[PATCH] D25255: Add a c_str() method to StringRef, similar to data() but asserting if the string isn't null terminated (NFC)

[Mehdi AMINI via llvm-commits]

mehdi_amini created this revision.
mehdi_amini added reviewers: dexonsmith, kimgr.
mehdi_amini added a subscriber: llvm-commits.

As I'm trying to replace our uses of raw "const char *"
with StringRef, one issue that came up is that calling .data()
on a StringRef is seen as "dangerous": there is no guarantee
that the String will be null terminated.

This is an attempt to alleviate this issue: instead of calling
data(), users that knows (because of an API contract) that a
StringRef must be null terminated can call c_str() instead.


https://reviews.llvm.org/D25255

Files:
  llvm/include/llvm/ADT/StringRef.h


Index: llvm/include/llvm/ADT/StringRef.h
===================================================================
--- llvm/include/llvm/ADT/StringRef.h
+++ llvm/include/llvm/ADT/StringRef.h
@@ -13,6 +13,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/Support/Compiler.h"
+#include "llvm/Support/ErrorHandling.h"
 #include <algorithm>
 #include <cassert>
 #include <cstring>
@@ -126,6 +127,18 @@
     LLVM_ATTRIBUTE_ALWAYS_INLINE
     const char *data() const { return Data; }
 
+    /// Get a pointer to the start of the string, enforcing that it is null
+    /// terminated. This is intended to be used when the contract of the API is
+    /// to return a null terminated string.
+    const char *c_str() const {
+#if !defined(NDEBUG) || LLVM_ADDRESS_SANITIZER_BUILD ||                        \
+    LLVM_MEMORY_SANITIZER_BUILD
+      if (Data[size()] != '\0')
+        report_fatal_error("c_str() called on a non-null terminated string");
+#endif
+      return Data;
+    }
+
     /// empty - Check if the string is empty.
     LLVM_ATTRIBUTE_ALWAYS_INLINE
     bool empty() const { return Length == 0; }


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