add new function to render the command line on windows

[vylsaz]

This function is based on this article, also see this

Because the command line situation on Windows is a mess, this solution is not secure e.g. when someone runs cmd.exe, but I think it's good enough...

[rexim]

I extremely apologize. I haven't read the article yet, but I'm wondering why exactly do we have to count consequent backslashes? Couldn't we just escape the string like this?

            nob_da_append(quoted, '\"');
            for (size_t j = 0; j < len; ++j) {
                char x = arg[j];
                switch (x) {
                case '\\': nob_sb_append_cstr(quoted, "\\\\"); break;
                case '\"': nob_sb_append_cstr(quoted, "\\\""); break;
                default:   nob_da_append(quoted, x);           break;
                }
            }
            nob_da_append(quoted, '\"');

Am I missing something weird about Windows here?

[vylsaz]

Yes, Windows is very weird here.

For example:

#include <stdio.h>
#include <windows.h>
int main(int argc, char **argv)
{
    WCHAR *cmdline = GetCommandLineW(); // this is the raw command line the process sees
    printf("raw   : %S\n", cmdline);
    printf("parsed: ");
    for (int i = 0; i < argc; ++i) {
        printf("`%s` ", argv[i]);
    }
    printf("\n");
    return 0;
}

compile as cmdline.exe and run in powershell:

PS D:\> .\cmdline "\test "   
raw   : "D:\cmdline.exe" "\test "
parsed: `D:\cmdline.exe` `\test `
PS D:\> .\cmdline "\\test "
raw   : "D:\cmdline.exe" "\\test "
parsed: `D:\cmdline.exe` `\\test `
PS D:\> .\cmdline "\""test "
raw   : "D:\cmdline.exe" "\\\"test "
parsed: `D:\cmdline.exe` `\"test `
PS D:\> .\cmdline "\\""test "
raw   : "D:\cmdline.exe" "\\\\\"test "
parsed: `D:\cmdline.exe` `\\"test `

(here powershell also looks for the full path of the executable which I didn't do)

[Mrjiong438]

In short, Windows escapes double quotes and a string of backslashes with a double quote in the end.
see detail in here

[rexim]

Thank you! Merge at 8927dcb