Add support for SQLITE_OPEN_NOFOLLOW.

FossilOrigin-Name: cb79c828496a703f1410f61458ebc1e15a92a63412b36f51945b2b5a32ec6e88

8 files changed, 60 insertions, 7 deletions

diff --git a/src/os_unix.c b/src/os_unix.c
index f2ac89f2c..7217a5d5f 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -6251,15 +6251,25 @@ static int unixAccess(
   SimulateIOError( return SQLITE_IOERR_ACCESS; );
   assert( pResOut!=0 );
 
-  /* The spec says there are three possible values for flags.  But only
-  ** two of them are actually used */
-  assert( flags==SQLITE_ACCESS_EXISTS || flags==SQLITE_ACCESS_READWRITE );
+  /* The spec says there are four possible values for flags.  But the
+  ** SQLITE_ACCESS_READ flag is never used */
+  assert( flags==SQLITE_ACCESS_EXISTS
+       || flags==SQLITE_ACCESS_READWRITE
+       || flags==SQLITE_ACCESS_SYMLINK );
 
   if( flags==SQLITE_ACCESS_EXISTS ){
     struct stat buf;
     *pResOut = (0==osStat(zPath, &buf) && buf.st_size>0);
-  }else{
+  }else if( flags==SQLITE_ACCESS_READWRITE ){
     *pResOut = osAccess(zPath, W_OK|R_OK)==0;
+  }else{
+#if !defined(HAVE_LSTAT)
+    *pResOut = 0;
+#else
+    struct stat buf;
+    *pResOut = (0==osLstat(zPath, &buf) && S_ISLNK(buf.st_mode));
+#endif
+    assert( flags==SQLITE_ACCESS_SYMLINK );
   }
   return SQLITE_OK;
 }
diff --git a/src/os_win.c b/src/os_win.c
index 32758ab76..2b492d6fa 100644
--- a/src/os_win.c
+++ b/src/os_win.c
@@ -5472,6 +5472,9 @@ static int winAccess(
       rc = attr!=INVALID_FILE_ATTRIBUTES &&
              (attr & FILE_ATTRIBUTE_READONLY)==0;
       break;
+    case SQLITE_ACCESS_SYMLINK:
+      rc = 0;  /* No symlinks on windows */
+      break;
     default:
       assert(!"Invalid flags argument");
   }
diff --git a/src/pager.c b/src/pager.c
index 9ec8f58df..095e3f5ac 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -4788,6 +4788,14 @@ int sqlite3PagerOpen(
   */
   if( zFilename && zFilename[0] ){
     const char *z;
+    if( (vfsFlags & SQLITE_OPEN_NOFOLLOW)!=0 ){
+      int isLink = 0;
+      if( sqlite3OsAccess(pVfs, zFilename, SQLITE_ACCESS_SYMLINK, &isLink)==0
+       && isLink
+      ){
+        return SQLITE_CANTOPEN_SYMLINK;
+      }
+    }
     nPathname = pVfs->mxPathname+1;
     zPathname = sqlite3DbMallocRaw(0, nPathname*2);
     if( zPathname==0 ){
diff --git a/src/shell.c.in b/src/shell.c.in
index 105cab6e5..e6b6f1a1b 100644
--- a/src/shell.c.in
+++ b/src/shell.c.in
@@ -1021,6 +1021,7 @@ struct ShellState {
   int outCount;          /* Revert to stdout when reaching zero */
   int cnt;               /* Number of records displayed so far */
   int lineno;            /* Line number of last line read from in */
+  int openFlags;         /* Additional flags to open.  (SQLITE_OPEN_NOFOLLOW) */
   FILE *in;              /* Read commands from this stream */
   FILE *out;             /* Write results here */
   FILE *traceOut;        /* Output for sqlite3_trace() */
@@ -3562,6 +3563,7 @@ static const char *(azHelp[]) = {
   "        --maxsize N     Maximum size for --hexdb or --deserialized database",
 #endif
   "        --new           Initialize FILE to an empty database",
+  "        --nofollow      Do not follow symbolic links",
   "        --readonly      Open FILE readonly",
   "        --zip           FILE is a ZIP archive",
   ".output ?FILE?           Send output to FILE or stdout if FILE is omitted",
@@ -4126,7 +4128,7 @@ static void open_db(ShellState *p, int openFlags){
     switch( p->openMode ){
       case SHELL_OPEN_APPENDVFS: {
         sqlite3_open_v2(p->zDbFilename, &p->db, 
-           SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE, "apndvfs");
+           SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|p->openFlags, "apndvfs");
         break;
