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[oota-llvm.git] / lib / Support / Unix / Signals.inc

diff --git a/lib/Support/Unix/Signals.inc b/lib/Support/Unix/Signals.inc
index 75b91eaf1f88669ddd0d05243b7dc7779707c859..9e98af736890035319d7153339f754724d65bbe0 100644 (file)
--- a/lib/Support/Unix/Signals.inc
+++ b/lib/Support/Unix/Signals.inc
@@ -15,8 +15,9 @@
 #include "Unix.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/Mutex.h"
-#include <vector>
 #include <algorithm>
+#include <string>
+#include <vector>
 #if HAVE_EXECINFO_H
 # include <execinfo.h>         // For backtrace().
 #endif
@@ -43,7 +44,7 @@ static SmartMutex<true> SignalsMutex;
 /// InterruptFunction - The function to call if ctrl-c is pressed.
 static void (*InterruptFunction)() = 0;
 
-static std::vector<sys::Path> FilesToRemove;
+static std::vector<std::string> FilesToRemove;
 static std::vector<std::pair<void(*)(void*), void*> > CallBacksToRun;
 
 // IntSigs - Signals that may interrupt the program at any time.
@@ -117,10 +118,32 @@ static void UnregisterHandlers() {
 
 /// RemoveFilesToRemove - Process the FilesToRemove list. This function
 /// should be called with the SignalsMutex lock held.
+/// NB: This must be an async signal safe function. It cannot allocate or free
+/// memory, even in debug builds.
 static void RemoveFilesToRemove() {
-  while (!FilesToRemove.empty()) {
-    FilesToRemove.back().eraseFromDisk(true);
-    FilesToRemove.pop_back();
+  // We avoid iterators in case of debug iterators that allocate or release
+  // memory.
+  for (unsigned i = 0, e = FilesToRemove.size(); i != e; ++i) {
+    // We rely on a std::string implementation for which repeated calls to
+    // 'c_str()' don't allocate memory. We pre-call 'c_str()' on all of these
+    // strings to try to ensure this is safe.
+    const char *path = FilesToRemove[i].c_str();
+
+    // Get the status so we can determine if it's a file or directory. If we
+    // can't stat the file, ignore it.
+    struct stat buf;
+    if (stat(path, &buf) != 0)
+      continue;
+
+    // If this is not a regular file, ignore it. We want to prevent removal of
+    // special files like /dev/null, even if the compiler is being run with the
+    // super-user permissions.
+    if (!S_ISREG(buf.st_mode))
+      continue;
+  
+    // Otherwise, remove the file. We ignore any errors here as there is nothing
+    // else we can do.
+    unlink(path);
   }
 }
 
@@ -178,7 +201,19 @@ void llvm::sys::SetInterruptFunction(void (*IF)()) {
 bool llvm::sys::RemoveFileOnSignal(const sys::Path &Filename,
                                    std::string* ErrMsg) {
   SignalsMutex.acquire();
-  FilesToRemove.push_back(Filename);
+  std::string *OldPtr = FilesToRemove.empty() ? 0 : &FilesToRemove[0];
+  FilesToRemove.push_back(Filename.str());
+
+  // We want to call 'c_str()' on every std::string in this vector so that if
+  // the underlying implementation requires a re-allocation, it happens here
+  // rather than inside of the signal handler. If we see the vector grow, we
+  // have to call it on every entry. If it remains in place, we only need to
+  // call it on the latest one.
+  if (OldPtr == &FilesToRemove[0])
+    FilesToRemove.back().c_str();
+  else
+    for (unsigned i = 0, e = FilesToRemove.size(); i != e; ++i)
+      FilesToRemove[i].c_str();
 
   SignalsMutex.release();
 
@@ -189,10 +224,19 @@ bool llvm::sys::RemoveFileOnSignal(const sys::Path &Filename,
 // DontRemoveFileOnSignal - The public API
 void llvm::sys::DontRemoveFileOnSignal(const sys::Path &Filename) {
   SignalsMutex.acquire();
-  std::vector<sys::Path>::reverse_iterator I =
-    std::find(FilesToRemove.rbegin(), FilesToRemove.rend(), Filename);
-  if (I != FilesToRemove.rend())
-    FilesToRemove.erase(I.base()-1);
+  std::vector<std::string>::reverse_iterator RI =
+    std::find(FilesToRemove.rbegin(), FilesToRemove.rend(), Filename.str());
+  std::vector<std::string>::iterator I = FilesToRemove.end();
+  if (RI != FilesToRemove.rend())
+    I = FilesToRemove.erase(RI.base()-1);
+
+  // We need to call c_str() on every element which would have been moved by
+  // the erase. These elements, in a C++98 implementation where c_str()
+  // requires a reallocation on the first call may have had the call to c_str()
+  // made on insertion become invalid by being copied down an element.
+  for (std::vector<std::string>::iterator E = FilesToRemove.end(); I != E; ++I)
+    I->c_str();
+
   SignalsMutex.release();
 }
 
@@ -211,7 +255,7 @@ void llvm::sys::AddSignalHandler(void (*FnPtr)(void *), void *Cookie) {
 // On glibc systems we have the 'backtrace' function, which works nicely, but
 // doesn't demangle symbols.
 static void PrintStackTrace(void *) {
-#ifdef HAVE_BACKTRACE
+#if defined(HAVE_BACKTRACE) && defined(ENABLE_BACKTRACES)
   static void* StackTrace[256];
   // Use backtrace() to output a backtrace on Linux systems with glibc.
   int depth = backtrace(StackTrace,
@@ -261,7 +305,7 @@ static void PrintStackTrace(void *) {
 #endif
 }
 
-/// PrintStackTraceOnErrorSignal - When an error signal (such as SIBABRT or
+/// PrintStackTraceOnErrorSignal - When an error signal (such as SIGABRT or
 /// SIGSEGV) is delivered to the process, print a stack trace and then exit.
 void llvm::sys::PrintStackTraceOnErrorSignal() {
   AddSignalHandler(PrintStackTrace, 0);
@@ -273,11 +317,11 @@ void llvm::sys::PrintStackTraceOnErrorSignal() {
 
     exception_mask_t mask = EXC_MASK_CRASH;
 
-    kern_return_t ret = task_set_exception_ports(self, 
+    kern_return_t ret = task_set_exception_ports(self,
                              mask,
-                             NULL,
-                             EXCEPTION_STATE_IDENTITY | MACH_EXCEPTION_CODES, 
-                             NULL);
+                             MACH_PORT_NULL,
+                             EXCEPTION_STATE_IDENTITY | MACH_EXCEPTION_CODES,
+                             THREAD_STATE_NONE);
     (void)ret;
   }
 #endif