Win32: UTF-8 <-> WCHAR conversion overhaul

1 files changed, 130 insertions, 3 deletions

diff --git a/src/win32/utf-conv.c b/src/win32/utf-conv.c
index a96385f10..fe94701a8 100644
--- a/src/win32/utf-conv.c
+++ b/src/win32/utf-conv.c
@@ -8,12 +8,139 @@
 #include "common.h"
 #include "utf-conv.h"
 
-int git__utf8_to_16(wchar_t * dest, size_t dest_size, const char *src)
+#ifndef WC_ERR_INVALID_CHARS
+#define WC_ERR_INVALID_CHARS	0x80
+#endif
+
+GIT_INLINE(DWORD) get_wc_flags(void)
 {
-	return MultiByteToWideChar(CP_UTF8, 0, src, -1, dest, (int)dest_size);
+	static char inited = 0;
+	static DWORD flags;
+
+	/* Invalid code point check supported on Vista+ only */
+	if (!inited) {
+		flags = git_has_win32_version(6, 0, 0) ? WC_ERR_INVALID_CHARS : 0;
+		inited = 1;
+	}
+
+	return flags;
 }
 
+/**
+ * Converts a UTF-8 string to wide characters.
+ *
+ * @param dest The buffer to receive the wide string.
+ * @param dest_size The size of the buffer, in characters.
+ * @param src The UTF-8 string to convert.
+ * @return The length of the wide string, in characters (not counting the NULL terminator), or < 0 for failure
+ */
+int git__utf8_to_16(wchar_t *dest, size_t dest_size, const char *src)
+{
+	/* Length of -1 indicates NULL termination of the input string. Subtract 1 from the result to
+	* turn 0 into -1 (an error code) and to not count the NULL terminator as part of the string's
+	* length. MultiByteToWideChar never returns int's minvalue, so underflow is not possible */
+	return MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, src, -1, dest, (int)dest_size) - 1;
+}
+
+/**
+ * Converts a wide string to UTF-8.
+ *
+ * @param dest The buffer to receive the UTF-8 string.
+ * @param dest_size The size of the buffer, in bytes.
+ * @param src The wide string to convert.
+ * @return The length of the UTF-8 string, in bytes (not counting the NULL terminator), or < 0 for failure
+ */
 int git__utf16_to_8(char *dest, size_t dest_size, const wchar_t *src)
 {
-	return WideCharToMultiByte(CP_UTF8, 0, src, -1, dest, (int)dest_size, NULL, NULL);
+	/* Length of -1 indicates NULL termination of the input string. Subtract 1 from the result to
+	 * turn 0 into -1 (an error code) and to not count the NULL terminator as part of the string's
+	 * length. WideCharToMultiByte never returns int's minvalue, so underflow is not possible */
+	return WideCharToMultiByte(CP_UTF8, get_wc_flags(), src, -1, dest, (int)dest_size, NULL, NULL) - 1;
+}
+
+/**
+ * Converts a UTF-8 string to wide characters.
+ * Memory is allocated to hold the converted string.
+ * The caller is responsible for freeing the string with git__free.
+ *
+ * @param dest Receives a pointer to the wide string.
+ * @param src The UTF-8 string to convert.
+ * @return The length of the wide string, in characters (not counting the NULL terminator), or < 0 for failure
+ */
+int git__utf8_to_16_alloc(wchar_t **dest, const char *src)
+{
+	int utf16_size;
+
+	*dest = NULL;
+
+	/* Length of -1 indicates NULL termination of the input string */
+	utf16_size = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, src, -1, NULL, 0);
+
+	if (!utf16_size)
+		return -1;
+
+	*dest = git__malloc(utf16_size * sizeof(wchar_t));
+
+	if (!*dest)
+		return -1;
+
+	utf16_size = MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, src, -1, *dest, utf16_size);
+
+	if (!utf16_size) {
+		/* Don't let git__free stomp on the thread-local last error code,
+		* so that the caller can call giterr_set(GITERR_OS, ...) */
+		DWORD last_error = GetLastError();
+		git__free(*dest);
+		*dest = NULL;
+		SetLastError(last_error);
+	}
+
+	/* Subtract 1 from the result to turn 0 into -1 (an error code) and to not count the NULL
+	 * terminator as part of the string's length. MultiByteToWideChar never returns int's minvalue,
+	 * so underflow is not possible */
+	return utf16_size - 1;
+}
+
+/**
+ * Converts a wide string to UTF-8.
+ * Memory is allocated to hold the converted string.
+ * The caller is responsible for freeing the string with git__free.
+ *
+ * @param dest Receives a pointer to the UTF-8 string.
+ * @param src The wide string to convert.
+ * @return The length of the UTF-8 string, in bytes (not counting the NULL terminator), or < 0 for failure
+ */
+int git__utf16_to_8_alloc(char **dest, const wchar_t *src)
+{
+	int utf8_size;
+	DWORD dwFlags = get_wc_flags();
+
+	*dest = NULL;
+
+	/* Length of -1 indicates NULL termination of the input string */
+	utf8_size = WideCharToMultiByte(CP_UTF8, dwFlags, src, -1, NULL, 0, NULL, NULL);
+
+	if (!utf8_size)
+		return -1;
+
+	*dest = git__malloc(utf8_size);
+
+	if (!*dest)
+		return -1;
+
+	utf8_size = WideCharToMultiByte(CP_UTF8, dwFlags, src, -1, *dest, utf8_size, NULL, NULL);
+
+	if (!utf8_size) {
+		/* Don't let git__free stomp on the thread-local last error code,
+		 * so that the caller can call giterr_set(GITERR_OS, ...) */
+		DWORD last_error = GetLastError();
+		git__free(*dest);
+		*dest = NULL;
+		SetLastError(last_error);
+	}
+
+	/* Subtract 1 from the result to turn 0 into -1 (an error code) and to not count the NULL
+	 * terminator as part of the string's length. MultiByteToWideChar never returns int's minvalue,
+	 * so underflow is not possible */
+	return utf8_size - 1;
 }