1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
/*
Portions Copyright 2019-2021 ZomboDB, LLC.
Portions Copyright 2021-2022 Technology Concepts & Design, Inc. <support@tcdi.com>
All rights reserved.
Use of this source code is governed by the MIT license that can be found in the LICENSE file.
*/
//! A safe wrapper around Postgres `StringInfo` structure
#![allow(dead_code, non_snake_case)]
use crate::{pg_sys, AllocatedByPostgres, AllocatedByRust, PgBox, WhoAllocated};
use core::fmt::{Display, Formatter};
use core::str::Utf8Error;
use std::io::Error;
/// StringInfoData holds information about an extensible string that is allocated by Postgres'
/// memory system, but generally follows Rust's drop semantics
pub struct StringInfo<AllocatedBy: WhoAllocated = AllocatedByRust> {
inner: PgBox<pg_sys::StringInfoData, AllocatedBy>,
}
impl<AllocatedBy: WhoAllocated> From<StringInfo<AllocatedBy>> for &'static std::ffi::CStr {
fn from(val: StringInfo<AllocatedBy>) -> Self {
let len = val.len();
let ptr = val.into_char_ptr();
unsafe {
std::ffi::CStr::from_bytes_with_nul_unchecked(std::slice::from_raw_parts(
ptr as *const u8,
(len + 1) as usize, // +1 to get the trailing null byte
))
}
}
}
impl<AllocatedBy: WhoAllocated> From<StringInfo<AllocatedBy>> for &'static crate::cstr_core::CStr {
fn from(val: StringInfo<AllocatedBy>) -> Self {
let len = val.len();
let ptr = val.into_char_ptr();
unsafe {
crate::cstr_core::CStr::from_bytes_with_nul_unchecked(std::slice::from_raw_parts(
ptr as *const u8,
(len + 1) as usize, // +1 to get the trailing null byte
))
}
}
}
impl<AllocatedBy: WhoAllocated> std::io::Write for StringInfo<AllocatedBy> {
fn write(&mut self, buf: &[u8]) -> Result<usize, Error> {
self.push_bytes(buf);
Ok(buf.len())
}
fn flush(&mut self) -> Result<(), Error> {
Ok(())
}
}
impl<AllocatedBy: WhoAllocated> Display for StringInfo<AllocatedBy> {
/// Convert this [`StringInfo`] into a Rust string. This uses [`String::from_utf8_lossy`] as
/// it's fine for a Postgres [`StringInfo`] to contain null bytes and also not even be proper
/// UTF8.
fn fmt(&self, f: &mut Formatter<'_>) -> core::fmt::Result {
f.write_str(&String::from_utf8_lossy(self.as_bytes()))
}
}
impl StringInfo<AllocatedByRust> {
/// Construct a new `StringInfo` of its default size, allocated in `CurrentMemoryContext`
///
/// Note that Postgres can only represent up to 1 gigabyte of data in a `StringInfo`
pub fn new() -> Self {
StringInfo {
inner: unsafe {
// SAFETY: makeStringInfo() always returns a valid StringInfoData pointer. It'll
// ereport if it can't
PgBox::<_, AllocatedByRust>::from_rust(pg_sys::makeStringInfo())
},
}
}
/// Construct a new `StringInfo`, allocated by Postgres in `CurrentMemoryContext`, ensuring it
/// has a capacity of the specified `len`.
///
/// Note that Postgres can only represent up to 1 gigabyte of data in a `StringInfo`
pub fn with_capacity(len: i32) -> Self {
let mut si = StringInfo::default();
si.enlarge(len);
si
}
}
impl StringInfo<AllocatedByPostgres> {
/// Construct a `StringInfo` from a Postgres-allocated `pg_sys::StringInfo`.
///
/// The backing `pg_sys::StringInfo` structure will be freed whenever the memory context in which
/// it was originally allocated is reset.
///
/// # Safety
///
/// This function is unsafe as it cannot confirm the provided [`pg_sys::StringInfo`] pointer is
/// valid
pub unsafe fn from_pg(sid: pg_sys::StringInfo) -> Option<Self> {
if sid.is_null() {
None
} else {
Some(StringInfo { inner: PgBox::from_pg(sid) })
}
}
}
impl<AllocatedBy: WhoAllocated> StringInfo<AllocatedBy> {
/// What is the length, excluding the trailing null byte
#[inline]
pub fn len(&self) -> usize {
self.inner.len as _
}
/// Do we have any characters?
