mysnprintf.c: Massive rewrite of PyOS_snprintf and PyOS_vsnprintf, to

use wrappers on all platforms, to make this as consistent as possible x-
platform (in particular, make sure there's at least one \0 byte in
the output buffer).  Also document more of the truth about what these do.

getargs.c, seterror():  Three computations of remaining buffer size were
backwards, thus telling PyOS_snprintf the buffer is larger than it
actually is.  This matters a lot now that PyOS_snprintf ensures there's a
trailing \0 byte (because it didn't get the truth about the buffer size,
it was storing \0 beyond the true end of the buffer).

sysmodule.c, mywrite():  Simplify, now that PyOS_vsnprintf guarantees to
produce a \0 byte.

1 files changed, 3 insertions, 3 deletions

diff --git a/Python/getargs.c b/Python/getargs.c
index a58816f..9df2a2e 100644
--- a/Python/getargs.c
+++ b/Python/getargs.c
@@ -231,7 +231,7 @@ seterror(int iarg, char *msg, int *levels, char *fname, char *message)
 			p += strlen(p);
 		}
 		if (iarg != 0) {
-			PyOS_snprintf(p, sizeof(buf) - (buf - p),
+			PyOS_snprintf(p, sizeof(buf) - (p - buf),
 				      "argument %d", iarg);
 			i = 0;
 			p += strlen(p);
@@ -243,10 +243,10 @@ seterror(int iarg, char *msg, int *levels, char *fname, char *message)
 			}
 		}
 		else {
-			PyOS_snprintf(p, sizeof(buf) - (buf - p), "argument");
+			PyOS_snprintf(p, sizeof(buf) - (p - buf), "argument");
 			p += strlen(p);
 		}
-		PyOS_snprintf(p, sizeof(buf) - (buf - p), " %.256s", msg);
+		PyOS_snprintf(p, sizeof(buf) - (p - buf), " %.256s", msg);
 		message = buf;
 	}
 	PyErr_SetString(PyExc_TypeError, message);