From a325cb9f0de6b005b31ce2ded230efdd953ec893 Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Mon, 18 Aug 2014 07:33:17 -0600
Subject: [PATCH] sscanf(): NuttX libc tried to guess how many characters to
parse, extracted them into a buffer, then ran strtol() on that buffer. That
guess is often wrong. A better approach would be to call strtol() directly on
the input data, using the endptr return value to determine how many
characters to skip after parsing. From Kosma Moczek
---
libc/stdio/lib_sscanf.c | 47 +++++++++++++++++++++--------------------
1 file changed, 24 insertions(+), 23 deletions(-)
diff --git a/libc/stdio/lib_sscanf.c b/libc/stdio/lib_sscanf.c
index a4802b2c5d..611a0edc0c 100644
--- a/libc/stdio/lib_sscanf.c
+++ b/libc/stdio/lib_sscanf.c
@@ -405,6 +405,10 @@ int vsscanf(FAR const char *buf, FAR const char *fmt, va_list ap)
if (*buf)
{
+ FAR char *endptr;
+ int errsave;
+ long tmplong;
+
/* Skip over any white space before the integer string */
while (isspace(*buf))
@@ -459,35 +463,32 @@ int vsscanf(FAR const char *buf, FAR const char *fmt, va_list ap)
lvdbg("vsscanf: tmp[]=\"%s\"\n", tmp);
/* Perform the integer conversion */
+ /* Preserve the errno value */
- buf += width;
- if (!noassign)
+ errsave = get_errno();
+ set_errno(0);
+ if (sign)
{
- FAR char *endptr;
- int errsave;
- long tmplong;
-
- /* Preserve the errno value */
+ tmplong = strtol(tmp, &endptr, base);
+ }
+ else
+ {
+ tmplong = strtoul(tmp, &endptr, base);
+ }
- errsave = get_errno();
- set_errno(0);
- if (sign)
- {
- tmplong = strtol(tmp, &endptr, base);
- }
- else
- {
- tmplong = strtoul(tmp, &endptr, base);
- }
+ /* Check if the number was successfully converted */
- /* Check if the number was successfully converted */
+ if (tmp == endptr || get_errno() == ERANGE)
+ {
+ return count;
+ }
- if (tmp == endptr || get_errno() == ERANGE)
- {
- return count;
- }
+ /* Move by the actual number of characters converted */
- set_errno(errsave);
+ buf += (endptr - tmp);
+ set_errno(errsave);
+ if (!noassign)
+ {
/* We have to check whether we need to return a long
* or an int.
--
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