Index: base/debug/format.h |
diff --git a/base/debug/format.h b/base/debug/format.h |
new file mode 100644 |
index 0000000000000000000000000000000000000000..78c8152f9fabe1c85f01dbd453bf5b4ac6249bbc |
--- /dev/null |
+++ b/base/debug/format.h |
@@ -0,0 +1,396 @@ |
+// Copyright (c) 2013 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#ifndef BASE_DEBUG_FORMAT_H_ |
+#define BASE_DEBUG_FORMAT_H_ |
+ |
+#include <stddef.h> |
+#include <stdint.h> |
+#include <stdlib.h> |
+ |
+#if defined(__unix__) |
+// For ssize_t |
+#include <unistd.h> |
+#endif |
+ |
+#include "base/base_export.h" |
+#include "base/basictypes.h" |
+ |
+namespace base { |
+namespace debug { |
+ |
+#if defined(_MSC_VER) |
+// Define ssize_t inside of our namespace. |
+typedef long ssize_t; |
+#endif |
+ |
+// Format() is a type-safe and async-signal-safe version of snprintf(). |
+// |
+// FormatN() is an alternative function signature that can be used when |
+// not dealing with fixed-sized buffers. When possible, Format() should always |
+// be used in favor of FormatN() |
+// |
+// These functions allow for formatting complicated messages from contexts that |
+// require strict async-signal-safety. In fact, it is safe to call them from |
+// any low-level execution context; even from contexts that have stricter |
+// requirements than just async-signal-safety. |
+// |
+// The code currently only supports a subset of format characters: |
+// %c, %d, %x, %X, %p, and %s. |
Jeffrey Yasskin
2013/07/30 23:13:53
Do you require %c to match characters or can it ta
|
+// |
+// All format characters take an optional width parameter. This must be a |
+// positive integer. For %d, %x, %X and %p, if the width starts with |
+// a leading '0', padding is done with '0' instead of ' ' characters. |
+// |
+// Returns the number of bytes needed to store the untruncated output. This |
+// does not include the terminating NUL byte. |
+// |
+// Returns -1, iff a fatal error happened. This typically can only happen, if |
+// the buffer size is a) negative, b) zero (i.e. not even the NUL byte can be |
+// written), or c) bigger than MAXINT. |
+// |
+// While the code supports type checking and while it is generally very careful |
+// to avoid printing incorrect values, it tends to be conservative in printing |
+// as much as possible, even when given incorrect parameters. Typically, in |
+// case of an error, the format string will not be expanded. (i.e. something |
+// like Format(buf, "%p %d", 1, 2) results in "%p 2"). |
+// |
+// The pre-C++11 version cannot handle more than ten arguments. |
+// |
+// Basic example: |
+// char buf[20]; |
+// base::debug::Format(buf, "The answer: %2d", 42); |
+// |
+// Example with dynamically sized buffer (async-signal-safe); this code won't |
+// work on Visual studio, as it requires dynamically allocating arrays on the |
+// stack: |
+// const size_t kInitialSize = 128; |
+// size_t sz = kInitialSize-1; |
+// for (;;) { |
+// char buf[sz+1]; |
+// sz = FormatN(buf, sz, "Error message \"%s\"\n", err); |
Jeffrey Yasskin
2013/07/30 23:13:53
The argument should be sz+1, right? (This interfac
|
+// if (sz >= sizeof(buf)) |
+// continue; |
+// write(2, buf, sz); |
+// break; |
+// } |
+ |
+namespace internal { |
+ // Helpers that use C++ overloading, templates, and specializations to deduce |
+ // and record type information from function arguments. This allows us to |
+ // later write a type-safe version of snprintf(). |
+ |
+ struct Arg { |
+ // Any integer-like value. |
+ Arg(signed char c) : i_(c), width_(sizeof(char)), type_(INT) { } |
+ Arg(unsigned char c) : i_(c), width_(sizeof(char)), type_(UINT) { } |
+ Arg(signed short i) : i_(i), width_(sizeof(short)), type_(INT) { } |
+ Arg(unsigned short i) : i_(i), width_(sizeof(short)), type_(UINT) { } |
+ Arg(signed int i) : i_(i), width_(sizeof(int)), type_(INT) { } |
+ Arg(unsigned int i) : i_(i), width_(sizeof(int)), type_(UINT) { } |
+ Arg(signed long i) : i_(i), width_(sizeof(long)), type_(INT) { } |
+ Arg(unsigned long i) : i_(i), width_(sizeof(long)), type_(UINT) { } |
+ Arg(signed long long i) : i_(i), width_(sizeof(long long)), |
+ type_(INT) { } |
+ Arg(unsigned long long i) : i_(i), width_(sizeof(long long)), |
+ type_(UINT) { } |
+ |
+ // A C-style text string. |
+ Arg(const char* s) : s_(s), type_(STRING) { } |
+ Arg(char* s) : s_(s), type_(STRING) { } |
+ |
+ // Any pointer value that can be cast to a "void*". |
+ template<class T> Arg(T* ptr) : ptr_((void*)ptr), type_(POINTER) { } |
+ |
+ union { |
+ // An integer-like value. |
+ struct { |
+ int64_t i_; |
+ unsigned char width_; |
+ }; |
+ |
+ // A C-style text string. |
+ const char* s_; |
+ |
+ // A pointer to an arbitrary object. |
+ const void* ptr_; |
+ }; |
+ const enum { INT, UINT, STRING, POINTER } type_; |
+ }; |
+ |
+ // This is the internal function that performs the actual formatting of |
+ // an snprintf()-style format string. |
+ BASE_EXPORT ssize_t FormatN(char* buf, size_t sz, const char* fmt, |
+ const Arg* args, size_t max_args); |
+} // namespace internal |
+ |
+#if __cplusplus >= 201103 // C++11 |
+ |
+template<typename... Args> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, Args... args) { |
Jeffrey Yasskin
2013/07/30 23:13:53
You may want to attach the gcc format attribute (h
|
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { args... }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, typename... Args> |
+ssize_t Format(char (&buf)[N], const char* fmt, Args... args) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { args... }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+#else // Pre-C++11 |
+ |
+// TODO(markus): C++11 has a much more concise and readable solution for |
+// expressing what we are doing here. Delete the fall-back code for older |
+// compilers as soon as we have fully switched to C++11 |
+ |
+template<class T0, class T1, class T2, class T3, class T4, |
+ class T5, class T6, class T7, class T8, class T9> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, |
+ T5 arg5, T6 arg6, T7 arg7, T8 arg8, T9 arg9) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { |
+ arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9 |
+ }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, |
+ class T0, class T1, class T2, class T3, class T4, |
+ class T5, class T6, class T7, class T8, class T9> |
+ssize_t Format(char (&buf)[N], const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, |
+ T5 arg5, T6 arg6, T7 arg7, T8 arg8, T9 arg9) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { |
+ arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9 |
+ }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<class T0, class T1, class T2, class T3, class T4, |
+ class T5, class T6, class T7, class T8> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, |
+ T5 arg5, T6 arg6, T7 arg7, T8 arg8) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { |
+ arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8 |
+ }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, |
+ class T0, class T1, class T2, class T3, class T4, class T5, |
+ class T6, class T7, class T8> |
+ssize_t Format(char (&buf)[N], const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, |
+ T5 arg5, T6 arg6, T7 arg7, T8 arg8) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { |
+ arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8 |
+ }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
Jeffrey Yasskin
2013/07/30 23:13:53
arraysize(arg_array) should work, since internal::
|
+} |
+ |
+template<class T0, class T1, class T2, class T3, class T4, class T5, |
+ class T6, class T7> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, |
+ T5 arg5, T6 arg6, T7 arg7) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { |
+ arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7 |
+ }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, |
+ class T0, class T1, class T2, class T3, class T4, class T5, |
+ class T6, class T7> |
+ssize_t Format(char (&buf)[N], const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, |
+ T5 arg5, T6 arg6, T7 arg7) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { |
+ arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7 |
+ }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<class T0, class T1, class T2, class T3, class T4, class T5, |
+ class T6> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, |
+ T5 arg5, T6 arg6) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { |
+ arg0, arg1, arg2, arg3, arg4, arg5, arg6 |
+ }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, |
+ class T0, class T1, class T2, class T3, class T4, class T5, |
+ class T6> |
+ssize_t Format(char (&buf)[N], const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, T5 arg5, T6 arg6) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { |
+ arg0, arg1, arg2, arg3, arg4, arg5, arg6 |
+ }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<class T0, class T1, class T2, class T3, class T4, class T5> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, T5 arg5) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0, arg1, arg2, arg3, arg4, arg5 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, |
+ class T0, class T1, class T2, class T3, class T4, class T5> |
+ssize_t Format(char (&buf)[N], const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4, T5 arg5) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0, arg1, arg2, arg3, arg4, arg5 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<class T0, class T1, class T2, class T3, class T4> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3, T4 arg4) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0, arg1, arg2, arg3, arg4 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, class T0, class T1, class T2, class T3, class T4> |
+ssize_t Format(char (&buf)[N], const char* fmt, T0 arg0, T1 arg1, |
+ T2 arg2, T3 arg3, T4 arg4) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0, arg1, arg2, arg3, arg4 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<class T0, class T1, class T2, class T3> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0, arg1, arg2, arg3 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, class T0, class T1, class T2, class T3> |
+ssize_t Format(char (&buf)[N], const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2, T3 arg3) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0, arg1, arg2, arg3 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<class T0, class T1, class T2> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, |
+ T0 arg0, T1 arg1, T2 arg2) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0, arg1, arg2 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, class T0, class T1, class T2> |
+ssize_t Format(char (&buf)[N], const char* fmt, T0 arg0, T1 arg1, T2 arg2) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0, arg1, arg2 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<class T0, class T1> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, T0 arg0, T1 arg1) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0, arg1 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, class T0, class T1> |
+ssize_t Format(char (&buf)[N], const char* fmt, T0 arg0, T1 arg1) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0, arg1 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<class T0> |
+ssize_t FormatN(char* buf, size_t N, const char* fmt, T0 arg0) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+ |
+template<size_t N, class T0> |
+ssize_t Format(char (&buf)[N], const char* fmt, T0 arg0) { |
+ // Use Arg() object to record type information and then copy arguments to an |
+ // array to make it easier to iterate over them. |
+ const internal::Arg arg_array[] = { arg0 }; |
+ return internal::FormatN(buf, N, fmt, arg_array, |
+ ARRAYSIZE_UNSAFE(arg_array)); |
+} |
+#endif |
+ |
+// Fast-path when we don't actually need to substitute any arguments. |
+BASE_EXPORT ssize_t FormatN(char* buf, size_t N, const char* fmt); |
+template<size_t N> |
+inline ssize_t Format(char (&buf)[N], const char* fmt) { |
+ return FormatN(buf, N, fmt); |
+} |
+ |
+} // namespace debug |
+} // namespace base |
+ |
+#endif // BASE_DEBUG_FORMAT_H_ |