1 files changed, 102 insertions, 53 deletions

diff --git a/src/os_unix.c b/src/os_unix.c
index 5bd611694..81422f215 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -149,6 +149,11 @@
 */
 #define MAX_PATHNAME 512
 
+/*
+** Maximum supported symbolic links
+*/
+#define SQLITE_MAX_SYMLINKS 100
+
 /* Always cast the getpid() return type for compatibility with
 ** kernel modules in VxWorks. */
 #define osGetpid(X) (pid_t)getpid()
@@ -475,6 +480,12 @@ static struct unix_syscall {
 #endif
 #define osReadlink ((ssize_t(*)(const char*,char*,size_t))aSyscall[26].pCurrent)
 
+#if defined(HAVE_LSTAT)
+  { "lstat",         (sqlite3_syscall_ptr)lstat,          0 },
+#else
+  { "lstat",         (sqlite3_syscall_ptr)0,              0 },
+#endif
+#define osLstat      ((int(*)(const char*,struct stat*))aSyscall[27].pCurrent)
 
 }; /* End of the overrideable system calls */
 
@@ -5927,6 +5938,32 @@ static int unixAccess(
   return SQLITE_OK;
 }
 
+/*
+**
+*/
+static int mkFullPathname(
+  const char *zPath,              /* Input path */
+  char *zOut,                     /* Output buffer */
+  int nOut                        /* Allocated size of buffer zOut */
+){
+  int nPath = sqlite3Strlen30(zPath);
+  int iOff = 0;
+  if( zPath[0]!='/' ){
+    if( osGetcwd(zOut, nOut-2)==0 ){
+      return unixLogError(SQLITE_CANTOPEN_BKPT, "getcwd", zPath);
+    }
+    iOff = sqlite3Strlen30(zOut);
+    zOut[iOff++] = '/';
+  }
+  if( (iOff+nPath+1)>nOut ){
+    /* SQLite assumes that xFullPathname() nul-terminates the output buffer
+    ** even if it returns an error.  */
+    zOut[iOff] = '\0';
+    return SQLITE_CANTOPEN_BKPT;
+  }
+  sqlite3_snprintf(nOut-iOff, &zOut[iOff], "%s", zPath);
+  return SQLITE_OK;
+}
 
 /*
 ** Turn a relative pathname into a full pathname. The relative path
@@ -5943,7 +5980,17 @@ static int unixFullPathname(
   int nOut,                     /* Size of output buffer in bytes */
   char *zOut                    /* Output buffer */
 ){
+#if !defined(HAVE_READLINK) || !defined(HAVE_LSTAT)
+  return mkFullPathname(zPath, zOut, nOut);
+#else
+  int rc = SQLITE_OK;
   int nByte;
+  int nLink = 1;                /* Number of symbolic links followed so far */
+  const char *zIn = zPath;      /* Input path for each iteration of loop */
+  char *zDel = 0;
+
+  assert( pVfs->mxPathname==MAX_PATHNAME );
+  UNUSED_PARAMETER(pVfs);
 
   /* It's odd to simulate an io-error here, but really this is just
   ** using the io-error infrastructure to test that SQLite handles this
@@ -5952,60 +5999,62 @@ static int unixFullPathname(
   */
   SimulateIOError( return SQLITE_ERROR );
 
-  assert( pVfs->mxPathname==MAX_PATHNAME );
-  UNUSED_PARAMETER(pVfs);
+  do {
 
-#if defined(HAVE_READLINK)
-  /* Attempt to resolve the path as if it were a symbolic link. If it is
-  ** a symbolic link, the resolved path is stored in buffer zOut[]. Or, if
-  ** the identified file is not a symbolic link or does not exist, then
-  ** zPath is copied directly into zOut. Either way, nByte is left set to
-  ** the size of the string copied into zOut[] in bytes.  */
-  nByte = osReadlink(zPath, zOut, nOut-1);
-  if( nByte<0 ){
-    if( errno!=EINVAL && errno!=ENOENT ){
-      return unixLogError(SQLITE_CANTOPEN_BKPT, "readlink", zPath);
-    }
-    sqlite3_snprintf(nOut, zOut, "%s", zPath);
-    nByte = sqlite3Strlen30(zOut);
-  }else{
-    zOut[nByte] = '\0';
-  }
-#endif
+    /* Call stat() on path zIn. Set bLink to true if the path is a symbolic
+    ** link, or false otherwise.  */
+    int bLink = 0;
+    struct stat buf;
+    if( osLstat(zIn, &buf)!=0 ){
+      if( errno!=ENOENT ){
+        rc = unixLogError(SQLITE_CANTOPEN_BKPT, "lstat", zIn);
+      }
+    }else{
+      bLink = S_ISLNK(buf.st_mode);
+    }
 
