Re: [PATCH 08/10] perf, tool: Add sysfs read file interface

From: Peter Zijlstra
Date: Wed Jul 04 2012 - 06:40:49 EST


On Wed, 2012-07-04 at 00:00 +0200, Jiri Olsa wrote:
> +int sysfs_read_file(const char *file, char *buf, size_t size)
> +{
> + char path[PATH_MAX];
> + FILE *fp;
> + int ret = 0;
> +
> + snprintf(path, PATH_MAX, "%s/%s", sysfs_mountpoint, file);
> +
> + fp = fopen(path, "r");
> + if (!fp)
> + return -errno;
> +
> + if (fread(buf, 1, size, fp) == 0)
> + ret = -errno;
> +
> + fclose(fp);
> + return ret;

Does sysfs guarantee a single read is complete? If not, we need a while
loop around that read until EOF or size.

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