s6-ioconnect.c | 45 +++++++++++++++++++++++++++----------------
 2 files changed, 35 insertions(+), 32 deletions(-)

diff --git a/doc/s6-ioconnect.html b/doc/s6-ioconnect.html
index 9a61c62..2621ff6 100644
--- a/doc/s6-ioconnect.html
+++ b/doc/s6-ioconnect.html
@@ -26,7 +26,7 @@ between two sets of open file descriptors.
 <h2> Interface </h2>
 
 <pre>
-     s6-ioconnect [ -t <em>millisecs</em> ] [ -r <em>fdr</em> ] [ -w <em>fdw</em> ] [ -0 ] [ -1 ] [ -6 ] [ -7 ]
+     s6-ioconnect [ -t <em>millisecs</em> ] [ -r <em>fdr</em> ] [ -w <em>fdw</em> ]
 </pre>
 
 <ul>
@@ -49,25 +49,17 @@ closes the connection on both ends and exits 1. By default,
 "remote" reading instead of fd 6. </li>
  <li> <tt>-w&nbsp;<em>fdw</em></tt>&nbsp;: Use fd <em>fdw</em> for
 "remote" writing instead of fd 7. </li>
- <li> <tt>-0</tt>: assume stdin is a socket and needs to be shut down
-for reading after an EOF. </li>
- <li> <tt>-1</tt>: assume stdout is a socket and needs to be shut down
-for writing to correctly transmit an EOF. </li>
- <li> <tt>-6</tt>: assume the remote reading fd is a socket and needs to be shut down
-for reading after an EOF. </li>
- <li> <tt>-7</tt>: assume the remote writing fd is a socket and needs to be shut down
-for writing to correctly transmit  an EOF. </li>
+ <li> The <tt>-0</tt>, <tt>-1</tt>, <tt>-6</tt> and <tt>-7</tt> options
+are still recognized for compatibility, but do nothing; they are
+deprecated. They were previously used to tell
+s6-ioconnect that the local reading, local writing, remote reading and
+remote writing endpoints, respectively, were sockets &mdash; but this is
+now autodetected. </li>
 </ul>
 
 <h2> Notes </h2>
 
 <ul>
- <li> Transmitting EOF across full-duplex sockets
-<a href="https://cr.yp.to/tcpip/twofd.html">is ugly</a>. The right thing
-in every case cannot be automatically determined, so it is up to the user
-to mention that a socket must be shut down. Most of the time, though,
-shutting down sockets after EOF <em>is</em> the right thing to do, so
-<tt>s6-ioconnect -67</tt> should be the common use case. </li>
  <li> The point of s6-ioconnect is to be used together with
 <a href="//skarnet.org/software/s6-networking/s6-tcpclient.html">s6-tcpclient</a> or
 <a href="s6-ipcclient.html">s6-ipcclient</a> to establish a full-
diff --git a/src/conn-tools/s6-ioconnect.c b/src/conn-tools/s6-ioconnect.c
index c86ec55..0b78277 100644
--- a/src/conn-tools/s6-ioconnect.c
+++ b/src/conn-tools/s6-ioconnect.c
@@ -2,6 +2,7 @@
 
 #include <errno.h>
 #include <signal.h>
+#include <sys/stat.h>
 
 #include <skalibs/types.h>
 #include <skalibs/allreadwrite.h>
@@ -15,7 +16,7 @@
 #include <skalibs/iopause.h>
 #include <skalibs/djbunix.h>
 
-#define USAGE "s6-ioconnect [ -t timeout ] [ -r fdr ] [ -w fdw ] [ -0 ] [ -1 ] [ -6 ] [ -7 ]"
+#define USAGE "s6-ioconnect [ -t timeout ] [ -r fdr ] [ -w fdw ]"
 #define dieusage() strerr_dieusage(100, USAGE)
 
