From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin-patches@cygwin.com
Subject: Re: [PATCH v2 1/2] Allow deriving the current user's home directory via the HOME variable
Date: Thu, 17 Dec 2015 20:20:00 -0000 [thread overview]
Message-ID: <20151217202023.GA3507@calimero.vinschen.de> (raw)
In-Reply-To: <047fe1d78c365afca7edfdf169fff5e1940c3837.1450375424.git.johannes.schindelin@gmx.de>
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Hi Johannes,
a few comments...
On Dec 17 19:05, Johannes Schindelin wrote:
> [...]
> diff --git a/winsup/cygwin/uinfo.cc b/winsup/cygwin/uinfo.cc
> index c9b3e09..a5d6270 100644
> --- a/winsup/cygwin/uinfo.cc
> +++ b/winsup/cygwin/uinfo.cc
> [...]
> +static size_t
> +fetch_env(LPCWSTR key, char *buf, size_t size)
^^^
space
> +{
> + WCHAR wbuf[32767];
Ok, there are a couple of problems here. First, since this buffer
is a filename buffer, use NT_MAX_PATH from winsup.h as buffer size.
But then again, please avoid allocating 64K buffers on the stack.
That's what tmp_pathbuf:w_get () is for.
> + DWORD max = sizeof wbuf / sizeof *wbuf;
> + DWORD len = GetEnvironmentVariableW (key, wbuf, max);
This call to GetEnvironmentVariableW looks gratuitous to me. Why don't
you simply call getenv? It did the entire job already, it avoids the
requirement for a local buffer, and in case of $HOME it even did the
Win32->POSIX path conversion. If there's a really good reason for using
GetEnvironmentVariableW it begs at least for a longish comment.
> +
> + if (!len || len >= max)
> + return 0;
> +
> + len = sys_wcstombs (buf, size, wbuf, len);
> + return len && len < size ? len : 0;
> +}
> +
> +static char *
> +fetch_home_env (void)
> +{
> + char home[32767];
> + size_t max = sizeof home / sizeof *home, len;
> +
> + if (fetch_env (L"HOME", home, max)
> + || ((len = fetch_env (L"HOMEDRIVE", home, max))
> + && fetch_env (L"HOMEPATH", home + len, max - len))
> + || fetch_env (L"USERPROFILE", home, max))
> + {
> + tmp_pathbuf tp;
> + cygwin_conv_path (CCP_WIN_A_TO_POSIX | CCP_ABSOLUTE,
> + home, tp.c_get(), NT_MAX_PATH);
^^^
space
> + return strdup(tp.c_get());
^^^ ^^^
space......s
Whoa, tp.c_get() twice to access the same space? That's a dirty trick
which may puzzle later readers of the code and heavily depends on
knowing the internals of tmp_pathbuf. Please use a variable and only
assign tp.c_get () once.
OTOH, the above's a case for a cygwin_create_path call, rather than
cygwin_conv_path+strdup. Also, if there's *really* a good reason to use
GetEnvironmentVariableW, you should collapse sys_wcstombs+cygwin_conv_path+
strdup into a single cygwin_create_path (CCP_WIN_W_TO_POSIX, ...).
> [...]
> @@ -1079,6 +1123,7 @@ cygheap_pwdgrp::get_shell (cyg_ldap *pldap, cygpsid &sid, PCWSTR dom,
> case NSS_SCHEME_FALLBACK:
> return NULL;
> case NSS_SCHEME_WINDOWS:
> + case NSS_SCHEME_ENV:
> break;
> case NSS_SCHEME_CYGWIN:
> if (pldap->fetch_ad_account (sid, false, dnsdomain))
You know that I don't exactly like the "env" idea, but if we implement
it anyway, wouldn't it make sense to add some kind of $SHELL handling as
well, for symmetry?
> [...]
> @@ -1487,6 +1497,16 @@ of each schema when used with <literal>db_home:</literal>
> for a detailed description.</listitem>
> </varlistentry>
> <varlistentry>
> + <term><literal>env</literal></term>
> + <listitem>Derives the home directory of the current user from the
> + environment variable <literal>HOME</literal> (falling back to
> + <literal>HOMEDRIVE\HOMEPATH</literal> and
> + <literal>USERPROFILE</literal>, in that order). This is faster
> + than the <term><literal>windows</literal></term> schema at the
> + expense of determining only the current user's home directory
> + correctly.</listitem>
In both case of the documentation it might make sense to add a few words
along the lines of "This schema is skipped for any other account",
wouldn't it?
