[sql] Move time-machine support from third_party/sqlite to sql/

sql/vfs_wrapper.cc

+// Copyright (c) 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "sql/vfs_wrapper.h"
+
+#include <algorithm>
+#include <string>
+#include <vector>
+
+#include "base/debug/leak_annotations.h"
+#include "base/logging.h"
+#include "base/memory/ptr_util.h"
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
+
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+#include <CoreFoundation/CoreFoundation.h>
+#include <CoreServices/CoreServices.h>
+
+#include "base/mac/mac_util.h"
+#include "base/mac/scoped_cftyperef.h"
+#endif
+
+namespace sql {
+namespace {
+
+// https://www.sqlite.org/vfs.html - documents the overall VFS system.
+//
+// https://www.sqlite.org/c3ref/vfs.html - VFS methods.  This code tucks the
+// wrapped VFS pointer into the wrapper's pAppData pointer.
+//
+// https://www.sqlite.org/c3ref/file.html - instance of an open file.  This code
+// allocates a VfsFile for this, which contains a pointer to the wrapped file.
+// Idiomatic SQLite would take the wrapped VFS szOsFile and increase it to store
+// additional data as a prefix.
+
+sqlite3_vfs* GetWrappedVfs(sqlite3_vfs* wrapped_vfs) {
+  return static_cast<sqlite3_vfs*>(wrapped_vfs->pAppData);
+}
+
+// NOTE(shess): This structure is allocated by SQLite using malloc.  Do not add
+// C++ objects, they will not be correctly constructed and destructed.  Instead,
+// manually manage a pointer to a C++ object in Open() and Close().
+struct VfsFile {
+  const sqlite3_io_methods* methods;
+  sqlite3_file* wrapped_file;
+};
+
+VfsFile* AsVfsFile(sqlite3_file* wrapper_file) {
+  return reinterpret_cast<VfsFile*>(wrapper_file);
+}
+
+sqlite3_file* GetWrappedFile(sqlite3_file* wrapper_file) {
+  return AsVfsFile(wrapper_file)->wrapped_file;
+}
+
+int Close(sqlite3_file* sqlite_file)
+{
+  VfsFile* file = AsVfsFile(sqlite_file);
+
+  int r = file->wrapped_file->pMethods->xClose(file->wrapped_file);
+  sqlite3_free(file->wrapped_file);
+  memset(file, 0, sizeof(*file));
+  return r;
+}
+
+int Read(sqlite3_file* sqlite_file, void* buf, int amt, sqlite3_int64 ofs)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xRead(wrapped_file, buf, amt, ofs);
+}
+
+int Write(sqlite3_file* sqlite_file, const void* buf, int amt,
+          sqlite3_int64 ofs)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xWrite(wrapped_file, buf, amt, ofs);
+}
+
+int Truncate(sqlite3_file* sqlite_file, sqlite3_int64 size)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xTruncate(wrapped_file, size);
+}
+
+int Sync(sqlite3_file* sqlite_file, int flags)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xSync(wrapped_file, flags);
+}
+
+int FileSize(sqlite3_file* sqlite_file, sqlite3_int64* size)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xFileSize(wrapped_file, size);
+}
+
+int Lock(sqlite3_file* sqlite_file, int file_lock)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xLock(wrapped_file, file_lock);
+}
+
+int Unlock(sqlite3_file* sqlite_file, int file_lock)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xUnlock(wrapped_file, file_lock);
+}
+
+int CheckReservedLock(sqlite3_file* sqlite_file, int* result)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xCheckReservedLock(wrapped_file, result);
+}
+
+int FileControl(sqlite3_file* sqlite_file, int op, void* arg)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xFileControl(wrapped_file, op, arg);
+}
+
+int SectorSize(sqlite3_file* sqlite_file)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xSectorSize(wrapped_file);
+}
+
+int DeviceCharacteristics(sqlite3_file* sqlite_file)
+{
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xDeviceCharacteristics(wrapped_file);
+}
+
+int ShmMap(sqlite3_file *sqlite_file, int region, int size,
+           int extend, void volatile **pp) {
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xShmMap(
+      wrapped_file, region, size, extend, pp);
+}
+
+int ShmLock(sqlite3_file *sqlite_file, int ofst, int n, int flags) {
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xShmLock(wrapped_file, ofst, n, flags);
+}
+
+void ShmBarrier(sqlite3_file *sqlite_file) {
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  wrapped_file->pMethods->xShmBarrier(wrapped_file);
+}
+
+int ShmUnmap(sqlite3_file *sqlite_file, int del) {
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xShmUnmap(wrapped_file, del);
+}
+
+int Fetch(sqlite3_file *sqlite_file, sqlite3_int64 off, int amt, void **pp) {
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xFetch(wrapped_file, off, amt, pp);
+}
+
+int Unfetch(sqlite3_file *sqlite_file, sqlite3_int64 off, void *p) {
+  sqlite3_file* wrapped_file = GetWrappedFile(sqlite_file);
+  return wrapped_file->pMethods->xUnfetch(wrapped_file, off, p);
+}
+
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+// Helper to convert a POSIX path into a CoreFoundation path.  Returns a bare
+// ref which must be released.
+CFURLRef CFURLRefForPath(const char* path){

