8.0

1 files changed, 43 insertions, 50 deletions

diff --git a/zen/file_io.cpp b/zen/file_io.cpp
index b385ce33..b4351ee8 100644
--- a/zen/file_io.cpp
+++ b/zen/file_io.cpp
@@ -152,6 +152,7 @@ FileInput::FileInput(const Zstring& filepath) : //throw FileError, ErrorFileLock
 
 #ifdef ZEN_WIN  //destructor call would lead to member double clean-up!!!
     ZEN_ON_SCOPE_FAIL(::CloseHandle(fileHandle));
+
 #elif defined ZEN_LINUX || defined ZEN_MAC
     ZEN_ON_SCOPE_FAIL(::close(fileHandle));
 #endif
@@ -178,45 +179,38 @@ FileInput::~FileInput()
 }
 
 
-size_t FileInput::read(void* buffer, size_t bytesToRead) //throw FileError; returns actual number of bytes read
+size_t FileInput::tryRead(void* buffer, size_t bytesToRead) //throw FileError; may return short, only 0 means EOF!
 {
-    size_t bytesReadTotal = 0;
+    if (bytesToRead == 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
 
-    while (bytesToRead > 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
-    {
 #ifdef ZEN_WIN
-        //test for end of file: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365690%28v=vs.85%29.aspx
-        DWORD bytesRead = 0;
-        if (!::ReadFile(fileHandle, //__in         HANDLE hFile,
-                        buffer,     //__out        LPVOID lpBuffer,
-                        static_cast<DWORD>(bytesToRead), //__in         DWORD nNumberOfBytesToRead,
-                        &bytesRead, //__out_opt    LPDWORD lpNumberOfBytesRead,
-                        nullptr))   //__inout_opt  LPOVERLAPPED lpOverlapped
-            THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot read file %x."), L"%x", fmtPath(getFilePath())), L"ReadFile");
+    //posix ::read() semantics: test for end of file: https://msdn.microsoft.com/en-us/library/windows/desktop/aa365690%28v=vs.85%29.aspx
+    DWORD bytesRead = 0;
+    if (!::ReadFile(fileHandle, //__in         HANDLE hFile,
+                    buffer,     //__out        LPVOID lpBuffer,
+                    static_cast<DWORD>(bytesToRead), //__in         DWORD nNumberOfBytesToRead,
+                    &bytesRead, //__out_opt    LPDWORD lpNumberOfBytesRead,
+                    nullptr))   //__inout_opt  LPOVERLAPPED lpOverlapped
+        THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot read file %x."), L"%x", fmtPath(getFilePath())), L"ReadFile");
 
 #elif defined ZEN_LINUX || defined ZEN_MAC
-        ssize_t bytesRead = 0;
-        do
-        {
-            bytesRead = ::read(fileHandle, buffer, bytesToRead);
-        }
-        while (bytesRead < 0 && errno == EINTR); //Compare copy_reg() in copy.c: ftp://ftp.gnu.org/gnu/coreutils/coreutils-8.23.tar.xz
+    ssize_t bytesRead = 0;
+    do
+    {
+        bytesRead = ::read(fileHandle, buffer, bytesToRead);
+    }
+    while (bytesRead < 0 && errno == EINTR); //Compare copy_reg() in copy.c: ftp://ftp.gnu.org/gnu/coreutils/coreutils-8.23.tar.xz
 
-        if (bytesRead < 0)
-            THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot read file %x."), L"%x", fmtPath(getFilePath())), L"read");
+    if (bytesRead < 0)
+        THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot read file %x."), L"%x", fmtPath(getFilePath())), L"read");
 #endif
-        if (bytesRead == 0) //"zero indicates end of file"
-            return bytesReadTotal;
+    if (static_cast<size_t>(bytesRead) > bytesToRead) //better safe than sorry
+        throw FileError(replaceCpy(_("Cannot read file %x."), L"%x", fmtPath(getFilePath())), L"ReadFile: buffer overflow."); //user should never see this
 
-        if (static_cast<size_t>(bytesRead) > bytesToRead) //better safe than sorry
-            throw FileError(replaceCpy(_("Cannot read file %x."), L"%x", fmtPath(getFilePath())), L"ReadFile: buffer overflow."); //user should never see this
+    //if ::read is interrupted (EINTR) right in the middle, it will return successfully with "bytesRead < bytesToRead" => loop!
 
