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Revert "Warn about unescape_string_xxx() behavior (and tweak slightly)"

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This reverts commit 76dc849fca.

The warning added in that commit is incorrect. The functions
unescape_string_url and unescape_string_var will not panic, because
char_at() return 0 if the index is equal to its length.
This commit is contained in:
ridiculousfish 2023-04-23 15:28:46 -07:00
parent 009650b7b5
commit 705874f2e4
1 changed files with 27 additions and 18 deletions
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45
fish-rust/src/common.rs
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@ -687,14 +687,10 @@ fn unescape_string_internal(input: &wstr, flags: UnescapeFlags) -> Option<WStrin
Some(result)
}
/// Reverse the effects of `escape_string_url()`. By definition the consists of just ASCII chars.
///
/// XXX: The C++ counterpart to this function didn't panic if passed a truncated or malformed
/// escaped string because it relied on always being able to read at least one more char until a NUL
/// is encountered. As currently written/ported, it can panic if the passed utf-32 char slice is
/// truncated or malformed since that is no longer guaranteed to be the case!
/// Reverse the effects of `escape_string_url()`. By definition the string has consist of just ASCII
/// chars.
fn unescape_string_url(input: &wstr) -> Option<WString> {
let mut result: Vec<u8> = Vec::with_capacity(input.len());
let mut result: Vec<u8> = vec![];
let mut i = 0;
while i < input.len() {
let c = input.char_at(i);
@ -709,9 +705,12 @@ fn unescape_string_url(input: &wstr) -> Option<WString> {
result.push(b'%');
i += 1;
} else {
let d1 = c1.to_digit(16)?;
let c2 = input.char_at(i + 2);
let d2 = c2.to_digit(16)?; // also fails if '\0' i.e. premature end
if c2 == '\0' {
return None; // string ended prematurely
}
let d1 = c1.to_digit(16)?;
let d2 = c2.to_digit(16)?;
result.push((16 * d1 + d2) as u8);
i += 2;
}
@ -724,15 +723,10 @@ fn unescape_string_url(input: &wstr) -> Option<WString> {
Some(str2wcstring(&result))
}
/// Reverse the effects of `escape_string_var()`. By definition the string consists of just ASCII
/// Reverse the effects of `escape_string_var()`. By definition the string has consist of just ASCII
/// chars.
///
/// XXX: The C++ counterpart to this function didn't panic if passed a truncated or malformed
/// escaped string because it relied on always being able to read at least one more char until a NUL
/// is encountered. As currently written/ported, it can panic if the passed utf-32 char slice is
/// truncated or malformed since that is no longer guaranteed to be the case!
fn unescape_string_var(input: &wstr) -> Option<WString> {
let mut result: Vec<u8> = Vec::with_capacity(input.len());
let mut result: Vec<u8> = vec![];
let mut prev_was_hex_encoded = false;
let mut i = 0;
while i < input.len() {
@ -752,9 +746,12 @@ fn unescape_string_var(input: &wstr) -> Option<WString> {
result.push(b'_');
i += 1;
} else if ('0'..='9').contains(&c1) || ('A'..='F').contains(&c1) {
let d1 = c1.to_digit(16)?;
let c2 = input.char_at(i + 2);
let d2 = c2.to_digit(16)?; // also fails if '\0' i.e. premature end
if c2 == '\0' {
return None; // string ended prematurely
}
let d1 = convert_hex_digit(c1)?;
let d2 = convert_hex_digit(c2)?;
result.push((16 * d1 + d2) as u8);
i += 2;
prev_was_hex_encoded = true;
@ -949,6 +946,18 @@ pub fn read_unquoted_escape(
Some(in_pos)
}
/// This is a specialization of `char::to_digit()` that only handles base 16 and only uppercase.
fn convert_hex_digit(d: char) -> Option<u32> {
let val = if ('0'..='9').contains(&d) {
u32::from(d) - u32::from('0')
} else if ('A'..='Z').contains(&d) {
10 + u32::from(d) - u32::from('A')
} else {
return None;
};
Some(val)
}
pub const fn char_offset(base: char, offset: u32) -> char {
match char::from_u32(base as u32 + offset) {
Some(c) => c,