From 39c8698842bc132cbc2f44aadb83f12efc3aa062 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Thu, 30 May 2019 06:25:59 -0700
Subject: posix: add close function.

* sysif.c (close_wrap): New static function.
(sysif_init): close intrinsic registered.

* txr.1: Documented.
---
 sysif.c | 17 +++++++++++++++++
 txr.1   | 22 ++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/sysif.c b/sysif.c
index 3556b262..808e0e91 100644
--- a/sysif.c
+++ b/sysif.c
@@ -609,6 +609,22 @@ static val dup_wrap(val old, val neu)
   return num(dup2(c_num(old), c_num(neu)));
 }
 
+static val close_wrap(val fd, val throw_on_error)
+{
+  int res = close(c_int(fd, lit("close")));
+
+  if (res < 0) {
+    if (default_null_arg(throw_on_error)) {
+      int eno = errno;
+      uw_throwf(errno_to_file_error(eno), lit("close ~a: ~d/~s"),
+                fd, num(eno), string_utf8(strerror(eno)), nao);
+    }
+    return nil;
+  }
+
+  return t;
+}
+
 val exec_wrap(val file, val args_opt)
 {
   val self = lit("execvp");
@@ -1846,6 +1862,7 @@ void sysif_init(void)
   reg_varl(intern(lit("w-continued"), user_package), num_fast(WCONTINUED));
 #endif
   reg_fun(intern(lit("dupfd"), user_package), func_n2o(dup_wrap, 1));
+  reg_fun(intern(lit("close"), user_package), func_n2o(close_wrap, 1));
 #endif
 #if HAVE_PIPE
   reg_fun(intern(lit("pipe"), user_package), func_n0(pipe_wrap));
diff --git a/txr.1 b/txr.1
index e66684c0..bde02f38 100644
--- a/txr.1
+++ b/txr.1
@@ -54730,6 +54730,28 @@ holds the write end.
 If the function fails, it throws an exception of type
 .codn file-error .
 
+.coNP Function @ close
+.synb
+.mets (close < fileno <> [  throw-on-error-p ])
+.syne
+.desc
+The
+.code close
+function passes the integer descriptor
+.meta fileno
+to the POSIX
+.code close
+function.  If the operation is successful, then
+.code t
+is returned. Otherwise an exception of type
+.code file-error
+is thrown, unless the
+.meta throw-on-error-p
+argument is present, with a true value. In that case,
+.code close
+indicates failure by returning
+.codn nil .
+
 .coNP Function @ poll
 .synb
 .mets (poll < poll-list <> [ timeout ])
-- 
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