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Author SHA1 Message Date
kayomn 449b56947e Improve memory safety of Oar archive lookups
continuous-integration/drone/pr Build is passing Details
continuous-integration/drone/push Build is passing Details
2022-10-15 21:11:15 +01:00
kayomn 98372cc85f Improve memory safety of hash table 2022-10-15 21:08:52 +01:00
3 changed files with 55 additions and 41 deletions

View File

@ -24,7 +24,7 @@ pub const Archive = struct {
/// ///
/// ///
/// ///
const IndexCache = table.Hashed([]const u8, Entry.Header, table.string_context); const IndexCache = table.Hashed([]const u8, u64, table.string_context);
/// ///
/// Finds an entry matching `entry_path` in `archive`. /// Finds an entry matching `entry_path` in `archive`.
@ -34,42 +34,52 @@ pub const Archive = struct {
pub fn find(archive: *Archive, entry_path: []const u8) FindError!Entry { pub fn find(archive: *Archive, entry_path: []const u8) FindError!Entry {
return Entry{ return Entry{
.header = find_header: { .header = find_header: {
if (archive.index_cache.lookup(entry_path)) |entry_header| var header = Entry.Header{
break: find_header entry_header.*; .revision = 0,
.file_size = 0,
.absolute_offset = 0
};
const header_size = @sizeOf(Entry.Header);
if (archive.index_cache.lookup(entry_path)) |cursor| {
try archive.file_access.seek(cursor);
if ((try archive.file_access.read(std.mem.asBytes(&header))) != header_size) {
std.debug.assert(archive.index_cache.remove(entry_path) != null);
return error.EntryNotFound;
}
break: find_header header;
} else {
const mem = std.mem;
// Start from beginning of archive. // Start from beginning of archive.
try archive.file_access.seek(0); try archive.file_access.seek(0);
var entry_header = Entry.Header{
.revision = 0,
.file_size = 0,
.file_offset = 0
};
const read_buffer = std.mem.asBytes(&entry_header);
// Read first entry. // Read first entry.
while ((try archive.file_access.read(read_buffer)) == @sizeOf(Entry.Header)) { while ((try archive.file_access.read(mem.asBytes(&header))) == header_size) {
if (std.mem.eql(u8, entry_path, entry_header. if (mem.eql(u8, entry_path, header.name_buffer[0 .. header.name_length])) {
name_buffer[0 .. entry_header.name_length])) {
// If caching fails... oh well... // If caching fails... oh well...
archive.index_cache.insert(entry_path, entry_header) catch {}; archive.index_cache.insert(entry_path, header.absolute_offset) catch {};
break: find_header entry_header; break: find_header header;
} }
// Move over file data following the entry. // Move over file data following the entry.
var to_skip = entry_header.file_size; var to_skip = header.file_size;
while (to_skip != 0) { while (to_skip != 0) {
const skipped = std.math.min(to_skip, std.math.maxInt(i64)); const math = std.math;
const skipped = math.min(to_skip, math.maxInt(i64));
try archive.file_access.skip(@intCast(i64, skipped)); try archive.file_access.skip(@intCast(i64, skipped));
to_skip -= skipped; to_skip -= skipped;
} }
} }
}
return error.EntryNotFound; return error.EntryNotFound;
}, },
@ -109,7 +119,7 @@ pub const Entry = struct {
name_buffer: [255]u8 = std.mem.zeroes([255]u8), name_buffer: [255]u8 = std.mem.zeroes([255]u8),
name_length: u8 = 0, name_length: u8 = 0,
file_size: u64, file_size: u64,
file_offset: u64, absolute_offset: u64,
padding: [232]u8 = std.mem.zeroes([232]u8), padding: [232]u8 = std.mem.zeroes([232]u8),
comptime { comptime {

View File

@ -487,7 +487,7 @@ pub const FileSystem = union(enum) {
if (archive_entry.cursor >= archive_entry.header.file_size) if (archive_entry.cursor >= archive_entry.header.file_size)
return error.FileInaccessible; return error.FileInaccessible;
try file_access.seek(archive_entry.header.file_offset); try file_access.seek(archive_entry.header.absolute_offset);
return file_access.read(buffer[0 .. std.math.min( return file_access.read(buffer[0 .. std.math.min(
buffer.len, archive_entry.header.file_size)]); buffer.len, archive_entry.header.file_size)]);

View File

@ -56,16 +56,18 @@ pub fn Hashed(comptime Key: type, comptime Value: type,
} }
/// ///
/// Searches for `key` to delete it, returning the deleted value or `null` if no matching /// Searches for `key` and deletes it from `self.
/// key was found.
/// ///
pub fn remove(self: Self, key: Key) ?Value { /// The removed value is returned or `null` if no key matching `key` was found.
///
pub fn remove(self: *Self, key: Key) ?Value {
var bucket = &(self.buckets[@mod(key_context.hash(key), self.buckets.len)]); var bucket = &(self.buckets[@mod(key_context.hash(key), self.buckets.len)]);
if (bucket.maybe_entry) |*entry| if (key_context.equals(entry.key, key)) { if (bucket.maybe_entry) |*entry| if (key_context.equals(entry.key, key)) {
defer entry.value = null; defer {
bucket.maybe_entry = null;
self.filled -= 1; self.filled -= 1;
}
return entry.value; return entry.value;
}; };
@ -74,9 +76,10 @@ pub fn Hashed(comptime Key: type, comptime Value: type,
bucket = &(self.buckets[index]); bucket = &(self.buckets[index]);
if (bucket.maybe_entry) |*entry| if (key_context.equals(entry.key, key)) { if (bucket.maybe_entry) |*entry| if (key_context.equals(entry.key, key)) {
defer entry.value = null; defer {
bucket.maybe_entry = null;
self.filled -= 1; self.filled -= 1;
}
return entry.value; return entry.value;
}; };
@ -129,20 +132,21 @@ pub fn Hashed(comptime Key: type, comptime Value: type,
} }
/// ///
/// Searches for a value indexed with `key` in `self`, returning it or `null` if no matching /// Searches for a value indexed with `key` in `self`.
/// entry was found.
/// ///
pub fn lookup(self: Self, key: Key) ?*Value { /// The found value is returned or `null` if an key matching `key` failed to be found.
///
pub fn lookup(self: Self, key: Key) ?Value {
var bucket = &(self.buckets[@mod(key_context.hash(key), self.buckets.len)]); var bucket = &(self.buckets[@mod(key_context.hash(key), self.buckets.len)]);
if (bucket.maybe_entry) |*entry| if (bucket.maybe_entry) |entry|
if (key_context.equals(entry.key, key)) return &entry.value; if (key_context.equals(entry.key, key)) return entry.value;
while (bucket.maybe_next_index) |index| { while (bucket.maybe_next_index) |index| {
bucket = &(self.buckets[index]); bucket = &(self.buckets[index]);
if (bucket.maybe_entry) |*entry| if (bucket.maybe_entry) |entry|
if (key_context.equals(entry.key, key)) return &entry.value; if (key_context.equals(entry.key, key)) return entry.value;
} }
return null; return null;