diesel/mysql/connection/stmt/
mod.rs

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1#![allow(unsafe_code)] // module uses ffi
2use mysqlclient_sys as ffi;
3use std::ffi::CStr;
4use std::os::raw as libc;
5use std::ptr::NonNull;
6
7use super::bind::{OutputBinds, PreparedStatementBinds};
8use crate::connection::statement_cache::MaybeCached;
9use crate::mysql::MysqlType;
10use crate::result::{DatabaseErrorKind, Error, QueryResult};
11
12pub(super) mod iterator;
13mod metadata;
14
15pub(super) use self::metadata::{MysqlFieldMetadata, StatementMetadata};
16
17#[allow(dead_code, missing_debug_implementations)]
18// https://github.com/rust-lang/rust/issues/81658
19pub struct Statement {
20    stmt: NonNull<ffi::MYSQL_STMT>,
21    input_binds: Option<PreparedStatementBinds>,
22}
23
24impl Statement {
25    pub(crate) fn new(stmt: NonNull<ffi::MYSQL_STMT>) -> Self {
26        Statement {
27            stmt,
28            input_binds: None,
29        }
30    }
31
32    pub fn prepare(&self, query: &str) -> QueryResult<()> {
33        unsafe {
34            ffi::mysql_stmt_prepare(
35                self.stmt.as_ptr(),
36                query.as_ptr() as *const libc::c_char,
37                query.len() as libc::c_ulong,
38            );
39        }
40        self.did_an_error_occur()
41    }
42
43    pub fn bind<Iter>(&mut self, binds: Iter) -> QueryResult<()>
44    where
45        Iter: IntoIterator<Item = (MysqlType, Option<Vec<u8>>)>,
46    {
47        let input_binds = PreparedStatementBinds::from_input_data(binds);
48        self.input_bind(input_binds)
49    }
50
51    pub(super) fn input_bind(
52        &mut self,
53        mut input_binds: PreparedStatementBinds,
54    ) -> QueryResult<()> {
55        input_binds.with_mysql_binds(|bind_ptr| {
56            // This relies on the invariant that the current value of `self.input_binds`
57            // will not change without this function being called
58            unsafe {
59                ffi::mysql_stmt_bind_param(self.stmt.as_ptr(), bind_ptr);
60            }
61        });
62        self.input_binds = Some(input_binds);
63        self.did_an_error_occur()
64    }
65
66    fn last_error_message(&self) -> String {
67        unsafe { CStr::from_ptr(ffi::mysql_stmt_error(self.stmt.as_ptr())) }
68            .to_string_lossy()
69            .into_owned()
70    }
71
72    pub(super) fn metadata(&self) -> QueryResult<StatementMetadata> {
73        use crate::result::Error::DeserializationError;
74
75        let result_ptr = unsafe { ffi::mysql_stmt_result_metadata(self.stmt.as_ptr()) };
76        self.did_an_error_occur()?;
77        NonNull::new(result_ptr)
78            .map(StatementMetadata::new)
79            .ok_or_else(|| DeserializationError("No metadata exists".into()))
80    }
81
82    pub(super) fn did_an_error_occur(&self) -> QueryResult<()> {
83        use crate::result::Error::DatabaseError;
84
85        let error_message = self.last_error_message();
86        if error_message.is_empty() {
87            Ok(())
88        } else {
89            Err(DatabaseError(
90                self.last_error_type(),
91                Box::new(error_message),
92            ))
93        }
94    }
95
96    fn last_error_type(&self) -> DatabaseErrorKind {
97        let last_error_number = unsafe { ffi::mysql_stmt_errno(self.stmt.as_ptr()) };
98        // These values are not exposed by the C API, but are documented
99        // at https://dev.mysql.com/doc/refman/8.0/en/server-error-reference.html
100        // and are from the ANSI SQLSTATE standard
101        match last_error_number {
102            1062 | 1586 | 1859 => DatabaseErrorKind::UniqueViolation,
103            1216 | 1217 | 1451 | 1452 | 1830 | 1834 => DatabaseErrorKind::ForeignKeyViolation,
104            1792 => DatabaseErrorKind::ReadOnlyTransaction,
105            1048 | 1364 => DatabaseErrorKind::NotNullViolation,
106            3819 => DatabaseErrorKind::CheckViolation,
107            1213 => DatabaseErrorKind::SerializationFailure,
108            _ => DatabaseErrorKind::Unknown,
109        }
110    }
111
112    /// If the pointers referenced by the `MYSQL_BIND` structures are invalidated,
113    /// you must call this function again before calling `mysql_stmt_fetch`.
