From: Tomi Ollila <tomi.ollila@iki.fi>
To: markwalters1009 <markwalters1009@gmail.com>, notmuch@notmuchmail.org
Subject: Re: [PATCH v2 1/7] cli: allow query to come from stdin
In-Reply-To: <1353763256-32336-2-git-send-email-markwalters1009@gmail.com>
References: <1353763256-32336-1-git-send-email-markwalters1009@gmail.com>
	<1353763256-32336-2-git-send-email-markwalters1009@gmail.com>
User-Agent: Notmuch/0.14+84~g8a199bf (http://notmuchmail.org) Emacs/24.2.1
	(x86_64-unknown-linux-gnu)
Date: Sun, 25 Nov 2012 00:34:19 +0200
Message-ID: <m238zyk4us.fsf@guru.guru-group.fi>
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Precedence: list

On Sat, Nov 24 2012, markwalters1009 wrote:

> From: Mark Walters <markwalters1009@gmail.com>
>
> After this series there will be times when a caller will want to pass
> a very large query string to notmuch (eg a list of 10,000 message-ids)
> and this can exceed the size of ARG_MAX. Hence allow notmuch to take
> the query from stdin (if the query is -).


> ---
>  query-string.c |   41 +++++++++++++++++++++++++++++++++++++++++
>  1 files changed, 41 insertions(+), 0 deletions(-)
>
> diff --git a/query-string.c b/query-string.c
> index 6536512..b1fbdeb 100644
> --- a/query-string.c
> +++ b/query-string.c
> @@ -20,6 +20,44 @@
>  
>  #include "notmuch-client.h"
>  
> +/* Read a single query string from STDIN, using
> + * 'ctx' as the talloc owner for all allocations.
> + *
> + * This function returns NULL in case of insufficient memory or read
> + * errors.
> + */
> +static char *
> +query_string_from_stdin (void *ctx)

Austin provided pretty nice alternative implementation of 
query_string_from_stdin() in his reply so I decline to
comment minor formatting issue below :D

> +{
> +    char *query_string;
> +    char buf[4096];
> +    ssize_t remain;
> +
> +    query_string = talloc_strdup (ctx, "");
> +    if (query_string == NULL)
> +	return NULL;
> +
> +    for (;;) {
> +	remain = read (STDIN_FILENO, buf, sizeof(buf) - 1);
> +	if (remain == 0)
> +	    break;
> +	if (remain < 0) {
> +	    if (errno == EINTR)
> +		continue;
> +	    fprintf (stderr, "Error: reading from standard input: %s\n",
> +		     strerror (errno));
> +	    return NULL;
> +	}
> +
> +	buf[remain] = '\0';
> +	query_string = talloc_strdup_append (query_string, buf);
> +	if (query_string == NULL)
> +	    return NULL;
> +    }
> +
> +    return query_string;
> +}
> +
>  /* Construct a single query string from the passed arguments, using
>   * 'ctx' as the talloc owner for all allocations.
>   *
> @@ -35,6 +73,9 @@ query_string_from_args (void *ctx, int argc, char *argv[])
>      char *query_string;
>      int i;
>  
> +    if ((argc == 1) && (strcmp ("-", argv[0]) == 0))

the argument order in strcmp() is not consistent with all the 
other uses of strcmp () in the codebase.

> +	return query_string_from_stdin (ctx);
> +
>      query_string = talloc_strdup (ctx, "");
>      if (query_string == NULL)
>  	return NULL;
> -- 
> 1.7.9.1

Tomi