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

Making this work reliably across platforms requires using #ifdef statements.

The below code finds the executable's path in Windows, Linux, MacOS, Solaris or FreeBSD (although FreeBSD is untested). It uses boost>=1.55.0 to simplify the code but it's easy enough to remove if you want. Just use defines like _MSC_VER and __linux as the OS and compiler require.

#include 
#include 

#if (BOOST_OS_WINDOWS)
#  include 
#elif (BOOST_OS_SOLARIS)
#  include 
#  include 
#elif (BOOST_OS_LINUX)
#  include 
#  include 
#elif (BOOST_OS_MACOS)
#  include 
#elif (BOOST_OS_BSD_FREE)
#  include 
#  include 
#endif

/*
 * Returns the full path to the currently running executable,
 * or an empty string in case of failure.
 */
std::string getExecutablePath() {
#if (BOOST_OS_WINDOWS)
    char *exePath;
    if (_get_pgmptr(&exePath) != 0)
        exePath = "";
#elif (BOOST_OS_SOLARIS)
    char exePath[PATH_MAX];
    if (realpath(getexecname(), exePath) == NULL)
        exePath[0] = '\0';
#elif (BOOST_OS_LINUX)
    char exePath[PATH_MAX];
    ssize_t len = ::readlink("/proc/self/exe", exePath, sizeof(exePath));
    if (len == -1 || len == sizeof(exePath))
        len = 0;
    exePath[len] = '\0';
#elif (BOOST_OS_MACOS)
    char exePath[PATH_MAX];
    uint32_t len = sizeof(exePath);
    if (_NSGetExecutablePath(exePath, &len) != 0) {
        exePath[0] = '\0'; // buffer too small (!)
    } else {
        // resolve symlinks, ., .. if possible
        char *canonicalPath = realpath(exePath, NULL);
        if (canonicalPath != NULL) {
            strncpy(exePath,canonicalPath,len);
            free(canonicalPath);
        }
    }
#elif (BOOST_OS_BSD_FREE)
    char exePath[2048];
    int mib[4];  mib[0] = CTL_KERN;  mib[1] = KERN_PROC;  mib[2] = KERN_PROC_PATHNAME;  mib[3] = -1;
    size_t len = sizeof(exePath);
    if (sysctl(mib, 4, exePath, &len, NULL, 0) != 0)
        exePath[0] = '\0';
#endif
    return std::string(exePath);
}

The above version returns full paths including the executable name. If instead you want the path without the executable name, #include boost/filesystem.hpp> and change the return statement to:

return strlen(exePath)>0 ? boost::filesystem::path(exePath).remove_filename().make_preferred().string() : std::string();