VuoUrl.c

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#include "type.h"
#include "VuoUrl.h"
#include "VuoOsStatus.h"
 
#include <regex.h>
#include <mach-o/dyld.h> // for _NSGetExecutablePath()
#include <libgen.h> // for dirname()
#include <CoreServices/CoreServices.h>
#include "VuoUrlParser.h"
 
 
#ifdef VUO_COMPILER
VuoModuleMetadata({
                     "title" : "URL",
                     "description" : "Uniform Resource Locator.",
                     "keywords" : [ "link" ],
                     "version" : "1.0.0",
                     "dependencies" : [
                        "CoreServices.framework",
                        "VuoInteger",
                        "VuoOsStatus",
                        "VuoText",
                        "VuoUrlParser"
                     ]
                 });
#endif
 
VuoUrl VuoUrl_makeFromJson(json_object *js)
{
    const char *textString = "";
    if (json_object_get_type(js) == json_type_string)
        textString = json_object_get_string(js);
 
    VuoUrl url;
    if (textString)
        url = strdup(textString);
    else
        url = strdup("");
    VuoRegister(url, free);
 
    return url;
}
 
json_object *VuoUrl_getJson(const VuoUrl value)
{
    if (!value)
        return json_object_new_string("");
 
    return json_object_new_string(value);
}
 
char *VuoUrl_getSummary(const VuoUrl value)
{
    VuoText t = VuoText_truncateWithEllipsis(value, 1024, VuoTextTruncation_End);
    VuoRetain(t);
    char *summary = strdup(t);
    VuoRelease(t);
    return summary;
}
 
bool VuoUrl_getParts(const VuoUrl url, VuoText *scheme, VuoText *user, VuoText *host, VuoInteger *port, VuoText *path, VuoText *query, VuoText *fragment)
{
    if (VuoText_isEmpty(url))
        return false;
 
    struct http_parser_url parsedUrl;
    size_t urlLen = strlen(url);
    if (http_parser_parse_url(url, urlLen, false, &parsedUrl))
    {
        // Maybe this is a "data:" URI (which http_parser_parse_url can't parse).
        if (strncmp(url, "data:", 5) == 0)
        {
            if (scheme)
                *scheme = VuoText_make("data");
            if (user)
                *user = NULL;
            if (host)
                *host = NULL;
            if (port)
                *port = 0;
            if (path)
                *path = NULL;
            if (query)
                *query = NULL;
            if (fragment)
                *fragment = NULL;
            return true;
        }
 
        // Maybe this is a "no-authority" `file:` URI (which http_parser_parse_url can't parse);
        // change it to an "empty-authority" URI.
        else if (strncmp(url, "file:/", 6) == 0 && urlLen > 6 && url[6] != '/')
        {
            char *urlWithEmptyAuthority = malloc(urlLen + 2 + 1);
            strcpy(urlWithEmptyAuthority, "file://");
            strcat(urlWithEmptyAuthority, url + 5);
            if (http_parser_parse_url(urlWithEmptyAuthority, urlLen + 2, false, &parsedUrl))
            {
                free(urlWithEmptyAuthority);
                return false;
            }
            free(urlWithEmptyAuthority);
        }
 
        else
            return false;
    }
 
    if (scheme)
    {
        if (parsedUrl.field_set & (1 << UF_SCHEMA))
            *scheme = VuoText_makeWithMaxLength(url + parsedUrl.field_data[UF_SCHEMA  ].off, parsedUrl.field_data[UF_SCHEMA  ].len);
        else
            *scheme = NULL;
    }
 
    if (user)
    {
        if (parsedUrl.field_set & (1 << UF_USERINFO))
            *user   = VuoText_makeWithMaxLength(url + parsedUrl.field_data[UF_USERINFO].off, parsedUrl.field_data[UF_USERINFO].len);
        else
            *user   = NULL;
    }
 
    if (host)
    {
        if (parsedUrl.field_set & (1 << UF_HOST))
            *host   = VuoText_makeWithMaxLength(url + parsedUrl.field_data[UF_HOST    ].off, parsedUrl.field_data[UF_HOST    ].len);
        else
            *host   = NULL;
    }
 
