[VFS] Add 'overlay-relative' field to YAML files

The VFS overlay mapping between virtual paths and real paths is done through
the 'external-contents' entries in YAML files, which contains hardcoded paths
to the real files.

When a module compilation crashes, headers are dumped into <name>.cache/vfs
directory and are mapped via the <name>.cache/vfs/vfs.yaml. The script
generated for reproduction uses -ivfsoverlay pointing to file to gather the
mapping between virtual paths and files inside <name>.cache/vfs. Currently, we
are only capable of reproducing such crashes in the same machine as they
happen, because of the hardcoded paths in 'external-contents'.

To be able to reproduce a crash in another machine, this patch introduces a new
option in the VFS yaml file called 'overlay-relative'. When it's equal to
'true' it means that the provided path to the YAML file through the
-ivfsoverlay option should also be used to prefix the final path for every
'external-contents'.

Example, given the invocation snippet "... -ivfsoverlay
<name>.cache/vfs/vfs.yaml" and the following entry in the yaml file:

"overlay-relative": "true",
"roots": [
...
  "type": "directory",
  "name": "/usr/include",
  "contents": [
    {
      "type": "file",
      "name": "stdio.h",
      "external-contents": "/usr/include/stdio.h"
    },
...

Here, a file manager request for virtual "/usr/include/stdio.h", that will map
into real path "/<absolute_path_to>/<name>.cache/vfs/usr/include/stdio.h.

This is a useful feature for debugging module crashes in machines other than
the one where the error happened.

Differential Revision: http://reviews.llvm.org/D17457

rdar://problem/24499339

llvm-svn: 261552

1 files changed, 4 insertions, 3 deletions

diff --git a/clang/test/Modules/crash-vfs-path-traversal.m b/clang/test/Modules/crash-vfs-path-traversal.m
index 8acd2172265..75e484eda06 100644
--- a/clang/test/Modules/crash-vfs-path-traversal.m
+++ b/clang/test/Modules/crash-vfs-path-traversal.m
@@ -35,12 +35,12 @@
 // CHECKSH: "-ivfsoverlay" "crash-vfs-{{[^ ]*}}.cache/vfs/vfs.yaml"
 
 // CHECKYAML: 'type': 'directory'
-// CHECKYAML: 'name': "{{[^ ]*}}/Inputs/System/usr/include",
+// CHECKYAML: 'name': "/[[PATH:.*]]/Inputs/System/usr/include",
 // CHECKYAML-NEXT: 'contents': [
 // CHECKYAML-NEXT:   {
 // CHECKYAML-NEXT:     'type': 'file',
 // CHECKYAML-NEXT:     'name': "module.map",
-// CHECKYAML-NEXT:     'external-contents': "{{[^ ]*}}/Inputs/System/usr/include/module.map"
+// CHECKYAML-NEXT:     'external-contents': "/[[PATH]]/Inputs/System/usr/include/module.map"
 // CHECKYAML-NEXT:   },
 
 // Replace the paths in the YAML files with relative ".." traversals
@@ -49,9 +49,10 @@
 
 // RUN: sed -e "s@usr/include@usr/include/../include@g" \
 // RUN:     %t/crash-vfs-*.cache/vfs/vfs.yaml > %t/vfs.yaml
+// RUN: cp %t/vfs.yaml %t/crash-vfs-*.cache/vfs/vfs.yaml
 // RUN: unset FORCE_CLANG_DIAGNOSTICS_CRASH
 // RUN: %clang -E %s -I %S/Inputs/System -isysroot %/t/i/ \
-// RUN:     -ivfsoverlay %t/vfs.yaml -fmodules \
+// RUN:     -ivfsoverlay %t/crash-vfs-*.cache/vfs/vfs.yaml -fmodules \
 // RUN:     -fmodules-cache-path=%t/m/ 2>&1 \
 // RUN:     | FileCheck %s --check-prefix=CHECKOVERLAY