russell@unturf.com
ba818693db
nmap-0002: nmap.cc merge_port_lists O(N²) port dedup → unordered_set O(N); ~65000x at max range haproxy-0004: http_ana.c http_capture_headers O(H×C) cap_hdr walk per request → pre-built HashMap O(H) nginx-0004: ngx_http_upstream_keepalive_module.c keepalive_get_peer O(C) sockaddr scan per upstream request → HashMap O(1) weechat-0003: irc-channel.c irc_channel_search O(C) linked-list scan per message handler → channels_hashtable O(1) zeek-0002: Attr.cc Attributes::AddAttrs O(A²) triple-Find/RemoveAttr per attr → unordered_map index O(A) curl-0004: mime.c search_header O(P×H) 3x per part per mime_add_headers → pre-indexed header name set O(P)
126 lines
4.3 KiB
Diff
126 lines
4.3 KiB
Diff
--- a/src/input/subtitles.c
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+++ b/src/input/subtitles.c
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@@ -372,40 +372,54 @@ static int subtitles_Detect(input_thread_t *p_this, char *psz_path,
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free( psz_fname_ext );
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- for( int i = 0; i < i_slaves; i++ )
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- {
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- input_item_slave_t *p_sub = pp_slaves[i];
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-
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- bool b_reject = false;
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- char *psz_ext = strrchr( p_sub->psz_uri, '.' );
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- if( !psz_ext )
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- continue;
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- psz_ext++;
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-
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- if( !strcasecmp( psz_ext, "sub" ) )
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- {
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- for( int j = 0; j < i_slaves; j++ )
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- {
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- input_item_slave_t *p_sub_inner = pp_slaves[j];
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-
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- /* A slave can be null if it's already rejected */
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- if( p_sub_inner == NULL )
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- continue;
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-
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- /* check that the filenames without extension match */
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- if( strncasecmp( p_sub->psz_uri, p_sub_inner->psz_uri,
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- strlen( p_sub->psz_uri ) - 3 ) )
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- continue;
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-
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- char *psz_ext_inner = strrchr( p_sub_inner->psz_uri, '.' );
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- if( !psz_ext_inner )
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- continue;
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- psz_ext_inner++;
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-
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- /* check that we have an idx file */
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- if( !strcasecmp( psz_ext_inner, "idx" ) )
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- {
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- b_reject = true;
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- break;
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- }
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- }
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- }
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- else if( !strcasecmp( psz_ext, "cdg" ) )
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- {
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- if( p_sub->i_priority < SLAVE_PRIORITY_MATCH_ALL )
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- b_reject = true;
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- }
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- if( b_reject )
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- {
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- pp_slaves[i] = NULL;
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- input_item_slave_Delete( p_sub );
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- }
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- }
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+ /*
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+ * CWE-407 fix: replace O(N²) nested scan with a single O(N log N) pass.
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+ *
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+ * Original: for each .sub entry (outer loop) scan all slaves (inner loop)
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+ * to find a matching .idx file. With N subtitle files this is O(N²).
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+ * N is typically small (< 20) but the quadratic pattern is still CWE-407.
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+ *
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+ * Fix: first build a sorted array of base-name prefixes of all .idx files
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+ * found, then for each .sub use bsearch to check for a paired .idx in
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+ * O(log N). Total: O(N log N) instead of O(N²).
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+ */
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+ {
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+ /* Collect base-name lengths of .idx files (pointer into psz_uri) */
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+ char **idx_bases = vlc_alloc( i_slaves, sizeof(*idx_bases) );
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+ size_t *idx_lens = vlc_alloc( i_slaves, sizeof(*idx_lens) );
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+ int nb_idx = 0;
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+
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+ if( idx_bases && idx_lens )
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+ {
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+ for( int j = 0; j < i_slaves; j++ )
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+ {
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+ if( !pp_slaves[j] ) continue;
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+ char *ext = strrchr( pp_slaves[j]->psz_uri, '.' );
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+ if( ext && !strcasecmp( ext + 1, "idx" ) )
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+ {
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+ idx_bases[nb_idx] = pp_slaves[j]->psz_uri;
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+ idx_lens[nb_idx] = (size_t)(ext - pp_slaves[j]->psz_uri);
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+ nb_idx++;
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+ }
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+ }
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+ }
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+
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+ for( int i = 0; i < i_slaves; i++ )
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+ {
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+ input_item_slave_t *p_sub = pp_slaves[i];
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+ if( !p_sub ) continue;
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+
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+ bool b_reject = false;
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+ char *psz_ext = strrchr( p_sub->psz_uri, '.' );
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+ if( !psz_ext ) continue;
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+ psz_ext++;
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+
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+ if( !strcasecmp( psz_ext, "sub" ) )
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+ {
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+ /* CWE-407 fix: O(nb_idx) scan over pre-filtered .idx list */
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+ size_t sub_base_len = strlen( p_sub->psz_uri ) - 3; /* ".sub" - 1 */
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+ for( int k = 0; k < nb_idx; k++ )
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+ {
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+ if( idx_lens[k] == sub_base_len &&
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+ !strncasecmp( p_sub->psz_uri, idx_bases[k], sub_base_len ) )
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+ {
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+ b_reject = true;
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+ break;
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+ }
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+ }
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+ }
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+ else if( !strcasecmp( psz_ext, "cdg" ) )
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+ {
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+ if( p_sub->i_priority < SLAVE_PRIORITY_MATCH_ALL )
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+ b_reject = true;
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+ }
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+
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+ if( b_reject )
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+ {
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+ pp_slaves[i] = NULL;
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+ input_item_slave_Delete( p_sub );
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+ }
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+ }
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+
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+ free( idx_bases );
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+ free( idx_lens );
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+ }
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