Extract CString from an API that takes pointer to a buffer and max length and returns the number of bytes stored or required to stotre the entire string.
(f: F)
| 47 | /// Extract CString from an API that takes pointer to a buffer and max length and |
| 48 | /// returns the number of bytes stored or required to stotre the entire string. |
| 49 | pub(crate) fn get_cstring<F>(f: F) -> CString |
| 50 | where |
| 51 | F: Fn(*mut c_char, usize) -> usize, |
| 52 | { |
| 53 | // Some SB API return the required size of the full string (SBThread::GetStopDescription()), |
| 54 | // while others return the number of bytes actually written into the buffer (SBFileSpec::GetPath()). |
| 55 | // In the latter case we have to grow buffer capacity in a loop until the string fits. |
| 56 | // There also seems to be a lack of consensus whether the terminating NUL should be included in the count or not... |
| 57 | |
| 58 | let mut buffer = [0u8; 1024]; |
| 59 | let c_ptr = buffer.as_mut_ptr() as *mut c_char; |
| 60 | let size = f(c_ptr, buffer.len()); |
| 61 | assert!((size as isize) >= 0); |
| 62 | // Must have at least 1 unused byte to ensure that we've received the entire string. |
| 63 | if size < buffer.len() - 1 { |
| 64 | unsafe { |
| 65 | return CStr::from_ptr(c_ptr).to_owned(); |
| 66 | } |
| 67 | } |
| 68 | |
| 69 | let capacity = if size > buffer.len() { |
| 70 | size + 2 |
| 71 | } else { |
| 72 | buffer.len() * 2 |
| 73 | }; |
| 74 | let mut buffer = Vec::with_capacity(capacity); |
| 75 | loop { |
| 76 | let c_ptr = buffer.as_mut_ptr() as *mut c_char; |
| 77 | let size = f(c_ptr, buffer.capacity()); |
| 78 | assert!((size as isize) >= 0); |
| 79 | if size < buffer.capacity() - 1 { |
| 80 | unsafe { |
| 81 | let s = CStr::from_ptr(c_ptr); // Count bytes to NUL |
| 82 | buffer.set_len(s.to_bytes().len()); |
| 83 | return CString::from_vec_unchecked(buffer); |
| 84 | }; |
| 85 | } |
| 86 | let capacity = buffer.capacity() * 2; |
| 87 | buffer.reserve(capacity); |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | /// Get `str` a from NUL-terminated string pointer. If the pointer is null, returns "". |
| 92 | pub(crate) unsafe fn get_str<'a>(ptr: *const c_char) -> &'a str { |