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make sure functions used by the security code are tamper-proof

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This commit is contained in:
mfranz 2008-07-22 21:22:59 +00:00
parent b9e7bb1b4b
commit 8b6ff24167
1 changed files with 51 additions and 24 deletions
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75
Nasal/string.nas
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@ -36,27 +36,6 @@ var trim = func(s, lr = 0) {
}
##
# Join all elements of a list inserting a separator between every two of them.
#
var join = func(sep, list) {
if (!size(list))
return "";
var str = list[0];
foreach (var s; subvec(list, 1))
str ~= sep ~ s;
return str;
}
##
# Replace all occurrences of 'old' by 'new'.
#
var replace = func(str, old, new) {
return join(new, split(old, str));
}
##
# return string converted to lower case letters
#
@ -88,6 +67,32 @@ var icmp = func(a, b) cmp(lc(a), lc(b));
var imatch = func(a, b) match(lc(a), lc(b));
##
# Functions that are used in the IO security code (io.nas) are defined in a
# closure that holds safe copies of system functions. Later manipulation of
# append(), pop() etc. doesn't affect them. Of course, any security code
# must itself store safe copies of these tamper-proof functions before user
# code can redefine them, and the closure() command must be made inaccessible.
##
var match = nil;
var fixpath = nil;
var join = nil;
var replace = nil;
(func {
var append = append;
var caller = caller;
var pop = pop;
var setsize = setsize;
var size = size;
var split = split;
var substr = substr;
var subvec = subvec;
##
# check if string <str> matches shell style pattern <patt>
#
@ -115,7 +120,7 @@ var imatch = func(a, b) match(lc(a), lc(b));
# Example:
# string.match(name, "*[0-9].xml"); ... true if 'name' ends with digit followed by ".xml"
#
var match = func(str, patt) {
match = func(str, patt) {
var s = 0;
for (var p = 0; p < size(patt) and s < size(str); ) {
if (patt[p] == `\\`) {
@ -135,11 +140,12 @@ var match = func(str, patt) {
return 1;
for (; s < size(str); s += 1)
if (match(substr(str, s), substr(patt, p)))
if (caller(0)[1](substr(str, s), substr(patt, p)))
return 1;
continue;
} elsif (patt[p] == `[`) {
print("**setsize**");
setsize(var x = [], 256);
var invert = 0;
if ((p += 1) < size(patt) and patt[p] == `^`) {
@ -184,7 +190,7 @@ var match = func(str, patt) {
# absolute property or file paths, otherwise ".." elements might
# be resolved wrongly.
#
var fixpath = func(path) {
fixpath = func(path) {
path = replace(path, "\\", "/");
var prefix = size(path) and path[0] == `/` ? "/" : "";
var stack = [];
@ -201,3 +207,24 @@ var fixpath = func(path) {
}
##
# Join all elements of a list inserting a separator between every two of them.
#
join = func(sep, list) {
if (!size(list))
return "";
var str = list[0];
foreach (var s; subvec(list, 1))
str ~= sep ~ s;
return str;
}
##
# Replace all occurrences of 'old' by 'new'.
#
replace = func(str, old, new) {
return join(new, split(old, str));
}
})(); # end tamper-proof environment