Thanks,
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
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next prev parent reply other threads:[~2015-12-17 20:20 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-16 13:06 [PATCH] Allow overriding the " Johannes Schindelin
2015-10-21 18:32 ` Corinna Vinschen
2015-10-22 15:38 ` Johannes Schindelin
2015-10-23 9:10 ` Corinna Vinschen
2015-10-23 9:41 ` Corinna Vinschen
2015-10-23 12:00 ` Johannes Schindelin
2015-12-17 18:05 ` [PATCH v2 0/2] Support deriving the current user's home directory via HOME Johannes Schindelin
2015-12-17 18:05 ` [PATCH v2 1/2] Allow deriving the current user's home directory via the HOME variable Johannes Schindelin
2015-12-17 20:20 ` Corinna Vinschen [this message]
2022-09-21 11:58 ` Johannes Schindelin
2022-10-18 17:02 ` Corinna Vinschen
2022-10-23 21:04 ` Johannes Schindelin
2022-10-24 11:37 ` Corinna Vinschen
2022-11-10 15:16 ` Johannes Schindelin
2022-11-10 15:22 ` Corinna Vinschen
2022-11-18 8:18 ` Johannes Schindelin
2022-11-21 11:41 ` Corinna Vinschen
2023-03-28 8:21 ` Johannes Schindelin
2015-12-17 18:05 ` [PATCH v2 2/2] Respect `db_home` setting even for the SYSTEM account Johannes Schindelin
2015-12-17 20:49 ` Corinna Vinschen
2015-12-17 21:02 ` Corinna Vinschen
2022-09-21 12:00 ` Johannes Schindelin
2022-09-21 11:51 ` [PATCH v3 0/3] Support deriving the current user's home directory via HOME Johannes Schindelin
2022-09-21 11:51 ` [PATCH v3 1/3] Allow deriving the current user's home directory via the HOME variable Johannes Schindelin
2022-09-21 11:52 ` [PATCH v3 2/3] Respect `db_home` setting even for SYSTEM/Microsoft accounts Johannes Schindelin
2022-09-21 11:52 ` [PATCH v3 3/3] Respect `db_home: env` even when no uid can be determined Johannes Schindelin
2023-03-28 8:17 ` [PATCH v4 0/3] Support deriving the current user's home directory via HOME Johannes Schindelin
2023-03-28 8:17 ` [PATCH v4 1/3] Allow deriving the current user's home directory via the HOME variable Johannes Schindelin
2023-03-28 10:35 ` Corinna Vinschen
2023-03-28 12:34 ` Jon Turney
2023-03-28 13:31 ` Corinna Vinschen
2023-03-29 8:36 ` Corinna Vinschen
2023-04-03 6:39 ` Johannes Schindelin
2023-03-28 8:17 ` [PATCH v4 2/3] Respect `db_home` setting even for SYSTEM/Microsoft accounts Johannes Schindelin
2023-03-28 10:16 ` Corinna Vinschen
2023-04-03 6:36 ` Johannes Schindelin
2023-04-03 10:59 ` Corinna Vinschen
2023-04-03 13:32 ` Johannes Schindelin
2023-03-28 8:17 ` [PATCH v4 3/3] Respect `db_home: env` even when no uid can be determined Johannes Schindelin
2023-03-28 10:17 ` Corinna Vinschen
2023-04-03 6:45 ` Johannes Schindelin
2023-04-03 13:12 ` Johannes Schindelin
2023-04-03 13:29 ` Corinna Vinschen
2023-04-03 13:57 ` Johannes Schindelin
2023-04-03 19:23 ` Corinna Vinschen
2023-04-04 15:11 ` Johannes Schindelin
2023-04-03 13:19 ` Johannes Schindelin
2023-04-03 14:44 ` [PATCH v5 0/3] Support deriving the current user's home directory via HOME Johannes Schindelin
2023-04-03 14:44 ` [PATCH v5 1/3] Allow deriving the current user's home directory via the HOME variable Johannes Schindelin
2023-04-03 18:36 ` Corinna Vinschen
2023-04-04 15:12 ` Johannes Schindelin
2023-04-03 14:45 ` [PATCH v5 2/3] Respect `db_home` setting even for SYSTEM/Microsoft accounts Johannes Schindelin
2023-04-03 18:37 ` Corinna Vinschen
2023-04-04 15:12 ` Johannes Schindelin
2023-04-03 14:45 ` [PATCH v5 3/3] Respect `db_home: env` even when no uid can be determined Johannes Schindelin
2023-04-04 15:07 ` [PATCH v6 0/4] Support deriving the current user's home directory via HOME Johannes Schindelin
2023-04-04 15:07 ` [PATCH v6 1/4] Allow deriving the current user's home directory via the HOME variable Johannes Schindelin
2023-04-04 15:07 ` [PATCH v6 2/4] Respect `db_home` setting even for SYSTEM/Microsoft accounts Johannes Schindelin
2023-04-04 15:07 ` [PATCH v6 3/4] uinfo: special-case IIS APPPOOL accounts Johannes Schindelin
2023-04-04 15:07 ` [PATCH v6 4/4] Do not rely on `getenv ("HOME")`'s path conversion Johannes Schindelin
2023-04-06 8:37 ` Corinna Vinschen
2023-04-06 9:54 ` Johannes Schindelin
2023-04-06 10:28 ` Corinna Vinschen
2023-05-22 11:12 ` [PATCH v7 0/4] Support deriving the current user's home directory via HOME Johannes Schindelin
2023-05-22 11:12 ` [PATCH v7 1/4] Allow deriving the current user's home directory via the HOME variable Johannes Schindelin
2023-05-22 11:12 ` [PATCH v7 2/4] Respect `db_home` setting even for SYSTEM/Microsoft accounts Johannes Schindelin
2023-05-22 11:12 ` [PATCH v7 3/4] uinfo: special-case IIS APPPOOL accounts Johannes Schindelin
2023-05-22 11:13 ` [PATCH v7 4/4] Do not rely on `getenv ("HOME")`'s path conversion Johannes Schindelin
2023-06-06 13:33 ` [PATCH v7 0/4] Support deriving the current user's home directory via HOME Corinna Vinschen
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