Daniel Nashed's Blog

Why is argv[0] in C/C++ not a good idea to use

argv[0] on Linux and Windows


Looking into the APIs for creating new processes shows that and application can specify any string as arg[0] when calling your process.
This leads to the conclusion that using argv[0] as a trustworthy information isn't a good idea.
I would even recommend not using it at all even for display purposes and would just skip argv[0] completely.


What would be a good way to determine the binary name?


On Linux the proc file system contains information about processes. It's by the way a very easy to use standardized way accessing process information.
There is even a special link "/proc/self" which represents the running process binary.

Using readlink ("/proc/self/exe"...) is a simple way to get the current binary name.

On Windows using GetModuleFileName (NULL, ...) is a good way to get the current binary name.

-- Daniel



Refrences


Linux:

https://man7.org/linux/man-pages/man3/exec.3.html

Example:

execl (szProgram, szProgram, szArg1, szArg2, NULL);


Windows:

https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessa

Example:

    bSuccess = CreateProcessAsUser(
        NULL, // Application name
        pszCommandLine,
        NULL,
        NULL,
        FALSE,
        NORMAL_PRIORITY_CLASS | CREATE_NEW_CONSOLE | CREATE_NEW_PROCESS_GROUP,
        NULL,
        pszWorkDir,
        &StartupInfo,
        &ProcessInfo);

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