Dynamically allocate JQ_COLORS escapes for truecolor support (#3282)

src/jv_print.c

@@ -27,43 +27,70 @@
 // Color table. See https://en.wikipedia.org/wiki/ANSI_escape_code#Colors
 // for how to choose these. The order is same as jv_kind definition, and
 // the last color is used for object keys.
-static char color_bufs[8][16];
-static const char *color_bufps[8];
-static const char *const def_colors[] =
-  {COL("0;90"),    COL("0;39"),      COL("0;39"),     COL("0;39"),
+#define DEFAULT_COLORS \
+  {COL("0;90"),    COL("0;39"),      COL("0;39"),     COL("0;39"),\
    COL("0;32"),    COL("1;39"),      COL("1;39"),     COL("1;34")};
+static const char *const default_colors[] = DEFAULT_COLORS;
+static const char *colors[] = DEFAULT_COLORS;
+#define COLORS_LEN (sizeof(colors) / sizeof(colors[0]))
 #define FIELD_COLOR (colors[7])
 
-static const char *const *colors = def_colors;
-
-int
-jq_set_colors(const char *c)
-{
-  const char *e;
-  size_t i;
-
-  if (c == NULL)
+static char *colors_buf = NULL;
+int jq_set_colors(const char *code_str) {
+  if (code_str == NULL)
     return 1;
-  colors = def_colors;
-  memset(color_bufs, 0, sizeof(color_bufs));
-  for (i = 0; i < sizeof(def_colors) / sizeof(def_colors[0]); i++)
-    color_bufps[i] = def_colors[i];
-  for (i = 0; i < sizeof(def_colors) / sizeof(def_colors[0]) && *c != '\0'; i++, c = e) {
-    if ((e = strchr(c, ':')) == NULL)
-      e = c + strlen(c);
-    if ((size_t)(e - c) > sizeof(color_bufs[i]) - 4 /* ESC [ m NUL */)
-      return 0;
-    color_bufs[i][0] = ESC[0];
-    color_bufs[i][1] = '[';
-    (void) strncpy(&color_bufs[i][2], c, e - c);
-    if (strspn(&color_bufs[i][2], "0123456789;") < strlen(&color_bufs[i][2]))
-      return 0;
-    color_bufs[i][2 + (e - c)] = 'm';
-    color_bufps[i] = color_bufs[i];
-    if (e[0] == ':')
-      e++;
+
+  // the start of each color code in the env var, and the byte after the end of the last one
+  const char *codes[COLORS_LEN + 1];
+  size_t num_colors;
+  // must be initialized before `goto default_colors`, used later to loop over every color
+  size_t ci = 0;
+
+  for (num_colors = 0;; num_colors++) {
+    codes[num_colors] = code_str;
+    code_str += strspn(code_str, "0123456789;");
+    if (code_str[0] == '\0' || num_colors + 1 >= COLORS_LEN) {
+      break;
+    } else if (code_str[0] != ':') {
+      return 0; // invalid character
+    }
+    code_str++;
   }
-  colors = color_bufps;
+  if (codes[num_colors] != code_str) {
+    // count the last color and store its end (plus one byte for consistency with starts)
+    // an empty last color would be ignored (for cases like "" and "0:")
+    num_colors++;
+    codes[num_colors] = code_str + 1;
+  } else if (num_colors == 0) {
+    if (colors_buf != NULL) {
+      jv_mem_free(colors_buf);
+      colors_buf = NULL;
+    }
+    goto default_colors;
+  }
+
+  colors_buf = jv_mem_realloc(
+    colors_buf,
+    // add ESC '[' 'm' to each string
+    // '\0' is already included in difference of codes
+    codes[num_colors] - codes[0] + 3 * num_colors
+  );
+  char *cb = colors_buf;
+  for (; ci < num_colors; ci++) {
+    colors[ci] = cb;
+    size_t len = codes[ci + 1] - 1 - codes[ci];
+
+    cb[0] = ESC[0];
+    cb[1] = '[';
+    memcpy(cb + 2, codes[ci], len);
+    cb[2 + len] = 'm';
+    cb[3 + len] = '\0';
+
+    cb += len + 4;
+  }
+  default_colors:
+  for (; ci < COLORS_LEN; ci++)
+    colors[ci] = default_colors[ci];
   return 1;
 }
 

src/main.c

@@ -554,7 +554,7 @@ int main(int argc, char* argv[]) {
   if (options & COLOR_OUTPUT) dumpopts |= JV_PRINT_COLOR;
   if (options & NO_COLOR_OUTPUT) dumpopts &= ~JV_PRINT_COLOR;
 
-  if (getenv("JQ_COLORS") != NULL && !jq_set_colors(getenv("JQ_COLORS")))
+  if (!jq_set_colors(getenv("JQ_COLORS")))
       fprintf(stderr, "Failed to set $JQ_COLORS\n");
 
   if (jv_get_kind(lib_search_paths) == JV_KIND_NULL) {