| #include "library_file.h" |
| #include <link.h> |
| #include <stdio.h> |
| // Make a duplicate "_r_debug" symbol that is visible. This is the global |
| // variable name that the dynamic loader uses to communicate changes in shared |
| // libraries that get loaded and unloaded. LLDB finds the address of this |
| // variable by reading the DT_DEBUG entry from the .dynamic section of the main |
| // executable. |
| // What will happen is the dynamic loader will use the "_r_debug" symbol from |
| // itself until the a.out executable gets loaded. At this point the new |
| // "_r_debug" symbol will take precedence over the orignal "_r_debug" symbol |
| // from the dynamic loader and the copy below will get updated with shared |
| // library state changes while the version that LLDB checks in the dynamic |
| // loader stays the same for ever after this. |
| // |
| // When our DYLDRendezvous.cpp tries to check the state in the _r_debug |
| // structure, it will continue to get the last eAdd as the state before the |
| // switch in symbol resolution. |
| // |
| // Before a fix in LLDB, this would mean that we wouldn't ever load any shared |
| // libraries since DYLDRendezvous was waiting to see a eAdd state followed by a |
| // eConsistent state which would trigger the adding of shared libraries, but we |
| // would never see this change because the local copy below is actually what |
| // would get updated. Now if DYLDRendezvous detects two eAdd states in a row, |
| // it will load the shared libraries instead of doing nothing and a log message |
| // will be printed out if "log enable lldb dyld" is active. |
| r_debug _r_debug; |
| |
| int main() { |
| library_function(); // Break here |
| return 0; |
| } |
