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Date: Wed, 3 Jun 2015 12:31:19 +0200
From: Jiri Olsa <jolsa@redhat.com>
To: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: mingo@redhat.com, ak@linux.intel.com,
 Michael Ellerman <mpe@ellerman.id.au>,
 Arnaldo Carvalho de Melo <acme@kernel.org>, namhyung@kernel.org,
 linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v13 02/14] perf, tools, jevents: Program to convert JSON
 file to C style file
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References: <1433265135-20426-1-git-send-email-sukadev@linux.vnet.ibm.com>
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On Tue, Jun 02, 2015 at 10:12:02AM -0700, Sukadev Bhattiprolu wrote:

SNIP

> + * If we fail to locate/process JSON and map files, create a NULL mapping
> + * table. This would at least allow perf to build even if we can't find/use
> + * the aliases.
> + */
> +static void create_empty_mapping(const char *output_file)
> +{
> +	FILE *outfp;
> +
> +	pr_info("%s: Creating empty pmu_events_map[] table\n", prog);
> +
> +	/* Unlink file to clear any partial writes to it */
> +	unlink(output_file);
> +
> +	outfp = fopen(output_file, "a");

you could open with "w+" and save the unlink call

SNIP

> +int main(int argc, char *argv[])
> +{
> +	int rc;
> +	int flags;
> +	int maxfds;
> +	char dirname[PATH_MAX];
> +
> +	const char *arch;
> +	const char *output_file;
> +	const char *start_dirname;
> +
> +	prog = basename(argv[0]);
> +	if (argc < 4) {
> +		pr_err("Usage: %s <arch> <starting_dir> <output_file>\n", prog);
> +		return 1;
> +	}
> +
> +	arch = argv[1];
> +	start_dirname = argv[2];
> +	output_file = argv[3];
> +
> +	if (argc > 4)
> +		verbose = atoi(argv[4]);
> +
> +	unlink(output_file);
> +	eventsfp = fopen(output_file, "a");

ditto

SNIP