VFD plugins (#602)

* Implement support for loading of Virtual File Drivers as plugins

Fix plugin caching for VOL connector and VFD plugins

Fix plugin iteration to skip paths that can't be opened

* Enable dynamic loading of VFDs with HDF5_DRIVER environment variable

* Temporarily disable error reporting during H5F_open double file open

* Default to using HDstat in h5_get_file_size for unknown VFDs

* Use macros for some environment variables that HDF5 interprets

* Update "null" and "ctl testing" VFDs

10 files changed, 120 insertions, 0 deletions

diff --git a/tools/test/h5diff/testfiles/h5diff_10.txt b/tools/test/h5diff/testfiles/h5diff_10.txt
index 3631db7..c8e8560 100644
--- a/tools/test/h5diff/testfiles/h5diff_10.txt
+++ b/tools/test/h5diff/testfiles/h5diff_10.txt
@@ -36,6 +36,18 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[ obj2]]
                            HDF5 file specified
    --vol-info-2            VOL-specific info to pass to the VOL connector used for
                            opening the second HDF5 file specified
+   --vfd-value-1           Value (ID) of the VFL driver to use for opening the
+                           first HDF5 file specified
+   --vfd-name-1            Name of the VFL driver to use for opening the first
+                           HDF5 file specified
+   --vfd-info-1            VFD-specific info to pass to the VFL driver used for
+                           opening the first HDF5 file specified
+   --vfd-value-2           Value (ID) of the VFL driver to use for opening the
+                           second HDF5 file specified
+   --vfd-name-2            Name of the VFL driver to use for opening the second
+                           HDF5 file specified
+   --vfd-info-2            VFD-specific info to pass to the VFL driver used for
+                           opening the second HDF5 file specified
    --follow-symlinks
          Follow symbolic links (soft links and external links and compare the)
          links' target objects.
diff --git a/tools/test/h5diff/testfiles/h5diff_600.txt b/tools/test/h5diff/testfiles/h5diff_600.txt
index 8a4ce6d..c8190ce 100644
--- a/tools/test/h5diff/testfiles/h5diff_600.txt
+++ b/tools/test/h5diff/testfiles/h5diff_600.txt
@@ -36,6 +36,18 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[ obj2]]
                            HDF5 file specified
    --vol-info-2            VOL-specific info to pass to the VOL connector used for
                            opening the second HDF5 file specified
+   --vfd-value-1           Value (ID) of the VFL driver to use for opening the
+                           first HDF5 file specified
+   --vfd-name-1            Name of the VFL driver to use for opening the first
+                           HDF5 file specified
+   --vfd-info-1            VFD-specific info to pass to the VFL driver used for
+                           opening the first HDF5 file specified
+   --vfd-value-2           Value (ID) of the VFL driver to use for opening the
+                           second HDF5 file specified
+   --vfd-name-2            Name of the VFL driver to use for opening the second
+                           HDF5 file specified
+   --vfd-info-2            VFD-specific info to pass to the VFL driver used for
+                           opening the second HDF5 file specified
    --follow-symlinks
          Follow symbolic links (soft links and external links and compare the)
          links' target objects.
diff --git a/tools/test/h5diff/testfiles/h5diff_603.txt b/tools/test/h5diff/testfiles/h5diff_603.txt
index d4c7336..03c23e7 100644
--- a/tools/test/h5diff/testfiles/h5diff_603.txt
+++ b/tools/test/h5diff/testfiles/h5diff_603.txt
@@ -37,6 +37,18 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[ obj2]]
                            HDF5 file specified
    --vol-info-2            VOL-specific info to pass to the VOL connector used for
                            opening the second HDF5 file specified
+   --vfd-value-1           Value (ID) of the VFL driver to use for opening the
+                           first HDF5 file specified
+   --vfd-name-1            Name of the VFL driver to use for opening the first
+                           HDF5 file specified
+   --vfd-info-1            VFD-specific info to pass to the VFL driver used for
+                           opening the first HDF5 file specified
+   --vfd-value-2           Value (ID) of the VFL driver to use for opening the
+                           second HDF5 file specified
+   --vfd-name-2            Name of the VFL driver to use for opening the second
+                           HDF5 file specified
+   --vfd-info-2            VFD-specific info to pass to the VFL driver used for
+                           opening the second HDF5 file specified
    --follow-symlinks
          Follow symbolic links (soft links and external links and compare the)
          links' target objects.
diff --git a/tools/test/h5diff/testfiles/h5diff_606.txt b/tools/test/h5diff/testfiles/h5diff_606.txt
index 3123587..0e9d5be 100644