 #define BSIZE 8192
@@ -32,12 +33,12 @@ static char buf[2][BSIZE] = { { '\0' }, { '\0' } } ;
 static ioblah a[2][2] =
 {
   {
-    { .b = BUFFER_INIT(&buffer_read, 0, buf[0], BSIZE), .xindex = 5, .flagsocket = 0 },
-    { .b = BUFFER_INIT(&buffer_write, 7, buf[0], BSIZE), .xindex = 5, .flagsocket = 0 }
+    { .b = BUFFER_INIT(&buffer_read, 0, buf[0], BSIZE), .xindex = 5 },
+    { .b = BUFFER_INIT(&buffer_write, 7, buf[0], BSIZE), .xindex = 5 }
   },
   {
-    { .b = BUFFER_INIT(&buffer_read, 6, buf[1], BSIZE), .xindex = 5, .flagsocket = 0 },
-    { .b = BUFFER_INIT(&buffer_write, 1, buf[1], BSIZE), .xindex = 5, .flagsocket = 0 }
+    { .b = BUFFER_INIT(&buffer_read, 6, buf[1], BSIZE), .xindex = 5 },
+    { .b = BUFFER_INIT(&buffer_write, 1, buf[1], BSIZE), .xindex = 5 }
   }
 } ;
 static iopause_fd x[5] = { [0] = { .fd = -1, .events = IOPAUSE_READ } } ;
@@ -99,10 +100,10 @@ int main (int argc, char const *const *argv)
       if (opt < 0) break ;
       switch (opt)
       {
-        case '0' : a[0][0].flagsocket = 1 ; break ;
-        case '1' : a[1][1].flagsocket = 1 ; break ;
-        case '6' : a[1][0].flagsocket = 1 ; break ;
-        case '7' : a[0][1].flagsocket = 1 ; break ;
+        case '0' : break ;  /* these options are deprecated */
+        case '1' : break ;  /* only there for compatibility */
+        case '6' : break ;  /* flagsocket is autodetected now */
+        case '7' : break ;
         case 't' : if (!uint0_scan(l.arg, &t)) dieusage() ; break ;
         case 'r' : if (!int0_scan(l.arg, &buffer_fd(&a[1][0].b))) dieusage() ; break ;
         case 'w' : if (!int0_scan(l.arg, &buffer_fd(&a[0][1].b))) dieusage() ; break ;
@@ -113,14 +114,24 @@ int main (int argc, char const *const *argv)
     argc -= l.ind ; argv += l.ind ;
   }
   if ((buffer_fd(&a[0][1].b) < 3) || (buffer_fd(&a[1][0].b) < 3)) dieusage() ;
-  for (i = 0 ; i < 2 ; i++)
-    for (j = 0 ; j < 2 ; j++)
-      if (ndelay_on(buffer_fd(&a[i][j].b)) == -1)
-      {
-        char fmt[INT_FMT] ;
-        fmt[int_fmt(fmt, buffer_fd(&a[i][j].b))] = 0 ;
-        strerr_diefu3sys(111, "set fd ", fmt, " non-blocking") ;
-      }
+  for (i = 0 ; i < 2 ; i++) for (j = 0 ; j < 2 ; j++)
+  {
+    int fd = buffer_fd(&a[i][j].b) ;
+    struct stat st ;
+    if (fstat(fd, &st) == -1)
+    {
+      char fmt[INT_FMT] ;
+      fmt[int_fmt(fmt, fd)] = 0 ;
+      strerr_diefu2sys(111, "fstat fd ", fmt) ;
+    }
+    a[i][j].flagsocket = !!S_ISSOCK(st.st_mode) ;
+    if (ndelay_on(fd) == -1)
+    {
+      char fmt[INT_FMT] ;
+      fmt[int_fmt(fmt, fd)] = 0 ;
+      strerr_diefu3sys(111, "set fd ", fmt, " non-blocking") ;
+    }
+  }
   if (!sig_ignore(SIGPIPE)) strerr_diefu1sys(111, "ignore SIGPIPE") ;
   tain_now_set_stopwatch_g() ;
   x[0].fd = selfpipe_init() ;
-- 
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