    if (port)
    {
        if (parsedUrl.field_set & (1 << UF_PORT))
            // Explicitly-specified port
            *port = parsedUrl.port;
        else
        {
            // Guess the port from the scheme
            *port = 0;
            if (strcmp(*scheme, "http") == 0)
                *port = 80;
            else if (strcmp(*scheme, "https") == 0)
                *port = 443;
        }
    }
 
    if (path)
    {
        if (parsedUrl.field_set & (1 << UF_PATH))
            *path     = VuoText_makeWithMaxLength(url + parsedUrl.field_data[UF_PATH    ].off, parsedUrl.field_data[UF_PATH    ].len);
        else
            *path     = NULL;
    }
 
    if (query)
    {
        if (parsedUrl.field_set & (1 << UF_QUERY))
            *query    = VuoText_makeWithMaxLength(url + parsedUrl.field_data[UF_QUERY   ].off, parsedUrl.field_data[UF_QUERY   ].len);
        else
            *query    = NULL;
    }
 
    if (fragment)
    {
        if (parsedUrl.field_set & (1 << UF_FRAGMENT))
            *fragment = VuoText_makeWithMaxLength(url + parsedUrl.field_data[UF_FRAGMENT].off, parsedUrl.field_data[UF_FRAGMENT].len);
        else
            *fragment = NULL;
    }
 
    return true;
}
 
bool VuoUrl_getFileParts(const VuoUrl url, VuoText *path, VuoText *folder, VuoText *filename, VuoText *extension)
{
    if (VuoText_isEmpty(url))
        return false;
 
    *path = VuoUrl_getPosixPath(url);
    if (!*path)
        return false;
 
    size_t separatorIndex = VuoText_findLastOccurrence(*path, "/");
    VuoText fileAndExtension;
    if (separatorIndex)
    {
        *folder = VuoText_substring(*path, 1, separatorIndex);
        size_t length = VuoText_length(*path);
        if (separatorIndex < length)
            fileAndExtension = VuoText_substring(*path, separatorIndex + 1, length);
        else
            fileAndExtension = NULL;
    }
    else
    {
        *folder = NULL;
        fileAndExtension = VuoText_make(*path);
    }
    VuoRetain(fileAndExtension);
 
    size_t dotIndex = VuoText_findLastOccurrence(fileAndExtension, ".");
    if (dotIndex)
    {
        *filename = VuoText_substring(fileAndExtension, 1, dotIndex - 1);
        *extension = VuoText_substring(fileAndExtension, dotIndex + 1, VuoText_length(fileAndExtension));
    }
    else
    {
        *filename = VuoText_make(fileAndExtension);
        *extension = NULL;
    }
 
    VuoRelease(fileAndExtension);
 
    return true;
}
 
bool VuoUrl_areEqual(const VuoText a, const VuoText b)
{
    return VuoText_areEqual(a,b);
}
 
bool VuoUrl_isLessThan(const VuoText a, const VuoText b)
{
    return VuoText_isLessThan(a,b);
}
 
static bool VuoUrl_urlContainsScheme(const char *url)
{
    const char *urlWithSchemePattern = "^[a-zA-Z][a-zA-Z0-9+-\\.]+:";
    regex_t    urlWithSchemeRegExp;
    size_t     nmatch = 0;
    regmatch_t pmatch[0];
 
    regcomp(&urlWithSchemeRegExp, urlWithSchemePattern, REG_EXTENDED);
    bool matchFound = !regexec(&urlWithSchemeRegExp, url, nmatch, pmatch, 0);
    regfree(&urlWithSchemeRegExp);
 
    return matchFound;
}
 
static bool VuoUrl_urlIsAbsoluteFilePath(const char *url)
{
    return ((strlen(url) >= 1) && (url[0] == '/'));
}
 
static bool VuoUrl_urlIsUserRelativeFilePath(const char *url)
{
    return ((strlen(url) >= 1) && (url[0] == '~'));
}
 
bool VuoUrl_isRelativePath(const VuoUrl url)
{
    return !((VuoText_length(url)==0) ||
             VuoUrl_urlContainsScheme(url) ||
             VuoUrl_urlIsAbsoluteFilePath(url) ||
             VuoUrl_urlIsUserRelativeFilePath(url));
}
 
static const char VuoUrl_reservedCharacters[] =
{
          0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
    '"', '$', '&', '+', ',', ':', ';', '=', '?', '@', '#', ' ',
    // Percent must be last, so we don't escape the escapes.
    '%'
};
 
