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Work around an UCRT issue with _wspawn() functions taking an environment block argument

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We were working around that with a call to chdir("."). Internally chdir()
sets up cmd shell-related environment variables, but only if the current
working directory belongs to a volume with a drive letter. For example,
if the current working directory is on a UNC volume like a network share,
the call to chdir() won't help.

Reference:
  https://developercommunity.visualstudio.com/t/UCRT-Crash-in-_wspawne-functions/10262748
This commit is contained in:
Luca Bacci 2023-02-21 14:48:45 +01:00 committed by Philip Withnall
parent 8b45b81150
commit 911d091866
1 changed files with 81 additions and 9 deletions
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90
glib/gspawn-win32.c
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@ -65,8 +65,10 @@
#include <wchar.h>
#ifdef _MSC_VER
#ifdef HAVE_VCRUNTIME_H
#include <vcruntime.h> /* for _UCRT */
#endif
#endif
#ifndef GSPAWN_HELPER
#ifdef G_SPAWN_WIN32_DEBUG
@ -163,8 +165,85 @@ safe_wspawnvpe (int _Mode,
#else
#define safe_wspawnve _wspawnve
#define safe_wspawnvpe _wspawnvpe
/**< private >
* ensure_cmd_environment:
*
* Workaround for an issue in the universal C Runtime library (UCRT). This adds
* a custom environment variable to this process's environment block that looks
* like the cmd.exe's shell-related environment variables, i.e the name starts
* with an equal sign character: '='. This is needed because the UCRT may crash
* if those environment variables are missing from the calling process's block.
*
* Reference:
*
* https://developercommunity.visualstudio.com/t/UCRT-Crash-in-_wspawne-functions/10262748
*/
static void
ensure_cmd_environment (void)
{
static gsize initialization_value = 0;
if (g_once_init_enter (&initialization_value))
{
wchar_t *block = GetEnvironmentStringsW ();
gboolean have_cmd_environment = FALSE;
if (block)
{
const wchar_t *p = block;
while (*p != L'\0')
{
if (*p == L'=')
{
have_cmd_environment = TRUE;
break;
}
p += wcslen (p) + 1;
}
if (!FreeEnvironmentStringsW (block))
g_warning ("%s failed with error code %u",
"FreeEnvironmentStrings",
(guint) GetLastError ());
}
if (!have_cmd_environment)
{
if (!SetEnvironmentVariableW (L"=GLIB", L"GLIB"))
{
g_critical ("%s failed with error code %u",
"SetEnvironmentVariable",
(guint) GetLastError ());
}
}
g_once_init_leave (&initialization_value, 1);
}
}
static intptr_t
safe_wspawnve (int _mode,
const wchar_t * _filename,
const wchar_t *const *_args,
const wchar_t *const *_env)
{
ensure_cmd_environment ();
return _wspawnve (_mode, _filename, _args, _env);;
}
static intptr_t
safe_wspawnvpe (int _mode,
const wchar_t * _filename,
const wchar_t *const *_args,
const wchar_t *const *_env)
{
ensure_cmd_environment ();
return _wspawnvpe (_mode, _filename, _args, _env);
}
#endif /* _UCRT */
@ -686,13 +765,6 @@ fork_exec (gint *exit_status,
argc = protect_argv (argv, &protected_argv);
/*
* FIXME: Workaround broken spawnvpe functions that SEGV when "=X:="
* environment variables are missing. Calling chdir() will set the magic
* environment variable again.
*/
_chdir (".");
if (stdin_fd == -1 && stdout_fd == -1 && stderr_fd == -1 &&
(flags & G_SPAWN_CHILD_INHERITS_STDIN) &&
!(flags & G_SPAWN_STDOUT_TO_DEV_NULL) &&