[asancov] Write coverage directly to a memory-mapped file.

This way does not require a __sanitizer_cov_dump() call. That's
important on Android, where apps can be killed at arbitrary time.

We write raw PCs to disk instead of module offsets; we also write
memory layout to a separate file. This increases dump size by the
factor of 2 on 64-bit systems.


git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@209653 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/sanitizer_common/sanitizer_posix.cc b/lib/sanitizer_common/sanitizer_posix.cc
index 2cd2a7c4d..8df1fa72a 100644
--- a/lib/sanitizer_common/sanitizer_posix.cc
+++ b/lib/sanitizer_common/sanitizer_posix.cc
@@ -206,6 +206,17 @@ void *MapFileToMemory(const char *file_name, uptr *buff_size) {
   return internal_iserror(map) ? 0 : (void *)map;
 }
 
+void *MapWritableFileToMemory(void *addr, uptr size, uptr fd, uptr offset) {
+  uptr flags = MAP_SHARED;
+  if (addr) flags |= MAP_FIXED;
+  uptr p = internal_mmap(addr, size, PROT_READ | PROT_WRITE, flags, fd, offset);
+  if (internal_iserror(p)) {
+    Printf("could not map writable file (%zd, %zu, %zu): %zd\n", fd, offset,
+           size, p);
+    return 0;
+  }
+  return (void *)p;
+}
 
 static inline bool IntervalsAreSeparate(uptr start1, uptr end1,
                                         uptr start2, uptr end2) {