Fix FileIO.readall() (new_buffersize()) for large files

Victor Stinner · Victor Stinner · commit c5af7730e34f · 2011-10-11T23:00:31.000+02:00
Truncate the buffer size to PY_SSIZE_T_MAX.
diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
@@ -564,7 +564,11 @@ new_buffersize(fileio *self, size_t currentsize
         */
         if (end >= SMALLCHUNK && end >= pos && pos >= 0) {
             /* Add 1 so if the file were to grow we'd notice. */
-            return currentsize + end - pos + 1;
+            Py_off_t bufsize = currentsize + end - pos + 1;
+            if (bufsize < PY_SSIZE_T_MAX)
+                return (size_t)bufsize;
+            else
+                return PY_SSIZE_T_MAX;
         }
     }
 #endif

Original file line number	Diff line number	Diff line change
`@@ -564,7 +564,11 @@ new_buffersize(fileio *self, size_t currentsize`
`564`	`564`	`*/`
`565`	`565`	`if (end >= SMALLCHUNK && end >= pos && pos >= 0) {`
`566`	`566`	`/* Add 1 so if the file were to grow we'd notice. */`
`567`		`- return currentsize + end - pos + 1;`
	`567`	`+ Py_off_t bufsize = currentsize + end - pos + 1;`
	`568`	`+ if (bufsize < PY_SSIZE_T_MAX)`
	`569`	`+ return (size_t)bufsize;`
	`570`	`+ else`
	`571`	`+ return PY_SSIZE_T_MAX;`
`568`	`572`	`}`
`569`	`573`	`}`
`570`	`574`	`#endif`