Hello All,
In reviewing the code at line 990 in bashfile.c, while the
issue of rl_line_buffer[0] = '\0', would it not be better to
use memset(rl_line_buffer, '\0', sizeof(rl_line_buffer)) to
clobber the entire line more effectively? The patch file
below addresses this issue:
--- bashline.c.orig 2015-07-08 14:43:45.000000000 -0700
+++ bashline.c 2015-07-08 14:45:08.000000000 -0700
@@ -987,7 +987,7 @@
/* Now erase the contents of the current line and undo the effects of the
rl_accept_line() above. We don't even want to make the text we just
executed available for undoing. */
- rl_line_buffer[0] = '\0'; /* XXX */
+ memset(rl_line_buffer, '\0', sizeof(rl_line_buffer)); /* clobber the entire buffer */
rl_point = rl_end = 0;
rl_done = 0;
rl_readline_state = rrs;
=======================================================================
Here is a test program which shows that the buffer does not get
clobbered in the case of 'rl_line_buffer[0]' is set to '\0':
#include <stdio.h>
#include <string.h>
int main(void)
{
char buffer[27];
printf("please enter a line of text ->");
fgets(buffer, sizeof(buffer), stdin);
printf("\n");
printf("The line entered is: %s\n", buffer);
buffer[0] = '\0'; /* does this clobber the buffer */
printf("\nvalue of buffer[0] is: %c\n", buffer[0]);
printf("value of buffer[11] is: %c\n", buffer[11]);
memset(buffer, '\0', sizeof(buffer));
printf("\nafter call to memset\n\n");
printf("value of buffer[0] is: %c\n", buffer[0]);
printf("value of buffer[11] is: %c\n", buffer[11]);
return 0;
}
Here is the output:
[bill@moocow ~]$ gcc -O2 testline.c
[bill@moocow ~]$ ./a.out
please enter a line of text ->abcdeFGHIJklmnoPQRSTuvwXyZ
The line entered is: abcdeFGHIJklmnoPQRSTuvwXyZ
value of buffer[0] is:
value of buffer[11] is: l
after call to memset
value of buffer[0] is:
value of buffer[11] is:
As you can see, setting buffer[0] to '\0' doesn't exactly
clobber the remaining data in buffer, but after calling
memset(), all of the data is clobbered.
Comments, Questions, Suggestions, Complaints? :)
I am attaching the patch file to this bug report.
Bill Parker (wp02855 at gmail dot com)
bashline.c.patch