Merge pull request #2770 in HDFFV/hdf5 from ~DEROBINS/hdf5_der:1_10_normalization to hdf5_1_10

* commit 'e9305abf48426f265d7ec3ae54538e3ded8889ea':
  Fixes missing chunk_info entry in CMake files
  Even more normalization with develop
  More normalizations with develop
  Misc normalizations with develop
  Normalization of perform directory with develop
  Brings monotonic timer changes from develop
  Brings Mirror VFD to 1.10 from develop
  Brings splitter VFD from develop
  Brings file locking changes from develop

1 files changed, 49 insertions, 6 deletions

diff --git a/src/H5FDdirect.c b/src/H5FDdirect.c
index 34c4346..4046050 100644
--- a/src/H5FDdirect.c
+++ b/src/H5FDdirect.c
@@ -38,6 +38,9 @@
 /* The driver identification number, initialized at runtime */
 static hid_t H5FD_DIRECT_g = 0;
 
+/* Whether to ignore file locks when disabled (env var value) */
+static htri_t ignore_disabled_file_locks_s = FAIL;
+
 /* File operations */
 #define OP_UNKNOWN  0
 #define OP_READ    1
@@ -71,6 +74,7 @@ typedef struct H5FD_direct_t {
     haddr_t  pos;      /*current file I/O position  */
     int    op;      /*last operation    */
     H5FD_direct_fapl_t  fa;    /*file access properties  */
+    hbool_t         ignore_disabled_file_locks;
 #ifndef H5_HAVE_WIN32_API
     /*
      * On most systems the combination of device and i-node number uniquely
@@ -193,10 +197,20 @@ DESCRIPTION
 static herr_t
 H5FD__init_package(void)
 {
+    char    *lock_env_var   = NULL;     /* Environment variable pointer */
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_STATIC
 
+    /* Check the use disabled file locks environment variable */
+    lock_env_var = HDgetenv("HDF5_USE_FILE_LOCKING");
+    if(lock_env_var && !HDstrcmp(lock_env_var, "BEST_EFFORT"))
+        ignore_disabled_file_locks_s = TRUE;    /* Override: Ignore disabled locks */
+    else if(lock_env_var && (!HDstrcmp(lock_env_var, "TRUE") || !HDstrcmp(lock_env_var, "1")))
+        ignore_disabled_file_locks_s = FALSE;   /* Override: Don't ignore disabled locks */
+    else
+        ignore_disabled_file_locks_s = FAIL;    /* Environment variable not set, or not set correctly */
+
     if(H5FD_direct_init() < 0)
         HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, FAIL, "unable to initialize direct VFD")
 
@@ -518,6 +532,16 @@ H5FD_direct_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxadd
     file->fa.fbsize = fa->fbsize;
     file->fa.cbsize = fa->cbsize;
 
+    /* Check the file locking flags in the fapl */
+    if(ignore_disabled_file_locks_s != FAIL)
+        /* The environment variable was set, so use that preferentially */
+        file->ignore_disabled_file_locks = ignore_disabled_file_locks_s;
+    else {
+        /* Use the value in the property list */
+        if(H5P_get(plist, H5F_ACS_IGNORE_DISABLED_FILE_LOCKS_NAME, &file->ignore_disabled_file_locks) < 0)
+            HGOTO_ERROR(H5E_VFL, H5E_CANTGET, NULL, "can't get ignore disabled file locks property")
+    }
+
     /* Try to decide if data alignment is required.  The reason to check it here
      * is to handle correctly the case that the file is in a different file system
      * than the one where the program is running.
@@ -1335,16 +1359,27 @@ static herr_t
 H5FD_direct_lock(H5FD_t *_file, hbool_t rw)
 {
     H5FD_direct_t  *file = (H5FD_direct_t*)_file;	/* VFD file struct */
-    const int lock = rw ? LOCK_EX : LOCK_SH;
+    int lock_flags;                                 /* file locking flags   */
     herr_t ret_value = SUCCEED;                 	/* Return value */
 
     FUNC_ENTER_NOAPI_NOINIT
 
     HDassert(file);
 
-    /* Place the lock with non-blocking */
-    if(HDflock(file->fd, lock | LOCK_NB) < 0)
-        HSYS_GOTO_ERROR(H5E_FILE, H5E_BADFILE, FAIL, "unable to flock file")
+    /* Set exclusive or shared lock based on rw status */
+    lock_flags = rw ? LOCK_EX : LOCK_SH;
+
+    /* Place a non-blocking lock on the file */
+    if(HDflock(file->fd, lock_flags | LOCK_NB) < 0) {
+        if(file->ignore_disabled_file_locks && ENOSYS == errno) {
+            /* When errno is set to ENOSYS, the file system does not support
+             * locking, so ignore it.
+             */
+            errno = 0;
+        }
+        else
+            HSYS_GOTO_ERROR(H5E_VFL, H5E_CANTLOCKFILE, FAIL, "unable to lock file")
+    }
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
@@ -1372,8 +1407,16 @@ H5FD_direct_unlock(H5FD_t *_file)
 
     HDassert(file);
 
-    if(HDflock(file->fd, LOCK_UN) < 0)
-        HSYS_GOTO_ERROR(H5E_FILE, H5E_BADFILE, FAIL, "unable to flock (unlock) file")
+    if(HDflock(file->fd, LOCK_UN) < 0) {
+        if(file->ignore_disabled_file_locks && ENOSYS == errno) {
+            /* When errno is set to ENOSYS, the file system does not support
+             * locking, so ignore it.
+             */
+            errno = 0;
+        }
+        else
+            HSYS_GOTO_ERROR(H5E_VFL, H5E_CANTUNLOCKFILE, FAIL, "unable to unlock file")
+    }
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)