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sencode: string length integer bijectivity

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This commit is contained in:
Mirek Kratochvil 2013-04-21 00:11:43 +02:00
parent 04b4b1670f
commit 236ec39579
1 changed files with 20 additions and 0 deletions
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20
src/sencode.cpp
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@ -43,6 +43,7 @@ static void parse_int (const std::string&str, int&pos, int len,
} else goto fail;
}
//parse the number
for (;;) {
if (pos >= len) goto fail; //not terminated
else if (str[pos] == 'e') break; //done good
@ -62,6 +63,23 @@ static void parse_string (const std::string&str, int&pos, int len,
{
//first, read the amount of bytes
unsigned int bytes = 0;
/*
* we need to keep this bijective, therefore avoid parsing of any
* incorrect cases with leading zeroes except for a single zero. Such
* cases can be distinguished very simply by having zero at first
* position and not having colon right after.
*/
if (pos >= len) goto fail;
if (str[pos] == '0') {
++pos;
if (pos < len && str[pos] == ':') {
bytes = 0;
return;
} else goto bytes_done;
}
//parse the number.
for (;;) {
if (pos >= len) goto fail;
else if (str[pos] == ':') break; //got it
@ -71,6 +89,8 @@ static void parse_string (const std::string&str, int&pos, int len,
++pos;
}
bytes_done:
++pos;
if (pos + bytes >= len) goto fail;
res = str.substr (pos, bytes);