From: Andrew M. Kuchling <amk@amk.ca>
Date: Mon, 22 Feb 2010 22:48:41 +0000 (+0000)
Subject: #2560: remove an unnecessary 'for' loop from my_fgets() in Parser/myreadline.c.
X-Git-Tag: v2.7a4~144
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b64d61369aeda5f0af40a0daf3af648c433492a3;p=python

#2560: remove an unnecessary 'for' loop from my_fgets() in Parser/myreadline.c.
Noted by Joseph Armbruster; patch by Jessica McKellar.

The original code was 'for (;;) {...}', where ... ended
with a 'return -2' statement and did not contain a 'break' or 'continue'
statement.  Therefore, the body of the loop is always executed once.

Once upon a time there was a 'continue' in the loop, but it was removed in
rev36346, committed by mwh on Wed Jul 7 17:44:12 2004.
---

diff --git a/Misc/NEWS b/Misc/NEWS
index 560aa017d4..89af2a4ab9 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,9 @@ What's New in Python 2.7 alpha 4?
 Core and Builtins
 -----------------
 
+- Issue #2560: remove an unnecessary 'for' loop from my_fgets() in
+  Parser/myreadline.c.
+
 - Issue #7988: Fix default alignment to be right aligned for
   complex.__format__. Now it matches other numeric types.
 
diff --git a/Parser/myreadline.c b/Parser/myreadline.c
index 32a1088ad0..433f995032 100644
--- a/Parser/myreadline.c
+++ b/Parser/myreadline.c
@@ -40,66 +40,63 @@ static int
 my_fgets(char *buf, int len, FILE *fp)
 {
 	char *p;
-	for (;;) {
-		if (PyOS_InputHook != NULL)
-			(void)(PyOS_InputHook)();
-		errno = 0;
-		p = fgets(buf, len, fp);
-		if (p != NULL)
-			return 0; /* No error */
+	if (PyOS_InputHook != NULL)
+		(void)(PyOS_InputHook)();
+	errno = 0;
+	p = fgets(buf, len, fp);
+	if (p != NULL)
+		return 0; /* No error */
 #ifdef MS_WINDOWS
-		/* In the case of a Ctrl+C or some other external event 
-		   interrupting the operation:
-		   Win2k/NT: ERROR_OPERATION_ABORTED is the most recent Win32 
-		   error code (and feof() returns TRUE).
-		   Win9x: Ctrl+C seems to have no effect on fgets() returning
-		   early - the signal handler is called, but the fgets()
-		   only returns "normally" (ie, when Enter hit or feof())
+	/* In the case of a Ctrl+C or some other external event 
+	   interrupting the operation:
+	   Win2k/NT: ERROR_OPERATION_ABORTED is the most recent Win32 
+	   error code (and feof() returns TRUE).
+	   Win9x: Ctrl+C seems to have no effect on fgets() returning
+	   early - the signal handler is called, but the fgets()
+	   only returns "normally" (ie, when Enter hit or feof())
+	*/
+	if (GetLastError()==ERROR_OPERATION_ABORTED) {
+		/* Signals come asynchronously, so we sleep a brief 
+		   moment before checking if the handler has been 
+		   triggered (we cant just return 1 before the 
+		   signal handler has been called, as the later 
+		   signal may be treated as a separate interrupt).
 		*/
-		if (GetLastError()==ERROR_OPERATION_ABORTED) {
-			/* Signals come asynchronously, so we sleep a brief 
-			   moment before checking if the handler has been 
-			   triggered (we cant just return 1 before the 
-			   signal handler has been called, as the later 
-			   signal may be treated as a separate interrupt).
-			*/
-			Sleep(1);
-			if (PyOS_InterruptOccurred()) {
-				return 1; /* Interrupt */
-			}
-			/* Either the sleep wasn't long enough (need a
-			   short loop retrying?) or not interrupted at all
-			   (in which case we should revisit the whole thing!)
-			   Logging some warning would be nice.  assert is not
-			   viable as under the debugger, the various dialogs
-			   mean the condition is not true.
-			*/
+		Sleep(1);
+		if (PyOS_InterruptOccurred()) {
+			return 1; /* Interrupt */
 		}
+		/* Either the sleep wasn't long enough (need a
+		   short loop retrying?) or not interrupted at all
+		   (in which case we should revisit the whole thing!)
+		   Logging some warning would be nice.  assert is not
+		   viable as under the debugger, the various dialogs
+		   mean the condition is not true.
+		*/
+	}
 #endif /* MS_WINDOWS */
-		if (feof(fp)) {
-			return -1; /* EOF */
-		}
+	if (feof(fp)) {
+		return -1; /* EOF */
+	}
 #ifdef EINTR
-		if (errno == EINTR) {
-			int s;
+	if (errno == EINTR) {
+		int s;
 #ifdef WITH_THREAD
-			PyEval_RestoreThread(_PyOS_ReadlineTState);
+		PyEval_RestoreThread(_PyOS_ReadlineTState);
 #endif
-			s = PyErr_CheckSignals();
+		s = PyErr_CheckSignals();
 #ifdef WITH_THREAD
-			PyEval_SaveThread();
+		PyEval_SaveThread();
 #endif
-			if (s < 0) {
-				return 1;
-			}
+		if (s < 0) {
+			return 1;
 		}
+	}
 #endif
-		if (PyOS_InterruptOccurred()) {
-			return 1; /* Interrupt */
-		}
-		return -2; /* Error */
+	if (PyOS_InterruptOccurred()) {
+		return 1; /* Interrupt */
 	}
-	/* NOTREACHED */
+	return -2; /* Error */
 }