1 /*
2 * Copyright (c) 2015 PLUMgrid, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 #include <cstring>
17 #include <memory>
18 #include <string>
19 #include <vector>
20 #include <unistd.h>
21 #include <errno.h>
22 #include <ftw.h>
23
24 namespace ebpf {
25
26 struct FileDeleter {
operatorFileDeleter27 void operator() (FILE *fp) {
28 fclose(fp);
29 }
30 };
31 typedef std::unique_ptr<FILE, FileDeleter> FILEPtr;
32
33 // Helper with pushd/popd semantics
34 class DirStack {
35 public:
DirStack(const std::string & dst)36 explicit DirStack(const std::string &dst) : ok_(false) {
37 if (getcwd(cwd_, sizeof(cwd_)) == NULL) {
38 ::perror("getcwd");
39 return;
40 }
41 if (::chdir(dst.c_str())) {
42 fprintf(stderr, "chdir(%s): %s\n", dst.c_str(), strerror(errno));
43 return;
44 }
45 ok_ = true;
46 }
~DirStack()47 ~DirStack() {
48 if (!ok_) return;
49 if (::chdir(cwd_)) {
50 fprintf(stderr, "chdir(%s): %s\n", cwd_, strerror(errno));
51 }
52 }
ok()53 bool ok() const { return ok_; }
cwd()54 const char * cwd() const { return cwd_; }
55 private:
56 bool ok_;
57 char cwd_[256];
58 };
59
ftw_cb(const char * path,const struct stat *,int,struct FTW *)60 static int ftw_cb(const char *path, const struct stat *, int, struct FTW *) {
61 return ::remove(path);
62 }
63
64 // Scoped class to manage the creation/deletion of tmpdirs
65 class TmpDir {
66 public:
67 explicit TmpDir(const std::string &prefix = "/tmp/bcc-")
ok_(false)68 : ok_(false), prefix_(prefix) {
69 prefix_ += "XXXXXX";
70 if (::mkdtemp((char *)prefix_.data()) == NULL)
71 ::perror("mkdtemp");
72 else
73 ok_ = true;
74 }
~TmpDir()75 ~TmpDir() {
76 if (::nftw(prefix_.c_str(), ftw_cb, 20, FTW_DEPTH) < 0)
77 ::perror("ftw");
78 else
79 ::remove(prefix_.c_str());
80 }
ok()81 bool ok() const { return ok_; }
str()82 const std::string & str() const { return prefix_; }
83 private:
84 bool ok_;
85 std::string prefix_;
86 };
87
88 // Compute the kbuild flags for the currently running kernel
89 // Do this by:
90 // 1. Create temp Makefile with stub dummy.c
91 // 2. Run module build on that makefile, saving the computed flags to a file
92 // 3. Cache the file for fast flag lookup in subsequent runs
93 // Note: Depending on environment, different cache locations may be desired. In
94 // case we eventually support non-root user programs, cache in $HOME.
95 class KBuildHelper {
96 public:
97 explicit KBuildHelper(const std::string &kdir, bool has_source_dir);
98 int get_flags(const char *uname_machine, std::vector<std::string> *cflags);
99 private:
100 std::string kdir_;
101 bool has_source_dir_;
102 };
103
104 } // namespace ebpf
105