[coreboot-gerrit] New patch to review for coreboot: 9f872cc console/vsprintf: Implement snprintf
Vladimir Serbinenko (phcoder@gmail.com)
gerrit at coreboot.org
Tue Nov 26 02:22:52 CET 2013
Vladimir Serbinenko (phcoder at gmail.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/4278
-gerrit
commit 9f872cccfd6fe85552a9a3e2ccb3b99dfa137957
Author: Vladimir Serbinenko <phcoder at gmail.com>
Date: Tue Nov 26 02:20:32 2013 +0100
console/vsprintf: Implement snprintf
snprintf is a safe variant of sprintf. To avoid buffer overflows we shouldn't
use sprintf at all. But for now let's start by implementing snprintf in first
place.
Change-Id: Ic17d94b8cd91b72f66b84b0589a06b8abef5e5c9
Signed-off-by: Vladimir Serbinenko <phcoder at gmail.com>
---
src/console/vsprintf.c | 30 +++++++++++++++++++++++++-----
src/include/string.h | 1 +
2 files changed, 26 insertions(+), 5 deletions(-)
diff --git a/src/console/vsprintf.c b/src/console/vsprintf.c
index 435401b..3d085e9 100644
--- a/src/console/vsprintf.c
+++ b/src/console/vsprintf.c
@@ -27,14 +27,18 @@
DECLARE_SPIN_LOCK(vsprintf_lock)
static char *str_buf;
+static size_t buf_limit;
static void str_tx_byte(unsigned char byte)
{
- *str_buf = byte;
- str_buf++;
+ if (buf_limit) {
+ *str_buf = byte;
+ str_buf++;
+ buf_limit--;
+ }
}
-static int vsprintf(char *buf, const char *fmt, va_list args)
+static int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
{
int i;
@@ -42,8 +46,10 @@ static int vsprintf(char *buf, const char *fmt, va_list args)
spin_lock(&vsprintf_lock);
str_buf = buf;
+ buf_limit = size ? size - 1 : 0;
i = vtxprintf(str_tx_byte, fmt, args);
- *str_buf = '\0';
+ if (size)
+ *str_buf = '\0';
spin_unlock(&vsprintf_lock);
ENABLE_TRACE;
@@ -57,7 +63,21 @@ int sprintf(char *buf, const char *fmt, ...)
int i;
va_start(args, fmt);
- i = vsprintf(buf, fmt, args);
+ /* A trick: we have at most (size_t)-1 adressable space anyway, so
+ if we output so much we'll crash anyway. */
+ i = vsnprintf(buf, -1, fmt, args);
+ va_end(args);
+
+ return i;
+}
+
+int snprintf(char *buf, size_t size, const char *fmt, ...)
+{
+ va_list args;
+ int i;
+
+ va_start(args, fmt);
+ i = vsnprintf(buf, size, fmt, args);
va_end(args);
return i;
diff --git a/src/include/string.h b/src/include/string.h
index 77985e1..dc125e1 100644
--- a/src/include/string.h
+++ b/src/include/string.h
@@ -17,6 +17,7 @@ int memcmp(const void *s1, const void *s2, size_t n);
void *memchr(const void *s, int c, size_t n);
#if !defined(__PRE_RAM__)
int sprintf(char * buf, const char *fmt, ...);
+int snprintf(char * buf, size_t size, const char *fmt, ...);
#endif
// simple string functions
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