From: dan <dan@noemail.net>
Date: Mon, 23 Oct 2017 11:48:00 +0000 (+0000)
Subject: In lsm (not SQLite), avoid opening the *-shm file before the database file is
X-Git-Tag: version-3.21.0~3^2~2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b5ef728db66284c47861ea66a7e906a9a4b33cb4;p=thirdparty%2Fsqlite.git

In lsm (not SQLite), avoid opening the *-shm file before the database file is
locked. Otherwise, there is a race condition whereby a connection in another
process process may unlink() it while it is still in use.

FossilOrigin-Name: c8b8b9b573665c2b4d278bb679a48ac407374b8d860f0c3f4d50a303043464ad
---

diff --git a/ext/lsm1/lsm_shared.c b/ext/lsm1/lsm_shared.c
index 83e44b4705..c4bb9d6a23 100644
--- a/ext/lsm1/lsm_shared.c
+++ b/ext/lsm1/lsm_shared.c
@@ -340,9 +340,6 @@ static int doDbConnect(lsm_db *pDb){
   /* Obtain a pointer to the shared-memory header */
   assert( pDb->pShmhdr==0 );
   assert( pDb->bReadonly==0 );
-  rc = lsmShmCacheChunks(pDb, 1);
-  if( rc!=LSM_OK ) return rc;
-  pDb->pShmhdr = (ShmHeader *)pDb->apShm[0];
 
   /* Block for an exclusive lock on DMS1. This lock serializes all calls
   ** to doDbConnect() and doDbDisconnect() across all processes.  */
@@ -353,10 +350,11 @@ static int doDbConnect(lsm_db *pDb){
     nUs = nUs * 2;
     if( nUs>nUsMax ) nUs = nUsMax;
   }
-  if( rc!=LSM_OK ){
-    pDb->pShmhdr = 0;
-    return rc;
+  if( rc==LSM_OK ){
+    rc = lsmShmCacheChunks(pDb, 1);
   }
+  if( rc!=LSM_OK ) return rc;
+  pDb->pShmhdr = (ShmHeader *)pDb->apShm[0];
 
   /* Try an exclusive lock on DMS2/DMS3. If successful, this is the first 
   ** and only connection to the database. In this case initialize the 
diff --git a/manifest b/manifest
index 994305976a..3bd79dea76 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\sminor\stest\sscript\sproblems\srevealed\sby\sreleasetest.tcl.
-D 2017-10-23T07:52:07.660
+C In\slsm\s(not\sSQLite),\savoid\sopening\sthe\s*-shm\sfile\sbefore\sthe\sdatabase\sfile\sis\nlocked.\sOtherwise,\sthere\sis\sa\srace\scondition\swhereby\sa\sconnection\sin\sanother\nprocess\sprocess\smay\sunlink()\sit\swhile\sit\sis\sstill\sin\suse.
+D 2017-10-23T11:48:00.248
 F Makefile.in e016061b23e60ac9ec27c65cb577292b6bde0307ca55abd874ab3487b3b1beb2
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 37740aba9c4bb359c627eadccf1cfd7be4f5f847078723777ea7763969e533b1
@@ -245,7 +245,7 @@ F ext/lsm1/lsm_log.c a8bf334532109bba05b09a504ee45fc393828b0d034ca61ab45e3940709
 F ext/lsm1/lsm_main.c 15e73ccdafdd44ddeefc29e332079d88ba8f00c12c797b3c2b63d3171b5afce8
 F ext/lsm1/lsm_mem.c 4c51ea9fa285ee6e35301b33491642d071740a0a
 F ext/lsm1/lsm_mutex.c 378edf0a2b142b4f7640ee982df06d50b98788ea
-F ext/lsm1/lsm_shared.c 5bc37768e558492f60d7196735ddd54843cd239bd66c1af6eb205a6348ca5e46
+F ext/lsm1/lsm_shared.c 1a76b7a5e89a003c24d58f1fb295c4203b48ef6acba9a194ac6003ade09fcd47
 F ext/lsm1/lsm_sorted.c a04518dfbfff0171fafb152a46e9fe9f45e1edbf3570e4533dd58ddb6567f0c9
 F ext/lsm1/lsm_str.c 65e361b488c87b10bf3e5c0070b14ffc602cf84f094880bece77bbf6678bca82
 F ext/lsm1/lsm_tree.c 682679d7ef2b8b6f2fe77aeb532c8d29695bca671c220b0abac77069de5fb9fb
@@ -1664,7 +1664,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 0fcf1e61ef2b6c1fb8f4846f973d2d427598ffbc80dbc49e56e71513b194bae7
-R e3bec412c3fcc940b80e7c9735d18bbe
+P 15e87d9bc81812fb9de86f9870389217dddb9f9c4d48e42acefce2d35ba293f1
+R 788a72b4e4bc49507efed4d645930eed
 U dan
-Z a4aaac778f287d83315a30f9e1092784
+Z 97cc68bc0ee206aadd31e81854de499f
diff --git a/manifest.uuid b/manifest.uuid
index be55c08755..abddaa098d 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-15e87d9bc81812fb9de86f9870389217dddb9f9c4d48e42acefce2d35ba293f1
\ No newline at end of file
+c8b8b9b573665c2b4d278bb679a48ac407374b8d860f0c3f4d50a303043464ad
\ No newline at end of file