#[inline]
pub fn is_empty(&self) -> bool {
self.len() == 0
}
/// Push a Rust character onto the end. A Rust `char` could be 4 bytes in total, so it
/// is converted into a String first to ensure unicode correctness
#[inline]
pub fn push(&mut self, ch: char) {
self.push_str(&ch.to_string());
}
/// Push a String reference onto the end
#[inline]
pub fn push_str(&mut self, s: &str) {
self.push_bytes(s.as_bytes())
}
/// Push arbitrary bytes onto the end. Any byte sequence is allowed, including those with
/// embedded NULLs
///
/// # Panics
///
/// This function will panic if the length of bytes is larger than an `i32`
#[inline]
pub fn push_bytes(&mut self, bytes: &[u8]) {
unsafe {
// SAFETY: self.inner will always be valid
pg_sys::appendBinaryStringInfo(
self.inner.as_ptr(),
bytes.as_ptr() as _,
bytes.len().try_into().expect("len of bytes doesn't fit in an i32"),
)
}
}
/// Push the bytes behind a raw pointer of a given length onto the end
///
/// # Safety
///
/// This function is unsafe as we cannot ensure the specified `ptr` and `len` arguments
/// are what you say that are and otherwise in agreement
#[inline]
pub unsafe fn push_raw(&mut self, ptr: *const std::os::raw::c_char, len: i32) {
unsafe {
// SAFETY: self.inner will always be a valid StringInfoData pointer
// and the caller gets to decide if `ptr` and `len` line up
pg_sys::appendBinaryStringInfo(self.inner.as_ptr(), ptr, len)
}
}
/// Reset the size of the `StringInfo` back to zero-length. This does/// *not** free any
/// previously-allocated memory
#[inline]
pub fn reset(&mut self) {
unsafe {
// SAFETY: self.inner will always be a valid StringInfoData pointer
pg_sys::resetStringInfo(self.inner.as_ptr())
}
}
/// Ensure that this `StringInfo` is at least `needed` bytes long
#[inline]
pub fn enlarge(&mut self, needed: i32) {
unsafe {
// SAFETY: self.inner will always be a valid StringInfoData pointer
pg_sys::enlargeStringInfo(self.inner.as_ptr(), needed)
}
}
/// A `&str` representation.
///
/// # Errors
///
/// If the contained bytes aren't valid UTF8, a [UTF8Error] is returned. Postgres StringInfo
/// is allowed to contain non-UTF8 byte sequences, so this is a real possibility.
#[inline]
pub fn as_str(&self) -> Result<&str, Utf8Error> {
std::str::from_utf8(self.as_bytes())
}
/// A pointer to the backing bytes
#[inline]
pub fn as_ptr(&self) -> *const std::os::raw::c_char {
self.inner.data
}
/// A mutable pointer to the backing bytes
#[inline]
pub fn as_mut_ptr(&self) -> *mut std::os::raw::c_char {
self.inner.data
}
/// A `&[u8]` byte slice representation
#[inline]
pub fn as_bytes(&self) -> &[u8] {
unsafe {
// SAFETY: self.inner will always be a valid StringInfoData pointer, and Postgres will
// never have self.inner.data be invalid
std::slice::from_raw_parts(self.inner.data as *const u8, self.len())
}
}
/// A mutable `&[u8]` byte slice representation
#[inline]
pub fn as_bytes_mut(&mut self) -> &mut [u8] {
unsafe {
// SAFETY: self.inner will always be a valid StringInfoData
// pointer, and Postgres will never have self.inner.data be invalid
std::slice::from_raw_parts_mut(self.inner.data as *mut u8, self.len())
}
}
/// Convert this `StringInfo` into one that is wholly owned and now managed by Postgres
#[inline]
pub fn into_pg(mut self) -> *mut pg_sys::StringInfoData {
// NB: We are replacing self.inner with a PgBox containing the null pointer. However,
// `self` will be dropped as soon as this function ends and we account for this case in our
// drop implementation
let inner = std::mem::replace(&mut self.inner, PgBox::<_, AllocatedBy>::null());
inner.into_pg()
}
/// Convert this `StringInfo` into a `"char *"` that is wholly owned and now managed by Postgres
#[inline]
pub fn into_char_ptr(self) -> *const std::os::raw::c_char {
// in case we're AllocatedByRust, we don't want drop to free `self.inner.data` now that we've
// consumed `self` and are returning a raw pointer to some memory we allocated, so we "round-trip"
// to ensure Rust thinks we're now `AllocatedByPostgres`, which has an empty drop impl
let sid_ptr = self.into_pg();
unsafe {
// SAFETY: we just made the StringInfoData pointer so we know it's valid and properly
// initialized throughout
sid_ptr.as_ref().unwrap_unchecked().data
}
}
}
impl Default for StringInfo<AllocatedByRust> {
fn default() -> Self {
Self::new()
}
}
impl From<String> for StringInfo<AllocatedByRust> {
fn from(s: String) -> Self {
StringInfo::from(s.as_str())
}
}
impl From<&str> for StringInfo<AllocatedByRust> {
fn from(s: &str) -> Self {
let mut rc = StringInfo::new();
rc.push_str(s);
rc
}
}
impl From<Vec<u8>> for StringInfo<AllocatedByRust> {
fn from(v: Vec<u8>) -> Self {
let mut rc = StringInfo::new();
rc.push_bytes(v.as_slice());
rc
}
}
impl From<&[u8]> for StringInfo<AllocatedByRust> {
fn from(v: &[u8]) -> Self {
let mut rc = StringInfo::new();
rc.push_bytes(v);
rc
}
}
impl<AllocatedBy: WhoAllocated> Drop for StringInfo<AllocatedBy> {
fn drop(&mut self) {
unsafe {
// SAFETY: self.inner could represent the null pointer, but if it doesn't, then it's
// one we can use as self.inner.data will always be allocated if self.inner is.
//
// It's also prescribed by Postgres that to fully deallocate a StringInfo pointer, the
// owner is responsible for freeing its .data member... and that's us
if !self.inner.is_null() {
AllocatedBy::maybe_pfree(self.inner.data.cast())
}
}
}
}