-        //if ::read is interrupted (EINTR) right in the middle, it will return successfully with "bytesRead < bytesToRead" => loop!
-        buffer = static_cast<char*>(buffer) + bytesRead; //suppress warning about pointer arithmetics on void*
-        bytesToRead -= bytesRead;
-        bytesReadTotal += bytesRead;
-    }
-    return bytesReadTotal;
+    return bytesRead; //"zero indicates end of file"
 }
 
 //----------------------------------------------------------------------------------------------------
@@ -355,8 +349,11 @@ void FileOutput::close() //throw FileError
 }
 
 
-void FileOutput::write(const void* buffer, size_t bytesToWrite) //throw FileError
+size_t FileOutput::tryWrite(const void* buffer, size_t bytesToWrite) //throw FileError; may return short! CONTRACT: bytesToWrite > 0
 {
+    if (bytesToWrite == 0)
+        throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__));
+
 #ifdef ZEN_WIN
     DWORD bytesWritten = 0; //this parameter is NOT optional: http://blogs.msdn.com/b/oldnewthing/archive/2013/04/04/10407417.aspx
     if (!::WriteFile(fileHandle,    //__in         HANDLE hFile,
@@ -370,28 +367,24 @@ void FileOutput::write(const void* buffer, size_t bytesToWrite) //throw FileErro
         throw FileError(replaceCpy(_("Cannot write file %x."), L"%x", fmtPath(getFilePath())), L"WriteFile: incomplete write."); //user should never see this
 
 #elif defined ZEN_LINUX || defined ZEN_MAC
-    while (bytesToWrite > 0)
+    ssize_t bytesWritten = 0;
+    do
     {
-        ssize_t bytesWritten = 0;
-        do
-        {
-            bytesWritten = ::write(fileHandle, buffer, bytesToWrite);
-        }
-        while (bytesWritten < 0 && errno == EINTR);
-
-        if (bytesWritten <= 0)
-        {
-            if (bytesWritten == 0) //comment in safe-read.c suggests to treat this as an error due to buggy drivers
-                errno = ENOSPC;
+        bytesWritten = ::write(fileHandle, buffer, bytesToWrite);
+    }
+    while (bytesWritten < 0 && errno == EINTR);
 
-            THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot write file %x."), L"%x", fmtPath(getFilePath())), L"write");
-        }
-        if (bytesWritten > static_cast<ssize_t>(bytesToWrite)) //better safe than sorry
-            throw FileError(replaceCpy(_("Cannot write file %x."), L"%x", fmtPath(getFilePath())), L"write: buffer overflow."); //user should never see this
+    if (bytesWritten <= 0)
+    {
+        if (bytesWritten == 0) //comment in safe-read.c suggests to treat this as an error due to buggy drivers
+            errno = ENOSPC;
 
-        //if ::write() is interrupted (EINTR) right in the middle, it will return successfully with "bytesWritten < bytesToWrite"!
-        buffer = static_cast<const char*>(buffer) + bytesWritten; //suppress warning about pointer arithmetics on void*
-        bytesToWrite -= bytesWritten;
+        THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot write file %x."), L"%x", fmtPath(getFilePath())), L"write");
     }
+    if (bytesWritten > static_cast<ssize_t>(bytesToWrite)) //better safe than sorry
+        throw FileError(replaceCpy(_("Cannot write file %x."), L"%x", fmtPath(getFilePath())), L"write: buffer overflow."); //user should never see this
+
+    //if ::write() is interrupted (EINTR) right in the middle, it will return successfully with "bytesWritten < bytesToWrite"!
 #endif
+    return bytesWritten;
 }