diff options
| -rw-r--r-- | Doc/lib/libstdtypes.tex | 4 | ||||
| -rw-r--r-- | Misc/NEWS | 3 | ||||
| -rw-r--r-- | Objects/fileobject.c | 33 |
3 files changed, 36 insertions, 4 deletions
diff --git a/Doc/lib/libstdtypes.tex b/Doc/lib/libstdtypes.tex index a104d85..6dee0c9 100644 --- a/Doc/lib/libstdtypes.tex +++ b/Doc/lib/libstdtypes.tex @@ -1205,7 +1205,9 @@ flush the read-ahead buffer. certain files, like ttys, it makes sense to continue reading after an \EOF{} is hit.) Note that this method may call the underlying C function \cfunction{fread()} more than once in an effort to - acquire as close to \var{size} bytes as possible. + acquire as close to \var{size} bytes as possible. Also note that + when in non-blocking mode, less data than what was requested may + be returned, even if no \var{size} parameter was given. \end{methoddesc} \begin{methoddesc}[file]{readline}{\optional{size}} @@ -335,6 +335,9 @@ Core and builtins general left to right evaluation order rule. Now {f1(): f2()} will evaluate f1 first. +- Fixed bug #521782: when a file was in non-blocking mode, file.read() + could silently lose data or wrongly throw an unknown error. + Extension modules ----------------- diff --git a/Objects/fileobject.c b/Objects/fileobject.c index 86620ff..612cefd 100644 --- a/Objects/fileobject.c +++ b/Objects/fileobject.c @@ -741,6 +741,20 @@ new_buffersize(PyFileObject *f, size_t currentsize) return currentsize + SMALLCHUNK; } +#if defined(EWOULDBLOCK) && defined(EAGAIN) && EWOULDBLOCK != EAGAIN +#define BLOCKED_ERRNO(x) ((x) == EWOULDBLOCK || (x) == EAGAIN) +#else +#ifdef EWOULDBLOCK +#define BLOCKED_ERRNO(x) ((x) == EWOULDBLOCK) +#else +#ifdef EAGAIN +#define BLOCKED_ERRNO(x) ((x) == EAGAIN) +#else +#define BLOCKED_ERRNO(x) 0 +#endif +#endif +#endif + static PyObject * file_read(PyFileObject *f, PyObject *args) { @@ -774,18 +788,29 @@ file_read(PyFileObject *f, PyObject *args) if (chunksize == 0) { if (!ferror(f->f_fp)) break; - PyErr_SetFromErrno(PyExc_IOError); 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 + * chunksize != 0, but bytesread < buffersize. */ + if (bytesread > 0 && BLOCKED_ERRNO(errno)) + break; + PyErr_SetFromErrno(PyExc_IOError); Py_DECREF(v); return NULL; } bytesread += chunksize; - if (bytesread < buffersize) + if (bytesread < buffersize) { + clearerr(f->f_fp); break; + } if (bytesrequested < 0) { buffersize = new_buffersize(f, buffersize); if (_PyString_Resize(&v, buffersize) < 0) return NULL; + } else { + assert(bytesread == bytesrequested); + break; } } if (bytesread != buffersize) @@ -1518,7 +1543,9 @@ PyDoc_STRVAR(readline_doc, PyDoc_STRVAR(read_doc, "read([size]) -> read at most size bytes, returned as a string.\n" "\n" -"If the size argument is negative or omitted, read until EOF is reached."); +"If the size argument is negative or omitted, read until EOF is reached.\n" +"Notice that when in non-blocking mode, less data than what was requested\n" +"may be returned, even if no size parameter was given."); PyDoc_STRVAR(write_doc, "write(str) -> None. Write string str to file.\n" |