From a1204dd3795bd9bd9d7ad7a78e568543d337fc6a Mon Sep 17 00:00:00 2001
From: Stephen Lombardo <sjlombardo@zetetic.net>
Date: Mon, 9 Oct 2023 14:17:11 -0400
Subject: [PATCH] add pragma page_size compatibility so it will operate on
 encrypted databases

---
 src/crypto.c                |  9 ++++++++-
 test/sqlcipher-core.test    | 46 ++++++++++++++++++++++++++++++++++++++++++++-
 test/sqlcipher-pragmas.test | 29 ++++++++++++++++++++++++++++
 3 files changed, 82 insertions(+), 2 deletions(-)

diff --git a/src/crypto.c b/src/crypto.c
index 9c722fd4..fcb1d9d6 100644
--- a/src/crypto.c
+++ b/src/crypto.c
@@ -260,7 +260,12 @@ int sqlcipher_codec_pragma(sqlite3* db, int iDb, Parse *pParse, const char *zLef
     sqlcipher_vdbe_return_string(pParse, "rekey_kdf_iter", message, P4_TRANSIENT);
     sqlite3_log(SQLITE_WARNING, message);
   }else
-  if( sqlite3_stricmp(zLeft,"cipher_page_size")==0 ){
+  if( sqlite3_stricmp(zLeft,"page_size")==0 || sqlite3_stricmp(zLeft,"cipher_page_size")==0 ){
+    /* PRAGMA cipher_page_size will alter the size of the database pages while ensuring that the
+       required reserve space is allocated at the end of each page. This will also override the
+       standard SQLite PRAGMA page_size behavior if a codec context is attached to the database handle.
+       If PRAGMA page_size is invoked but a codec context is not attached (i.e. dealing with a standard
+       unencrypted database) then return early and allow the standard PRAGMA page_size logic to apply. */
     if(ctx) {
       if( zRight ) {
         int size = atoi(zRight);
@@ -272,6 +277,8 @@ int sqlcipher_codec_pragma(sqlite3* db, int iDb, Parse *pParse, const char *zLef
         char * page_size = sqlite3_mprintf("%d", sqlcipher_codec_ctx_get_pagesize(ctx));
         sqlcipher_vdbe_return_string(pParse, "cipher_page_size", page_size, P4_DYNAMIC);
       }
+    } else {
+      return 0; /* return early so that the PragTyp_PAGE_SIZE case logic in pragma.c will take effect */
     }
   }else
   if( sqlite3_stricmp(zLeft,"cipher_default_page_size")==0 ){
diff --git a/test/sqlcipher-core.test b/test/sqlcipher-core.test
index 5aed9fb6..c4b5e3bf 100644
--- a/test/sqlcipher-core.test
+++ b/test/sqlcipher-core.test
@@ -498,7 +498,7 @@ file delete -force test.db
 #    key and page size
 # 4. verify that the table is readable
 #    and the data just inserted is visible
-do_test custom-pagesize {
+do_test custom-pagesize-pragma-cipher-page-size {
   sqlite_orig db test.db
 
   execsql {
@@ -528,11 +528,55 @@ do_test custom-pagesize {
 
 } {ok 1000}
 db close
+file delete -force test.db
+
+# run the same logic as previous test but use
+# pragma page_size instead
+do_test custom-pagesize-pragma-pagesize {
+  sqlite_orig db test.db
+
+  execsql {
+    PRAGMA key = 'testkey';
+    PRAGMA page_size = 8192;
+    CREATE table t1(a,b);
+    BEGIN;
+  }
+
+  for {set i 1} {$i<=1000} {incr i} {
+    set r [expr {int(rand()*500000)}]
+    execsql "INSERT INTO t1 VALUES($i,'value $r');"
+  }
+
+  execsql {
+    COMMIT;
+  }
+
+  db close
+  sqlite_orig db test.db
+
+  execsql {
+    PRAGMA key = 'testkey';
+    PRAGMA page_size = 8192;
+    SELECT count(*) FROM t1;
+  }
+
+} {ok 1000}
+db close
+file delete -force test.db
 
 # open the database with the default page size
 ## and verfiy that it is not readable 
 do_test custom-pagesize-must-match {
   sqlite_orig db test.db
+  execsql {
+    PRAGMA key = 'testkey';
+    PRAGMA cipher_page_size = 8192;
+    CREATE table t1(a,b);
+  }
+
+  db close
+  sqlite_orig db test.db
+
   catchsql {
     PRAGMA key = 'testkey';
     SELECT name FROM sqlite_schema WHERE type='table';
diff --git a/test/sqlcipher-pragmas.test b/test/sqlcipher-pragmas.test
index daf7f8a9..c7087bb9 100644
--- a/test/sqlcipher-pragmas.test
+++ b/test/sqlcipher-pragmas.test
@@ -202,6 +202,35 @@ do_test verify-pragma-cipher-page-size-changed {
 db close
 file delete -force test.db
 
+# verify that a call to pragma page_size
+# will report change via both page_size and cipher_page_size
+# when there is an attached codec
+do_test verify-pragma-page-size-encrypted {
+    sqlite_orig db test.db
+    execsql {
+        PRAGMA key = 'test';
+        PRAGMA page_size = 8192;
+        PRAGMA page_size;
+        PRAGMA cipher_page_size;
+    }
+} {ok 8192 8192}
+db close
+file delete -force test.db
+
+# verify that a call to pragma page_size
+# will not report a change to cipher_page_size for an
+# unencrypted database
+do_test verify-pragma-page-size-plaintext {
+    sqlite_orig db test.db
+    execsql {
+        PRAGMA page_size = 8192;
+        PRAGMA page_size;
+        PRAGMA cipher_page_size;
+    }
+} {8192}
+db close
+file delete -force test.db
+
 # verify setting cipher_store_pass before key
 # does not cause segfault
 do_test verify-cipher-store-pass-before-key-does-not-segfault {
-- 
2.11.4.GIT