libi3: Implement i3String

New type designed to handle UCS-2/UTF-8 conversion nicely

include/libi3.h

@@ -18,6 +18,12 @@
 #include <xcb/xproto.h>
 #include <xcb/xcb_keysyms.h>
 
+/**
+ * Opaque data structure for storing strings.
+ *
+ */
+typedef struct _i3String i3String;
+
 typedef struct Font i3Font;
 
 /**
@@ -91,6 +97,71 @@ char *sstrdup(const char *str);
  */
 int sasprintf(char **strp, const char *fmt, ...);
 
+/**
+ * Build an i3String from an UTF-8 encoded string.
+ * Returns the newly-allocated i3String.
+ *
+ */
+i3String *i3string_from_utf8(const char *from_utf8);
+
+/**
+ * Build an i3String from an UTF-8 encoded string with fixed length.
+ * To be used when no proper NUL-terminaison is available.
+ * Returns the newly-allocated i3String.
+ *
+ */
+i3String *i3string_from_utf8_with_length(const char *from_utf8, size_t num_bytes);
+
+/**
+ * Build an i3String from an UCS-2 encoded string.
+ * Returns the newly-allocated i3String.
+ *
+ */
+i3String *i3string_from_ucs2(const xcb_char2b_t *from_ucs2, size_t num_glyphs);
+
+/**
+ * Free an i3String.
+ *
+ */
+void i3string_free(i3String *str);
+
+/**
+ * Securely i3string_free by setting the pointer to NULL
+ * to prevent accidentally using freed memory.
+ *
+ */
+#define I3STRING_FREE(str) \
+do { \
+ if (str != NULL) { \
+ i3string_free(str); \
+ str = NULL; \
+ } \
+} while (0)
+
+/**
+ * Returns the UTF-8 encoded version of the i3String.
+ *
+ */
+const char *i3string_as_utf8(i3String *str);
+
+/**
+ * Returns the UCS-2 encoded version of the i3String.
+ *
+ */
+const xcb_char2b_t *i3string_as_ucs2(i3String *str);
+
+/**
+ * Returns the number of bytes (UTF-8 encoded) in an i3String.
+ *
+ */
+size_t i3string_get_num_bytes(i3String *str);
+
+/**
+ * Returns the number of glyphs in an i3String.
+ *
+ */
+size_t i3string_get_num_glyphs(i3String *str);
+
 /**
  * Connects to the i3 IPC socket and returns the file descriptor for the
  * socket. die()s if anything goes wrong.

libi3/string.c

@@ -0,0 +1,143 @@
+/*
+ * vim:ts=4:sw=4:expandtab
+ *
+ * i3 - an improved dynamic tiling window manager
+ * © 2009-2011 Michael Stapelberg and contributors (see also: LICENSE)
+ *
+ * string.c: Define an i3String type to automagically handle UTF-8/UCS-2
+ *           conversions. Some font backends need UCS-2 (X core fonts),
+ *           others want UTF-8 (Pango).
+ *
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "libi3.h"
+
+struct _i3String {
+    char *utf8;
+    xcb_char2b_t *ucs2;
+    size_t num_glyphs;
+    size_t num_bytes;
+};
+
+/*
+ * Build an i3String from an UTF-8 encoded string.
+ * Returns the newly-allocated i3String.
+ *
+ */
+i3String *i3string_from_utf8(const char *from_utf8) {
+    i3String *str = scalloc(sizeof(i3String));
+
+    /* Get the text */
+    str->utf8 = sstrdup(from_utf8);
+
+    /* Compute and store the length */
+    str->num_bytes = strlen(str->utf8);
+
+    return str;
+}
+
+/*
+ * Build an i3String from an UTF-8 encoded string with fixed length.
+ * To be used when no proper NUL-terminaison is available.
+ * Returns the newly-allocated i3String.
+ *
+ */
+i3String *i3string_from_utf8_with_length(const char *from_utf8, size_t num_bytes) {
+    i3String *str = scalloc(sizeof(i3String));
+
+    /* Copy the actual text to our i3String */
+    str->utf8 = scalloc(sizeof(char) * (num_bytes + 1));
+    strncpy(str->utf8, from_utf8, num_bytes);
+    str->utf8[num_bytes] = '\0';
+
+    /* Store the length */
+    str->num_bytes = num_bytes;
+
+    return str;
+}
+
+/*
+ * Build an i3String from an UCS-2 encoded string.
+ * Returns the newly-allocated i3String.
+ *
+ */
+i3String *i3string_from_ucs2(const xcb_char2b_t *from_ucs2, size_t num_glyphs) {
+    i3String *str = scalloc(sizeof(i3String));
+
+    /* Copy the actual text to our i3String */
+    size_t num_bytes = num_glyphs * sizeof(xcb_char2b_t);
+    str->ucs2 = scalloc(num_bytes);
+    memcpy(str->ucs2, from_ucs2, num_bytes);
+
+    /* Store the length */
+    str->num_glyphs = num_glyphs;
+
+    str->utf8 = NULL;
+    str->num_bytes = 0;
+
+    return str;
+}
+
+/*
+ * Free an i3String.
+ *
+ */
+void i3string_free(i3String *str) {
+    if (str == NULL)
+        return;
+    free(str->utf8);
+    free(str->ucs2);
+    free(str);
+}
+
+static void i3string_ensure_utf8(i3String *str) {
+    if (str->utf8 != NULL)
+        return;
+    if ((str->utf8 = convert_ucs2_to_utf8(str->ucs2, str->num_glyphs)) != NULL)
+        str->num_bytes = strlen(str->utf8);
+}
+
+static void i3string_ensure_ucs2(i3String *str) {
+    if (str->ucs2 != NULL)
+        return;
+    str->ucs2 = convert_utf8_to_ucs2(str->utf8, &str->num_glyphs);
+}
+
+/*
+ * Returns the UTF-8 encoded version of the i3String.
+ *
+ */
+const char *i3string_as_utf8(i3String *str) {
+    i3string_ensure_utf8(str);
+    return str->utf8;
+}
+
+/*
+ * Returns the UCS-2 encoded version of the i3String.
+ *
+ */
+const xcb_char2b_t *i3string_as_ucs2(i3String *str) {
+    i3string_ensure_ucs2(str);
+    return str->ucs2;
+}
+
+/*
+ * Returns the number of bytes (UTF-8 encoded) in an i3String.
+ *
+ */
+size_t i3string_get_num_bytes(i3String *str) {
+    i3string_ensure_utf8(str);
+    return str->num_bytes;
+}
+
+/*
+ * Returns the number of glyphs in an i3String.
+ *
+ */
+size_t i3string_get_num_glyphs(i3String *str) {
+    i3string_ensure_ucs2(str);
+    return str->num_glyphs;
+}