114    pub unsafe fn bind_result(&self, binds: *mut ffi::MYSQL_BIND) -> QueryResult<()> {
115        ffi::mysql_stmt_bind_result(self.stmt.as_ptr(), binds);
116        self.did_an_error_occur()
117    }
118}
119
120impl<'a> MaybeCached<'a, Statement> {
121    pub(super) fn execute_statement(
122        self,
123        binds: &mut OutputBinds,
124    ) -> QueryResult<StatementUse<'a>> {
125        unsafe {
126            binds.with_mysql_binds(|bind_ptr| self.bind_result(bind_ptr))?;
127            self.execute()
128        }
129    }
130
131    /// This function should be called instead of `results` on queries which
132    /// have no return value. It should never be called on a statement on
133    /// which `results` has previously been called?
134    pub(super) unsafe fn execute(self) -> QueryResult<StatementUse<'a>> {
135        ffi::mysql_stmt_execute(self.stmt.as_ptr());
136        self.did_an_error_occur()?;
137        ffi::mysql_stmt_store_result(self.stmt.as_ptr());
138        let ret = StatementUse { inner: self };
139        ret.inner.did_an_error_occur()?;
140        Ok(ret)
141    }
142}
143
144impl Drop for Statement {
145    fn drop(&mut self) {
146        unsafe { ffi::mysql_stmt_close(self.stmt.as_ptr()) };
147    }
148}
149
150#[allow(missing_debug_implementations)]
151pub(super) struct StatementUse<'a> {
152    inner: MaybeCached<'a, Statement>,
153}
154
155impl StatementUse<'_> {
156    pub(in crate::mysql::connection) fn affected_rows(&self) -> QueryResult<usize> {
157        let affected_rows = unsafe { ffi::mysql_stmt_affected_rows(self.inner.stmt.as_ptr()) };
158        affected_rows
159            .try_into()
160            .map_err(|e| Error::DeserializationError(Box::new(e)))
161    }
162
163    /// This function should be called after `execute` only
164    /// otherwise it's not guaranteed to return a valid result
165    pub(in crate::mysql::connection) unsafe fn result_size(&mut self) -> QueryResult<usize> {
166        let size = ffi::mysql_stmt_num_rows(self.inner.stmt.as_ptr());
167        usize::try_from(size).map_err(|e| Error::DeserializationError(Box::new(e)))
168    }
169
170    pub(super) fn populate_row_buffers(&self, binds: &mut OutputBinds) -> QueryResult<Option<()>> {
171        let next_row_result = unsafe { ffi::mysql_stmt_fetch(self.inner.stmt.as_ptr()) };
172        if next_row_result < 0 {
173            self.inner.did_an_error_occur().map(Some)
174        } else {
175            #[allow(clippy::cast_sign_loss)] // that's how it's supposed to be based on the API
176            match next_row_result as libc::c_uint {
177                ffi::MYSQL_NO_DATA => Ok(None),
178                ffi::MYSQL_DATA_TRUNCATED => binds.populate_dynamic_buffers(self).map(Some),
179                0 => {
180                    binds.update_buffer_lengths();
181                    Ok(Some(()))
182                }
183                _error => self.inner.did_an_error_occur().map(Some),
184            }
185        }
186    }
187
188    pub(in crate::mysql::connection) unsafe fn fetch_column(
189        &self,
190        bind: &mut ffi::MYSQL_BIND,
191        idx: usize,
192        offset: usize,
193    ) -> QueryResult<()> {
194        ffi::mysql_stmt_fetch_column(
195            self.inner.stmt.as_ptr(),
196            bind,
197            idx.try_into()
198                .map_err(|e| Error::DeserializationError(Box::new(e)))?,
199            offset as libc::c_ulong,
200        );
201        self.inner.did_an_error_occur()
202    }
203
204    /// If the pointers referenced by the `MYSQL_BIND` structures are invalidated,
205    /// you must call this function again before calling `mysql_stmt_fetch`.
206    pub(in crate::mysql::connection) unsafe fn bind_result(
207        &self,
208        binds: *mut ffi::MYSQL_BIND,
209    ) -> QueryResult<()> {
210        self.inner.bind_result(binds)
211    }
212}
213
214impl Drop for StatementUse<'_> {
215    fn drop(&mut self) {
216        unsafe {
217            ffi::mysql_stmt_free_result(self.inner.stmt.as_ptr());
218        }
219    }
220}
diesel/mysql/connection/stmt/mod.rs

diesel/mysql/connection/stmt/
mod.rs
