diff -r 1492a42b8308 Objects/fileobject.c
--- a/Objects/fileobject.c	Wed Jul 02 23:12:48 2014 +0200
+++ b/Objects/fileobject.c	Thu Jul 03 00:33:35 2014 +0200
@@ -1053,7 +1053,7 @@ file_read(PyFileObject *f, PyObject *arg
 {
     long bytesrequested = -1;
     size_t bytesread, buffersize, chunksize;
-    PyObject *v;
+    PyObject *v = NULL;
 
     if (f->f_fp == NULL)
         return err_closed();
@@ -1072,34 +1072,29 @@ file_read(PyFileObject *f, PyObject *arg
         buffersize = bytesrequested;
     if (buffersize > PY_SSIZE_T_MAX) {
         PyErr_SetString(PyExc_OverflowError,
-    "requested number of bytes is more than a Python string can hold");
-        return NULL;
+                        "requested number of bytes is more than "
+                        "a Python string can hold");
+        goto error;
     }
     v = PyString_FromStringAndSize((char *)NULL, buffersize);
     if (v == NULL)
-        return NULL;
+        goto error;
     bytesread = 0;
     for (;;) {
         int interrupted;
         FILE_BEGIN_ALLOW_THREADS(f)
-        errno = 0;
         chunksize = Py_UniversalNewlineFread(BUF(v) + bytesread,
                   buffersize - bytesread, f->f_fp, (PyObject *)f);
         interrupted = ferror(f->f_fp) && errno == EINTR;
         FILE_END_ALLOW_THREADS(f)
-        if (interrupted) {
+        bytesread += chunksize;
+        if (ferror(f->f_fp)) {
             clearerr(f->f_fp);
-            if (PyErr_CheckSignals()) {
-                Py_DECREF(v);
-                return NULL;
+            if (interrupted) {
+                if (PyErr_CheckSignals())
+                    goto error;
+                continue;
             }
-        }
-        if (chunksize == 0) {
-            if (interrupted)
-                continue;
-            if (!ferror(f->f_fp))
-                break;
-            clearerr(f->f_fp);
             /* When in non-blocking mode, data shouldn't
              * be discarded if a blocking signal was
              * received. That will also happen if
@@ -1107,10 +1102,10 @@ file_read(PyFileObject *f, PyObject *arg
             if (bytesread > 0 && BLOCKED_ERRNO(errno))
                 break;
             PyErr_SetFromErrno(PyExc_IOError);
-            Py_DECREF(v);
-            return NULL;
+            goto error;
         }
-        bytesread += chunksize;
+        if (chunksize == 0)
+            break;
         if (bytesread < buffersize && !interrupted) {
             clearerr(f->f_fp);
             break;
@@ -1118,15 +1113,19 @@ file_read(PyFileObject *f, PyObject *arg
         if (bytesrequested < 0) {
             buffersize = new_buffersize(f, buffersize);
             if (_PyString_Resize(&v, buffersize) < 0)
-                return NULL;
+                goto error;
         } else {
             /* Got what was requested. */
             break;
         }
     }
     if (bytesread != buffersize && _PyString_Resize(&v, bytesread))
-        return NULL;
+        goto error;
     return v;
+
+error:
+    Py_XDECREF(v);
+    return NULL;
 }
 
 static PyObject *
@@ -1154,33 +1153,31 @@ file_readinto(PyFileObject *f, PyObject 
     while (ntodo > 0) {
         int interrupted;
         FILE_BEGIN_ALLOW_THREADS(f)
-        errno = 0;
         nnow = Py_UniversalNewlineFread(ptr+ndone, ntodo, f->f_fp,
                                         (PyObject *)f);
         interrupted = ferror(f->f_fp) && errno == EINTR;
         FILE_END_ALLOW_THREADS(f)
-        if (interrupted) {
-            clearerr(f->f_fp);
-            if (PyErr_CheckSignals()) {
-                PyBuffer_Release(&pbuf);
-                return NULL;
-            }
-        }
-        if (nnow == 0) {
-            if (interrupted)
-                continue;
-            if (!ferror(f->f_fp))
-                break;
-            PyErr_SetFromErrno(PyExc_IOError);
-            clearerr(f->f_fp);
-            PyBuffer_Release(&pbuf);
-            return NULL;
-        }
         ndone += nnow;
         ntodo -= nnow;
+        if (ferror(f->f_fp)) {
+            clearerr(f->f_fp);
+            if (interrupted) {
+                if (PyErr_CheckSignals())
+                    goto error;
+                continue;
+            }
+            PyErr_SetFromErrno(PyExc_IOError);
+            goto error;
+        }
+        if (nnow == 0)
+            break;
     }
     PyBuffer_Release(&pbuf);
     return PyInt_FromSsize_t(ndone);
+
+error:
+    PyBuffer_Release(&pbuf);
+    return NULL;
 }
 
