Added support for "%[]" sscanf syntax

Fixes https://github.com/libsdl-org/SDL/issues/8423

(cherry picked from commit 39a961ba41430788774f1b8c0e6d63f7308116e7)

src/stdlib/SDL_string.c

@@ -1114,6 +1114,39 @@ int SDL_vsscanf(const char *text, const char *fmt, va_list ap)
     return vsscanf(text, fmt, ap);
 }
 #else
+static SDL_bool CharacterMatchesSet(char c, const char *set, size_t set_len)
+{
+    SDL_bool invert = SDL_FALSE;
+    SDL_bool result = SDL_FALSE;
+
+    if (*set == '^') {
+        invert = SDL_TRUE;
+        ++set;
+        --set_len;
+    }
+    while (set_len > 0 && !result) {
+        if (set_len >= 3 && set[1] == '-') {
+            char low_char = SDL_min(set[0], set[2]);
+            char high_char = SDL_max(set[0], set[2]);
+            if (c >= low_char && c <= high_char) {
+                result = SDL_TRUE;
+            }
+            set += 3;
+            set_len -= 3;
+        } else {
+            if (c == *set) {
+                result = SDL_TRUE;
+            }
+            ++set;
+            --set_len;
+        }
+    }
+    if (invert) {
+        result = result ? SDL_FALSE : SDL_TRUE;
+    }
+    return result;
+}
+
 /* NOLINTNEXTLINE(readability-non-const-parameter) */
 int SDL_vsscanf(const char *text, const char *fmt, va_list ap)
 {
@@ -1387,6 +1420,44 @@ int SDL_vsscanf(const char *text, const char *fmt, va_list ap)
                     }
                     done = SDL_TRUE;
                     break;
+                case '[':
+                {
+                    const char *set = fmt + 1;
+                    while (*fmt && *fmt != ']') {
+                        ++fmt;
+                    }
+                    if (*fmt) {
+                        size_t set_len = (fmt - set);
+                        if (suppress) {
+                            while (CharacterMatchesSet(*text, set, set_len)) {
+                                ++text;
+                                if (count) {
+                                    if (--count == 0) {
+                                        break;
+                                    }
+                                }
+                            }
+                        } else {
+                            SDL_bool had_match = SDL_FALSE;
+                            char *valuep = va_arg(ap, char *);
+                            while (CharacterMatchesSet(*text, set, set_len)) {
+                                had_match = SDL_TRUE;
+                                *valuep++ = *text++;
+                                if (count) {
+                                    if (--count == 0) {
+                                        break;
+                                    }
+                                }
+                            }
+                            *valuep = '\0';
+                            if (had_match) {
+                                ++retval;
+                            }
+                        }
+                    }
+                }
+                    done = SDL_TRUE;
+                    break;
                 default:
                     done = SDL_TRUE;
                     break;

test/testautomation_stdlib.c

@@ -351,7 +351,7 @@ int stdlib_sscanf(void *arg)
     long long_output, expected_long_output;
     long long long_long_output, expected_long_long_output;
     size_t size_output, expected_size_output;
-    char text[128];
+    char text[128], text2[128];
 
     expected_output = output = 123;
     expected_result = -1;
@@ -415,6 +415,82 @@ int stdlib_sscanf(void *arg)
     SDLTest_AssertCheck(expected_size_output == size_output, "Check output, expected: %zu, got: %zu", expected_size_output, size_output);
     SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
 
