Try to detect process ID changes due to fork() calls in os_unix.c and

reset the PRNG when a process ID change is detected.

FossilOrigin-Name: e1eba1fb09d7db49d77928bd115b27b8002ae640

diff --git a/manifest b/manifest
index df2e8029abffdbc9afa4cdbf4426ca027d78f260..e254e7cba03167c9165b43beb7f8b2af3ff2867f 100644 (file)
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Enhance\ssqlite3_randomness(N,P)\ssuch\sthat\sit\sresets\sthe\sinternal\sPRNG\nif\sN\sis\sless\sthan\s1.\s\sSubsequent\scalls\sto\ssqlite3_randomness()\swill\sreinitialize\nthe\sinternal\sPRNG\sby\scalling\sthe\sxRandomness()\smethod\sof\sthe\sdefault\sVFS.
-D 2014-01-01T14:00:13.905
+C Try\sto\sdetect\sprocess\sID\schanges\sdue\sto\sfork()\scalls\sin\sos_unix.c\sand\nreset\sthe\sPRNG\swhen\sa\sprocess\sID\schange\sis\sdetected.
+D 2014-01-01T15:18:36.453
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 2ef13430cd359f7b361bb863504e227b25cc7f81
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -205,7 +205,7 @@ F src/notify.c 976dd0f6171d4588e89e874fcc765e92914b6d30
 F src/os.c 1b147e4cf7cc39e618115c14a086aed44bc91ace
 F src/os.h 4a46270a64e9193af4a0aaa3bc2c66dc07c29b3f
 F src/os_common.h 92815ed65f805560b66166e3583470ff94478f04
-F src/os_unix.c 60a7b3b23e6fcf83a50d1e320b280b551724e11f
+F src/os_unix.c abeb9d54036aaea6f4395050ce823f51217ae4d4
 F src/os_win.c 16eac0961603182ffc10c02b39fe830126538e07
 F src/pager.c efa923693e958696eee69b205a20bfbc402c8480
 F src/pager.h ffd5607f7b3e4590b415b007a4382f693334d428
@@ -1147,7 +1147,7 @@ F tool/vdbe-compress.tcl 0cf56e9263a152b84da86e75a5c0cdcdb7a47891
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
 F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
-P cc72c5aec7fe93d4a1368517aab949dc98d33003
-R 4dbb82094f79fe324b8594c5661b9532
+P a221aa82bb5496885fd0bf76e4601443799511de
+R 0b5cbfb8643918ccfe030368af8a9f9c
 U drh
-Z 7f33812905741a2d8942dba59b43dd66
+Z 8d0b25dd26eff92b0e8709464c57dd81

diff --git a/manifest.uuid b/manifest.uuid
index 691c3bd9a813859b1bb5c2258f7952c1c9f7fdc5..002b2fbf682d07dc001174b7de6a8ba157d7b18a 100644 (file)
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-a221aa82bb5496885fd0bf76e4601443799511de
\ No newline at end of file
+e1eba1fb09d7db49d77928bd115b27b8002ae640
\ No newline at end of file

diff --git a/src/os_unix.c b/src/os_unix.c
index 485b32fd90c8ec65de4108fdf8d14a588c902f90..4b76d4fec4cb7b11b946a78e1708f496235eb726 100644 (file)
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -260,6 +260,12 @@ struct unixFile {
 #endif
 };
 
+/* This variable holds the process id (pid) from when the xRandomness()
+** method was called.  If xOpen() is called from a different process id,
+** indicating that a fork() has occurred, the PRNG will be reset.
+*/
+static int randomnessPid = 0;
+
 /*
 ** Allowed values for the unixFile.ctrlFlags bitmask:
 */
@@ -5651,6 +5657,16 @@ static int unixOpen(
        || eType==SQLITE_OPEN_TRANSIENT_DB || eType==SQLITE_OPEN_WAL
   );
 
+  /* Detect a pid change and reset the PRNG.  There is a race condition
+  ** here such that two or more threads all trying to open databases at
+  ** the same instant might all reset the PRNG.  But multiple resets
+  ** are harmless.
+  */
+  if( randomnessPid!=getpid() ){
+    randomnessPid = getpid();
+    sqlite3_randomness(0,0);
+  }
+
   memset(p, 0, sizeof(unixFile));
 
   if( eType==SQLITE_OPEN_MAIN_DB ){
@@ -6038,18 +6054,18 @@ static int unixRandomness(sqlite3_vfs *NotUsed, int nBuf, char *zBuf){
   ** tests repeatable.
   */
   memset(zBuf, 0, nBuf);
+  randomnessPid = getpid();  
 #if !defined(SQLITE_TEST)
   {
-    int pid, fd, got;
+    int fd, got;
     fd = robust_open("/dev/urandom", O_RDONLY, 0);
     if( fd<0 ){
       time_t t;
       time(&t);
       memcpy(zBuf, &t, sizeof(t));
-      pid = getpid();
-      memcpy(&zBuf[sizeof(t)], &pid, sizeof(pid));
-      assert( sizeof(t)+sizeof(pid)<=(size_t)nBuf );
-      nBuf = sizeof(t) + sizeof(pid);
+      memcpy(&zBuf[sizeof(t)], &randomnessPid, sizeof(randomnessPid));
+      assert( sizeof(t)+sizeof(randomnessPid)<=(size_t)nBuf );
+      nBuf = sizeof(t) + sizeof(randomnessPid);
     }else{
       do{ got = osRead(fd, zBuf, nBuf); }while( got<0 && errno==EINTR );
       robust_close(0, fd, __LINE__);