--- a/tools/test/h5diff/testfiles/h5diff_606.txt
+++ b/tools/test/h5diff/testfiles/h5diff_606.txt
@@ -37,6 +37,18 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[ obj2]]
                            HDF5 file specified
    --vol-info-2            VOL-specific info to pass to the VOL connector used for
                            opening the second HDF5 file specified
+   --vfd-value-1           Value (ID) of the VFL driver to use for opening the
+                           first HDF5 file specified
+   --vfd-name-1            Name of the VFL driver to use for opening the first
+                           HDF5 file specified
+   --vfd-info-1            VFD-specific info to pass to the VFL driver used for
+                           opening the first HDF5 file specified
+   --vfd-value-2           Value (ID) of the VFL driver to use for opening the
+                           second HDF5 file specified
+   --vfd-name-2            Name of the VFL driver to use for opening the second
+                           HDF5 file specified
+   --vfd-info-2            VFD-specific info to pass to the VFL driver used for
+                           opening the second HDF5 file specified
    --follow-symlinks
          Follow symbolic links (soft links and external links and compare the)
          links' target objects.
diff --git a/tools/test/h5diff/testfiles/h5diff_612.txt b/tools/test/h5diff/testfiles/h5diff_612.txt
index ce2d887..ac19926 100644
--- a/tools/test/h5diff/testfiles/h5diff_612.txt
+++ b/tools/test/h5diff/testfiles/h5diff_612.txt
@@ -37,6 +37,18 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[ obj2]]
                            HDF5 file specified
    --vol-info-2            VOL-specific info to pass to the VOL connector used for
                            opening the second HDF5 file specified
+   --vfd-value-1           Value (ID) of the VFL driver to use for opening the
+                           first HDF5 file specified
+   --vfd-name-1            Name of the VFL driver to use for opening the first
+                           HDF5 file specified
+   --vfd-info-1            VFD-specific info to pass to the VFL driver used for
+                           opening the first HDF5 file specified
+   --vfd-value-2           Value (ID) of the VFL driver to use for opening the
+                           second HDF5 file specified
+   --vfd-name-2            Name of the VFL driver to use for opening the second
+                           HDF5 file specified
+   --vfd-info-2            VFD-specific info to pass to the VFL driver used for
+                           opening the second HDF5 file specified
    --follow-symlinks
          Follow symbolic links (soft links and external links and compare the)
          links' target objects.
diff --git a/tools/test/h5diff/testfiles/h5diff_615.txt b/tools/test/h5diff/testfiles/h5diff_615.txt
index 61fd036..44eba43 100644
--- a/tools/test/h5diff/testfiles/h5diff_615.txt
+++ b/tools/test/h5diff/testfiles/h5diff_615.txt
@@ -37,6 +37,18 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[ obj2]]
                            HDF5 file specified
    --vol-info-2            VOL-specific info to pass to the VOL connector used for
                            opening the second HDF5 file specified
+   --vfd-value-1           Value (ID) of the VFL driver to use for opening the
+                           first HDF5 file specified
+   --vfd-name-1            Name of the VFL driver to use for opening the first
+                           HDF5 file specified
+   --vfd-info-1            VFD-specific info to pass to the VFL driver used for
+                           opening the first HDF5 file specified
+   --vfd-value-2           Value (ID) of the VFL driver to use for opening the
+                           second HDF5 file specified
+   --vfd-name-2            Name of the VFL driver to use for opening the second
+                           HDF5 file specified
+   --vfd-info-2            VFD-specific info to pass to the VFL driver used for
+                           opening the second HDF5 file specified
    --follow-symlinks
          Follow symbolic links (soft links and external links and compare the)
          links' target objects.
diff --git a/tools/test/h5diff/testfiles/h5diff_621.txt b/tools/test/h5diff/testfiles/h5diff_621.txt
index dc8655d..32310eb 100644
--- a/tools/test/h5diff/testfiles/h5diff_621.txt
+++ b/tools/test/h5diff/testfiles/h5diff_621.txt
@@ -37,6 +37,18 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[ obj2]]
                            HDF5 file specified
    --vol-info-2            VOL-specific info to pass to the VOL connector used for
                            opening the second HDF5 file specified
+   --vfd-value-1           Value (ID) of the VFL driver to use for opening the
+                           first HDF5 file specified
+   --vfd-name-1            Name of the VFL driver to use for opening the first
+                           HDF5 file specified
