meson: FD-passing

meson.build

@@ -123,6 +123,7 @@ subdir('meson' / 'libbsd')
 subdir('meson' / 'libc')
 subdir('meson' / 'random')
 subdir('meson' / 'ioloop')
+subdir('meson' / 'fd')
 
 dovecot_moduledir = get_option('moduledir')
 if dovecot_moduledir == ''

meson/fd/fd-passing.c

@@ -0,0 +1,60 @@
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include "fdpass.h"
+
+static int nopen(void) {
+  int i, n;
+  struct stat sb;
+  for (i = n = 0; i < 256; i++) {
+      if (fstat(i, &sb) == 0) n++;
+  }
+  return n;
+}
+
+int main(void) {
+  int fd[2], send_fd, recv_fd, status, n1, n2;
+  struct stat st, st2;
+  char data;
+
+  send_fd = creat("conftest.fdpass", 0600);
+  if (send_fd == -1) {
+	  return 2;
+  }
+
+  unlink("conftest.fdpass");
+
+  if (fstat(send_fd, &st) < 0) {
+	  return 2;
+  }
+
+  if (socketpair(AF_UNIX, SOCK_STREAM, 0, fd) < 0) {
+	  return 2;
+  }
+
+  n1 = nopen();
+
+  switch (fork()) {
+  case -1:
+          return 2;
+  case 0:
+          alarm(1);
+          if (fd_send(fd[0], send_fd, &data, 1) != 1) return 2;
+          return 0;
+  default:
+          alarm(2);
+          if (wait(&status) == -1)
+            return 2;
+          if (status != 0)
+            return status;
+          if (fd_read(fd[1], &data, 1, &recv_fd) != 1) return 1;
+          if (fstat(recv_fd, &st2) < 0) return 2;
+          /* nopen check is for making sure that only a single fd
+             was received */
+          n2 = nopen();
+          return st.st_ino == st2.st_ino && n2 == n1 + 1 ? 0 : 1;
+  }
+}

meson/fd/meson.build

@@ -0,0 +1,18 @@
+fs = import('fs')
+
+fdpass_c_file = meson.global_source_root() / 'src' / 'lib' / 'fdpass.c'
+fdpass_include = meson.global_source_root() / 'src' / 'lib'
+
+fd_pass_check = fs.read('fd-passing.c')
+args = [f'-I@fdpass_include@', fdpass_c_file]
+
+if cc.run(fd_pass_check, args: args, name: 'fd passing').returncode() != 0
+  args += '-DBUGGY_CMSG_MACROS'
+  if cc.run(fd_pass_check, args: args, name: 'fd passing').returncode() == 0
+    conf.set10('BUGGY_CMSG_MACROS', true)
+  endif
+endif
+
+if system == 'darwin'
+  conf.set10('BUGGY_CMSG_MACROS', true)
+endif