[sql] Rewrite sqlite patching "system".

third_party/sqlite/patches/0006-Modify-default-VFS-to-support-WebDatabase.patch

-The WebDatabase implementation in the renderer users a custom vfs to
-broker file open and other requests.  This modifies the built-in vfs
-implementation to let that code share much of the implementation
-details.
+From fbe968c746d928b8372ea354229aef6772606336 Mon Sep 17 00:00:00 2001
+From: Scott Hess <shess@chromium.org>
+Date: Tue, 16 Dec 2014 13:03:36 -0800
+Subject: [PATCH 06/24] Modify default VFS to support WebDatabase.
 
-diff --git src/os_unix.c src/os_unix.c
-index ef04a72..e5e1509 100644
---- src/os_unix.c
-+++ src/os_unix.c
-@@ -3496,9 +3496,16 @@ typedef const sqlite3_io_methods *(*finder_type)(const char*,unixFile*);
+The renderer WebDatabase implementation needs to broker certain requests
+to the browser.  This modifies SQLite to allow monkey-patching the VFS
+to support this.
+
+NOTE(shess): This patch relies on core SQLite implementation details
+remaining unchanged.  When importing a new version of SQLite, pay very
+close attention to whether the change is still doing what is intended.
+---
+ third_party/sqlite/src/src/os_unix.c | 98 +++++++++++++++++++++++++++++-------
+ third_party/sqlite/src/src/os_win.c  |  7 +++
+ 2 files changed, 88 insertions(+), 17 deletions(-)
+
+diff --git a/third_party/sqlite/src/src/os_unix.c b/third_party/sqlite/src/src/os_unix.c
+index 998e353..766b52a 100644
+--- a/third_party/sqlite/src/src/os_unix.c
++++ b/third_party/sqlite/src/src/os_unix.c
+@@ -4418,9 +4418,16 @@ typedef const sqlite3_io_methods *(*finder_type)(const char*,unixFile*);
  */
  
  /*
 +** Initializes a unixFile structure with zeros.
 +*/
 +void initUnixFile(sqlite3_file* file) {
 +  memset(file, 0, sizeof(unixFile));
 +}
 +
 +/*
  ** Initialize the contents of the unixFile structure pointed to by pId.
  */
 -static int fillInUnixFile(
 +int fillInUnixFile(
    sqlite3_vfs *pVfs,      /* Pointer to vfs object */
    int h,                  /* Open file descriptor of file being opened */
    int dirfd,              /* Directory file descriptor */
-@@ -3812,6 +3819,73 @@ static UnixUnusedFd *findReusableFd(const char *zPath, int flags){
+@@ -4834,6 +4841,73 @@ static int findCreateFileMode(
  }
  
  /*
 +** Initializes a unixFile structure with zeros.
 +*/
 +void chromium_sqlite3_initialize_unix_sqlite3_file(sqlite3_file* file) {
 +  memset(file, 0, sizeof(unixFile));
 +}
 +
 +int chromium_sqlite3_fill_in_unix_sqlite3_file(sqlite3_vfs* vfs,
@@ skipping 53 matching lines @@
 +*/
 +void chromium_sqlite3_destroy_reusable_file_handle(sqlite3_file* file) {
 +  unixFile* unixSQLite3File = (unixFile*)file;
 +  sqlite3_free(unixSQLite3File->pUnused);
 +}
 +
 +/*
  ** Open the file zPath.
  ** 
  ** Previously, the SQLite OS layer used three functions in place of this
-@@ -3893,20 +3967,13 @@ static int unixOpen(
-        || eType==SQLITE_OPEN_TRANSIENT_DB
+@@ -4921,20 +4995,13 @@ static int unixOpen(
+        || eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL
    );
  
 -  memset(p, 0, sizeof(unixFile));
 +  chromium_sqlite3_initialize_unix_sqlite3_file(pFile);
  
    if( eType==SQLITE_OPEN_MAIN_DB ){
 -    UnixUnusedFd *pUnused;
 -    pUnused = findReusableFd(zName, flags);
 -    if( pUnused ){
 -      fd = pUnused->fd;
 -    }else{
 -      pUnused = sqlite3_malloc(sizeof(*pUnused));
 -      if( !pUnused ){
 -        return SQLITE_NOMEM;
 -      }
 +    rc = chromium_sqlite3_get_reusable_file_handle(pFile, zName, flags, &fd);
 +    if( rc!=SQLITE_OK ){
 +      return rc;
      }
 -    p->pUnused = pUnused;
    }else if( !zName ){
      /* If zName is NULL, the upper layer is requesting a temp file. */
      assert(isDelete && !isOpenDirectory);
-@@ -3949,10 +4016,7 @@ static int unixOpen(
+@@ -4984,10 +5051,7 @@ static int unixOpen(
      *pOutFlags = flags;
    }
  
 -  if( p->pUnused ){
 -    p->pUnused->fd = fd;
 -    p->pUnused->flags = flags;
 -  }
 +  chromium_sqlite3_update_reusable_file_handle(pFile, fd, flags);
  
    if( isDelete ){
  #if OS_VXWORKS
-@@ -4028,7 +4092,7 @@ static int unixOpen(
-   rc = fillInUnixFile(pVfs, fd, dirfd, pFile, zPath, noLock, isDelete);
+@@ -5090,7 +5154,7 @@ static int unixOpen(
+                       isDelete, isReadonly);
  open_finished:
    if( rc!=SQLITE_OK ){
 -    sqlite3_free(p->pUnused);
 +    chromium_sqlite3_destroy_reusable_file_handle(pFile);
    }
    return rc;
  }
-diff --git src/os_win.c src/os_win.c
-index bc03a4b..06539d7 100644
---- src/os_win.c
-+++ src/os_win.c
-@@ -1890,4 +1890,11 @@ int sqlite3_os_end(void){
+diff --git a/third_party/sqlite/src/src/os_win.c b/third_party/sqlite/src/src/os_win.c
+index c876833..78e58b5 100644
+--- a/third_party/sqlite/src/src/os_win.c
++++ b/third_party/sqlite/src/src/os_win.c
+@@ -2784,4 +2784,11 @@ int sqlite3_os_end(void){
    return SQLITE_OK;
  }
  
 +void chromium_sqlite3_initialize_win_sqlite3_file(sqlite3_file* file, HANDLE handle) {
 +  winFile* winSQLite3File = (winFile*)file;
 +  memset(file, 0, sizeof(*file));
 +  winSQLite3File->pMethod = &winIoMethod;
 +  winSQLite3File->h = handle;
 +}
 +
  #endif /* SQLITE_OS_WIN */
+-- 
+2.2.1
+