VuoText VuoUrl_escapePosixPath(const VuoText path)
{
    // Figure out how many characters we need to allocate for the escaped string.
    unsigned long inLength = strlen(path);
    unsigned long escapedLength = 0;
    for (unsigned long i = 0; i < inLength; ++i)
    {
        char c = path[i];
        for (int j = 0; j < sizeof(VuoUrl_reservedCharacters); ++j)
            if (c == VuoUrl_reservedCharacters[j])
            {
                escapedLength += 2; // Expanding 1 character to "%xx"
                break;
            }
        ++escapedLength;
    }
 
    // Escape the string.
    char *escapedUrl = (char *)malloc(escapedLength + 1);
    unsigned long outIndex = 0;
    const char *hexCharSet = "0123456789ABCDEF";  // Uppercase per https://tools.ietf.org/html/rfc3987#section-3.1
    for (unsigned long inIndex = 0; inIndex < inLength; ++inIndex)
    {
        unsigned char c = path[inIndex];
        bool foundEscape = false;
        for (int j = 0; j < sizeof(VuoUrl_reservedCharacters); ++j)
            if (c == VuoUrl_reservedCharacters[j])
            {
                escapedUrl[outIndex++] = '%';
                escapedUrl[outIndex++] = hexCharSet[c >> 4];
                escapedUrl[outIndex++] = hexCharSet[c & 0x0f];
                foundEscape = true;
                break;
            }
 
        // https://b33p.net/kosada/node/12361
        // If it's a UTF-8 "Modifier Letter Colon", translate it back into an escaped ASCII-7 colon
        // (since URLs can handle colons, unlike POSIX paths on macOS).
        if (inIndex+2 < inLength)
            if (c == 0xea && (unsigned char)path[inIndex+1] == 0x9e && (unsigned char)path[inIndex+2] == 0x89)
            {
                escapedUrl[outIndex++] = '%';
                escapedUrl[outIndex++] = hexCharSet[':' >> 4];
                escapedUrl[outIndex++] = hexCharSet[':' & 0x0f];
                foundEscape = true;
                inIndex += 2;
            }
 
        if (!foundEscape)
            escapedUrl[outIndex++] = c;
    }
    escapedUrl[outIndex] = 0;
 
    VuoText escapedUrlVT = VuoText_make(escapedUrl);
    free(escapedUrl);
 
    return escapedUrlVT;
}
 
VuoText VuoUrl_escapeUTF8(const VuoText url)
{
    // Figure out how many characters we need to allocate for the escaped string.
    unsigned long inLength = strlen(url);
    unsigned long escapedLength = 0;
    for (unsigned long i = 0; i < inLength; ++i)
    {
        if ((unsigned char)url[i] > 0x7f)
            escapedLength += 2;  // Expanding 1 character to "%xx"
        ++escapedLength;
    }
 
    // Escape the string.
    char *escapedUrl = (char *)malloc(escapedLength + 1);
    unsigned long outIndex = 0;
    const char *hexCharSet = "0123456789ABCDEF";  // Uppercase per https://tools.ietf.org/html/rfc3987#section-3.1
    for (unsigned long inIndex = 0; inIndex < inLength; ++inIndex)
    {
        unsigned char c = url[inIndex];
        if (c > 0x7f)
        {
            escapedUrl[outIndex++] = '%';
            escapedUrl[outIndex++] = hexCharSet[c >> 4];
            escapedUrl[outIndex++] = hexCharSet[c & 0x0f];
        }
        else
            escapedUrl[outIndex++] = c;
    }
    escapedUrl[outIndex] = 0;
 