       }
       case SHELL_OPEN_HEXDB:
@@ -4139,12 +4141,14 @@ static void open_db(ShellState *p, int openFlags){
         break;
       }
       case SHELL_OPEN_READONLY: {
-        sqlite3_open_v2(p->zDbFilename, &p->db, SQLITE_OPEN_READONLY, 0);
+        sqlite3_open_v2(p->zDbFilename, &p->db,
+            SQLITE_OPEN_READONLY|p->openFlags, 0);
         break;
       }
       case SHELL_OPEN_UNSPEC:
       case SHELL_OPEN_NORMAL: {
-        sqlite3_open(p->zDbFilename, &p->db);
+        sqlite3_open_v2(p->zDbFilename, &p->db,
+           SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|p->openFlags, 0);
         break;
       }
     }
@@ -8042,6 +8046,7 @@ static int do_meta_command(char *zLine, ShellState *p){
     sqlite3_free(p->zFreeOnClose);
     p->zFreeOnClose = 0;
     p->openMode = SHELL_OPEN_UNSPEC;
+    p->openFlags = 0;
     p->szMax = 0;
     /* Check for command-line arguments */
     for(iName=1; iName<nArg && azArg[iName][0]=='-'; iName++){
@@ -8056,6 +8061,8 @@ static int do_meta_command(char *zLine, ShellState *p){
         p->openMode = SHELL_OPEN_APPENDVFS;
       }else if( optionMatch(z, "readonly") ){
         p->openMode = SHELL_OPEN_READONLY;
+      }else if( optionMatch(z, "nofollow") ){
+        p->openFlags |= SQLITE_OPEN_NOFOLLOW;
 #ifdef SQLITE_ENABLE_DESERIALIZE
       }else if( optionMatch(z, "deserialize") ){
         p->openMode = SHELL_OPEN_DESERIALIZE;
@@ -9976,6 +9983,7 @@ static const char zOptions[] =
   "   -multiplex           enable the multiplexor VFS\n"
 #endif
   "   -newline SEP         set output row separator. Default: '\\n'\n"
+  "   -nofollow            refuse to open symbolic links to database files\n"
   "   -nullvalue TEXT      set text string for NULL values. Default ''\n"
   "   -pagecache SIZE N    use N slots of SZ bytes each for page cache memory\n"
   "   -quote               set output mode to 'quote'\n"
@@ -10286,6 +10294,8 @@ int SQLITE_CDECL wmain(int argc, wchar_t **wargv){
 #endif
     }else if( strcmp(z,"-readonly")==0 ){
       data.openMode = SHELL_OPEN_READONLY;
+    }else if( strcmp(z,"-nofollow")==0 ){
+      data.openFlags = SQLITE_OPEN_NOFOLLOW;
 #if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(SQLITE_HAVE_ZLIB)
     }else if( strncmp(z, "-A",2)==0 ){
       /* All remaining command-line arguments are passed to the ".archive"
@@ -10389,6 +10399,8 @@ int SQLITE_CDECL wmain(int argc, wchar_t **wargv){
 #endif
     }else if( strcmp(z,"-readonly")==0 ){
       data.openMode = SHELL_OPEN_READONLY;
+    }else if( strcmp(z,"-nofollow")==0 ){
+      data.openFlags |= SQLITE_OPEN_NOFOLLOW;
     }else if( strcmp(z,"-ascii")==0 ){
       data.mode = MODE_Ascii;
       sqlite3_snprintf(sizeof(data.colSeparator), data.colSeparator,
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index 91d3158ee..8373f5c7f 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -516,6 +516,7 @@ int sqlite3_exec(
 #define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
 #define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
 #define SQLITE_CANTOPEN_DIRTYWAL       (SQLITE_CANTOPEN | (5<<8)) /* Not Used */
+#define SQLITE_CANTOPEN_SYMLINK        (SQLITE_CANTOPEN | (6<<8))
 #define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
 #define SQLITE_CORRUPT_SEQUENCE        (SQLITE_CORRUPT | (2<<8))
 #define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
@@ -568,6 +569,7 @@ int sqlite3_exec(
 #define SQLITE_OPEN_SHAREDCACHE      0x00020000  /* Ok for sqlite3_open_v2() */
 #define SQLITE_OPEN_PRIVATECACHE     0x00040000  /* Ok for sqlite3_open_v2() */
 #define SQLITE_OPEN_WAL              0x00080000  /* VFS only */
+#define SQLITE_OPEN_NOFOLLOW         0x01000000  /* Ok for sqlite3_open_v2() */
 
