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Implement StringIO#pread (#56)

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Both for being closer to real IOs and also because it's a convenient API
in multithreaded scenarios.

Co-authored-by: Jean Boussier <jean.boussier@gmail.com>
This commit is contained in:
Jean byroot Boussier 2023-06-08 05:27:04 +02:00 committed by Hiroshi SHIBATA
parent 201fd57518
commit fd8dd71996
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GPG Key ID: F9CF13417264FAC2
2 changed files with 62 additions and 0 deletions
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43
ext/stringio/stringio.c
View File

@ -1583,6 +1583,48 @@ strio_read(int argc, VALUE *argv, VALUE self)
return str;
}
/*
* call-seq:
* pread(maxlen, offset) -> string
* pread(maxlen, offset, out_string) -> string
*
* See IO#pread.
*/
static VALUE
strio_pread(int argc, VALUE *argv, VALUE self)
{
VALUE rb_len, rb_offset, rb_buf;
rb_scan_args(argc, argv, "21", &rb_len, &rb_offset, &rb_buf);
long len = NUM2LONG(rb_len);
long offset = NUM2LONG(rb_offset);
if (len < 0) {
rb_raise(rb_eArgError, "negative string size (or size too big): %" PRIsVALUE, rb_len);
}
if (offset < 0) {
rb_syserr_fail_str(EINVAL, rb_sprintf("pread: Invalid offset argument: %" PRIsVALUE, rb_offset));
}
struct StringIO *ptr = readable(self);
if (offset >= RSTRING_LEN(ptr->string)) {
rb_eof_error();
}
if (NIL_P(rb_buf)) {
return strio_substr(ptr, offset, len, rb_ascii8bit_encoding());
}
long rest = RSTRING_LEN(ptr->string) - offset;
if (len > rest) len = rest;
rb_str_resize(rb_buf, len);
rb_enc_associate(rb_buf, rb_ascii8bit_encoding());
MEMCPY(RSTRING_PTR(rb_buf), RSTRING_PTR(ptr->string) + offset, char, len);
return rb_buf;
}
/*
* call-seq:
* strio.sysread(integer[, outbuf]) -> string
@ -1843,6 +1885,7 @@ Init_stringio(void)
rb_define_method(StringIO, "gets", strio_gets, -1);
rb_define_method(StringIO, "readlines", strio_readlines, -1);
rb_define_method(StringIO, "read", strio_read, -1);
rb_define_method(StringIO, "pread", strio_pread, -1);
rb_define_method(StringIO, "write", strio_write_m, -1);
rb_define_method(StringIO, "putc", strio_putc, 1);

19
test/stringio/test_stringio.rb
View File

@ -729,6 +729,25 @@ class TestStringIO < Test::Unit::TestCase
assert_equal Encoding::ASCII_8BIT, f.sysread(3).encoding
end
def test_pread
f = StringIO.new("pread")
f.read
assert_equal "pre".b, f.pread(3, 0)
assert_equal "read".b, f.pread(4, 1)
assert_equal Encoding::ASCII_8BIT, f.pread(4, 1).encoding
buf = "".b
f.pread(3, 0, buf)
assert_equal "pre".b, buf
f.pread(4, 1, buf)
assert_equal "read".b, buf
assert_raise(EOFError) { f.pread(1, 5) }
assert_raise(ArgumentError) { f.pread(-1, 0) }
assert_raise(Errno::EINVAL) { f.pread(3, -1) }
end
def test_size
f = StringIO.new("1234")
assert_equal(4, f.size)