+   --vfd-info-1            VFD-specific info to pass to the VFL driver used for
+                           opening the first HDF5 file specified
+   --vfd-value-2           Value (ID) of the VFL driver to use for opening the
+                           second HDF5 file specified
+   --vfd-name-2            Name of the VFL driver to use for opening the second
+                           HDF5 file specified
+   --vfd-info-2            VFD-specific info to pass to the VFL driver used for
+                           opening the second HDF5 file specified
    --follow-symlinks
          Follow symbolic links (soft links and external links and compare the)
          links' target objects.
diff --git a/tools/test/h5diff/testfiles/h5diff_622.txt b/tools/test/h5diff/testfiles/h5diff_622.txt
index f20ffbe..630184f 100644
--- a/tools/test/h5diff/testfiles/h5diff_622.txt
+++ b/tools/test/h5diff/testfiles/h5diff_622.txt
@@ -37,6 +37,18 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[ obj2]]
                            HDF5 file specified
    --vol-info-2            VOL-specific info to pass to the VOL connector used for
                            opening the second HDF5 file specified
+   --vfd-value-1           Value (ID) of the VFL driver to use for opening the
+                           first HDF5 file specified
+   --vfd-name-1            Name of the VFL driver to use for opening the first
+                           HDF5 file specified
+   --vfd-info-1            VFD-specific info to pass to the VFL driver used for
+                           opening the first HDF5 file specified
+   --vfd-value-2           Value (ID) of the VFL driver to use for opening the
+                           second HDF5 file specified
+   --vfd-name-2            Name of the VFL driver to use for opening the second
+                           HDF5 file specified
+   --vfd-info-2            VFD-specific info to pass to the VFL driver used for
+                           opening the second HDF5 file specified
    --follow-symlinks
          Follow symbolic links (soft links and external links and compare the)
          links' target objects.
diff --git a/tools/test/h5diff/testfiles/h5diff_623.txt b/tools/test/h5diff/testfiles/h5diff_623.txt
index f73d202..82c4ce2 100644
--- a/tools/test/h5diff/testfiles/h5diff_623.txt
+++ b/tools/test/h5diff/testfiles/h5diff_623.txt
@@ -37,6 +37,18 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[ obj2]]
                            HDF5 file specified
    --vol-info-2            VOL-specific info to pass to the VOL connector used for
                            opening the second HDF5 file specified
+   --vfd-value-1           Value (ID) of the VFL driver to use for opening the
+                           first HDF5 file specified
+   --vfd-name-1            Name of the VFL driver to use for opening the first
+                           HDF5 file specified
+   --vfd-info-1            VFD-specific info to pass to the VFL driver used for
+                           opening the first HDF5 file specified
+   --vfd-value-2           Value (ID) of the VFL driver to use for opening the
+                           second HDF5 file specified
+   --vfd-name-2            Name of the VFL driver to use for opening the second
+                           HDF5 file specified
+   --vfd-info-2            VFD-specific info to pass to the VFL driver used for
+                           opening the second HDF5 file specified
    --follow-symlinks
          Follow symbolic links (soft links and external links and compare the)
          links' target objects.
diff --git a/tools/test/h5diff/testfiles/h5diff_624.txt b/tools/test/h5diff/testfiles/h5diff_624.txt
index 903b738..a675ec6 100644
--- a/tools/test/h5diff/testfiles/h5diff_624.txt
+++ b/tools/test/h5diff/testfiles/h5diff_624.txt
@@ -37,6 +37,18 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[ obj2]]
                            HDF5 file specified
    --vol-info-2            VOL-specific info to pass to the VOL connector used for
                            opening the second HDF5 file specified
+   --vfd-value-1           Value (ID) of the VFL driver to use for opening the
+                           first HDF5 file specified
+   --vfd-name-1            Name of the VFL driver to use for opening the first
+                           HDF5 file specified
+   --vfd-info-1            VFD-specific info to pass to the VFL driver used for
+                           opening the first HDF5 file specified
+   --vfd-value-2           Value (ID) of the VFL driver to use for opening the
+                           second HDF5 file specified
+   --vfd-name-2            Name of the VFL driver to use for opening the second
+                           HDF5 file specified
+   --vfd-info-2            VFD-specific info to pass to the VFL driver used for
+                           opening the second HDF5 file specified
    --follow-symlinks
          Follow symbolic links (soft links and external links and compare the)
          links' target objects.