StdLib: Fix IIO_Write() to return the number of bytes consumed, not characters output.

Depending upon termios settings, writing to a terminal device may result in
many more characters being output than were in the buffer provided to the
IIO_Write() function.

IIO_Write() is supposed to return the number of BYTES written, not characters.
Since the provided buffer contains MBCS characters, there can be up to three
bytes per character.  Due to the expansion that may occur, "BYTES written"
is interpreted to mean the number of BYTES consumed from the MBCS buffer
provided as a parameter to IIO_Write.

These changes ensure that the correct number of characters are consumed from
the internal Output buffer and the correct number of BYTES consumed from the
buffer parameter are counted and returned.

Update copyright.
Fix some indentation and white space issues.
Improve comments for IIO_Write().
Add debugging instrumentation to count unconsumed data in the Input and Output buffers.
Modify IIO_Write() to:
  Accurately count input bytes CONSUMED.
  Consume only as many expanded (cooked) characters from the output buffer
  as were actually sent to the device.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Daryl McDaniel <edk2-lists@mc2research.org>
Reviewed-by: Erik Bjorge <erik.c.bjorge@intel.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@19589 6f19259b-4bc3-4df7-8a09-765794883524

diff --git a/StdLib/LibC/Uefi/InteractiveIO/IIO.c b/StdLib/LibC/Uefi/InteractiveIO/IIO.c
index 65b61d9bccde4f4c1e5c46a8cc7ea552dfcf37b4..547fdb3874f8a08b2f32ef49313ee285aaf104cc 100644 (file)
--- a/StdLib/LibC/Uefi/InteractiveIO/IIO.c
+++ b/StdLib/LibC/Uefi/InteractiveIO/IIO.c
@@ -3,6 +3,7 @@
 \r
   The functions assume that isatty() is TRUE at the time they are called.\r
 \r
+  Copyright (c) 2016, Daryl McDaniel. All rights reserved.<BR>\r
   Copyright (c) 2012, Intel Corporation. All rights reserved.<BR>\r
   This program and the accompanying materials are licensed and made available\r
   under the terms and conditions of the BSD License which accompanies this\r
@@ -26,6 +27,20 @@
 #include  "IIOutilities.h"\r
 #include  "IIOechoCtrl.h"\r
 \r
+// Instrumentation used for debugging\r
+#define   IIO_C_DEBUG   0       ///< Set to 1 to enable instrumentation, 0 to disable\r
+\r
+#if IIO_C_DEBUG\r
+  static volatile size_t  IIO_C_WRemainder = 0;   ///< Characters in Out buffer after IIO_Write\r
+  static volatile size_t  IIO_C_RRemainder = 0;   ///< Characters in In buffer after IIO_Read\r
+\r
+  #define W_INSTRUMENT  IIO_C_WRemainder =\r
+  #define R_INSTRUMENT  IIO_C_RRemainder =\r
+#else // ! IIO_C_DEBUG -- don't instrument code\r
+  #define W_INSTRUMENT  (void)\r
+  #define R_INSTRUMENT  (void)\r
+#endif  // IIO_C_DEBUG\r
+\r
 /** Read from an Interactive IO device.\r
 \r
   NOTE: If _S_IWTTY is set, the internal buffer contains WIDE characters.\r
@@ -82,24 +97,44 @@ IIO_Read(
       NumRead = wcstombs((char *)Buffer, (const wchar_t *)gMD->UString2, XlateSz);\r
 \r
       // Consume the translated characters\r
-      (void)This->InBuf->Flush(This->InBuf, Needed);\r
+      (void) This->InBuf->Flush(This->InBuf, Needed);\r
     }\r
     else {\r
       // Data in InBuf is narrow characters.  Use verbatim.\r
