Re: [PATCH] Cygwin: spawn: Treat empty path as the current directory.
On 6/30/2022 11:45 AM, Ken Brown wrote: On 6/27/2022 8:44 AM, Takashi Yano wrote: - With this patch, the empty path (empty element in PATH or PATH is absent) is treated as the current directory as Linux does. Addresses: https://cygwin.com/pipermail/cygwin/2022-June/251730.html It might be a good idea to include a comment in the code and the commit message that this feature is being added for Linux compatibility but that it is deprecated. According to https://man7.org/linux/man-pages/man7/environ.7.html, As a legacy feature, a zero-length prefix (specified as two adjacent colons, or an initial or terminating colon) is interpreted to mean the current working directory. However, use of this feature is deprecated, and POSIX notes that a conforming application shall use an explicit pathname (e.g., .) to specify the current working directory. Alternatively, maybe this is a case where we should prefer POSIX compliance to Linux compatibility. Corinna, WDYT? I withdraw my suggestion. There's already a comment in the code saying, "An empty path or '.' means the current directory", so it's clear that the intention was to support that feature, and the code was simply buggy. I've now read through the patch, and it looks good to me. This was pretty tricky to get right. Ken
Re: [EXTERNAL] Re: [PATCH] Cygwin: spawn: Treat empty path as the current directory.
On Thu, 30 Jun 2022 18:35:04 + "Lavrentiev, Anton \(NIH/NLM/NCBI\) \[C\] wrote: > >However, use of this feature is deprecated, and POSIX > >notes that a conforming application shall use an explicit > >pathname (e.g., .) to specify the current working > >directory. > > Since "SHALL" does not mean "MUST", I think this patch is correct. In the POSIX standard, "SHALL" is used almost interchangeably with "MUST" as other standard documents do. https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xbd_chap01.html#tag_21_01_09 -- Takashi Yano
Re: [EXTERNAL] Re: [PATCH] Cygwin: spawn: Treat empty path as the current directory.
On 2022-06-30 12:35, Lavrentiev, Anton (NIH/NLM/NCBI) [C] via Cygwin-patches wrote: However, use of this feature is deprecated, and POSIX notes that a conforming application shall use an explicit pathname (e.g., .) to specify the current working directory. Since "SHALL" does not mean "MUST", I think this patch is correct. It appears you may be confusing POSIX's (1.5 Terminology) *shall* (mandatory) and *should* (recommended): "*SHALL* For an implementation that conforms to POSIX.1-2017, describes a feature or behavior that is mandatory. An application can rely on the existence of the feature or behavior. For an application or user, describes a behavior that is mandatory. *SHOULD* For an implementation that conforms to POSIX.1-2017, describes a feature or behavior that is recommended but not mandatory. An application should not rely on the existence of the feature or behavior. An application that relies on such a feature or behavior cannot be assured to be portable across conforming implementations. For an application, describes a feature or behavior that is recommended programming practice for optimum portability." -- Take care. Thanks, Brian Inglis, Calgary, Alberta, Canada This email may be disturbing to some readers as it contains too much technical detail. Reader discretion is advised. [Data in binary units and prefixes, physical quantities in SI.]
RE: [EXTERNAL] Re: [PATCH] Cygwin: spawn: Treat empty path as the current directory.
>However, use of this feature is deprecated, and POSIX >notes that a conforming application shall use an explicit >pathname (e.g., .) to specify the current working >directory. Since "SHALL" does not mean "MUST", I think this patch is correct. Anton Lavrentiev Contractor NIH/NLM/NCBI
Re: [PATCH] Cygwin: poll: Fix a bug on inquiring same fd with different events.
On 6/26/2022 9:50 PM, Takashi Yano wrote: - poll() has a bug that it returns event which is not inquired if events are inquired in multiple pollfd entries on the same fd at the same time. This patch fixes the issue. Addresses: https://cygwin.com/pipermail/cygwin/2022-June/251732.html LGTM (but I haven't tested it). Ken
Re: [PATCH] Cygwin: spawn: Treat empty path as the current directory.
On 6/27/2022 8:44 AM, Takashi Yano wrote: - With this patch, the empty path (empty element in PATH or PATH is absent) is treated as the current directory as Linux does. Addresses: https://cygwin.com/pipermail/cygwin/2022-June/251730.html It might be a good idea to include a comment in the code and the commit message that this feature is being added for Linux compatibility but that it is deprecated. According to https://man7.org/linux/man-pages/man7/environ.7.html, As a legacy feature, a zero-length prefix (specified as two adjacent colons, or an initial or terminating colon) is interpreted to mean the current working directory. However, use of this feature is deprecated, and POSIX notes that a conforming application shall use an explicit pathname (e.g., .) to specify the current working directory. Alternatively, maybe this is a case where we should prefer POSIX compliance to Linux compatibility. Corinna, WDYT? Ken
