/* regex.c * Copyright 2023 Anon Anonson, Ognjen 'xolatile' Milan Robovic, Emil Williams * SPDX Identifier: GPL-3.0-only / NO WARRANTY / NO GUARANTEE */ #include "regex.h" #include #include // ------------------ // ### Char tests ### // ------------------ static bool is_quantifier(const char c) { for (const char * s = "+*?="; *s != '\00'; s++) { if (*s == c) { return true; } } return false; } bool is_magic(const char c) { if (is_quantifier(c)) { return true; } for (const char * s = "\\[]"; *s != '\00'; s++) { if (*s == c) { return true; } } return false; } // ---------------------- // ### Internal Types ### // ---------------------- typedef struct { int in; char input; int to; int width; } delta_t; typedef struct { int in; int to; } offshoot_t; typedef struct { bool * do_catch; bool * is_negative; int * state; int * width; char * whitelist; regex_t * regex; } compiler_state; // ---------------------------------- // ### Regex creation/destruction ### // ---------------------------------- static int escape_1_to_1(const char c, char * whitelist) { switch (c) { case 't': { strcat(whitelist, "\t"); } return 1; case 'n': { strcat(whitelist, "\n"); } return 1; case 'r': { strcat(whitelist, "\r"); } return 1; case 'b': { strcat(whitelist, "\b"); } return 1; case '[': { strcat(whitelist, "["); } return 1; case ']': { strcat(whitelist, "]"); } return 1; case '.': { strcat(whitelist, "."); } return 1; case '=': { strcat(whitelist, "="); } return 1; case '?': { strcat(whitelist, "?"); } return 1; case '+': { strcat(whitelist, "+"); } return 1; case '*': { strcat(whitelist, "*"); } return 1; case '\\': { strcat(whitelist, "\\"); } return 1; } return 0; } static int escape_1_to_N(const char c, char * whitelist) { switch(c) { case 'i': { const char identifier_chars[] = "@0123456789_" "\300\301\302\303\304" "\305\306\307\310\311" "\312\313\314\315\316" "\317\320\321\322\323" "\324\325\326\327\330" "\331\332\333\334\335" "\336\337"; strcpy(whitelist, identifier_chars); return sizeof(identifier_chars)-1; }; case 'I': { const char identifier_chars[] = "@_" "\300\301\302\303\304" "\305\306\307\310\311" "\312\313\314\315\316" "\317\320\321\322\323" "\324\325\326\327\330" "\331\332\333\334\335" "\336\337"; strcpy(whitelist, identifier_chars); return sizeof(identifier_chars)-1; }; case 'k': { const char keyword_chars[] = "@0123456789_" "\300\301\302\303\304" "\305\306\307\310\311" "\312\313\314\315\316" "\317\320\321\322\323" "\324\325\326\327\330" "\331\332\333\334\335" "\336\337"; strcpy(whitelist, keyword_chars); return sizeof(keyword_chars)-1; }; case 'K': { const char keyword_chars[] = "@_" "\300\301\302\303\304" "\305\306\307\310\311" "\312\313\314\315\316" "\317\320\321\322\323" "\324\325\326\327\330" "\331\332\333\334\335" "\336\337"; strcpy(whitelist, keyword_chars); return sizeof(keyword_chars)-1; }; case 'f': { const char filename_chars[] = "@0123456789/.-_+,#$%~="; strcpy(whitelist, filename_chars); return sizeof(filename_chars)-1; }; case 'F': { const char filename_chars[] = "@/.-_+,#$%~="; strcpy(whitelist, filename_chars); return sizeof(filename_chars)-1; }; case 'p': { const char printable_chars[] = "@" "\241\242\243\244\245" "\246\247\250\251\252" "\253\254\255\256\257" "\260\261\262\263\264" "\265\266\267\270\271" "\272\273\274\275\276" "\277" "\300\301\302\303\304" "\305\306\307\310\311" "\312\313\314\315\316" "\317\320\321\322\323" "\324\325\326\327\330" "\331\332\333\334\335" "\336\337"; strcpy(whitelist, printable_chars); return sizeof(printable_chars)-1; }; case 'P': { const char printable_chars[] = "@" "\241\242\243\244\245" "\246\247\250\251\252" "\253\254\255\256\257" "\260\261\262\263\264" "\265\266\267\270\271" "\272\273\274\275\276" "\277" "\300\301\302\303\304" "\305\306\307\310\311" "\312\313\314\315\316" "\317\320\321\322\323" "\324\325\326\327\330" "\331\332\333\334\335" "\336\337"; strcpy(whitelist, printable_chars); return sizeof(printable_chars)-1; }; case 's': { const char whitespace_chars[] = " \t\v\n"; strcpy(whitelist, whitespace_chars); return sizeof(whitespace_chars)-1; }; case 'd': { const char digit_chars[] = "0123456789"; strcpy(whitelist, digit_chars); return sizeof(digit_chars)-1; }; case 'x': { const char hex_chars[] = "0123456789" "abcdef" "ABCDEF"; strcpy(whitelist, hex_chars); return sizeof(hex_chars)-1; }; case 'o': { const char oct_chars[] = "01234567"; strcpy(whitelist, oct_chars); return sizeof(oct_chars)-1; }; case 'w': { const char word_chars[] = "0123456789" "abcdefghijklmnopqrstuwxyz" "ABCDEFGHIJKLMNOPQRSTUWXYZ" "_"; strcpy(whitelist, word_chars); return sizeof(word_chars)-1; }; case 'h': { const char very_word_chars[] = "abcdefghijklmnopqrstuwxyz" "ABCDEFGHIJKLMNOPQRSTUWXYZ" "_"; strcpy(whitelist, very_word_chars); return sizeof(very_word_chars)-1; }; case 'a': { const char