perf tools: Move the temp file processing into decompress_kmodule

We will add a compression check in the following patch and it makes it
easier if the file processing is done in a single place. It also makes
the current code simpler.

The decompress_kmodule function now returns the fd of the uncompressed
file and the file name in the pathname arg, if it's provided.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20180817094813.15086-10-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/dso.c

@@ -250,8 +250,10 @@ bool dso__needs_decompress(struct dso *dso)
 		dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE_COMP;
 }
 
-static int decompress_kmodule(struct dso *dso, const char *name, char *tmpbuf)
+static int decompress_kmodule(struct dso *dso, const char *name,
+			      char *pathname, size_t len)
 {
+	char tmpbuf[] = KMOD_DECOMP_NAME;
 	int fd = -1;
 
 	if (!dso__needs_decompress(dso))
@@ -272,34 +274,27 @@ static int decompress_kmodule(struct dso *dso, const char *name, char *tmpbuf)
 		fd = -1;
 	}
 
+	if (!pathname || (fd < 0))
+		unlink(tmpbuf);
+
+	if (pathname && (fd >= 0))
+		strncpy(pathname, tmpbuf, len);
+
 	return fd;
 }
 
 int dso__decompress_kmodule_fd(struct dso *dso, const char *name)
 {
-	char tmpbuf[] = KMOD_DECOMP_NAME;
-	int fd;
-
-	fd = decompress_kmodule(dso, name, tmpbuf);
-	unlink(tmpbuf);
-	return fd;
+	return decompress_kmodule(dso, name, NULL, 0);
 }
 
 int dso__decompress_kmodule_path(struct dso *dso, const char *name,
 				 char *pathname, size_t len)
 {
-	char tmpbuf[] = KMOD_DECOMP_NAME;
-	int fd;
-
-	fd = decompress_kmodule(dso, name, tmpbuf);
-	if (fd < 0) {
-		unlink(tmpbuf);
-		return -1;
-	}
+	int fd = decompress_kmodule(dso, name, pathname, len);
 
-	strncpy(pathname, tmpbuf, len);
 	close(fd);
-	return 0;
+	return fd >= 0 ? 0 : -1;
 }
 
 /*