perf llvm: Use realpath to canonicalize paths

To kill the last user of make_nonrelative_path(), that gets ditched,
one more panicking function killed.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-3hu56rvyh4q5gxogovb6ko8a@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/Build

@@ -1,4 +1,3 @@
-libperf-y += abspath.o
 libperf-y += alias.o
 libperf-y += annotate.o
 libperf-y += build-id.o

tools/perf/util/cache.h

@@ -64,7 +64,6 @@ static inline int is_absolute_path(const char *path)
 	return path[0] == '/';
 }
 
-const char *make_nonrelative_path(const char *path);
 char *strip_path_suffix(const char *path, const char *suffix);
 
 char *mkpath(const char *fmt, ...) __attribute__((format (printf, 1, 2)));

tools/perf/util/llvm-utils.c

@@ -3,11 +3,11 @@
  * Copyright (C) 2015, Huawei Inc.
  */
 
+#include <limits.h>
 #include <stdio.h>
-#include "util.h"
+#include <stdlib.h>
 #include "debug.h"
 #include "llvm-utils.h"
-#include "cache.h"
 
 #define CLANG_BPF_CMD_DEFAULT_TEMPLATE				\
 		"$CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS "\
@@ -334,10 +334,18 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
 	unsigned int kernel_version;
 	char linux_version_code_str[64];
 	const char *clang_opt = llvm_param.clang_opt;
-	char clang_path[PATH_MAX], nr_cpus_avail_str[64];
+	char clang_path[PATH_MAX], abspath[PATH_MAX], nr_cpus_avail_str[64];
+	char serr[STRERR_BUFSIZE];
 	char *kbuild_dir = NULL, *kbuild_include_opts = NULL;
 	const char *template = llvm_param.clang_bpf_cmd_template;
 
+	if (path[0] != '-' && realpath(path, abspath) == NULL) {
+		err = errno;
+		pr_err("ERROR: problems with path %s: %s\n",
+		       path, strerror_r(err, serr, sizeof(serr)));
+		return -err;
+	}
+
 	if (!template)
 		template = CLANG_BPF_CMD_DEFAULT_TEMPLATE;
 
@@ -387,8 +395,7 @@ int llvm__compile_bpf(const char *path, void **p_obj_buf,
 	 * stdin to be source file (testing).
 	 */
 	force_set_env("CLANG_SOURCE",
-		      (path[0] == '-') ? path :
-		      make_nonrelative_path(path));
+		      (path[0] == '-') ? path : abspath);
 
 	pr_debug("llvm compiling command template: %s\n", template);
 	err = read_from_pipe(template, &obj_buf, &obj_buf_sz);