[Marijn Kruisselbrink, 2017/01/23 19:20:21]

nit: wouldn't it be safer if this returns a ScopedCFTypeRef rather than a bare
ref?

[Scott Hess - ex-Googler, 2017/01/23 21:18:50]

Done.

+  base::ScopedCFTypeRef<CFStringRef> urlString(
+      CFStringCreateWithFileSystemRepresentation(kCFAllocatorDefault, path));
+  return CFURLCreateWithFileSystemPath(kCFAllocatorDefault, urlString,
+                                       kCFURLPOSIXPathStyle, FALSE);
+}
+#endif
+
+int Open(sqlite3_vfs* vfs, const char* file_name, sqlite3_file* id,

[Marijn Kruisselbrink, 2017/01/23 19:20:21]

nit: why is the sqlite3_file parameter called "id"?

[Scott Hess - ex-Googler, 2017/01/23 21:18:50]

Probably historical reasons related to which experimenting-with-vfs local branch
I started with, and what SQLite was using whenever I wrote that branch.  Changed
to |wrapper_file|.

+         int desired_flags, int* used_flags) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+
+  sqlite3_file* wrapped_file = static_cast<sqlite3_file*>(
+      sqlite3_malloc(wrapped_vfs->szOsFile));
+  if (!wrapped_file)
+    return SQLITE_NOMEM;
+
+  // NOTE(shess): SQLite's unixOpen() makes assumptions about the structure of
+  // |file_name|.  Do not pass a local copy, here, only the passed-in value.
+  int rc = wrapped_vfs->xOpen(wrapped_vfs,
+                              file_name, wrapped_file,
+                              desired_flags, used_flags);
+  if (rc != SQLITE_OK) {
+    sqlite3_free(wrapped_file);
+    return rc;
+  }
+  // NOTE(shess): Any early exit from here needs to call xClose() on
+  // |wrapped_file|.
+
+#if defined(OS_MACOSX) && !defined(OS_IOS)
+  // When opening journal files, propagate time-machine exclusion from db.
+  static int kJournalFlags =
+      SQLITE_OPEN_MAIN_JOURNAL | SQLITE_OPEN_TEMP_JOURNAL |
+      SQLITE_OPEN_SUBJOURNAL | SQLITE_OPEN_MASTER_JOURNAL;
+  if (file_name && (desired_flags & kJournalFlags)) {
+    // https://www.sqlite.org/c3ref/vfs.html indicates that the journal path
+    // will have a "-suffix".
+    char* dash = rindex(file_name, '-');

[Marijn Kruisselbrink, 2017/01/23 19:20:21]

nit: I think strrchr() is the more common/actually standard C version of
rindex()?
(or base::rfind, but I suppose that doesn't buy you anything since you're
dealing with c style strings anyway)

[Scott Hess - ex-Googler, 2017/01/23 21:18:50]

Done.  You might catch me dropping bzero() here and there, too...
Shifted to rfind() because it felt like finding the index was a tiny bit more
the goal than finding the pointer.

Explicitly didn't go on to use a StringPiece proxy for rfind() to ref and to
replace db_name with as_string() because, honestly, it started to look horribly
verbose for what it was doing.

