On Wednesday, 1 July 2020 at 05:09:47 UTC, Cym13 wrote:
On Wednesday, 1 July 2020 at 05:04:28 UTC, Anthony wrote:
I'm trying to convert this c function:
bson_t *bson_new_from_json (const uint8_t *data, ssize_t len,
bson_error_t *error);
Into a D function. This is my attempt:
extern(C) {
struct bson_t;
struct bson_error_t;
bson_t* bson_new_from_json(const uint8_t* data, long len,
bson_error_t* error);
}
However when I try it, for example:
auto str_utf8 = str.toUTF8();
bson_error_t error
auto bson = bson_new_from_json(cast(const
uint8_t*)str_utf8.ptr, -1, &error);
I get a "Program exited with code -11" message.
Does anyone know what I'm doing wrong?
Thanks
I don't know the exact function you are trying to use, but -11
means "segmentation fault" on linux. This means that your
program is trying to read or write a memory location that it is
not supposed to. This typically happens during buffer overflows
and similar memory corruption bugs.
One thing that jumps to me is the -1 in your call instead of
the length. Without knowing the C function's implementation I
would expect it to mean either "read before the array" which
would be a buffer overflow or to have the special meaning of
"deduce the string size yourself". In that last case I would
expect bson_new_from_json to expect a NUL-terminated array, but
I don't know if your UTF8 array is NUL-terminated.
Thanks for getting back to me.
Yeah I figured it was a segmentation fault, however, I don't know
exactly how to pinpoint where this is happening. I'm wondering if
there's anything wrong with how I'm casting the data since
everything is self contained (assuming bson_new_from_json is
correct since it works using c directly).
void foo() {
import std.utf;
import core.stdc.stdint;
auto str_utf8 = "{\"a\":1}";
bson_error_t error;
bson_new_from_json(cast(uint8_t*)str_utf8,
(cast(uint8_t[])str_utf8).length, &error);
}
Re -1 in the call: Apparently it uses strlen() to deduce the
size. However, I tried explicitly state the array length but had
no luck.