    VuoText escapedUrlVT = VuoText_make(escapedUrl);
    free(escapedUrl);
 
    return escapedUrlVT;
}
 
static const char *VuoUrl_fileScheme = "file:"; 
static const char *VuoUrl_httpScheme = "http://"; 
 
VuoUrl VuoUrl_normalize(const VuoText url, enum VuoUrlNormalizeFlags flags)
{
    if (!url)
        return NULL;
 
    // Trim off the file schema, if present, and handle such URLs via the absolute/user-relative/relative file path cases below.
    VuoText trimmedUrl;
    unsigned long fileSchemeLength = strlen(VuoUrl_fileScheme);
    if (strncmp(url, VuoUrl_fileScheme, fileSchemeLength) == 0)
    {
        VuoText u = url + fileSchemeLength;
        if (strncmp(u, "//", 2) == 0)
            u += 2;
 
        // Assume a URL with a schema is already escaped; unescape it for consistent processing below.
        trimmedUrl = VuoUrl_decodeRFC3986(u);
    }
    else
        trimmedUrl = url;
    VuoRetain(trimmedUrl);
 
    char *resolvedUrl;
 
    // Case: The url contains a scheme.
    if (VuoUrl_urlContainsScheme(trimmedUrl))
    {
        // Some URLs have literal spaces, which we need to transform into '%20' before passing to cURL.
        size_t urlLen = strlen(trimmedUrl);
        size_t spaceCount = 0;
        for (size_t i = 0; i < urlLen; ++i)
            if (trimmedUrl[i] == ' ')
                ++spaceCount;
        if (spaceCount)
        {
            resolvedUrl = (char *)malloc(strlen(trimmedUrl) + spaceCount*2);
            size_t p = 0;
            for (size_t i = 0; i < urlLen; ++i)
                if (trimmedUrl[i] == ' ')
                {
                    resolvedUrl[p++] = '%';
                    resolvedUrl[p++] = '2';
                    resolvedUrl[p++] = '0';
                }
                else
                    resolvedUrl[p++] = trimmedUrl[i];
            resolvedUrl[p] = 0;
        }
        else
            resolvedUrl = strdup(trimmedUrl);
    }
 
    // Case: The url contains an absolute file path.
    else if (VuoUrl_urlIsAbsoluteFilePath(trimmedUrl))
    {
        char *filePath = (char *)trimmedUrl;
 
        if (!(flags & VuoUrlNormalize_forSaving) && strncmp(filePath, "/tmp/", 5) == 0)
        {
            // We're trying to read a file from `/tmp`.
            // If it doesn't exist there, also check the user's private temporary directory.
            // Enables protocol driver compositions to find their default images.
            if (access(filePath, 0) != 0)
            {
                char userTempDir[PATH_MAX];
                size_t userTempDirLen;
                if ((userTempDirLen = confstr(_CS_DARWIN_USER_TEMP_DIR, userTempDir, PATH_MAX)) > 0)
                {
                    size_t filePathLen = strlen(filePath);
                    size_t mallocSize = userTempDirLen + filePathLen + 1;
                    char *privateFilePath = (char *)malloc(mallocSize);
                    strlcpy(privateFilePath, userTempDir, mallocSize);
                    strlcat(privateFilePath, filePath + 4, mallocSize);
                    filePath = privateFilePath;
                }
            }
        }
 
        char *realPath = realpath(filePath, NULL);
        // If realpath() fails, it's probably because the path doesn't exist, so just use the non-realpath()ed path.
        VuoText escapedPath = VuoUrl_escapePosixPath(realPath ? realPath : filePath);
        VuoRetain(escapedPath);
        if (realPath)
            free(realPath);
        if (filePath != trimmedUrl)
            free(filePath);
 
        size_t mallocSize = strlen(VuoUrl_fileScheme) + strlen(escapedPath) + 1;
        resolvedUrl = (char *)malloc(mallocSize);
        strlcpy(resolvedUrl, VuoUrl_fileScheme, mallocSize);
        strlcat(resolvedUrl, escapedPath, mallocSize);
 
