Limit dyld image suffixes guessed by guessLibraryShortName()

Summary:
guessLibraryShortName() separates a full Mach-O dylib install name path
into a short name and a dyld image suffix. The short name is the name
of the dylib without its path or extension. The dyld image suffix is a
string used by dyld to load variants of dylibs if available at runtime;
for example, "when binding this process, load 'debug' variants of all
required dylibs." dyld knows exactly what the image suffix is, but
by convention diagnostic tools such as llvm-nm attempt to guess suffix
names by looking at the install name path. 

These dyld image suffixes are separated from the short name by a '_'
character. Because the '_' character is commonly used to separate words
in filenames guessLibraryShortName() cannot reliably separate a dylib's
short name from an arbitrary image suffix; imagine if both the short
name and the suffix contains an '_' character! To better deal with this
ambiguity, guessLibraryShortName() will recognize only "_debug" and
"_profile" as valid Suffix values. Calling code needs to be tolerant of
guessLibraryShortName() guessing incorrectly.

The previous implementation of guessLibraryShortName() did not allow
'_' characters to appear in short names. When present, the short name
would be  truncated, e.g., "libcompiler_rt" => "libcompiler". This
change allows "libcompiler_rt" and "libcompiler_rt_debug" to both be
recognized as "libcompiler_rt".

rdar://47412244

Reviewers: kledzik, lhames, pete

Reviewed By: pete

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D56978

llvm-svn: 352104

1 files changed, 18 insertions, 3 deletions

diff --git a/llvm/lib/Object/MachOObjectFile.cpp b/llvm/lib/Object/MachOObjectFile.cpp
index a1cbef2c281..69e69bdcf93 100644
--- a/llvm/lib/Object/MachOObjectFile.cpp
+++ b/llvm/lib/Object/MachOObjectFile.cpp
@@ -2241,9 +2241,18 @@ uint8_t MachOObjectFile::getRelocationLength(DataRefImpl Rel) const {
 // one of the two following forms:
 //      libFoo.A.dylib
 //      libFoo.dylib
+//
 // The library may have a suffix trailing the name Foo of the form:
 //      libFoo_profile.A.dylib
 //      libFoo_profile.dylib
+// These dyld image suffixes are separated from the short name by a '_'
+// character. Because the '_' character is commonly used to separate words in
+// filenames guessLibraryShortName() cannot reliably separate a dylib's short
+// name from an arbitrary image suffix; imagine if both the short name and the
+// suffix contains an '_' character! To better deal with this ambiguity,
+// guessLibraryShortName() will recognize only "_debug" and "_profile" as valid
+// Suffix values. Calling code needs to be tolerant of guessLibraryShortName()
+// guessing incorrectly.
 //
 // The Name of the dynamic library is also recognized as a library name if it
 // has the following form:
@@ -2251,7 +2260,6 @@ uint8_t MachOObjectFile::getRelocationLength(DataRefImpl Rel) const {
 //
 // If the Name of the dynamic library is none of the forms above then a NULL
 // StringRef is returned.
-//
 StringRef MachOObjectFile::guessLibraryShortName(StringRef Name,
                                                  bool &isFramework,
                                                  StringRef &Suffix) {
@@ -2271,7 +2279,10 @@ StringRef MachOObjectFile::guessLibraryShortName(StringRef Name,
   Idx = Foo.rfind('_');
   if (Idx != Foo.npos && Foo.size() >= 2) {
     Suffix = Foo.slice(Idx, Foo.npos);
-    Foo = Foo.slice(0, Idx);
+    if (Suffix != "_debug" && Suffix != "_profile")
+      Suffix = StringRef();
+    else
+      Foo = Foo.slice(0, Idx);
   }
 
   // First look for the form Foo.framework/Foo
@@ -2332,10 +2343,14 @@ guess_library:
   else
     b = b+1;
   // ignore any suffix after an underbar like Foo_profile.A.dylib
-  Idx = Name.find('_', b);
+  Idx = Name.rfind('_');
   if (Idx != Name.npos && Idx != b) {
     Lib = Name.slice(b, Idx);
     Suffix = Name.slice(Idx, a);
+    if (Suffix != "_debug" && Suffix != "_profile") {
+      Suffix = StringRef();
+      Lib = Name.slice(b, a);
+    }
   }
   else
     Lib = Name.slice(b, a);