From c1aa0f7a3d42f0b3747f9fa8fbb6fb1254d65af9 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Tue, 12 Sep 2017 14:18:34 +1000
Subject: [PATCH] io: slurp should default to providing bytes, not chars

std::byte has less potential for abuse. if you want an array of chars
you should ask for it.
---
 backtrace_execinfo.cpp |  2 +-
 io.cpp                 | 34 +++++++++++++++++++++++++++-------
 io.hpp                 | 10 +++++++---
 3 files changed, 35 insertions(+), 11 deletions(-)

diff --git a/backtrace_execinfo.cpp b/backtrace_execinfo.cpp
index 4bb0c8d4..40176d78 100644
--- a/backtrace_execinfo.cpp
+++ b/backtrace_execinfo.cpp
@@ -60,7 +60,7 @@ addr2line (const void *addr)
     );
 
     // inefficient to copy from vector to string, but it's not a high priority path
-    auto data = util::slurp (stream.get ());
+    auto data = util::slurp<char> (stream.get ());
     return std::string (data.cbegin (), data.cend ());
 
 #else
diff --git a/io.cpp b/io.cpp
index f984633b..218e3a10 100644
--- a/io.cpp
+++ b/io.cpp
@@ -32,10 +32,15 @@
 using namespace util;
 
 
-//----------------------------------------------------------------------------
-std::vector<char>
+//////////////////////////////////////////////////////////////////////////////
+template <typename T>
+std::vector<T>
 util::slurp (const std::experimental::filesystem::path &path)
 {
+    static_assert (
+        sizeof (T) == 1,
+        "slurp is designed for grabbing bytes, not complex structures"
+    );
     posix::fd out (path, O_RDONLY | O_BINARY);
 
     // Calculate the total file size
@@ -47,11 +52,11 @@ util::slurp (const std::experimental::filesystem::path &path)
         throw errno_error ();
 
     // Allocate a buffer, and keep reading until it's full.
-    std::vector<char> buffer (size);
+    std::vector<T> buffer (size);
 
     CHECK_GE (size, 0);
     size_t remaining = (size_t)size;
-    char *cursor = buffer.data ();
+    T *cursor = buffer.data ();
 
     while (remaining) {
         ssize_t consumed = ::read (out, cursor, remaining);
@@ -69,9 +74,20 @@ util::slurp (const std::experimental::filesystem::path &path)
 
 
 //-----------------------------------------------------------------------------
-std::vector<char>
+template std::vector<char> util::slurp (const std::experimental::filesystem::path&);
+template std::vector<std::byte> util::slurp (const std::experimental::filesystem::path&);
+
+
+///////////////////////////////////////////////////////////////////////////////
+template <typename T>
+std::vector<T>
 util::slurp (FILE *stream)
 {
+    static_assert (
+        sizeof (T) == 1,
+        "slurp is designed for grabbing bytes, not complex structures"
+    );
+
     // find how much data is in this file
     const int desc = fileno (stream);
     if (desc < 0)
@@ -81,7 +97,7 @@ util::slurp (FILE *stream)
     if (fstat (desc, &meta) < 0)
         errno_error::throw_code ();
 
-    std::vector<char> buf;
+    std::vector<T> buf;
 
     // we think we know the size, so try to do a simple read
     if (meta.st_size) {
@@ -113,8 +129,12 @@ util::slurp (FILE *stream)
 }
 
 
-
 //-----------------------------------------------------------------------------
+template std::vector<char> util::slurp (FILE*);
+template std::vector<std::byte> util::slurp (FILE*);
+
+
+///////////////////////////////////////////////////////////////////////////////
 void
 util::write (const posix::fd &out,
              const void *restrict data,
diff --git a/io.hpp b/io.hpp
index 521109b5..f3bbe42b 100644
--- a/io.hpp
+++ b/io.hpp
@@ -20,8 +20,9 @@
 #include "platform.hpp"
 #include "posix/fd.hpp"
 
-#include <cstdio>
+#include <cstddef>
 #include <cstdint>
+#include <cstdio>
 #include <experimental/filesystem>
 #include <vector>
 #include <streambuf>
@@ -35,8 +36,11 @@
 namespace util {
     //-------------------------------------------------------------------------
     /// Reads an entire file into memory.
-    std::vector<char> slurp (const std::experimental::filesystem::path&);
-    std::vector<char> slurp (FILE *);
+    template <typename T = std::byte>
+    std::vector<T> slurp (const std::experimental::filesystem::path&);
+
+    template <typename T = std::byte>
+    std::vector<T> slurp (FILE *);
 
 
     //-------------------------------------------------------------------------