        VuoRelease(escapedPath);
    }
 
    // Case: The url contains a user-relative (`~/…`) file path.
    else if (VuoUrl_urlIsUserRelativeFilePath(trimmedUrl))
    {
        // 1. Expand the tilde into an absolute path.
        VuoText absolutePath;
        {
            char *homeDir = getenv("HOME");
            VuoText paths[2] = { homeDir, trimmedUrl+1 };
            absolutePath = VuoText_append(paths, 2);
        }
        VuoLocal(absolutePath);
 
        // 2. Try to canonicalize the absolute path, and URL-escape it.
        char *realPath = realpath(absolutePath, NULL);
        // If realpath() fails, it's probably because the path doesn't exist, so just use the non-realpath()ed path.
        VuoText escapedPath = VuoUrl_escapePosixPath(realPath ? realPath : absolutePath);
        VuoLocal(escapedPath);
        if (realPath)
            free(realPath);
 
        // 3. Prepend the URL scheme.
        size_t mallocSize = strlen(VuoUrl_fileScheme) + strlen(escapedPath) + 1;
        resolvedUrl = (char *)malloc(mallocSize);
        strlcpy(resolvedUrl, VuoUrl_fileScheme, mallocSize);
        strlcat(resolvedUrl, escapedPath, mallocSize);
    }
 
    // Case: The url contains a web link without a protocol/scheme.
    else if (flags & VuoUrlNormalize_assumeHttp)
    {
        // Prepend the URL scheme.
        size_t mallocSize = strlen(VuoUrl_httpScheme) + strlen(trimmedUrl) + 1;
        resolvedUrl = (char *)malloc(mallocSize);
        strlcpy(resolvedUrl, VuoUrl_httpScheme, mallocSize);
        strlcat(resolvedUrl, trimmedUrl, mallocSize);
    }
 
    // Case: The url contains a relative file path.
    else
    {
        const char *currentWorkingDir = VuoGetWorkingDirectory();
 
        // - When macOS LaunchServices launches an app, it sets the current working directory to root.
        // - When macOS ScreenSaverEngine launches a plugin, it sets the current working directory to
        //   `~/Library/Containers/com.apple.ScreenSaver.Engine.legacyScreenSaver/Data`.
        bool compositionIsExportedAppOrPlugin = false;
        char *absolutePath;
        if (strcmp(currentWorkingDir, "/") == 0
         || strstr(currentWorkingDir, "/Library/Containers/"))
        {
            // If we're running as an exported app or plugin,
            // resolve loaded resources relative to the app bundle's "Resources" directory, and
            // resolve saved resources relative to the user's Desktop.
 
            // Get the exported executable path.
            char rawExecutablePath[PATH_MAX+1];
            uint32_t size = sizeof(rawExecutablePath);
            _NSGetExecutablePath(rawExecutablePath, &size);
 
            char cleanedExecutablePath[PATH_MAX+1];
            realpath(rawExecutablePath, cleanedExecutablePath);
 
            // Derive the path of the app bundle's "Resources" directory from its executable path.
            size_t pathSize = PATH_MAX + 1;
            char executableDir[pathSize];
            strlcpy(executableDir, dirname(cleanedExecutablePath), pathSize);
 
            const char *resourcesPathFromExecutable = "/../Resources";
            pathSize = strlen(executableDir) + strlen(resourcesPathFromExecutable) + 1;
            char rawResourcesPath[pathSize];
            strlcpy(rawResourcesPath, executableDir, pathSize);
            strlcat(rawResourcesPath, resourcesPathFromExecutable, pathSize);
 
            char cleanedResourcesPath[PATH_MAX+1];
            realpath(rawResourcesPath, cleanedResourcesPath);
 
