3 ms·

"Windows’ own API calls for creating new processes (such as CreateProcess [6], ShellExecute [7]) do not allow you to set argv[0]: it sets it for you, based on h

by skobes 2y ago

"Windows’ own API calls for creating new processes (such as CreateProcess [6], ShellExecute [7]) do not allow you to set argv[0]: it sets it for you, based on how the path to the executable was provided." Isn't this contradicted by the docs? CreateProcess receives lpApplicationName and lpCommandLine, and they can be different.

magicalhippo 2y ago
Not the way I understand it. In the execv documentation[1], you pass the program name twice: int execv(const char *path, char *const argv[]); The argument path points to a pathname that identifies the new process image file. The argument argv is an array of character pointers to null-terminated strings. [..] The value in argv[0] should point to a filename string that is associated with the process being started by one of the exec functions. Windows does not allow you to do that, AFAIK. [1]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/execve.html https://pubs.opengroup.org/onlinepubs/9699919799/functions/e...
- skobes 2y ago
  > Windows does not allow you to do that, AFAIK. It does though, using the lpCommandLine parameter to CreateProcess as I said. CreateProcess("main.exe", "foobar", ...) argv[0] is "foobar"
  - magicalhippo 2y ago
    I stand corrected. Been ages since I used Win32 API a lot, and I realized I can't recall using both of those arguments when calling CreateProcess.
deleted 2y ago
[deleted]
DSMan195276 2y ago
Yeah they have this incorrect. if you provide `lpApplicationName` and `lpCommandLine` then the application name is not automatically added to the command line string, you have to add it yourself to the string provided as `lpCommandLine`. I checked and the docs for `CreateProcess` briefly mention this issue: > If both lpApplicationName and lpCommandLine are non-NULL, the null-terminated string pointed to by lpApplicationName specifies the module to execute, and the null-terminated string pointed to by lpCommandLine specifies the command line. The new process can use GetCommandLine to retrieve the entire command line. Console processes written in C can use the argc and argv arguments to parse the command line. _Because argv[0] is the module name, C programmers generally repeat the module name as the first token in the command line._

by skobes 2y ago

magicalhippo 2y ago

Not the way I understand it. In the execv documentation[1], you pass the program name twice: int execv(const char *path, char *const argv[]); The argument path points to a pathname that identifies the new process image file. The argument argv is an array of character pointers to null-terminated strings. [..] The value in argv[0] should point to a filename string that is associated with the process being started by one of the exec functions. Windows does not allow you to do that, AFAIK. [1]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/execve.html https://pubs.opengroup.org/onlinepubs/9699919799/functions/e...

skobes 2y ago
> Windows does not allow you to do that, AFAIK. It does though, using the lpCommandLine parameter to CreateProcess as I said. CreateProcess("main.exe", "foobar", ...) argv[0] is "foobar"
- magicalhippo 2y ago
  I stand corrected. Been ages since I used Win32 API a lot, and I realized I can't recall using both of those arguments when calling CreateProcess.

deleted 2y ago

[deleted]

DSMan195276 2y ago

Yeah they have this incorrect. if you provide `lpApplicationName` and `lpCommandLine` then the application name is not automatically added to the command line string, you have to add it yourself to the string provided as `lpCommandLine`. I checked and the docs for `CreateProcess` briefly mention this issue: > If both lpApplicationName and lpCommandLine are non-NULL, the null-terminated string pointed to by lpApplicationName specifies the module to execute, and the null-terminated string pointed to by lpCommandLine specifies the command line. The new process can use GetCommandLine to retrieve the entire command line. Console processes written in C can use the argc and argv arguments to parse the command line. _Because argv[0] is the module name, C programmers generally repeat the module name as the first token in the command line._