alpha_chars[] = "abcdefghijklmnopqrstuwxyz" "ABCDEFGHIJKLMNOPQRSTUWXYZ"; strcpy(whitelist, alpha_chars); return sizeof(alpha_chars)-1; }; case 'l': { const char lower_alpha_chars[] = "abcdefghijklmnopqrstuwxyz"; strcpy(whitelist, lower_alpha_chars); return sizeof(lower_alpha_chars)-1; }; case 'u': { const char upper_alpha_chars[] = "ABCDEFGHIJKLMNOPQRSTUWXYZ"; strcpy(whitelist, upper_alpha_chars); return sizeof(upper_alpha_chars)-1; }; } return 0; } //static int compile_hologram(char * hologram, char * whitelist) { // if (hologram[0] == '\\') { // switch (hologram[1]) { // case '<': { // const char very_word_chars[] = "abcdefghijklmnopqrstuwxyz" // "ABCDEFGHIJKLMNOPQRSTUWXYZ" // "_"; // strcat(whitelist, very_word_chars); // is_negative = true; // HOOK_ALL(0, whitelist, 0) // } break; // } // } //} static int compile_range(const char * const range, char * whitelist, bool * is_negative) { assert((range[0] == '[') && "Not a range."); const char * s; if (range[1] == '^') { *is_negative = true; s = range + 2; } else { s = range + 1; } for (; *s != ']'; s++) { assert((*s != '\0') && "Unclosed range."); char c = *s; if (escape_1_to_1(c, whitelist) || escape_1_to_N(c, whitelist)) { ; } else if (*(s+1) == '-') { char end = *(s+2); assert((c < end) && "Endless range."); for (char cc = c; cc < end+1; cc++) { strncat(whitelist, &cc, 1); strncat(whitelist, "\0", 1); } s += 2; } else { strncat(whitelist, &c, 1); strncat(whitelist, "\00", 1); } } return ((s - range) + 1); } static bool catch_(const regex_t * const regex, int * const state) { for (size_t i = 0; i < regex->catch_table.element_count; i++){ const offshoot_t * const offshoot = *(offshoot_t**)vector_get(®ex->catch_table, i); if (offshoot->in == *state) { *state = offshoot->to; return true; } } return false; } #define HALT_AND_CATCH_FIRE -1 void HOOK_ALL(int from, const char * const str, int to, compiler_state * cs) { int hook_to = (*cs->is_negative) ? HALT_AND_CATCH_FIRE : *cs->state + to; for (const char * s = str; *s != '\0'; s++) { delta_t * delta = malloc(sizeof(delta_t)); delta->in = *cs->state + from; delta->input = *s; delta->to = hook_to; delta->width = *cs->width; vector_push(&cs->regex->delta_table, &delta); } if (cs->do_catch || cs->is_negative) { offshoot_t * offshoot = malloc(sizeof(offshoot_t)); offshoot->in = *cs->state + from; offshoot->to = hook_to; vector_push(&cs->regex->catch_table, &offshoot); } } #define EAT(n) do { \ s += n; \ } while (0) regex_t * regex_compile(const char * const pattern) { regex_t * regex = (regex_t *)malloc(sizeof(regex_t)); regex->str = strdup(pattern); vector_init(®ex->delta_table, sizeof(delta_t*), 0UL); vector_init(®ex->catch_table, sizeof(offshoot_t*), 0UL); int state = 0; bool do_catch; bool is_negative; int width; char whitelist[64]; compiler_state cs = { .do_catch = &do_catch, .is_negative = &is_negative, .state = &state, .width = &width, .whitelist = whitelist, .regex = regex, }; for (const char * s = pattern; *s != '\00';) { // Get token assert(!is_quantifier(*pattern) && "Pattern starts with quantifier."); whitelist[0] = '\00'; do_catch = false; width = 1; switch (*s) { case '.': { do_catch = true; } break; case '\\': { //if (compile_hologram(*s, whitelist)) { // break; //} EAT(1); if(escape_1_to_1(*s, whitelist) || escape_1_to_N(*s, whitelist)){ ; } else { assert(!"Unknown escape."); } } break; case '[': { EAT(compile_range(s, whitelist, &is_negative)-1); } break; default: { whitelist[0] = *s; whitelist[1] = '\00'; } break; } EAT(1); // Get quantifier switch (*s) { case '=': case '?': { HOOK_ALL(0, whitelist, +1, &cs); EAT(1); } break; case '*': { HOOK_ALL(0, whitelist, 0, &cs); EAT(1); } break; case '+': { HOOK_ALL(0, whitelist, +1, &cs); state += 1; HOOK_ALL(0, whitelist, 0, &cs); EAT(1); } break; default: { // Literal HOOK_ALL(0, whitelist, +1, &cs); state += 1; } break; } } regex->accepting_state = state; return regex; } int regex_free(regex_t * const regex) { free(regex->str); vector_free(®ex->delta_table); vector_free(®ex->catch_table); free(regex); return 0; } // ----------------- // ### Searching ### // ----------------- static bool regex_assert(const regex_t * const regex, const char * const string, int state) { for (const char * s = string; *s != '\00'; s++) { // delta for (size_t i = 0; i < regex->delta_table.element_count; i++) { const delta_t * const delta = *(delta_t**)vector_get(®ex->delta_table, i); if ((delta->in == state) && (delta->input == *s)) { if(regex_assert(regex, s + delta->width, delta->to)){ return true; } } } if (catch_(regex, &state)) { continue; } return false; } return (state == regex->accepting_state); } bool regex_search( regex_t * regex, const char * const string) { if (regex == NULL) { return false; } if (string == NULL) { return true; } return regex_assert(regex, string, 0); }