Finding current executable's path without /proc/self/exe

Question

It seems to me that Linux has it easy with /proc/self/exe. But I\'d like to know if there is a convenient way to find the current application\'s directory in C/C++ with cros

Answer 1

Just my two cents. You can find the current application's directory in C/C++ with cross-platform interfaces by using this code.

void getExecutablePath(char ** path, unsigned int * pathLength)
{
    // Early exit when invalid out-parameters are passed
    if (!checkStringOutParameter(path, pathLength))
    {
        return;
    }

#if defined SYSTEM_LINUX

    // Preallocate PATH_MAX (e.g., 4096) characters and hope the executable path isn't longer (including null byte)
    char exePath[PATH_MAX];

    // Return written bytes, indicating if memory was sufficient
    int len = readlink("/proc/self/exe", exePath, PATH_MAX);

    if (len <= 0 || len == PATH_MAX) // memory not sufficient or general error occured
    {
        invalidateStringOutParameter(path, pathLength);
        return;
    }

    // Copy contents to caller, create caller ownership
    copyToStringOutParameter(exePath, len, path, pathLength);

#elif defined SYSTEM_WINDOWS

    // Preallocate MAX_PATH (e.g., 4095) characters and hope the executable path isn't longer (including null byte)
    char exePath[MAX_PATH];

    // Return written bytes, indicating if memory was sufficient
    unsigned int len = GetModuleFileNameA(GetModuleHandleA(0x0), exePath, MAX_PATH);
    if (len == 0) // memory not sufficient or general error occured
    {
        invalidateStringOutParameter(path, pathLength);
        return;
    }

    // Copy contents to caller, create caller ownership
    copyToStringOutParameter(exePath, len, path, pathLength);

#elif defined SYSTEM_SOLARIS

    // Preallocate PATH_MAX (e.g., 4096) characters and hope the executable path isn't longer (including null byte)
    char exePath[PATH_MAX];

    // Convert executable path to canonical path, return null pointer on error
    if (realpath(getexecname(), exePath) == 0x0)
    {
        invalidateStringOutParameter(path, pathLength);
        return;
    }

    // Copy contents to caller, create caller ownership
    unsigned int len = strlen(exePath);
    copyToStringOutParameter(exePath, len, path, pathLength);

#elif defined SYSTEM_DARWIN

    // Preallocate PATH_MAX (e.g., 4096) characters and hope the executable path isn't longer (including null byte)
    char exePath[PATH_MAX];

    unsigned int len = (unsigned int)PATH_MAX;

    // Obtain executable path to canonical path, return zero on success
    if (_NSGetExecutablePath(exePath, &len) == 0)
    {
        // Convert executable path to canonical path, return null pointer on error
        char * realPath = realpath(exePath, 0x0);

        if (realPath == 0x0)
        {
            invalidateStringOutParameter(path, pathLength);
            return;
        }

        // Copy contents to caller, create caller ownership
        unsigned int len = strlen(realPath);
        copyToStringOutParameter(realPath, len, path, pathLength);

        free(realPath);
    }
    else // len is initialized with the required number of bytes (including zero byte)
    {
        char * intermediatePath = (char *)malloc(sizeof(char) * len);

        // Convert executable path to canonical path, return null pointer on error
        if (_NSGetExecutablePath(intermediatePath, &len) != 0)
        {
            free(intermediatePath);
            invalidateStringOutParameter(path, pathLength);
            return;
        }

        char * realPath = realpath(intermediatePath, 0x0);

        free(intermediatePath);

        // Check if conversion to canonical path succeeded
        if (realPath == 0x0)
        {
            invalidateStringOutParameter(path, pathLength);
            return;
        }

        // Copy contents to caller, create caller ownership
        unsigned int len = strlen(realPath);
        copyToStringOutParameter(realPath, len, path, pathLength);

        free(realPath);
    }

#elif defined SYSTEM_FREEBSD

    // Preallocate characters and hope the executable path isn't longer (including null byte)
    char exePath[2048];

    unsigned int len = 2048;

    int mib[] = { CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1 };

    // Obtain executable path by syscall
    if (sysctl(mib, 4, exePath, &len, 0x0, 0) != 0)
    {
        invalidateStringOutParameter(path, pathLength);
        return;
    }

    // Copy contents to caller, create caller ownership
    copyToStringOutParameter(exePath, len, path, pathLength);

#else

    // If no OS could be detected ... degrade gracefully
    invalidateStringOutParameter(path, pathLength);

#endif
}

You can take a look in detail here.