-  /* If buffer zOut[] now contains an absolute path there is nothing more
-  ** to do. If it contains a relative path, do the following:
-  **
-  **   * move the relative path string so that it is at the end of th
-  **     zOut[] buffer.
-  **   * Call getcwd() to read the path of the current working directory 
-  **     into the start of the zOut[] buffer.
-  **   * Append a '/' character to the cwd string and move the 
-  **     relative path back within the buffer so that it immediately 
-  **     follows the '/'.
-  **
-  ** This code is written so that if the combination of the CWD and relative
-  ** path are larger than the allocated size of zOut[] the CWD is silently
-  ** truncated to make it fit. This is Ok, as SQLite refuses to open any
-  ** file for which this function returns a full path larger than (nOut-8)
-  ** bytes in size.  */
-  testcase( nByte==nOut-5 );
-  testcase( nByte==nOut-4 );
-  if( zOut[0]!='/' && nByte<nOut-4 ){
-    int nCwd;
-    int nRem = nOut-nByte-1;
-    memmove(&zOut[nRem], zOut, nByte+1);
-    zOut[nRem-1] = '\0';
-    if( osGetcwd(zOut, nRem-1)==0 ){
-      return unixLogError(SQLITE_CANTOPEN_BKPT, "getcwd", zPath);
+    if( bLink ){
+      if( zDel==0 ){
+        zDel = sqlite3_malloc(nOut);
+        if( zDel==0 ) rc = SQLITE_NOMEM;
+      }else if( ++nLink>SQLITE_MAX_SYMLINKS ){
+        rc = SQLITE_CANTOPEN_BKPT;
+      }
+
+      if( rc==SQLITE_OK ){
+        nByte = osReadlink(zIn, zDel, nOut-1);
+        if( nByte<0 ){
+          rc = unixLogError(SQLITE_CANTOPEN_BKPT, "readlink", zIn);
+        }else{
+          if( zDel[0]!='/' ){
+            int n;
+            for(n = sqlite3Strlen30(zIn); n>0 && zIn[n-1]!='/'; n--);
+            if( nByte+n+1>nOut ){
+              rc = SQLITE_CANTOPEN_BKPT;
+            }else{
+              memmove(&zDel[n], zDel, nByte+1);
+              memcpy(zDel, zIn, n);
+              nByte += n;
+            }
+          }
+          zDel[nByte] = '\0';
+        }
+      }
+
+      zIn = zDel;
     }
-    nCwd = sqlite3Strlen30(zOut);
-    assert( nCwd<=nRem-1 );
-    zOut[nCwd] = '/';
-    memmove(&zOut[nCwd+1], &zOut[nRem], nByte+1);
-  }
 
-  return SQLITE_OK;
+    assert( rc!=SQLITE_OK || zIn!=zOut || zIn[0]=='/' );
+    if( rc==SQLITE_OK && zIn!=zOut ){
+      rc = mkFullPathname(zIn, zOut, nOut);
+    }
+    if( bLink==0 ) break;
+    zIn = zOut;
+  }while( rc==SQLITE_OK );
+
+  sqlite3_free(zDel);
+  return rc;
+#endif   /* HAVE_READLINK && HAVE_LSTAT */
 }
 
 
@@ -6187,7 +6236,7 @@ static int unixCurrentTimeInt64(sqlite3_vfs *NotUsed, sqlite3_int64 *piNow){
   return rc;
 }
 
-#if 0 /* Not used */
+#ifndef SQLITE_OMIT_DEPRECATED
 /*
 ** Find the current time (in Universal Coordinated Time).  Write the
 ** current time and date as a Julian Day number into *prNow and
@@ -6205,7 +6254,7 @@ static int unixCurrentTime(sqlite3_vfs *NotUsed, double *prNow){
 # define unixCurrentTime 0
 #endif
 
-#if 0  /* Not used */
+#ifndef SQLITE_OMIT_DEPRECATED
 /*
 ** We added the xGetLastError() method with the intention of providing
 ** better low-level error messages when operating-system problems come up
@@ -7504,7 +7553,7 @@ int sqlite3_os_init(void){
 
   /* Double-check that the aSyscall[] array has been constructed
   ** correctly.  See ticket [bb3a86e890c8e96ab] */
-  assert( ArraySize(aSyscall)==27 );
+  assert( ArraySize(aSyscall)==28 );
 
   /* Register all VFSes defined in the aVfs[] array */
   for(i=0; i<(sizeof(aVfs)/sizeof(sqlite3_vfs)); i++){