            // If the "Resources" directory does not exist, we must not be dealing with an exported app after all.
            // If it does, proceed under the assumption that we are.
            if (access(cleanedResourcesPath, 0) == 0)
            {
                compositionIsExportedAppOrPlugin = true;
 
                if (flags & VuoUrlNormalize_forSaving)
                {
                    char *homeDir = getenv("HOME");
                    const char *desktop = "/Desktop/";
                    size_t mallocSize = strlen(homeDir) + strlen(desktop) + strlen(trimmedUrl) + 1;
                    absolutePath = (char *)malloc(mallocSize);
                    strlcpy(absolutePath, homeDir, mallocSize);
                    strlcat(absolutePath, desktop, mallocSize);
                    strlcat(absolutePath, trimmedUrl, mallocSize);
                }
                else
                {
                    size_t mallocSize = strlen(cleanedResourcesPath) + strlen("/") + strlen(trimmedUrl) + 1;
                    absolutePath = (char *)malloc(mallocSize);
                    strlcpy(absolutePath, cleanedResourcesPath, mallocSize);
                    strlcat(absolutePath, "/", mallocSize);
                    strlcat(absolutePath, trimmedUrl, mallocSize);
                }
            }
        }
 
        // If we are not working with an exported app, resolve resources relative to the current working directory.
        if (!compositionIsExportedAppOrPlugin)
        {
            size_t mallocSize = strlen(currentWorkingDir) + strlen("/") + strlen(trimmedUrl) + 1;
            absolutePath = (char *)malloc(mallocSize);
            strlcpy(absolutePath, currentWorkingDir, mallocSize);
            strlcat(absolutePath, "/", mallocSize);
            strlcat(absolutePath, trimmedUrl, mallocSize);
        }
 
        char *realPath = realpath(absolutePath, NULL);
        // If realpath() fails, it's probably because the path doesn't exist, so just use the non-realpath()ed path.
        VuoText escapedPath = VuoUrl_escapePosixPath(realPath ? realPath : absolutePath);
        VuoLocal(escapedPath);
        if (realPath)
            free(realPath);
        free(absolutePath);
 
        // Prepend the URL scheme.
        size_t mallocSize = strlen(VuoUrl_fileScheme) + strlen(escapedPath) + 1;
        resolvedUrl = (char *)malloc(mallocSize);
        strlcpy(resolvedUrl, VuoUrl_fileScheme, mallocSize);
        strlcat(resolvedUrl, escapedPath, mallocSize);
    }
 
    VuoRelease(trimmedUrl);
 
    // Remove trailing slash, if any.
    size_t lastIndex = strlen(resolvedUrl) - 1;
    if (resolvedUrl[lastIndex] == '/')
        resolvedUrl[lastIndex] = 0;
 
    VuoText resolvedUrlVT = VuoText_make(resolvedUrl);
    VuoRetain(resolvedUrlVT);
    free(resolvedUrl);
 
    VuoText escapedUrl = VuoUrl_escapeUTF8(resolvedUrlVT);
    VuoRelease(resolvedUrlVT);
    return escapedUrl;
}
 
VuoText VuoUrl_decodeRFC3986(const VuoUrl url)
{
    unsigned long inLength = strlen(url);
    char *unescapedUrl = (char *)malloc(inLength + 1);
    unsigned long outIndex = 0;
    for (unsigned long inIndex = 0; inIndex < inLength; ++inIndex, ++outIndex)
    {
        char c = url[inIndex];
        if (c == '%')
        {
            if (inIndex + 2 >= inLength)
                break;
            char highNibbleASCII = url[++inIndex];
            char lowNibbleASCII = url[++inIndex];
            unescapedUrl[outIndex] = (VuoInteger_makeFromHexByte(highNibbleASCII) << 4) + VuoInteger_makeFromHexByte(lowNibbleASCII);
        }
        else
            unescapedUrl[outIndex] = c;
    }
    unescapedUrl[outIndex] = 0;
 
    VuoText unescapedUrlVT = VuoText_make(unescapedUrl);
    free(unescapedUrl);
    return unescapedUrlVT;
}
 
VuoText VuoUrl_getPosixPath(const VuoUrl url)
{
    if (!url)
        return NULL;
 
    unsigned long fileSchemeLength = strlen(VuoUrl_fileScheme);
    if (strncmp(url, VuoUrl_fileScheme, fileSchemeLength) != 0)
        return NULL;
 
