Class: Kgio::File

Inherits:
File
  • Object
show all
Includes:
PipeMethods
Defined in:
ext/kgio/tryopen.c,
ext/kgio/tryopen.c

Overview

This subclass of the core File class adds the “tryopen” singleton method for opening files. A single “tryopen” and check for the return value may be used to avoid unnecessary stat(2) syscalls or File.open exceptions when checking for the existence of a file and opening it.

Class Method Summary collapse

Methods included from DefaultWaiters

#kgio_wait_readable, #kgio_wait_writable

Class Method Details

.tryopen(*args) ⇒ Object

Kgio::File.tryopen(filename, [, mode [, perm]]) -> Kgio::File or Symbol

Returns a Kgio::File object on a successful open. filename is a path to any file on the filesystem. If specified, mode is a bitmask of flags (see IO.sysopen) and perm should be an octal number.

This does not raise errors for most failures, but installs returns a Ruby symbol for the constant in the Errno::* namespace.

Common error symbols are:

  • :ENOENT

  • :EACCES

See your open(2) manpage for more information on open(2) errors.



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# File 'ext/kgio/tryopen.c', line 84

static VALUE s_tryopen(int argc, VALUE *argv, VALUE klass)
{
	long fd;
	VALUE pathname, flags, mode;
	struct open_args o;
	int retried = 0;
	VALUE rv;

	rb_scan_args(argc, argv, "12", &pathname, &flags, &mode);
	if (rb_respond_to(pathname, id_to_path))
		pathname = rb_funcall(pathname, id_to_path, 0);
	o.pathname = StringValueCStr(pathname);

	switch (TYPE(flags)) {
	case T_NIL: o.flags = O_RDONLY; break;
	case T_FIXNUM: o.flags = FIX2INT(flags); break;
	case T_BIGNUM: o.flags = NUM2INT(flags); break;
	default: rb_raise(rb_eArgError, "flags must be an Integer");
	}
	switch (TYPE(mode)) {
	case T_NIL: o.mode = 0666; break;
	case T_FIXNUM: o.mode = FIX2INT(mode); break;
	case T_BIGNUM: o.mode = NUM2INT(mode); break;
	default: rb_raise(rb_eArgError, "mode must be an Integer");
	}

retry:
	fd = (long)KGIO_WITHOUT_GVL(nogvl_open, &o, RUBY_UBF_IO, 0);
	if (fd < 0) {
		if (errno == EMFILE || errno == ENFILE || errno == ENOMEM) {
			rb_gc();
			if (retried)
				rb_sys_fail(o.pathname);
			retried = 1;
			goto retry;
		}
		if (fd < 0) {
			int saved_errno = errno;

			if (!st_lookup(errno2sym, (st_data_t)errno, &rv)) {
				errno = saved_errno;
				rb_sys_fail(o.pathname);
			}
			return rv;
		}
	}
	rv = rb_funcall(klass, id_for_fd, 1, LONG2FIX(fd));
	set_file_path(rv, pathname);
	return rv;
}