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Bug #1472

closed

rb_f_syscall converts string value to null terminated c string, but syscall structs can contain nulls.

Added by JohnCarter (John Carter) over 15 years ago. Updated about 8 years ago.

Status:
Closed
Assignee:
nobu (Nobuyoshi Nakada)
Target version:
-
ruby -v:
ruby 1.8.7 (2009-04-08 patchlevel 160) [i686-linux]
[ruby-core:23460]

Description

=begin
The following snippet invokes the statfs64 syscall.
bug.rb================================================================
string = " "* 84
p syscall( 268, "/", string.size, string)
string = "\0"* 84
p syscall( 268, "/", string.size, string)

If I run this under ruby 1.8.6, both invocations work.

If I run this under ruby 1.8.7, the second one fails with...
ruby -w bug.rb
0
bug.rb:4:in `syscall': string contains null byte (ArgumentError)
from bug.rb:4

The reason is in ruby-1.8.7-p22/io.c in the function rb_f_syscall
there is this code....

if (!NIL_P(v)) {
    StringValue(v);
    rb_str_modify(v);
    arg[i] = (unsigned long)StringValueCStr(v);
}

In ruby 1.8.6 is was

if (!NIL_P(v)) {
    StringValue(v);
    rb_str_modify(v);
    arg[i] = (unsigned long)RSTRING(v)->ptr;
}

The macro StringValueCStr is defined in ruby.h as....
#define StringValueCStr(v) rb_string_value_cstr(&(v))

The function rb_string_value_cstr is defined in string.c as ....

rb_string_value_cstr(ptr)
volatile VALUE *ptr;
{
VALUE str = rb_string_value(ptr);
char *s = RSTRING(str)->ptr;

 if (!s || RSTRING(str)->len != strlen(s)) {
rb_raise(rb_eArgError, "string contains null byte");
 }
 return s;

}

I believe the original 1.8.6 implementation was correct and this
particular changed should be rolled back.

Thanks.

http://rubyforge.org/tracker/index.php?func=detail&aid=20895&group_id=426&atid=1698

Applies to 1.8.7 and 1.9.1 p 129
=end

Files

ruby_1_8_7_io_syscall.patch (345 Bytes) ruby_1_8_7_io_syscall.patch patch JohnCarter (John Carter), 05/15/2009 05:41 PM
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