+    if (dash) {
+      std::string db_name(file_name, dash - file_name);
+      base::ScopedCFTypeRef<CFURLRef> db_url(CFURLRefForPath(db_name.c_str()));
+      if (CSBackupIsItemExcluded(db_url, NULL)) {
+        base::ScopedCFTypeRef<CFURLRef> journal_url(CFURLRefForPath(file_name));
+        CSBackupSetItemExcluded(journal_url, TRUE, FALSE);
+      }
+    }
+  }
+#endif
+
+  // The wrapper instances must support a specific |iVersion|, but there is no
+  // explicit guarantee that the wrapped VFS will always vend instances with the
+  // same |iVersion| (though I believe this is always the case in practice).
+  // Vend a distinct set of IO methods for each version supported.
+  //
+  // |iVersion| determines what methods SQLite may call on the instance.  Having
+  // the methods which can't be proxied return an error may cause SQLite to
+  // operate differently than if it didn't call those methods at all.  Another
+  // solution would be to fail if the wrapped file does not have the expected
+  // version, which may cause problems on platforms which use the system SQLite
+  // (iOS and some Linux distros).
+  VfsFile* file = AsVfsFile(id);
+  file->wrapped_file = wrapped_file;
+  if (wrapped_file->pMethods->iVersion == 1) {
+    static const sqlite3_io_methods io_methods = {
+      1,
+      Close,
+      Read,
+      Write,
+      Truncate,
+      Sync,
+      FileSize,
+      Lock,
+      Unlock,
+      CheckReservedLock,
+      FileControl,
+      SectorSize,
+      DeviceCharacteristics,
+    };
+    file->methods = &io_methods;
+  } else if (wrapped_file->pMethods->iVersion == 2) {
+    static const sqlite3_io_methods io_methods = {
+      2,
+      Close,
+      Read,
+      Write,
+      Truncate,
+      Sync,
+      FileSize,
+      Lock,
+      Unlock,
+      CheckReservedLock,
+      FileControl,
+      SectorSize,
+      DeviceCharacteristics,
+      // Methods above are valid for version 1.
+      ShmMap,
+      ShmLock,
+      ShmBarrier,
+      ShmUnmap,
+    };
+    file->methods = &io_methods;
+  } else {
+    static const sqlite3_io_methods io_methods = {
+      3,
+      Close,
+      Read,
+      Write,
+      Truncate,
+      Sync,
+      FileSize,
+      Lock,
+      Unlock,
+      CheckReservedLock,
+      FileControl,
+      SectorSize,
+      DeviceCharacteristics,
+      // Methods above are valid for version 1.
+      ShmMap,
+      ShmLock,
+      ShmBarrier,
+      ShmUnmap,
+      // Methods above are valid for version 2.
+      Fetch,
+      Unfetch,
+    };
+    file->methods = &io_methods;
+  }
+  return SQLITE_OK;
+}
+
+int Delete(sqlite3_vfs* vfs, const char* file_name, int sync_dir) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xDelete(wrapped_vfs, file_name, sync_dir);
+}
+
+int Access(sqlite3_vfs* vfs, const char* file_name, int flag, int* res) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xAccess(wrapped_vfs, file_name, flag, res);
+}
+
+int FullPathname(sqlite3_vfs* vfs, const char* relative_path,
+                 int buf_size, char* absolute_path) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xFullPathname(
+      wrapped_vfs, relative_path, buf_size, absolute_path);
+}
+
+void* DlOpen(sqlite3_vfs* vfs, const char* filename) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xDlOpen(wrapped_vfs, filename);
+}
+
+void DlError(sqlite3_vfs* vfs, int buf_size, char* error_buffer) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  wrapped_vfs->xDlError(wrapped_vfs, buf_size, error_buffer);
+}
+
+void(*DlSym(sqlite3_vfs* vfs, void* handle, const char* sym))(void) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xDlSym(wrapped_vfs, handle, sym);
+}
+
+void DlClose(sqlite3_vfs* vfs, void* handle) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  wrapped_vfs->xDlClose(wrapped_vfs, handle);
+}
+
+int Randomness(sqlite3_vfs* vfs, int buf_size, char* buffer) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xRandomness(wrapped_vfs, buf_size, buffer);
+}
+
+int Sleep(sqlite3_vfs* vfs, int microseconds) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xSleep(wrapped_vfs, microseconds);
+}
+
+int CurrentTime(sqlite3_vfs* vfs, double* now) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xCurrentTime(wrapped_vfs, now);
+}
+
+int GetLastError(sqlite3_vfs* vfs, int e, char* s) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xGetLastError(wrapped_vfs, e, s);
+}
+
+int CurrentTimeInt64(sqlite3_vfs* vfs, sqlite3_int64* now) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xCurrentTimeInt64(wrapped_vfs, now);
+}
+
+int SetSystemCall(sqlite3_vfs* vfs, const char* name,
+                  sqlite3_syscall_ptr func) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xSetSystemCall(wrapped_vfs, name, func);
+}
+
+sqlite3_syscall_ptr GetSystemCall(sqlite3_vfs* vfs, const char* name) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xGetSystemCall(wrapped_vfs, name);
+}
+
+const char* NextSystemCall(sqlite3_vfs* vfs, const char* name) {
+  sqlite3_vfs* wrapped_vfs = GetWrappedVfs(vfs);
+  return wrapped_vfs->xNextSystemCall(wrapped_vfs, name);
+}
+
+}  // namespace
+
+sqlite3_vfs* VFSWrapper() {
+  const char* kVFSName = "VFSWrapper";
+
+  // Return existing version if already registered.
+  {
+    sqlite3_vfs* vfs = sqlite3_vfs_find(kVFSName);
+    if (vfs != nullptr)
+      return vfs;
+  }
+
+  // Get the default VFS for this platform.  If no default VFS, give up.
+  sqlite3_vfs* wrapped_vfs = sqlite3_vfs_find(nullptr);
+  if (!wrapped_vfs)
+    return nullptr;
+
+  std::unique_ptr<sqlite3_vfs, std::function<void(sqlite3_vfs*)>> wrapper_vfs(
+      static_cast<sqlite3_vfs*>(sqlite3_malloc(sizeof(sqlite3_vfs))),
+      [](sqlite3_vfs* v) {
+        sqlite3_free(v);
+      });
+  memset(wrapper_vfs.get(), '\0', sizeof(sqlite3_vfs));

