Cygwin: introduce close_range(2)

This function closes or sets the close-on-exec flag for a specified
range of file descriptors.  It is available on FreeBSD and Linux.

Signed-off-by: Christian Franke <christian.franke@t-online.de>

6 files changed, 56 insertions, 1 deletions

diff --git a/winsup/cygwin/cygwin.din b/winsup/cygwin/cygwin.din
index 9b76ce67a..9e354acc6 100644
--- a/winsup/cygwin/cygwin.din
+++ b/winsup/cygwin/cygwin.din
@@ -347,6 +347,7 @@ clog10l NOSIGFE
 clogf NOSIGFE
 clogl NOSIGFE
 close SIGFE
+close_range SIGFE
 closedir SIGFE
 closelog SIGFE
 cnd_broadcast SIGFE
diff --git a/winsup/cygwin/include/cygwin/version.h b/winsup/cygwin/include/cygwin/version.h
index c8177c2b1..3036878c4 100644
--- a/winsup/cygwin/include/cygwin/version.h
+++ b/winsup/cygwin/include/cygwin/version.h
@@ -484,12 +484,13 @@ details. */
   347: Add c16rtomb, c32rtomb, mbrtoc16, mbrtoc32.
   348: Add c8rtomb, mbrtoc.
   349: Add fallocate.
+  350: Add close_range.
 
   Note that we forgot to bump the api for ualarm, strtoll, strtoull,
   sigaltstack, sethostname. */
 
 #define CYGWIN_VERSION_API_MAJOR 0
-#define CYGWIN_VERSION_API_MINOR 349
+#define CYGWIN_VERSION_API_MINOR 350
 
 /* There is also a compatibity version number associated with the shared memory
    regions.  It is incremented when incompatible changes are made to the shared
diff --git a/winsup/cygwin/release/3.5.0 b/winsup/cygwin/release/3.5.0
index d0a6c2fc8..6209064a6 100644
--- a/winsup/cygwin/release/3.5.0
+++ b/winsup/cygwin/release/3.5.0
@@ -43,6 +43,8 @@ What's new:
 
 - New API calls: c8rtomb, c16rtomb, c32rtomb, mbrtoc8, mbrtoc16, mbrtoc32.
 
+- New API call: close_range (available on FreeBSD and Linux).
+
 - New API call: fallocate (Linux-specific).
 
 - Implement OSS-based sound mixer device (/dev/mixer).
diff --git a/winsup/cygwin/syscalls.cc b/winsup/cygwin/syscalls.cc
index 486db1db6..9d88b60b0 100644
--- a/winsup/cygwin/syscalls.cc
+++ b/winsup/cygwin/syscalls.cc
@@ -85,6 +85,48 @@ close_all_files (bool norelease)
   cygheap->fdtab.unlock ();
 }
 
+/* Close or set the close-on-exec flag for all open file descriptors
+   from firstfd to lastfd.  CLOSE_RANGE_UNSHARE is not supported.
+   Available on FreeBSD since 13 and Linux since 5.9 */
+extern "C" int
+close_range (unsigned int firstfd, unsigned int lastfd, int flags)
+{
+  pthread_testcancel ();
+
+  if (!(firstfd <= lastfd && !(flags & ~CLOSE_RANGE_CLOEXEC)))
+    {
+      set_errno (EINVAL);
+      return -1;
+    }
+
+  cygheap->fdtab.lock ();
+
+  unsigned int size = (lastfd < cygheap->fdtab.size ? lastfd + 1 :
+		      cygheap->fdtab.size);
+
+  for (unsigned int i = firstfd; i < size; i++)
+    {
+      cygheap_fdget cfd ((int) i, false, false);
+      if (cfd < 0)
+	continue;
+
+      if (flags & CLOSE_RANGE_CLOEXEC)
+	{
+	  syscall_printf ("set FD_CLOEXEC on fd %u", i);
+	  cfd->fcntl (F_SETFD, FD_CLOEXEC);
+	}
+      else
+	{
+	  syscall_printf ("closing fd %u", i);
+	  cfd->close_with_arch ();
+	  cfd.release ();
+	}
+    }
+
+  cygheap->fdtab.unlock ();
+  return 0;
+}
+
 extern "C" int
 dup (int fd)
 {
diff --git a/winsup/doc/new-features.xml b/winsup/doc/new-features.xml
index 6ae420031..0abe1c41c 100644
--- a/winsup/doc/new-features.xml
+++ b/winsup/doc/new-features.xml
@@ -75,6 +75,10 @@ New API calls: c8rtomb, c16rtomb, c32rtomb, mbrtoc8, mbrtoc16, mbrtoc32.
 </para></listitem>
 
 <listitem><para>
+New API call: close_range (available on FreeBSD and Linux).
+</para></listitem>
+
+<listitem><para>
 New API call: fallocate (Linux-specific).
 </para></listitem>
 
diff --git a/winsup/doc/posix.xml b/winsup/doc/posix.xml
index 1a4eee1ab..89056915b 100644
--- a/winsup/doc/posix.xml
+++ b/winsup/doc/posix.xml
@@ -1143,6 +1143,7 @@ also IEEE Std 1003.1-2017 (POSIX.1-2017).</para>
     cfmakeraw
     cfsetspeed
     clearerr_unlocked
+    close_range
     daemon
     dn_comp
     dn_expand
@@ -1297,6 +1298,7 @@ also IEEE Std 1003.1-2017 (POSIX.1-2017).</para>
     clog10
     clog10f
     clog10l
+    close_range			(see <xref linkend="std-notes">chapter "Implementation Notes"</xref>)
     crypt_r			(available in external "crypt" library)
     dladdr			(see <xref linkend="std-notes">chapter "Implementation Notes"</xref>)
     dremf
@@ -1656,6 +1658,9 @@ CLOCK_REALTIME and CLOCK_MONOTONIC.  <function>clock_setres</function>,
 <function>clock_settime</function>, and <function>timer_create</function>
 currently support only CLOCK_REALTIME.</para>
 
+<para><function>close_range</function> does not support the Linux-specific
+flag CLOSE_RANGE_UNSHARE.</para>
+
 <para>POSIX file locks via <function>fcntl</function> or
 <function>lockf</function>, as well as BSD <function>flock</function> locks
 are advisory locks.  They don't interact with Windows mandatory locks, nor