 /**************************************************************************
@@ -1673,7 +1670,6 @@ file_readlines(PyFileObject *f, PyObject
     size_t totalread = 0;
     char *p, *q, *end;
     int err;
-    int shortread = 0;  /* bool, did the previous read come up short? */
 
     if (f->f_fp == NULL)
         return err_closed();
@@ -1689,33 +1685,35 @@ file_readlines(PyFileObject *f, PyObject
     if ((list = PyList_New(0)) == NULL)
         return NULL;
     for (;;) {
+        int shortread = 0;  /* bool, did the previous read come up short? */
+        int interrupted;
+
         if (shortread)
-            nread = 0;
-        else {
-            FILE_BEGIN_ALLOW_THREADS(f)
-            errno = 0;
-            nread = Py_UniversalNewlineFread(buffer+nfilled,
-                buffersize-nfilled, f->f_fp, (PyObject *)f);
-            FILE_END_ALLOW_THREADS(f)
-            shortread = (nread < buffersize-nfilled);
-        }
-        if (nread == 0) {
-            sizehint = 0;
-            if (!ferror(f->f_fp))
-                break;
-            if (errno == EINTR) {
-                if (PyErr_CheckSignals()) {
+            break;
+
+        FILE_BEGIN_ALLOW_THREADS(f)
+        nread = Py_UniversalNewlineFread(buffer+nfilled,
+            buffersize-nfilled, f->f_fp, (PyObject *)f);
+        interrupted = ferror(f->f_fp) && errno == EINTR;
+        FILE_END_ALLOW_THREADS(f)
+
+        shortread = (nread < buffersize-nfilled);
+        totalread += nread;
+
+        if (ferror(f->f_fp)) {
+            clearerr(f->f_fp);
+            if (interrupted) {
+                if (PyErr_CheckSignals())
                     goto error;
-                }
-                clearerr(f->f_fp);
-                shortread = 0;
                 continue;
             }
             PyErr_SetFromErrno(PyExc_IOError);
-            clearerr(f->f_fp);
             goto error;
         }
-        totalread += nread;
+
+        if (nread == 0)
+            break;
+
         p = (char *)memchr(buffer+nfilled, '\n', nread);
         if (p == NULL) {
             /* Need a larger buffer to fit this line */
@@ -1761,10 +1759,12 @@ file_readlines(PyFileObject *f, PyObject
         /* Move the remaining incomplete line to the start */
         nfilled = end-q;
         memmove(buffer, q, nfilled);
-        if (sizehint > 0)
+        if (sizehint > 0) {
             if (totalread >= (size_t)sizehint)
                 break;
+        }
     }
+
     if (nfilled != 0) {
         /* Partial last line */
         line = PyString_FromStringAndSize(buffer, nfilled);
@@ -2239,6 +2239,7 @@ static int
 readahead(PyFileObject *f, int bufsize)
 {
     Py_ssize_t chunksize;
+    int interrupted;
 
     if (f->f_buf != NULL) {
         if( (f->f_bufend - f->f_bufptr) >= 1)
@@ -2251,14 +2252,18 @@ readahead(PyFileObject *f, int bufsize)
         return -1;
     }
     FILE_BEGIN_ALLOW_THREADS(f)
-    errno = 0;
     chunksize = Py_UniversalNewlineFread(
         f->f_buf, bufsize, f->f_fp, (PyObject *)f);
+    interrupted = ferror(f->f_fp) && errno == EINTR;
     FILE_END_ALLOW_THREADS(f)
-    if (chunksize == 0) {
-        if (ferror(f->f_fp)) {
+    if (ferror(f->f_fp)) {
+        clearerr(f->f_fp);
+        if (interrupted) {
+            if (PyErr_CheckSignals())
+                return -1;
+        }
+        else {
             PyErr_SetFromErrno(PyExc_IOError);
-            clearerr(f->f_fp);
             drop_readahead(f);
             return -1;
         }
@@ -2824,6 +2829,9 @@ Py_UniversalNewlineFread(char *buf, size
     assert(buf != NULL);
     assert(stream != NULL);
 
+    clearerr(stream);
+    errno = 0;
+
     if (!fobj || !PyFile_Check(fobj)) {
         errno = ENXIO;          /* What can you do... */
         return 0;