[Marijn Kruisselbrink, 2017/01/23 19:20:21]

nit: maybe be consistent with what zero you pass to memset? Above you pass 0,
here you pass '\0'

[Scott Hess - ex-Googler, 2017/01/23 21:18:51]

Done.  That's weird, I've had a decades-long habit of '\0' for these things.

+
+  // VFS implementations should always work with a SQLite that only knows about
+  // earlier versions.
+  wrapper_vfs->iVersion = std::min(wrapped_vfs->iVersion, 3);
+
+  // Caller of xOpen() allocates this much space.
+  wrapper_vfs->szOsFile = sizeof(VfsFile);
+
+  wrapper_vfs->mxPathname = wrapped_vfs->mxPathname;
+  wrapper_vfs->pNext = NULL;

[Marijn Kruisselbrink, 2017/01/23 19:20:21]

nullptr

[Scott Hess - ex-Googler, 2017/01/23 21:18:50]

Done.

+  wrapper_vfs->zName = kVFSName;
+
+  // Keep a reference to the wrapped vfs for use in methods.
+  wrapper_vfs->pAppData = wrapped_vfs;
+
+  // VFS methods.
+  wrapper_vfs->xOpen = &Open;
+  wrapper_vfs->xDelete = &Delete;
+  wrapper_vfs->xAccess = &Access;
+  wrapper_vfs->xFullPathname = &FullPathname;
+  wrapper_vfs->xDlOpen = &DlOpen;
+  wrapper_vfs->xDlError = &DlError;
+  wrapper_vfs->xDlSym = &DlSym;
+  wrapper_vfs->xDlClose = &DlClose;
+  wrapper_vfs->xRandomness = &Randomness;
+  wrapper_vfs->xSleep = &Sleep;
+  wrapper_vfs->xCurrentTime = &CurrentTime;
+  wrapper_vfs->xGetLastError = &GetLastError;
+  // The methods above are in version 1 of sqlite_vfs.
+  // There were VFS implementations with NULL for |xCurrentTimeInt64|.
+  wrapper_vfs->xCurrentTimeInt64 =
+      (wrapped_vfs->xCurrentTimeInt64 ? &CurrentTimeInt64 : NULL);

[Marijn Kruisselbrink, 2017/01/23 19:20:21]

nullptr

[Scott Hess - ex-Googler, 2017/01/23 21:18:50]

Done.

+  // The methods above are in version 2 of sqlite_vfs.
+  wrapper_vfs->xSetSystemCall = &SetSystemCall;
+  wrapper_vfs->xGetSystemCall = &GetSystemCall;
+  wrapper_vfs->xNextSystemCall = &NextSystemCall;
+  // The methods above are in version 3 of sqlite_vfs.
+
+  if (SQLITE_OK == sqlite3_vfs_register(wrapper_vfs.get(), 0)) {
+    ANNOTATE_LEAKING_OBJECT_PTR(wrapper_vfs.get());
+    wrapper_vfs.release();
+  }
+
+  return sqlite3_vfs_find(kVFSName);
+}
+
+}  // namespace sql