Add 'ppaml_tracer_init_from_env'

This new API function is similar to 'ppaml_tracer_init', but instead of
accepting the report base name as an argument, it pulls it from the
'PPAMLTRACER_TRACE_BASE' environment variable.  This is useful for users
who want to be able to vary the locations of trace reports but do not
want to build tracing into their configuration file / command-line
argument parsers.

1 files changed, 18 insertions, 0 deletions

diff --git a/src/tracer.c b/src/tracer.c
index be2f3cc..3b39759 100644
--- a/src/tracer.c
+++ b/src/tracer.c
@@ -24,6 +24,7 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include <otf.h>
 
@@ -59,6 +60,23 @@ int ppaml_tracer_init(
 done:	return r;
 }
 
+int ppaml_tracer_init_from_env(ppaml_tracer_t *const tracer)
+{
+	int r = 0;
+	// Figure out where to put the trace.
+	const char *const report_name_base = getenv("PPAMLTRACER_TRACE_BASE");
+	require_nonnull(report_name_base, 5);
+	if (report_name_base[0] == '\0') {
+		/* The variable exists, but it's empty, so we can't do anything
+		 * with it. */
+		r = 5;
+		goto done;
+	}
+	// Create the trace.
+	r = ppaml_tracer_init(tracer, report_name_base);
+done:	return r;
+}
+
 int ppaml_tracer_done(ppaml_tracer_t *const tracer)
 {
 	int r = 0;