From: Jens Axboe <jens.axboe@oracle.com>
Date: Fri, 13 Nov 2009 11:19:49 +0000 (+0100)
Subject: Support simple math on reserved keyword expressions
X-Git-Tag: fio-1.36-rc1~17
X-Git-Url: https://git.kernel.dk/?p=fio.git;a=commitdiff_plain;h=892a6ffc5363ad7f1750df9f3ec98624016660cd

Support simple math on reserved keyword expressions

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
---

diff --git a/HOWTO b/HOWTO
index cdd6473b..9b3a6848 100644
--- a/HOWTO
+++ b/HOWTO
@@ -203,7 +203,13 @@ $ncpus		Number of online available CPUs
 
 These can be used on the command line or in the job file, and will be
 automatically substituted with the current system values when the job
-is run.
+is run. Simple math is also supported on these keywords, so you can
+perform actions like:
+
+size=8*$mb_memory
+
+and get that properly expanded to 8 times the size of memory in the
+machine.
 
 
 5.0 Detailed list of parameters
diff --git a/options.c b/options.c
index 5b882558..211bca74 100644
--- a/options.c
+++ b/options.c
@@ -1788,6 +1788,61 @@ void fio_keywords_init(void)
 	fio_keywords[2].replace = strdup(buf);
 }
 
+#define BC_APP		"bc"
+
+static char *bc_calc(char *str)
+{
+	char *buf, *tmp, opt[80];
+	FILE *f;
+	int ret;
+
+	/*
+	 * No math, just return string
+	 */
+	if (!strchr(str, '+') && !strchr(str, '-') && !strchr(str, '*') &&
+	    !strchr(str, '/'))
+		return str;
+
+	/*
+	 * Split option from value, we only need to calculate the value
+	 */
+	tmp = strchr(str, '=');
+	if (!tmp)
+		return str;
+
+	tmp++;
+	strncpy(opt, str, tmp - str);
+
+	buf = malloc(128);
+
+	sprintf(buf, "which %s > /dev/null", BC_APP);
+	if (system(buf)) {
+		log_err("fio: bc is needed for performing math\n");
+		free(buf);
+		return NULL;
+	}
+
+	sprintf(buf, "echo %s | %s", tmp, BC_APP);
+	f = popen(buf, "r");
+	if (!f) {
+		free(buf);
+		return NULL;
+	}
+
+	ret = fread(buf, 1, 128, f);
+	if (ret <= 0) {
+		free(buf);
+		return NULL;
+	}
+
+	buf[ret - 1] = '\0';
+	strcat(opt, buf);
+	strcpy(buf, opt);
+	pclose(f);
+	free(str);
+	return buf;
+}
+
 /*
  * Look for reserved variable names and replace them with real values
  */
@@ -1828,7 +1883,10 @@ static char *fio_keyword_replace(char *opt)
 		}
 	}
 
-	return opt;
+	/*
+	 * Check for potential math and invoke bc, if possible
+	 */
+	return bc_calc(opt);
 }
 
 int fio_options_parse(struct thread_data *td, char **opts, int num_opts)