Merge 'Add load_extension function, resolve shared lib extensions' from Preston Thorpe

This PR adds the `load_extension` function, and allows for platform
agnostic arguments: e.g. `select
load_extension('target/debug/liblimbo_uuid');` omitting the file
extension.

Closes #680

COMPAT.md

@@ -120,7 +120,7 @@ Feature support of [sqlite expr syntax](https://www.sqlite.org/lang_expr.html).
 | like(X,Y,Z)                  | Yes    |         |
 | likelihood(X,Y)              | No     |         |
 | likely(X)                    | No     |         |
-| load_extension(X)            | No     |         |
+| load_extension(X)            | Yes    | sqlite3 extensions not yet supported |
 | load_extension(X,Y)          | No     |         |
 | lower(X)                     | Yes    |         |
 | ltrim(X)                     | Yes    |         |

cli/app.rs

@@ -325,7 +325,10 @@ impl Limbo {
 
     #[cfg(not(target_family = "wasm"))]
     fn handle_load_extension(&mut self, path: &str) -> Result<(), String> {
-        self.conn.load_extension(path).map_err(|e| e.to_string())
+        let ext_path = limbo_core::resolve_ext_path(path).map_err(|e| e.to_string())?;
+        self.conn
+            .load_extension(ext_path)
+            .map_err(|e| e.to_string())
     }
 
     fn display_in_memory(&mut self) -> std::io::Result<()> {

core/function.rs

@@ -136,6 +136,8 @@ pub enum ScalarFunc {
     ZeroBlob,
     LastInsertRowid,
     Replace,
+    #[cfg(not(target_family = "wasm"))]
+    LoadExtension,
 }
 
 impl Display for ScalarFunc {
@@ -185,6 +187,8 @@ impl Display for ScalarFunc {
             Self::LastInsertRowid => "last_insert_rowid".to_string(),
             Self::Replace => "replace".to_string(),
             Self::DateTime => "datetime".to_string(),
+            #[cfg(not(target_family = "wasm"))]
+            Self::LoadExtension => "load_extension".to_string(),
         };
         write!(f, "{}", str)
     }
@@ -426,6 +430,8 @@ impl Func {
             "tan" => Ok(Self::Math(MathFunc::Tan)),
             "tanh" => Ok(Self::Math(MathFunc::Tanh)),
             "trunc" => Ok(Self::Math(MathFunc::Trunc)),
+            #[cfg(not(target_family = "wasm"))]
+            "load_extension" => Ok(Self::Scalar(ScalarFunc::LoadExtension)),
             _ => Err(()),
         }
     }

core/lib.rs

@@ -182,7 +182,7 @@ impl Database {
     }
 
     #[cfg(not(target_family = "wasm"))]
-    pub fn load_extension(&self, path: &str) -> Result<()> {
+    pub fn load_extension<P: AsRef<std::ffi::OsStr>>(&self, path: P) -> Result<()> {
         let api = Box::new(self.build_limbo_extension());
         let lib =
             unsafe { Library::new(path).map_err(|e| LimboError::ExtensionError(e.to_string()))? };
@@ -401,7 +401,7 @@ impl Connection {
     }
 
     #[cfg(not(target_family = "wasm"))]
-    pub fn load_extension(&self, path: &str) -> Result<()> {
+    pub fn load_extension<P: AsRef<std::ffi::OsStr>>(&self, path: P) -> Result<()> {
         Database::load_extension(self.db.as_ref(), path)
     }
 
@@ -515,6 +515,33 @@ impl std::fmt::Debug for SymbolTable {
     }
 }
 
+fn is_shared_library(path: &std::path::Path) -> bool {
+    path.extension()
+        .map_or(false, |ext| ext == "so" || ext == "dylib" || ext == "dll")
+}
+
+pub fn resolve_ext_path(extpath: &str) -> Result<std::path::PathBuf> {
+    let path = std::path::Path::new(extpath);
+    if !path.exists() {
+        if is_shared_library(path) {
+            return Err(LimboError::ExtensionError(format!(
+                "Extension file not found: {}",
+                extpath
+            )));
+        };
+        let maybe = path.with_extension(std::env::consts::DLL_EXTENSION);
+        maybe
+            .exists()
+            .then_some(maybe)
+            .ok_or(LimboError::ExtensionError(format!(
+                "Extension file not found: {}",
+                extpath
+            )))
+    } else {
+        Ok(path.to_path_buf())
+    }
+}
+
 impl SymbolTable {
     pub fn new() -> Self {
         Self {

core/translate/expr.rs

@@ -1092,6 +1092,19 @@ pub fn translate_expr(
                             });
                             Ok(target_register)
                         }
+                        #[cfg(not(target_family = "wasm"))]
+                        ScalarFunc::LoadExtension => {
+                            let args = expect_arguments_exact!(args, 1, srf);
+                            let reg =
+                                translate_and_mark(program, referenced_tables, &args[0], resolver)?;
+                            program.emit_insn(Insn::Function {
+                                constant_mask: 0,
+                                start_reg: reg,
+                                dest: target_register,
+                                func: func_ctx,
+                            });
+                            Ok(target_register)
+                        }
                         ScalarFunc::Random => {
                             if args.is_some() {
                                 crate::bail_parse_error!(

core/vdbe/mod.rs

@@ -41,7 +41,7 @@ use crate::{
     json::json_arrow_extract, json::json_arrow_shift_extract, json::json_error_position,
     json::json_extract, json::json_type,
 };
-use crate::{Connection, Result, Rows, TransactionState, DATABASE_VERSION};
+use crate::{resolve_ext_path, Connection, Result, Rows, TransactionState, DATABASE_VERSION};
 use datetime::{exec_date, exec_datetime_full, exec_julianday, exec_time, exec_unixepoch};
 use insn::{
     exec_add, exec_bit_and, exec_bit_not, exec_bit_or, exec_divide, exec_multiply, exec_remainder,
@@ -1863,6 +1863,14 @@ impl Program {
                                 let replacement = &state.registers[*start_reg + 2];
                                 state.registers[*dest] = exec_replace(source, pattern, replacement);
                             }
+                            #[cfg(not(target_family = "wasm"))]
+                            ScalarFunc::LoadExtension => {
+                                let extension = &state.registers[*start_reg];
+                                let ext = resolve_ext_path(&extension.to_string())?;
+                                if let Some(conn) = self.connection.upgrade() {
+                                    conn.load_extension(ext)?;
+                                }
+                            }
                         },
                         crate::function::Func::External(f) => {
                             call_external_function! {f.func, *dest, state, arg_count, *start_reg };