    // https://tools.ietf.org/html/rfc8089#appendix-B
    if (strncmp(url + fileSchemeLength, "//", 2) == 0)
        fileSchemeLength += 2;
 
    // Unescape the string.
    unsigned long inLength = strlen(url);
    // Make room for Unicode colons.
    char *unescapedUrl = (char *)malloc(inLength*3 + 1);
    unsigned long outIndex = 0;
    for (unsigned long inIndex = fileSchemeLength; inIndex < inLength; ++inIndex, ++outIndex)
    {
        char c = url[inIndex];
        if (c == '%')
        {
            char highNibbleASCII = url[++inIndex];
            char lowNibbleASCII = url[++inIndex];
            unescapedUrl[outIndex] = (VuoInteger_makeFromHexByte(highNibbleASCII) << 4) + VuoInteger_makeFromHexByte(lowNibbleASCII);
        }
        else
            unescapedUrl[outIndex] = c;
 
        // https://b33p.net/kosada/node/12361
        // macOS presents colons as forward-slashes (https://developer.apple.com/library/mac/qa/qa1392/).
        // To avoid confusion with dates, change ASCII-7 colon to UTF-8 "Modifier Letter Colon"
        // (which looks visually identical to ASCII-7 colon).
        if (unescapedUrl[outIndex] == ':')
        {
            unescapedUrl[outIndex++] = 0xea;
            unescapedUrl[outIndex++] = 0x9e;
            unescapedUrl[outIndex]   = 0x89;
        }
    }
    unescapedUrl[outIndex] = 0;
 
    VuoText unescapedUrlVT = VuoText_make(unescapedUrl);
    free(unescapedUrl);
 
    return unescapedUrlVT;
}
 
bool VuoUrl_isBundle(const VuoUrl url)
{
    if (VuoText_isEmpty(url))
        return false;
 
    {
        VuoText path = VuoUrl_getPosixPath(url);
        if (!path)
            return false;
        VuoRetain(path);
        VuoRelease(path);
    }
 
    CFStringRef urlCFS = CFStringCreateWithCString(NULL, url, kCFStringEncodingUTF8);
    CFURLRef cfurl = CFURLCreateWithString(NULL, urlCFS, NULL);
    CFRelease(urlCFS);
    if (!cfurl)
    {
        VUserLog("Error: Couldn't check '%s': Invalid URL.", url);
        return false;
    }
 
    LSItemInfoRecord outItemInfo;
    OSStatus ret = LSCopyItemInfoForURL(cfurl, kLSRequestAllFlags, &outItemInfo);
    CFRelease(cfurl);
    if (ret)
    {
        char *errorString = VuoOsStatus_getText(ret);
        VUserLog("Error: Couldn't check '%s': %s", url, errorString);
        free(errorString);
        return false;
    }
    return outItemInfo.flags & kLSItemInfoIsPackage;
}
 
VuoUrl VuoUrl_appendFileExtension(const char *filename, struct json_object *validExtensions)
{
    char* fileSuffix = strrchr(filename, '.');
    char* curExtension = fileSuffix != NULL ? strdup(fileSuffix+1) : NULL;
 
    if(curExtension != NULL)
        for(char *p = &curExtension[0]; *p; p++) *p = tolower(*p);
 
    // if the string already has one of the valid file extension suffixes, return.
    for (int i = 0; i < json_object_array_length(validExtensions); ++i)
    {
        if (curExtension != NULL && strcmp(curExtension, json_object_get_string(json_object_array_get_idx(validExtensions, i))) == 0)
        {
            free(curExtension);
            return VuoText_make(filename);
        }
    }
 
    free(curExtension);
 
    const char *chosenExtension = json_object_get_string(json_object_array_get_idx(validExtensions, 0));
    size_t buf_size             = strlen(filename) + strlen(chosenExtension) + 2;
    char* newfilepath = (char*)malloc(buf_size * sizeof(char));
    snprintf(newfilepath, buf_size, "%s.%s", filename, chosenExtension);
 
    VuoText text = VuoText_make(newfilepath);
    free(newfilepath);
 
    return text;
}