       NumRead = This->InBuf->Read(This->InBuf, Buffer, (INT32)BufferSize);\r
     }\r
+#if IIO_C_DEBUG\r
+    IIO_C_RRemainder = This->InBuf->Count(This->InBuf, AsElements);\r
+#endif // IIO_C_DEBUG\r
   }\r
   return NumRead;\r
 }\r
 \r
-/** Process characters from buffer buf and write them to the output device\r
+/** Handle write to a Terminal (Interactive) device.\r
+\r
+    Processes characters from buffer buf and writes them to the Terminal device\r
     specified by filp.\r
 \r
+    The parameter buf points to a MBCS string to be output. This is processed\r
+    and buffered one character at a time by IIO_WriteOne() which handles TAB\r
+    expansion, NEWLINE to CARRIAGE_RETURN + NEWLINE expansion, as well as\r
+    basic line editing functions. The number of characters actually written to\r
+    the output device will seldom equal the number of characters consumed from\r
+    buf.\r
+\r
+    In this implementation, all of the special characters processed by\r
+    IIO_WriteOne() are single-byte characters with values less than 128.\r
+    (7-bit ASCII or the single-byte UTF-8 characters)\r
+\r
+    Every byte that is not one of the recognized special characters is passed,\r
+    unchanged, to the Terminal device.\r
+\r
     @param[in]      filp      Pointer to a file descriptor structure.\r
     @param[in]      buf       Pointer to the MBCS string to be output.\r
     @param[in]      N         Number of bytes in buf.\r
 \r
-    @retval   >=0    Number of bytes sent to the output device.\r
+    @retval   >=0     Number of bytes consumed from buf and sent to the\r
+                      Terminal device.\r
 **/\r
 static\r
 ssize_t\r
@@ -114,16 +149,15 @@ IIO_Write(
   cFIFO      *OutBuf;\r
   mbstate_t  *OutState;\r
   char       *MbcsPtr;\r
-  ssize_t     NumWritten;\r
+  ssize_t     NumConsumed;\r
   ssize_t     NumProc;\r
   size_t      CharLen;\r
   UINTN       MaxColumn;\r
   UINTN       MaxRow;\r
-  wchar_t     OutChar[2];     // Just in case we run into 4-byte MBCS character\r
+  wchar_t     OutChar[2];     // Just in case we run into a 4-byte MBCS character\r
   int         OutMode;\r
 \r
-  errno = 0;          // indicate no error as default\r
-  NumWritten = -1;\r
+  NumConsumed = -1;\r
 \r
   /* Determine what the current screen size is. Also validates the output device. */\r
   OutMode = IIO_GetOutputSize(filp->MyFD, &MaxColumn, &MaxRow);\r
@@ -148,51 +182,61 @@ IIO_Write(
     This->CurrentXY.Column  = This->InitialXY.Column;\r
     This->CurrentXY.Row     = This->InitialXY.Row;\r
 \r
-\r
-    NumWritten = 0;\r
-    OutChar[0] = (wchar_t)buf[0];\r
-    while((OutChar[0] != 0) && (NumWritten < N)) {\r
-      CharLen = mbrtowc(OutChar, (const char *)&buf[NumWritten], MB_CUR_MAX, OutState);\r
+    NumConsumed = 0;\r
+    OutChar[0]  = (wchar_t)buf[0];\r
+    while((OutChar[0] != 0) && (NumConsumed < N)) {\r
+      CharLen = mbrtowc(OutChar, (const char *)&buf[NumConsumed], MB_CUR_MAX, OutState);\r
+      if (CharLen < 0) {  // Encoding Error\r
+        OutChar[0] = BLOCKELEMENT_LIGHT_SHADE;\r
+        CharLen = 1;  // Consume a byte\r
+        (void)mbrtowc(NULL, NULL, 1, OutState);  // Re-Initialize the conversion state\r
+      }\r
       NumProc = IIO_WriteOne(filp, OutBuf, OutChar[0]);\r
-      if(NumProc > 0) {\r
+      if(NumProc >= 0) {\r
