Improvements to the "demoDelete" method in the demovfs, suggested by

[forum:/forumpost/cad18961c2|forum post cad18961c2].

FossilOrigin-Name: d76a301e22e0572262917dfe9557a5051339a65416a473dd2d9989a49975403e

manifest

@@ -1,5 +1,5 @@
-C Fix\smisuse\sof\sthe\ssqlite3_set_auxdata()\sinterface\sin\sthe\sICU\sextension.
-D 2022-09-28T19:14:01.801
+C Improvements\sto\sthe\s"demoDelete"\smethod\sin\sthe\sdemovfs,\ssuggested\sby\n[forum:/forumpost/cad18961c2|forum\spost\scad18961c2].
+D 2022-09-30T14:35:18.306
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -615,7 +615,7 @@ F src/test_blob.c ae4a0620b478548afb67963095a7417cd06a4ec0a56adb453542203bfdcb31
 F src/test_btree.c 8b2dc8b8848cf3a4db93f11578f075e82252a274
 F src/test_config.c 8264637b06a3c1f0727c88d1ea32dcf7986b9e7e358a970cae87cdac8a5b2708
 F src/test_delete.c e2fe07646dff6300b48d49b2fee2fe192ed389e834dd635e3b3bac0ce0bf9f8f
-F src/test_demovfs.c 86142ba864d4297d54c5b2e972e74f3141ae4b30f05b3a95824184ed2d3d7f91
+F src/test_demovfs.c 7b3be8cdf07d00f025309fbb2453cb5f0fd9ed74f40543c7f4353dcac2879aa7
 F src/test_devsym.c aff2255ea290d7718da08af30cdf18e470ff7325a5eff63e0057b1496ed66593
 F src/test_fs.c ba1e1dc18fd3159fdba0b9c4256f14032159785320dfbd6776eb9973cb75d480
 F src/test_func.c 24df3a346c012b1fc9e1001d346db6054deb426db0a7437e92490630e71c9b0a
@@ -2000,8 +2000,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 584de6a996c78b8e41bdfcd05a8e2a3844664c6b4efedb5883c8b8af388462b5
-R d79b3651cd76ebe372f6bfce59942639
+P f25cf63471cbed1edb27591e57fead62550d4046dbdcb61312288f0f6f24c646
+R 1d883d051102da05e54bf9f370b714ba
 U drh
-Z 79f3fdc2db5301812c92ae8ca64cb084
+Z fa066d9d8da6a5ee78227c4b8bbd23f3
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-f25cf63471cbed1edb27591e57fead62550d4046dbdcb61312288f0f6f24c646
+d76a301e22e0572262917dfe9557a5051339a65416a473dd2d9989a49975403e

src/test_demovfs.c

@@ -462,21 +462,23 @@ static int demoDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
   if( rc==0 && dirSync ){
     int dfd;                      /* File descriptor open on directory */
     int i;                        /* Iterator variable */
+    char *zSlash;
     char zDir[MAXPATHNAME+1];     /* Name of directory containing file zPath */
 
     /* Figure out the directory name from the path of the file deleted. */
     sqlite3_snprintf(MAXPATHNAME, zDir, "%s", zPath);
     zDir[MAXPATHNAME] = '\0';
-    for(i=strlen(zDir); i>1 && zDir[i]!='/'; i++);
-    zDir[i] = '\0';
-
-    /* Open a file-descriptor on the directory. Sync. Close. */
-    dfd = open(zDir, O_RDONLY, 0);
-    if( dfd<0 ){
-      rc = -1;
-    }else{
-      rc = fsync(dfd);
-      close(dfd);
+    zSlash = strrchr(zPath,'/');
+    if( zSlash ){
+      /* Open a file-descriptor on the directory. Sync. Close. */
+      zSlash[0] = 0;
+      dfd = open(zDir, O_RDONLY, 0);
+      if( dfd<0 ){
+        rc = -1;
+      }else{
+        rc = fsync(dfd);
+        close(dfd);
+      }
     }
   }
   return (rc==0 ? SQLITE_OK : SQLITE_IOERR_DELETE);