Subject: Re: [PATCH v4 19/27] wrapper.c: wrapper to open a file, fprintf then close

From: Torsten Bögershausen <[email-masked]>
Date: Sat, 01 Mar 2014 18:11:24 +0100

On 2014-03-01 13.12, Nguyễn Thái Ngọc Duy wrote:
> Signed-off-by: Nguyễn Thái Ngọc Duy <[email-masked]>
> ---
>  cache.h   |  2 ++
>  wrapper.c | 31 +++++++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/cache.h b/cache.h
> index 98b5dd3..99b86d9 100644
> --- a/cache.h
> +++ b/cache.h
> @@ -1239,6 +1239,8 @@ static inline ssize_t write_str_in_full(int fd, const char *str)
>  {
>  	return write_in_full(fd, str, strlen(str));
>  }
> +__attribute__((format (printf,3,4)))
> +extern int write_file(const char *path, int fatal, const char *fmt, ...);
>  
>  /* pager.c */
>  extern void setup_pager(void);
> diff --git a/wrapper.c b/wrapper.c
> index 0cc5636..5ced50d 100644
> --- a/wrapper.c
> +++ b/wrapper.c
> @@ -455,3 +455,34 @@ struct passwd *xgetpwuid_self(void)
>  		    errno ? strerror(errno) : _("no such user"));
>  	return pw;
>  }
> +
> +int write_file(const char *path, int fatal, const char *fmt, ...)
> +{
> +	struct strbuf sb = STRBUF_INIT;
> +	int fd = open(path, O_RDWR | O_CREAT | O_TRUNC, 0666);
> +	va_list params;
> +	if (fd < 0) {
> +		if (fatal)
> +			die_errno(_("could not open %s for writing"), path);
> +		return -1;
> +	}
> +	va_start(params, fmt);
> +	strbuf_vaddf(&sb, fmt, params);
> +	va_end(params);
> +	if (write_in_full(fd, sb.buf, sb.len) != sb.len) {
> +		int err = errno;
> +		close(fd);
> +		errno = err;
> +		strbuf_release(&sb);
Micro nit:
Today we now what strbuf_release() is doing, but if we ever change the
implementation, it is 3% safer to keep err a little bit longer like this:
> +		strbuf_release(&sb);
> +		errno = err;