         // Successfully processed and buffered one character\r
-        NumWritten += CharLen;   // Index of start of next character\r
-      }\r
-      else if(NumProc == -1) {\r
-        // Encoding Error\r
-        (void)mbrtowc(NULL, NULL, 1, OutState);  // Re-Initialize the conversion state\r
-        errno = EILSEQ;\r
-        break;\r
+        NumConsumed += CharLen;   // Index of start of next character\r
       }\r
       else {\r
-        // Last character was incomplete\r
-        break;\r
+        if (errno == ENOSPC) {\r
+          // Not enough room in OutBuf to hold a potentially expanded character\r
+          break;\r
+        }\r
+        return -1;    // Something corrupted and filp->devdata is now NULL\r
       }\r
     }\r
     // At this point, the characters to write are in OutBuf\r
     // First, linearize the buffer\r
-    NumWritten = OutBuf->Copy(OutBuf, gMD->UString, UNICODE_STRING_MAX-1);\r
-    gMD->UString[NumWritten] = 0;   // Ensure that the buffer is terminated\r
+    NumProc = OutBuf->Copy(OutBuf, gMD->UString, UNICODE_STRING_MAX-1);\r
+    gMD->UString[NumProc] = 0;   // Ensure that the buffer is terminated\r
 \r
     if(filp->f_iflags & _S_IWTTY) {\r
       // Output device expects wide characters, Output what we have\r
-      NumWritten = filp->f_ops->fo_write(filp, NULL, NumWritten, gMD->UString);\r
+      NumProc = filp->f_ops->fo_write(filp, NULL, NumProc, gMD->UString);\r
+\r
+      // Consume the output characters\r
+      W_INSTRUMENT OutBuf->Flush(OutBuf, NumProc);\r
     }\r
     else {\r
       // Output device expects narrow characters, convert to MBCS\r
       MbcsPtr = (char *)gMD->UString2;\r
-      // Determine the needed space\r
+      // Determine the needed space. NumProc is the number of bytes needed.\r
       NumProc = (ssize_t)EstimateWtoM((const wchar_t *)gMD->UString, UNICODE_STRING_MAX * sizeof(wchar_t), &CharLen);\r
 \r
-      // Now translate this into MBCS in Buffer\r
-      NumWritten = wcstombs(MbcsPtr, (const wchar_t *)gMD->UString, NumProc);\r
-      MbcsPtr[NumWritten] = 0;   // Ensure the buffer is terminated\r
+      // Now translate this into MBCS in the buffer pointed to by MbcsPtr.\r
+      // The returned value, NumProc, is the resulting number of bytes.\r
+      NumProc = wcstombs(MbcsPtr, (const wchar_t *)gMD->UString, NumProc);\r
+      MbcsPtr[NumProc] = 0;   // Ensure the buffer is terminated\r
 \r
       // Send the MBCS buffer to Output\r
-      NumWritten = filp->f_ops->fo_write(filp, NULL, NumWritten, MbcsPtr);\r
+      NumProc = filp->f_ops->fo_write(filp, NULL, NumProc, MbcsPtr);\r
+      // Mark the Mbcs buffer after the last byte actually written\r
+      MbcsPtr[NumProc] = 0;\r
+      // Count the CHARACTERS actually sent\r
+      CharLen = CountMbcsChars(MbcsPtr);\r
+\r
+      // Consume the number of output characters actually sent\r
+      W_INSTRUMENT OutBuf->Flush(OutBuf, CharLen);\r
     }\r
-    // Consume the translated characters\r
-    (void)OutBuf->Flush(OutBuf, NumWritten);\r
   }\r
   else {\r
     if(This == NULL) {\r
@@ -200,7 +244,7 @@ IIO_Write(
     }\r
     // Otherwise, errno is already set.\r
   }\r
-  return NumWritten;\r
+  return NumConsumed;\r
 }\r
 \r
 /** Echo a character to an output device.\r