enhancement: switch from obsolete PCRE 8.x to current PCRE2 10.x

[stapelberg]

reported in http://bugs.debian.org/1000105

[i3bot]

Please note that new features which require additional configuration will usually not be considered. We are happy with the feature set of i3 and want to focus in fixing bugs instead. We do accept feature requests, however, and will evaluate whether the added benefit (clearly) outweighs the complexity it adds to i3.

Keep in mind that i3 provides a powerful way to interact with it through its IPC interface: https://i3wm.org/docs/ipc.html.

[psychon]

I have no clue what I am doing and I have never used pcre/pcre2 before, but the following at least compiles and survives the test suite. Feel free to take this, make it nice, and turn it into a PR.

diff --git a/include/data.h b/include/data.h
index 95acd66d..293d14ef 100644
--- a/include/data.h
+++ b/include/data.h
@@ -9,11 +9,13 @@
  */
 #pragma once
 
+#define PCRE2_CODE_UNIT_WIDTH 8
+
 #define SN_API_NOT_YET_FROZEN 1
 #include <libsn/sn-launcher.h>
 
 #include <xcb/randr.h>
-#include <pcre.h>
+#include <pcre2.h>
 #include <sys/time.h>
 #include <cairo/cairo.h>
 
@@ -248,8 +250,7 @@ struct Startup_Sequence {
  */
 struct regex {
     char *pattern;
-    pcre *regex;
-    pcre_extra *extra;
+    pcre2_code *regex;
 };
 
 /**
diff --git a/meson.build b/meson.build
index 27fc9fb5..2d35cfee 100644
--- a/meson.build
+++ b/meson.build
@@ -316,7 +316,7 @@ xcb_util_xrm_dep = dependency('xcb-xrm', method: 'pkg-config')
 xkbcommon_dep = dependency('xkbcommon', method: 'pkg-config')
 xkbcommon_x11_dep = dependency('xkbcommon-x11', method: 'pkg-config')
 yajl_dep = dependency('yajl', method: 'pkg-config')
-libpcre_dep = dependency('libpcre', version: '>=8.10', method: 'pkg-config')
+libpcre_dep = dependency('libpcre2-8', version: '>=8.10', method: 'pkg-config')
 cairo_dep = dependency('cairo', version: '>=1.14.4', method: 'pkg-config')
 pangocairo_dep = dependency('pangocairo', method: 'pkg-config')
 glib_dep = dependency('glib-2.0', method: 'pkg-config')
diff --git a/src/regex.c b/src/regex.c
index 8f039157..668005ad 100644
--- a/src/regex.c
+++ b/src/regex.c
@@ -20,34 +20,23 @@
  *
  */
 struct regex *regex_new(const char *pattern) {
-    const char *error;
-    int errorcode, offset;
+    int errorcode;
+    PCRE2_SIZE offset;
 
     struct regex *re = scalloc(1, sizeof(struct regex));
     re->pattern = sstrdup(pattern);
-    int options = PCRE_UTF8;
+    uint32_t options = PCRE2_UTF;
     /* We use PCRE_UCP so that \B, \b, \D, \d, \S, \s, \W, \w and some POSIX
      * character classes play nicely with Unicode */
-    options |= PCRE_UCP;
-    while (!(re->regex = pcre_compile2(pattern, options, &errorcode, &error, &offset, NULL))) {
-        /* If the error is that PCRE was not compiled with UTF-8 support we
-         * disable it and try again */
-        if (errorcode == 32) {
-            options &= ~PCRE_UTF8;
-            continue;
-        }
-        ELOG("PCRE regular expression compilation failed at %d: %s\n",
-             offset, error);
+    options |= PCRE2_UCP;
+    if (!(re->regex = pcre2_compile((PCRE2_SPTR)pattern, PCRE2_ZERO_TERMINATED, options, &errorcode, &offset, NULL))) {
+        PCRE2_UCHAR buffer[256];
+        pcre2_get_error_message(errorcode, buffer, sizeof(buffer));
+        ELOG("PCRE regular expression compilation failed at %lu: %s\n",
+             offset, buffer);
         regex_free(re);
         return NULL;
     }
-    re->extra = pcre_study(re->regex, 0, &error);
-    /* If an error happened, we print the error message, but continue.
-     * Studying the regular expression leads to faster matching, but it’s not
-     * absolutely necessary. */
-    if (error) {
-        ELOG("PCRE regular expression studying failed: %s\n", error);
-    }
     return re;
 }
 
@@ -60,7 +49,6 @@ void regex_free(struct regex *regex) {
         return;
     FREE(regex->pattern);
     FREE(regex->regex);
-    FREE(regex->extra);
     FREE(regex);
 }
 
@@ -71,17 +59,22 @@ void regex_free(struct regex *regex) {
  *
  */
 bool regex_matches(struct regex *regex, const char *input) {
+    pcre2_match_data *match_data;
     int rc;
 
+    match_data = pcre2_match_data_create_from_pattern(regex->regex, NULL);
+
     /* We use strlen() because pcre_exec() expects the length of the input
      * string in bytes */
-    if ((rc = pcre_exec(regex->regex, regex->extra, input, strlen(input), 0, 0, NULL, 0)) == 0) {
+    if ((rc = pcre2_match(regex->regex, (PCRE2_SPTR)input, strlen(input), 0, 0, match_data, NULL)) > 0) {
+        pcre2_match_data_free(match_data);
         LOG("Regular expression \"%s\" matches \"%s\"\n",
             regex->pattern, input);
         return true;
     }
+    pcre2_match_data_free(match_data);
 
-    if (rc == PCRE_ERROR_NOMATCH) {
+    if (rc == PCRE2_ERROR_NOMATCH) {
         LOG("Regular expression \"%s\" does not match \"%s\"\n",
             regex->pattern, input);
         return false;

[stapelberg]

Your patch looks good and seems to work for me! Can you just send it as a pull request please? :)

[kamahen]

Shouldn't the version test be for 10.x? (10.39 seems to be the latest)
in this line: libpcre_dep = dependency('libpcre2-8', version: '>=8.10', method: 'pkg-config')