gecko-dev/mozglue/linker/Utils.h

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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef Utils_h
#define Utils_h
#include <stdint.h>
#include <stddef.h>
#include <sys/mman.h>
#include <unistd.h>
#include "mozilla/Assertions.h"
#include "mozilla/Scoped.h"
/**
* On architectures that are little endian and that support unaligned reads,
* we can use direct type, but on others, we want to have a special class
* to handle conversion and alignment issues.
*/
#if !defined(DEBUG) && (defined(__i386__) || defined(__x86_64__))
typedef uint16_t le_uint16;
typedef uint32_t le_uint32;
#else
/**
* Template that allows to find an unsigned int type from a (computed) bit size
*/
template <int s> struct UInt { };
template <> struct UInt<16> { typedef uint16_t Type; };
template <> struct UInt<32> { typedef uint32_t Type; };
/**
* Template to access 2 n-bit sized words as a 2*n-bit sized word, doing
* conversion from little endian and avoiding alignment issues.
*/
template <typename T>
class le_to_cpu
{
public:
typedef typename UInt<16 * sizeof(T)>::Type Type;
operator Type() const
{
return (b << (sizeof(T) * 8)) | a;
}
const le_to_cpu& operator =(const Type &v)
{
a = v & ((1 << (sizeof(T) * 8)) - 1);
b = v >> (sizeof(T) * 8);
return *this;
}
le_to_cpu() { }
le_to_cpu(const Type &v)
{
operator =(v);
}
const le_to_cpu& operator +=(const Type &v)
{
return operator =(operator Type() + v);
}
const le_to_cpu& operator ++(int)
{
return operator =(operator Type() + 1);
}
private:
T a, b;
};
/**
* Type definitions
*/
typedef le_to_cpu<unsigned char> le_uint16;
typedef le_to_cpu<le_uint16> le_uint32;
#endif
/**
* AutoCloseFD is a RAII wrapper for POSIX file descriptors
*/
struct AutoCloseFDTraits
{
typedef int type;
static int empty() { return -1; }
static void release(int fd) { close(fd); }
};
typedef mozilla::Scoped<AutoCloseFDTraits> AutoCloseFD;
/**
* MappedPtr is a RAII wrapper for mmap()ed memory. It can be used as
* a simple void * or unsigned char *.
*
* It is defined as a derivative of a template that allows to use a
* different unmapping strategy.
*/
template <typename T>
class GenericMappedPtr
{
public:
GenericMappedPtr(void *buf, size_t length): buf(buf), length(length) { }
GenericMappedPtr(): buf(MAP_FAILED), length(0) { }
void Assign(void *b, size_t len) {
if (buf != MAP_FAILED)
static_cast<T *>(this)->munmap(buf, length);
buf = b;
length = len;
}
~GenericMappedPtr()
{
if (buf != MAP_FAILED)
static_cast<T *>(this)->munmap(buf, length);
}
operator void *() const
{
return buf;
}
operator unsigned char *() const
{
return reinterpret_cast<unsigned char *>(buf);
}
bool operator ==(void *ptr) const {
return buf == ptr;
}
bool operator ==(unsigned char *ptr) const {
return buf == ptr;
}
void *operator +(off_t offset) const
{
return reinterpret_cast<char *>(buf) + offset;
}
/**
* Returns whether the given address is within the mapped range
*/
bool Contains(void *ptr) const
{
return (ptr >= buf) && (ptr < reinterpret_cast<char *>(buf) + length);
}
/**
* Returns the length of the mapped range
*/
size_t GetLength() const
{
return length;
}
private:
void *buf;
size_t length;
};
struct MappedPtr: public GenericMappedPtr<MappedPtr>
{
MappedPtr(void *buf, size_t length)
: GenericMappedPtr<MappedPtr>(buf, length) { }
MappedPtr(): GenericMappedPtr<MappedPtr>() { }
private:
friend class GenericMappedPtr<MappedPtr>;
void munmap(void *buf, size_t length)
{
::munmap(buf, length);
}
};
/**
* UnsizedArray is a way to access raw arrays of data in memory.
*
* struct S { ... };
* UnsizedArray<S> a(buf);
* UnsizedArray<S> b; b.Init(buf);
*
* This is roughly equivalent to
* const S *a = reinterpret_cast<const S *>(buf);
* const S *b = NULL; b = reinterpret_cast<const S *>(buf);
*
* An UnsizedArray has no known length, and it's up to the caller to make
* sure the accessed memory is mapped and makes sense.
