[PATCH] make sscanf honor %n at end of input string
I was playing with some code that sometimes got a string where a %n
match should have been done where the input string ended, for example
like this:
sscanf("abc123", "abc%d%n", , );
However, the scanf function in the kernel doesn't convert the %n in that
case because it has already matched the complete input after %d. This
patch changes that.
Signed-off-by: Johannes Berg <[EMAIL PROTECTED]>
---
Shrug. My use case for this collapsed, but I figured having scanf doing
that correctly might be a good thing.
lib/vsprintf.c |9 +
1 file changed, 9 insertions(+)
--- wireless-dev.orig/lib/vsprintf.c2007-03-01 00:28:31.776381760 +0100
+++ wireless-dev/lib/vsprintf.c 2007-03-01 00:59:33.256381760 +0100
@@ -825,6 +825,15 @@ int vsscanf(const char * buf, const char
break;
str = next;
}
+
+ /* Now we've come all the way through so either the input string or
+* the format ended. In the former case, there can be a %n at the
+* current position in the format that needs to be filled. */
+ if (*fmt == '%' && *(fmt+1) == 'n') {
+ int *i = (int *)va_arg(args,int*);
+ *i = str - buf;
+ }
+
return num;
}
-
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[PATCH] make sscanf honor %n at end of input string
I was playing with some code that sometimes got a string where a %n
match should have been done where the input string ended, for example
like this:
sscanf(abc123, abc%d%n, a, n);
However, the scanf function in the kernel doesn't convert the %n in that
case because it has already matched the complete input after %d. This
patch changes that.
Signed-off-by: Johannes Berg [EMAIL PROTECTED]
---
Shrug. My use case for this collapsed, but I figured having scanf doing
that correctly might be a good thing.
lib/vsprintf.c |9 +
1 file changed, 9 insertions(+)
--- wireless-dev.orig/lib/vsprintf.c2007-03-01 00:28:31.776381760 +0100
+++ wireless-dev/lib/vsprintf.c 2007-03-01 00:59:33.256381760 +0100
@@ -825,6 +825,15 @@ int vsscanf(const char * buf, const char
break;
str = next;
}
+
+ /* Now we've come all the way through so either the input string or
+* the format ended. In the former case, there can be a %n at the
+* current position in the format that needs to be filled. */
+ if (*fmt == '%' *(fmt+1) == 'n') {
+ int *i = (int *)va_arg(args,int*);
+ *i = str - buf;
+ }
+
return num;
}
-
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Please read the FAQ at http://www.tux.org/lkml/
