Add support for GNU Hurd in Path.inc and other places

[sylvestre.ledru]

Summary

Patch by Svante Signell & myself

[sylvestre.ledru]

add path_max def

[JDevlieghere]

Can you provide some more information about why this is needed?

[efriedma]

tools/dsymutil/DwarfLinker.cpp

107

This seems unnecessary; as far as I can tell, this file doesn't refer to PATH_MAX at all.

[sylvestre.ledru]

Debian still proposes a GNU Hurd port of this distro. As LLVM is now key, the porters have been trying to get llvm ported.
This fixes a bunch of issues and make llvm work correctly on gnu hurd.

https://buildd.debian.org/status/logs.php?pkg=llvm-toolchain-6.0&arch=hurd-i386

[sylvestre.ledru]

Remove the DwarfLinker.cpp declaration (useless)

[efriedma]

LGTM

lib/Support/Unix/Path.inc

52

We really shouldn't be using PATH_MAX/MAXPATHLEN at all, but this isn't any worse than what we're already doing.

lib/Support/Unix/Path.inc

 // stdcxx's cstdio doesn't include stdio.h, so it doesn't #undef the macros
 // either.
 #undef ferror
 #undef feof
 
 // For GNU Hurd
 #if defined(__GNU__) && !defined(PATH_MAX)
 # define PATH_MAX 4096
+# define MAXPATHLEN 4096
 #endif
 
 #include <sys/types.h>
 #if !defined(__APPLE__) && !defined(__OpenBSD__) && !defined(__FreeBSD__) &&   \
     !defined(__linux__)
 #include <sys/statvfs.h>
 #define STATVFS statvfs
 #define FSTATVFS fstatvfs

 #else
 #include <sys/mount.h>
 #endif
 #define STATVFS statfs
 #define FSTATVFS fstatfs
 #define STATVFS_F_FRSIZE(vfs) static_cast<uint64_t>(vfs.f_bsize)
 #endif
 
-#if defined(__NetBSD__)
+#if defined(__NetBSD__) || defined(__GNU__)
 #define STATVFS_F_FLAG(vfs) (vfs).f_flag
 #else
 #define STATVFS_F_FLAG(vfs) (vfs).f_flags
 #endif
 
 using namespace llvm;
 
 namespace llvm {
 namespace sys  {
 namespace fs {
 
 const file_t kInvalidFile = -1;
 
 #if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) ||     \
     defined(__minix) || defined(__FreeBSD_kernel__) || defined(__linux__) ||   \
-    defined(__CYGWIN__) || defined(__DragonFly__) || defined(_AIX)
+    defined(__CYGWIN__) || defined(__DragonFly__) || defined(_AIX) || defined(__GNU__)
 static int
 test_dir(char ret[PATH_MAX], const char *dir, const char *bin)
 {
   struct stat sb;
   char fullpath[PATH_MAX];
 
   snprintf(fullpath, PATH_MAX, "%s/%s", dir, bin);
   if (!realpath(fullpath, ret))
if (::remove(p.begin()) == -1) {
     if (errno != ENOENT || !IgnoreNonExisting)
       return std::error_code(errno, std::generic_category());
   }
 
   return std::error_code();
 }
 
 static bool is_local_impl(struct STATVFS &Vfs) {
-#if defined(__linux__)
+#if defined(__linux__) || defined(__GNU__)
 #ifndef NFS_SUPER_MAGIC
 #define NFS_SUPER_MAGIC 0x6969
 #endif
 #ifndef SMB_SUPER_MAGIC
 #define SMB_SUPER_MAGIC 0x517B
 #endif
 #ifndef CIFS_MAGIC_NUMBER
 #define CIFS_MAGIC_NUMBER 0xFF534D42
 #endif
+#ifdef __GNU__
+  switch ((uint32_t)Vfs.__f_type) {
+#else
   switch ((uint32_t)Vfs.f_type) {
+#endif
   case NFS_SUPER_MAGIC:
   case SMB_SUPER_MAGIC:
   case CIFS_MAGIC_NUMBER:
     return false;
   default:
     return true;
   }
 #elif defined(__CYGWIN__)

tools/dsymutil/DwarfLinker.cpp

 #include <map>
 #include <memory>
 #include <string>
 #include <system_error>
 #include <tuple>
 #include <utility>
 #include <vector>
 
+// For GNU Hurd
+#if defined(__GNU__) && !defined(PATH_MAX)
+# define PATH_MAX 4096
+#endif
+
 namespace llvm {
 namespace dsymutil {
 
 /// Similar to DWARFUnitSection::getUnitForOffset(), but returning our
 /// CompileUnit object instead.
 static CompileUnit *getUnitForOffset(const UnitListTy &Units, unsigned Offset) {
   auto CU = std::upper_bound(
       Units.begin(), Units.end(), Offset,