+    expected_result = 1;
+    text[0] = '\0';
+    result = SDL_sscanf("abc def", "%s", text);
+    SDLTest_AssertPass("Call to SDL_sscanf(\"abc def\", \"%%s\", text)");
+    SDLTest_AssertCheck(SDL_strcmp(text, "abc") == 0, "Check output, expected: \"abc\", got: \"%s\"", text);
+    SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
+
+    expected_result = 1;
+    text[0] = '\0';
+    result = SDL_sscanf("abc,def", "%s", text);
+    SDLTest_AssertPass("Call to SDL_sscanf(\"abc,def\", \"%%s\", text)");
+    SDLTest_AssertCheck(SDL_strcmp(text, "abc,def") == 0, "Check output, expected: \"abc\", got: \"%s\"", text);
+    SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
+
+    expected_result = 1;
+    text[0] = '\0';
+    result = SDL_sscanf("abc,def", "%[cba]", text);
+    SDLTest_AssertPass("Call to SDL_sscanf(\"abc,def\", \"%%[cba]\", text)");
+    SDLTest_AssertCheck(SDL_strcmp(text, "abc") == 0, "Check output, expected: \"abc\", got: \"%s\"", text);
+    SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
+
+    expected_result = 1;
+    text[0] = '\0';
+    result = SDL_sscanf("abc,def", "%[a-z]", text);
+    SDLTest_AssertPass("Call to SDL_sscanf(\"abc,def\", \"%%[z-a]\", text)");
+    SDLTest_AssertCheck(SDL_strcmp(text, "abc") == 0, "Check output, expected: \"abc\", got: \"%s\"", text);
+    SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
+
+    expected_result = 1;
+    text[0] = '\0';
+    result = SDL_sscanf("abc,def", "%[^,]", text);
+    SDLTest_AssertPass("Call to SDL_sscanf(\"abc,def\", \"%%[^,]\", text)");
+    SDLTest_AssertCheck(SDL_strcmp(text, "abc") == 0, "Check output, expected: \"abc\", got: \"%s\"", text);
+    SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
+
+    expected_result = 0;
+    text[0] = '\0';
+    result = SDL_sscanf("abc,def", "%[A-Z]", text);
+    SDLTest_AssertPass("Call to SDL_sscanf(\"abc,def\", \"%%[A-Z]\", text)");
+    SDLTest_AssertCheck(SDL_strcmp(text, "") == 0, "Check output, expected: \"\", got: \"%s\"", text);
+    SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
+
+    expected_result = 2;
+    text[0] = '\0';
+    text2[0] = '\0';
+    result = SDL_sscanf("abc,def", "%[abc],%[def]", text, text2);
+    SDLTest_AssertPass("Call to SDL_sscanf(\"abc,def\", \"%%[abc],%%[def]\", text)");
+    SDLTest_AssertCheck(SDL_strcmp(text, "abc") == 0, "Check output, expected: \"abc\", got: \"%s\"", text);
+    SDLTest_AssertCheck(SDL_strcmp(text2, "def") == 0, "Check output, expected: \"def\", got: \"%s\"", text2);
+    SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
+
+    expected_result = 2;
+    text[0] = '\0';
+    text2[0] = '\0';
+    result = SDL_sscanf("abc,def", "%[abc]%*[,]%[def]", text, text2);
+    SDLTest_AssertPass("Call to SDL_sscanf(\"abc,def\", \"%%[abc]%%*[,]%%[def]\", text)");
+    SDLTest_AssertCheck(SDL_strcmp(text, "abc") == 0, "Check output, expected: \"abc\", got: \"%s\"", text);
+    SDLTest_AssertCheck(SDL_strcmp(text2, "def") == 0, "Check output, expected: \"def\", got: \"%s\"", text2);
+    SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
+
+    expected_result = 2;
+    text[0] = '\0';
+    text2[0] = '\0';
+    result = SDL_sscanf("abc   def", "%[abc] %[def]", text, text2);
+    SDLTest_AssertPass("Call to SDL_sscanf(\"abc   def\", \"%%[abc] %%[def]\", text)");
+    SDLTest_AssertCheck(SDL_strcmp(text, "abc") == 0, "Check output, expected: \"abc\", got: \"%s\"", text);
+    SDLTest_AssertCheck(SDL_strcmp(text2, "def") == 0, "Check output, expected: \"def\", got: \"%s\"", text2);
+    SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
+
+    expected_result = 1;
+    text[0] = '\0';
+    result = SDL_sscanf("abc123XYZ", "%[a-zA-Z0-9]", text);
+    SDLTest_AssertPass("Call to SDL_sscanf(\"abc123XYZ\", \"%%[a-zA-Z0-9]\", text)");
+    SDLTest_AssertCheck(SDL_strcmp(text, "abc123XYZ") == 0, "Check output, expected: \"abc123XYZ\", got: \"%s\"", text);
+    SDLTest_AssertCheck(expected_result == result, "Check return value, expected: %i, got: %i", expected_result, result);
+
     return TEST_COMPLETED;
 }