mem: Resolve TrafficGen trace relative to the config

The traffic generator currently resolves relative trace paths relative
to gem5's current working directory. This can lead to surprising
results for relative paths where the expectation would normally be
that they are resolved relative to the configuration file. This
changeset implements config-relative trace file lookups. The old
behavior is kept as a fallback for configs that expect that behavior.

Change-Id: I1bda4e16725842666ffc37dcb6838c23a6ff138c
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>

3 files changed, 42 insertions, 2 deletions

diff --git a/src/cpu/testers/traffic_gen/traffic_gen.cc b/src/cpu/testers/traffic_gen/traffic_gen.cc
index af1976784..1a12b7675 100644
--- a/src/cpu/testers/traffic_gen/traffic_gen.cc
+++ b/src/cpu/testers/traffic_gen/traffic_gen.cc
@@ -38,12 +38,15 @@
  *          Andreas Hansson
  *          Sascha Bischoff
  */
+#include "cpu/testers/traffic_gen/traffic_gen.hh"
+
+#include <libgen.h>
+#include <unistd.h>
 
 #include <sstream>
 
 #include "base/intmath.hh"
 #include "base/random.hh"
-#include "cpu/testers/traffic_gen/traffic_gen.hh"
 #include "debug/Checkpoint.hh"
 #include "debug/TrafficGen.hh"
 #include "sim/stats.hh"
@@ -229,6 +232,27 @@ TrafficGen::update()
     }
 }
 
+std::string
+TrafficGen::resolveFile(const std::string &name)
+{
+    // Do nothing for empty and absolute file names
+    if (name.empty() || name[0] == '/')
+        return name;
+
+    char *config_path = strdup(configFile.c_str());
+    char *config_dir = dirname(config_path);
+    const std::string config_rel = csprintf("%s/%s", config_dir, name);
+    free(config_path);
+
+    // Check the path relative to the config file first
+    if (access(config_rel.c_str(), R_OK) == 0)
+        return config_rel;
+
+    // Fall back to the old behavior and search relative to the
+    // current working directory.
+    return name;
+}
+
 void
 TrafficGen::parseConfig()
 {
@@ -273,6 +297,7 @@ TrafficGen::parseConfig()
                     Addr addrOffset;
 
                     is >> traceFile >> addrOffset;
+                    traceFile = resolveFile(traceFile);
 
                     states[id] = new TraceGen(name(), masterID, duration,
                                               traceFile, addrOffset);
diff --git a/src/cpu/testers/traffic_gen/traffic_gen.hh b/src/cpu/testers/traffic_gen/traffic_gen.hh
index 0715c5965..6b3ccbe30 100644
--- a/src/cpu/testers/traffic_gen/traffic_gen.hh
+++ b/src/cpu/testers/traffic_gen/traffic_gen.hh
@@ -76,6 +76,21 @@ class TrafficGen : public MemObject
     void enterState(uint32_t newState);
 
     /**
+     * Resolve a file path in the configuration file.
+     *
+     * This method resolves a relative path to a file that has been
+     * referenced in the configuration file. It first tries to resolve
+     * the file relative to the configuration file's path. If that
+     * fails, it falls back to constructing a path relative to the
+     * current working directory.
+     *
+     * Absolute paths are returned unmodified.
+     *
+     * @param name Path to resolve
+     */
+    std::string resolveFile(const std::string &name);
+
+    /**
      * Parse the config file and build the state map and
      * transition matrix.
      */
diff --git a/tests/quick/se/70.tgen/tgen-simple-mem.cfg b/tests/quick/se/70.tgen/tgen-simple-mem.cfg
index 326140ce2..c09fc2f44 100644
--- a/tests/quick/se/70.tgen/tgen-simple-mem.cfg
+++ b/tests/quick/se/70.tgen/tgen-simple-mem.cfg
@@ -19,7 +19,7 @@
 # and random state is from a uniform random distribution over the
 # interval. If a specific value is desired, then the min and max can
 # be set to the same value.
-STATE 0 1000000 TRACE tests/quick/se/70.tgen/tgen-simple-mem.trc 100
+STATE 0 1000000 TRACE tgen-simple-mem.trc 100
 STATE 1 100000000 RANDOM 0 0 134217728 64 30000 30000 0
 STATE 2 1000000000 IDLE
 STATE 3 100000000 LINEAR 0 0 134217728 64 30000 30000 0