Change use of ferror() in uClibc++ so that is does not use more capability than is currently supported by the NuttX ferror()

2 files changed, 24 insertions, 18 deletions

diff --git a/misc/uClibc++/ChangeLog.txt b/misc/uClibc++/ChangeLog.txt
index 8c680392c..2de53129c 100644
--- a/misc/uClibc++/ChangeLog.txt
+++ b/misc/uClibc++/ChangeLog.txt
@@ -5,3 +5,10 @@ uClibc++-1.0 2011-11-05 <gnutt@nuttx.org>
       David for the RGMP team.
 
 uClibc++-1.1 2011-xx-xx <gnutt@nuttx.org>
+
+    * misc/uClibc++/include/uClibc++/fstream:  Remove move of ferror()
+      and feof() to determine if fopen() and fread() were successful.
+      The NuttX version of ferror() is only fragmentary.  The usage of
+      ferror() in this file exceeds the capability of the current
+      implementatino (2013-6-20).
+
diff --git a/misc/uClibc++/include/uClibc++/fstream b/misc/uClibc++/include/uClibc++/fstream
index 0f0388e5d..8bfeb9781 100644
--- a/misc/uClibc++/include/uClibc++/fstream
+++ b/misc/uClibc++/include/uClibc++/fstream
@@ -176,15 +176,10 @@ namespace std
         fp = fopen(s, "w+b");
       }
 
-      if (fp == 0)
-      {
-        return 0;
-      }
+      // Check for a failure to open the file
 
-      if (ferror(fp))
+      if (fp == 0)
       {
-        fclose(fp);
-        fp = 0;
         return 0;
       }
 
@@ -272,9 +267,14 @@ namespace std
 
         charT c;
         int retval;
+
+        // Read one element of size sizeof(charT)
+
         retval = fread(&c, sizeof(charT), 1, fp);
 
-        if (retval == 0 || feof(fp) || ferror(fp))
+        // retval will be less than 1 only if an error or end-of-file is encountered
+
+        if (retval <= 0)
         {
           return traits::eof();
         }
@@ -318,18 +318,13 @@ namespace std
         offset,
         fp);
 
-      // Clear problems where we didn't read in enough characters
-
-      if (EAGAIN == errno)
-      {
-        clearerr(fp);
-      }
-
       // Restore file descriptor clase
 
       fcntl(fileno(fp), F_SETFL, fcntl_flags);
 
-      // Now we are going to make sure that we read in at least one character.  The hard way.
+      // fread() will return a value < offset if an error or end-of-file
+      // occurred.  If nothing was read, make sure that we read in at least
+      // one character.  The hard way.
 
       if (retval == 0)
       {
@@ -339,6 +334,8 @@ namespace std
 
         fcntl(fileno(fp), F_SETFL, fcntl_flags & ~O_NONBLOCK);
 
+        // Read one element of size sizeof(charT)
+
         retval = fread(basic_streambuf<charT,traits>::egptr() - 
           basic_streambuf<charT,traits>::gptr() + basic_streambuf<charT,traits>::eback(),
           sizeof(charT),
@@ -350,7 +347,7 @@ namespace std
         fcntl(fileno(fp), F_SETFL, fcntl_flags);
       }
 
-      if (retval !=offset)
+      if (retval != offset)
       {
         // Slide buffer forward again
 
@@ -363,7 +360,9 @@ namespace std
 
       basic_streambuf<charT,traits>::mgnext -= retval;
 
-      if ((retval <= 0 && feof(fp)) || ferror(fp))
+      // retval will be less than 1 only if an error or end-of-file is encountered
+
+      if ((retval <= 0)
       {
         return traits::eof();
       }