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bpo-29700: try not to crash when using readline with high FDs. #540

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bpo-29700: try not to crash when using readline with high FDs. #540

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50 changes: 46 additions & 4 deletions Modules/readline.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,10 @@
#include <errno.h>
#include <sys/time.h>

#ifdef HAVE_POLL_H
#include <poll.h>
#endif

#if defined(HAVE_SETLOCALE)
/* GNU readline() mistakenly sets the LC_CTYPE locale.
* This is evil. Only the user or the app's main() should do this!
Expand Down Expand Up @@ -996,7 +1000,15 @@ setup_readline(void)
/* Wrapper around GNU readline that handles signals differently. */


#if defined(HAVE_RL_CALLBACK) && defined(HAVE_SELECT)
#if defined(HAVE_RL_CALLBACK) && (defined(HAVE_SELECT) || defined(HAVE_POLL))
/* Issue #26870: poll() does not work with terminals on all OSes.
* Be conservative and use select() on non-Linux.
* TODO(marienz) "glibc" is probably the wrong thing to check,
* but I cannot find an existing "OS is Linux" #define...
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Maybe __linux__? https://sourceforge.net/p/predef/wiki/OperatingSystems/#linux-kernel

*/
#if defined(HAVE_POLL) && defined(__GLIBC__)
#define READLINE_USE_POLL 1
#endif

static char *completed_input_string;
static void
Expand All @@ -1010,40 +1022,70 @@ static char *
readline_until_enter_or_signal(char *prompt, int *signal)
{
char * not_done_reading = "";
#ifdef READLINE_USE_POLL
struct pollfd pollfd;
#else
fd_set selectset;
#endif

*signal = 0;
#ifdef HAVE_RL_CATCH_SIGNAL
rl_catch_signals = 0;
#endif

rl_callback_handler_install (prompt, rlhandler);
#ifdef READLINE_USE_POLL
pollfd.fd = fileno(rl_instream);
pollfd.events = POLLIN;
#else
FD_ZERO(&selectset);
if (fileno(rl_instream) >= FD_SETSIZE) {
#ifdef WITH_THREAD
PyEval_RestoreThread(_PyOS_ReadlineTState);
#endif
PyErr_SetString(PyExc_ValueError, "input fd too large for select");
#ifdef WITH_THREAD
PyEval_SaveThread();
#endif
*signal = -1;
return NULL;
}
#endif

completed_input_string = not_done_reading;

while (completed_input_string == not_done_reading) {
int has_input = 0;

while (!has_input)
{ struct timeval timeout = {0, 100000}; /* 0.1 seconds */

{
#ifdef READLINE_USE_POLL
int timeout = -1;
if (PyOS_InputHook)
timeout = 100; /* 0.1 seconds */
#else
struct timeval timeout = {0, 100000}; /* 0.1 seconds */
/* [Bug #1552726] Only limit the pause if an input hook has been
defined. */
struct timeval *timeoutp = NULL;
if (PyOS_InputHook)
timeoutp = &timeout;
#endif
#ifdef HAVE_RL_RESIZE_TERMINAL
/* Update readline's view of the window size after SIGWINCH */
if (sigwinch_received) {
sigwinch_received = 0;
rl_resize_terminal();
}
#endif
#ifdef READLINE_USE_POLL
has_input = poll(&pollfd, 1, timeout);
#else
FD_SET(fileno(rl_instream), &selectset);
/* select resets selectset if no input was available */
has_input = select(fileno(rl_instream) + 1, &selectset,
NULL, NULL, timeoutp);
#endif
if(PyOS_InputHook) PyOS_InputHook();
}

Expand Down Expand Up @@ -1114,7 +1156,7 @@ readline_until_enter_or_signal(char *prompt, int *signal)

return p;
}
#endif /*defined(HAVE_RL_CALLBACK) && defined(HAVE_SELECT) */
#endif /*defined(HAVE_RL_CALLBACK) && (defined(HAVE_SELECT) || defined(HAVE_POLL)) */


static char *
Expand Down