 /* Reserved:                         0x00F00000 */
 
@@ -1406,6 +1408,7 @@ struct sqlite3_vfs {
 #define SQLITE_ACCESS_EXISTS    0
 #define SQLITE_ACCESS_READWRITE 1   /* Used by PRAGMA temp_store_directory */
 #define SQLITE_ACCESS_READ      2   /* Unused */
+#define SQLITE_ACCESS_SYMLINK   3   /* Test if file is symbolic link */
 
 /*
 ** CAPI3REF: Flags for the xShmLock VFS method
diff --git a/src/tclsqlite.c b/src/tclsqlite.c
index 80a057262..a691898dc 100644
--- a/src/tclsqlite.c
+++ b/src/tclsqlite.c
@@ -3670,6 +3670,7 @@ static int sqliteCmdUsage(
 ){
   Tcl_WrongNumArgs(interp, 1, objv,
     "HANDLE ?FILENAME? ?-vfs VFSNAME? ?-readonly BOOLEAN? ?-create BOOLEAN?"
+    " ?-nofollow BOOLEAN?"
     " ?-nomutex BOOLEAN? ?-fullmutex BOOLEAN? ?-uri BOOLEAN?"
 #if defined(SQLITE_HAS_CODEC) && !defined(SQLITE_OMIT_CODEC_FROM_TCL)
     " ?-key CODECKEY?"
@@ -3681,6 +3682,7 @@ static int sqliteCmdUsage(
 /*
 **   sqlite3 DBNAME FILENAME ?-vfs VFSNAME? ?-key KEY? ?-readonly BOOLEAN?
 **                           ?-create BOOLEAN? ?-nomutex BOOLEAN?
+**                           ?-nofollow BOOLEAN?
 **
 ** This is the main Tcl command.  When the "sqlite" Tcl command is
 ** invoked, this routine runs to process that command.
@@ -3779,6 +3781,14 @@ static int SQLITE_TCLAPI DbMain(
       }else{
         flags &= ~SQLITE_OPEN_CREATE;
       }
+    }else if( strcmp(zArg, "-nofollow")==0 ){
+      int b;
+      if( Tcl_GetBooleanFromObj(interp, objv[i], &b) ) return TCL_ERROR;
+      if( b ){
+        flags |= SQLITE_OPEN_NOFOLLOW;
+      }else{
+        flags &= ~SQLITE_OPEN_NOFOLLOW;
+      }
     }else if( strcmp(zArg, "-nomutex")==0 ){
       int b;
       if( Tcl_GetBooleanFromObj(interp, objv[i], &b) ) return TCL_ERROR;
diff --git a/src/test_demovfs.c b/src/test_demovfs.c
index eaba20873..baf14b10b 100644
--- a/src/test_demovfs.c
+++ b/src/test_demovfs.c
@@ -508,8 +508,14 @@ static int demoAccess(
   assert( flags==SQLITE_ACCESS_EXISTS       /* access(zPath, F_OK) */
        || flags==SQLITE_ACCESS_READ         /* access(zPath, R_OK) */
        || flags==SQLITE_ACCESS_READWRITE    /* access(zPath, R_OK|W_OK) */
+       || flags==SQLITE_ACCESS_SYMLINK      /* Always false */
   );
 
+  if( flags==SQLITE_ACCESS_SYMLINK ){
+    /* For this demo implementation, assume that symlinks do not exist. */
+    *pResOut = 0;
+    return SQLITE_OK;
+  }
   if( flags==SQLITE_ACCESS_READWRITE ) eAccess = R_OK|W_OK;
   if( flags==SQLITE_ACCESS_READ )      eAccess = R_OK;
 
diff --git a/src/test_vfs.c b/src/test_vfs.c
index 3357a0a27..84baeb943 100644
--- a/src/test_vfs.c
+++ b/src/test_vfs.c
@@ -732,6 +732,7 @@ static int tvfsAccess(
     if( flags==SQLITE_ACCESS_EXISTS ) zArg = "SQLITE_ACCESS_EXISTS";
     if( flags==SQLITE_ACCESS_READWRITE ) zArg = "SQLITE_ACCESS_READWRITE";
     if( flags==SQLITE_ACCESS_READ ) zArg = "SQLITE_ACCESS_READ";
+    if( flags==SQLITE_ACCESS_SYMLINK ) zArg = "SQLITE_ACCESS_SYMLINK";
     tvfsExecTcl(p, "xAccess", 
         Tcl_NewStringObj(zPath, -1), Tcl_NewStringObj(zArg, -1), 0, 0
     );