Support parametrized statements

c_src/sqlite3_drv.c

@@ -1,5 +1,6 @@
 #include "sqlite3_drv.h"
 #include "ei.h"
+#include "assert.h"
 
 // MSVC needs "__inline" instead of "inline" in C-source files.
 #if defined(_MSC_VER)
@@ -107,6 +108,9 @@ static int control(ErlDrvData drv_data, unsigned int command, char *buf,
   case CMD_SQL_EXEC:
     sql_exec(driver_data, buf, len);
     break;
+  case CMD_SQL_BIND_AND_EXEC:
+    sql_bind_and_exec(driver_data, buf, len);
+    break;
   default:
     unknown(driver_data, buf, len);
   }
@@ -129,23 +133,19 @@ static inline int return_error(sqlite3_drv_t *drv, const char *error,
   return 0;
 }
 
-static int sql_exec(sqlite3_drv_t *drv, char *command, int command_size) {
-  int result, next_row;
-  char *rest = NULL;
-  sqlite3_stmt *statement;
+static inline int output_error(sqlite3_drv_t *drv, const char *error) {
+  ErlDrvTermData *dataset;
+  int term_count;
+  return_error(drv, error, &dataset, &term_count);
+  driver_output_term(drv->port, dataset, term_count);
+  return 0;
+}
 
-  // fprintf(drv->log, "Preexec: %.*s\n", command_size, command);
-  // fflush(drv->log);
-  result = sqlite3_prepare_v2(drv->db, command, command_size, &statement,
-                              (const char **) &rest);
-  if (result != SQLITE_OK) {
-    ErlDrvTermData *dataset;
-    int term_count;
-    return_error(drv, sqlite3_errmsg(drv->db), &dataset, &term_count);
-    driver_output_term(drv->port, dataset, term_count);
-    return 0;
-  }
+static inline int output_db_error(sqlite3_drv_t *drv) {
+  return output_error(drv, sqlite3_errmsg(drv->db));
+}
 
+static inline int sql_exec_statement(sqlite3_drv_t *drv, sqlite3_stmt *statement) {
   async_sqlite3_command *async_command =
     (async_sqlite3_command *) calloc(1, sizeof(async_sqlite3_command));
   async_command->driver_data = drv;
@@ -157,7 +157,7 @@ static int sql_exec(sqlite3_drv_t *drv, char *command, int command_size) {
   if (sqlite3_threadsafe()) {
     drv->async_handle =
       driver_async(drv->port, &drv->key, sql_exec_async,
-                   async_command, sql_free_async);
+             async_command, sql_free_async);
   } else {
     sql_exec_async(async_command);
     ready_async((ErlDrvData) drv, (ErlDrvThreadData) async_command);
@@ -166,6 +166,193 @@ static int sql_exec(sqlite3_drv_t *drv, char *command, int command_size) {
   return 0;
 }
 