*/
template <typename T>
class UnsizedArray
{
public:
typedef size_t idx_t;
/**
* Constructors and Initializers
*/
UnsizedArray(): contents(NULL) { }
UnsizedArray(const void *buf): contents(reinterpret_cast<const T *>(buf)) { }
void Init(const void *buf)
{
MOZ_ASSERT(contents == NULL);
contents = reinterpret_cast<const T *>(buf);
}
/**
* Returns the nth element of the array
*/
const T &operator[](const idx_t index) const
{
MOZ_ASSERT(contents);
return contents[index];
}
/**
* Returns whether the array points somewhere
*/
operator bool() const
{
return contents != NULL;
}
private:
const T *contents;
};
/**
* Array, like UnsizedArray, is a way to access raw arrays of data in memory.
* Unlike UnsizedArray, it has a known length, and is enumerable with an
* iterator.
*
* struct S { ... };
* Array<S> a(buf, len);
* UnsizedArray<S> b; b.Init(buf, len);
*
* In the above examples, len is the number of elements in the array. It is
* also possible to initialize an Array with the buffer size:
*
* Array<S> c; c.InitSize(buf, size);
*
* It is also possible to initialize an Array in two steps, only providing
* one data at a time:
*
* Array<S> d;
* d.Init(buf);
* d.Init(len); // or d.InitSize(size);
*
*/
template <typename T>
class Array: public UnsizedArray<T>
{
public:
typedef typename UnsizedArray<T>::idx_t idx_t;
/**
* Constructors and Initializers
*/
Array(): UnsizedArray<T>(), length(0) { }
Array(const void *buf, const idx_t length)
: UnsizedArray<T>(buf), length(length) { }
void Init(const void *buf)
{
UnsizedArray<T>::Init(buf);
}
void Init(const idx_t len)
{
MOZ_ASSERT(length == 0);
length = len;
}
void InitSize(const idx_t size)
{
Init(size / sizeof(T));
}
void Init(const void *buf, const idx_t len)
{
UnsizedArray<T>::Init(buf);
Init(len);
}
void InitSize(const void *buf, const idx_t size)
{
UnsizedArray<T>::Init(buf);
InitSize(size);
}
/**
* Returns the nth element of the array
*/
const T &operator[](const idx_t index) const
{
MOZ_ASSERT(index < length);
MOZ_ASSERT(operator bool());
return UnsizedArray<T>::operator[](index);
}
/**
* Returns the number of elements in the array
*/
idx_t numElements() const
{
return length;
}
/**
* Returns whether the array points somewhere and has at least one element.
*/
operator bool() const
{
return (length > 0) && UnsizedArray<T>::operator bool();
}
/**
* Iterator for an Array. Use is similar to that of STL const_iterators:
*
* struct S { ... };
* Array<S> a(buf, len);
* for (Array<S>::iterator it = a.begin(); it < a.end(); ++it) {
* // Do something with *it.
* }
*/
class iterator
{
public:
iterator(): item(NULL) { }
const T &operator *() const
{
return *item;
}
const T *operator ->() const
{
return item;
}
iterator &operator ++()
{
++item;
return *this;
}
bool operator<(const iterator &other) const
{
return item < other.item;
}
protected:
friend class Array<T>;
iterator(const T &item): item(&item) { }
private:
const T *item;
};
/**
* Returns an iterator pointing at the beginning of the Array
*/
iterator begin() const {
if (length)
return iterator(UnsizedArray<T>::operator[](0));
return iterator();
}
/**
* Returns an iterator pointing past the end of the Array
*/
iterator end() const {
if (length)
return iterator(UnsizedArray<T>::operator[](length));
return iterator();
}
/**
* Reverse iterator for an Array. Use is similar to that of STL
* const_reverse_iterators:
*
* struct S { ... };
* Array<S> a(buf, len);
* for (Array<S>::reverse_iterator it = a.rbegin(); it < a.rend(); ++it) {
* // Do something with *it.
* }
*/
class reverse_iterator
{
public:
reverse_iterator(): item(NULL) { }
const T &operator *() const
{
const T *tmp = item;
return *--tmp;
}
const T *operator ->() const
{
return &operator*();
}
reverse_iterator &operator ++()
{
--item;
return *this;
}
bool operator<(const reverse_iterator &other) const
{
return item > other.item;
}
protected:
friend class Array<T>;
reverse_iterator(const T &item): item(&item) { }
private:
const T *item;
};
/**
* Returns a reverse iterator pointing at the end of the Array
*/
reverse_iterator rbegin() const {
if (length)
return reverse_iterator(UnsizedArray<T>::operator[](length));
return reverse_iterator();
}
/**
* Returns a reverse iterator pointing past the beginning of the Array
*/
reverse_iterator rend() const {
if (length)
return reverse_iterator(UnsizedArray<T>::operator[](0));
return reverse_iterator();
}
private:
idx_t length;
};
/**
* Transforms a pointer-to-function to a pointer-to-object pointing at the
* same address.
*/
template <typename T>
void *FunctionPtr(T func)
{
union {
void *ptr;
T func;
} f;
f.func = func;
return f.ptr;
}
#endif /* Utils_h */