+static int sql_exec(sqlite3_drv_t *drv, char *command, int command_size) {
+  int result;
+  char *rest = NULL;
+  sqlite3_stmt *statement;
+
+  // fprintf(drv->log, "Preexec: %.*s\n", command_size, command);
+  // fflush(drv->log);
+  result = sqlite3_prepare_v2(drv->db, command, command_size, &statement,
+                              (const char **) &rest);
+  if (result != SQLITE_OK) {
+    return output_db_error(drv);
+  }
+
+  return sql_exec_statement(drv, statement);
+}
+
+static inline int decode_and_bind_param(
+    sqlite3_drv_t *drv, char *buffer, int *index, sqlite3_stmt *statement, int param_index, int *type, int *size) {
+  int result;
+  ei_get_type(buffer, index, type, size);
+  long long_val;
+  sqlite3_int64 int64_val;
+  double double_val;
+  char* char_buf_val;
+  switch (*type) {
+  case ERL_SMALL_INTEGER_EXT:
+    ei_decode_long(buffer, index, &long_val);
+    result = sqlite3_bind_int(statement, param_index, long_val);
+    break;
+  case ERL_INTEGER_EXT:
+    ei_decode_longlong(buffer, index, &int64_val);
+    result = sqlite3_bind_int64(statement, param_index, int64_val);
+    break;
+  case ERL_FLOAT_EXT:
+  case NEW_FLOAT_EXT: // what's the difference?
+    ei_decode_double(buffer, index, &double_val);
+    result = sqlite3_bind_double(statement, param_index, double_val);
+    break;
+  case ERL_ATOM_EXT:
+    char_buf_val = malloc((*size + 1) * sizeof(char));
+    ei_decode_atom(buffer, index, char_buf_val);
+    if (strncmp(char_buf_val, "null", 5) == 0) {
+      result = sqlite3_bind_null(statement, param_index);
+    }
+    else {
+      output_error(drv, "Non-null atom as parameter");
+      return 1;
+    }
+    break;
+  case ERL_STRING_EXT:
+    char_buf_val = malloc((*size + 1) * sizeof(char)); // space for null separator
+    ei_decode_string(buffer, index, char_buf_val);
+    result = sqlite3_bind_text(statement, param_index, char_buf_val, *size, &free);
+    break;
+  case ERL_BINARY_EXT:
+    char_buf_val = malloc(*size * sizeof(char));
+    ei_decode_binary(buffer, index, char_buf_val, size);
+    result = sqlite3_bind_text(statement, param_index, char_buf_val, *size, &free);
+    break;
+  case ERL_SMALL_TUPLE_EXT:
+    // assume this is {blob, Blob}
+    ei_get_type(buffer, index, type, size);
+    ei_decode_tuple_header(buffer, index, size);
+    assert (*size == 2);
+    ei_skip_term(buffer, index); // skipped the atom 'blob'
+    ei_get_type(buffer, index, type, size);
+    assert (*type == ERL_BINARY_EXT);
+    char_buf_val = malloc(*size * sizeof(char));
+    ei_decode_binary(buffer, index, char_buf_val, size);
+    result = sqlite3_bind_blob(statement, param_index, char_buf_val, *size, &free);
+    break;
+  default:
+    output_error(drv, "bad parameter type");
+    return 1;
+  }
+  if (result != SQLITE_OK) {
+    output_db_error(drv);
+    return result;
+  }
+  return SQLITE_OK;
+}
+
+static int sql_bind_and_exec(sqlite3_drv_t *drv, char *buffer, int buffer_size) {
+  int result;
+  int index = 0;
+  int type, size;
+  char *rest = NULL;
+  sqlite3_stmt *statement;
+
+  // fprintf(drv->log, "Preexec: %.*s\n", command_size, command);
+  // fflush(drv->log);
+
+  ei_decode_version(buffer, &index, NULL);
+  result = ei_decode_tuple_header(buffer, &index, &size);
+  if (size != 2) {
+    return output_error(drv, "bad argument");
+  }
+
+  // decode SQL statement
+  ei_get_type(buffer, &index, &type, &size);
+  if (type != ERL_BINARY_EXT) {
+    return output_error(drv, "bad argument");
+  }
+
+  char *command = malloc(size * sizeof(char));
+  ei_decode_binary(buffer, &index, command, &size);
+  // printf("size: %d, command: %.*s\n", size, size, command);
+  result = sqlite3_prepare_v2(drv->db, command, size, &statement,
+                              (const char **) &rest);
+  free(command);
+
+  if (result != SQLITE_OK) {
+    return output_db_error(drv);
+  }
+
+  // decoding parameters
+  int i, cur_list_size = -1, param_index = 1, param_indices_are_explicit = 0;
+  char param_name[MAXATOMLEN + 1]; // parameter names shouldn't be longer than 256!
+  while (index < buffer_size) {
+    ei_decode_list_header(buffer, &index, &cur_list_size);
+    // note the finish condition; the last element is the tail and we shouldn't decode it!
+    for (i = 0; i < cur_list_size; i++) {
+      ei_get_type(buffer, &index, &type, &size);
+      if (type == ERL_SMALL_TUPLE_EXT) {
+        int old_index = index;
+        // param with name or explicit index
+        param_indices_are_explicit = 1;
+        if (size != 2) {
+          return output_error(drv, "bad argument");
+        }
+        ei_decode_tuple_header(buffer, &index, &size);
+        ei_get_type(buffer, &index, &type, &size);
+        // first element of tuple is int (index), atom, or string (name)
+        switch (type) {
+        case ERL_SMALL_INTEGER_EXT:
+          ei_decode_long(buffer, &index, &param_index);
+          break;
+        case ERL_ATOM_EXT:
+          ei_decode_atom(buffer, &index, param_name);
+          // insert zero terminator
+          param_name[size] = '\0';
+          if (strncmp(param_name, "blob", 5) == 0) {
+            // this isn't really a parameter name!
+            index = old_index;
+            param_indices_are_explicit = 0;
+            goto IMPLICIT_INDEX; // yuck
+          }
+          else {
+            param_index = sqlite3_bind_parameter_index(statement, param_name);
+          }
+          break;
+        case ERL_STRING_EXT:
+          if (size >= MAXATOMLEN) {
+            return output_error(drv, "parameter name too long");
+          }
+          ei_decode_string(buffer, &index, param_name);
+          // insert zero terminator
+          param_name[size] = '\0';
+          param_index = sqlite3_bind_parameter_index(statement, param_name);
+          break;
+        default:
+          return output_error(drv, "parameter index must be given as integer, atom, or string");
+        }
+        result = decode_and_bind_param(drv, buffer, &index, statement, param_index, &type, &size);
+        if (result != SQLITE_OK) {
+          return result; // error has already been output
+        }
+      }
+      else {
+        IMPLICIT_INDEX:
+        if (param_indices_are_explicit) {
+          return output_error(drv,
+            "parameters without indices shouldn't follow indexed or named parameters");
+        }
+
+        result = decode_and_bind_param(drv, buffer, &index, statement, param_index, &type, &size);
+        if (result != SQLITE_OK) {
+          return result; // error has already been output
+        }
+        ++param_index;
+      }
+    }
+  }
+
+  return sql_exec_statement(drv, statement);
+}
+
 static void sql_free_async(void *_async_command) {
   int i;
   async_sqlite3_command *async_command =

c_src/sqlite3_drv.h

@@ -18,6 +18,7 @@
 // Binary commands between Erlang VM and Driver
 #define CMD_SQL_EXEC 2
 // #define CMD_DEL 3
+#define CMD_SQL_BIND_AND_EXEC 4
 
 // Number of bytes for each key
 // (160 bits for SHA1 hash)
@@ -61,6 +62,7 @@ static void stop(ErlDrvData handle);
 static int control(ErlDrvData drv_data, unsigned int command, char *buf, 
                    int len, char **rbuf, int rlen);
 static int sql_exec(sqlite3_drv_t *drv, char *buf, int len);
+static int sql_bind_and_exec(sqlite3_drv_t *drv, char *buf, int len);
 static void sql_exec_async(void *async_command);
 static void sql_free_async(void *async_command);
 static void ready_async(ErlDrvData drv_data, ErlDrvThreadData thread_data);