[COMMIT osv master] vfs: implement linkat() except for AT_SYMLINK_FOLLOW

[Commit Bot]

From: Waldemar Kozaczuk <jwkoz...@gmail.com>
Committer: WALDEMAR KOZACZUK <jwkoz...@gmail.com>
Branch: master

vfs: implement linkat() except for AT_SYMLINK_FOLLOW

Signed-off-by: Waldemar Kozaczuk <jwkoz...@gmail.com>

---
diff --git a/fs/vfs/main.cc b/fs/vfs/main.cc
--- a/fs/vfs/main.cc
+++ b/fs/vfs/main.cc
@@ -1096,7 +1096,7 @@ int renameat(int olddirfd, const char *oldpath,
} else {
char absolute_newpath[PATH_MAX];
auto error = vfs_fun_at(newdirfd, newpath, [&absolute_newpath](const char *absolute_path) {
- strcpy(absolute_newpath, absolute_path);
+ strlcpy(absolute_newpath, absolute_path, PATH_MAX);
return 0;
});

@@ -1245,6 +1245,40 @@ int link(const char *oldpath, const char *newpath)
return -1;
}

+OSV_LIBC_API
+int linkat(int olddirfd, const char *oldpath, int newdirfd, const char *newpath, int flags)
+{
+ if (flags & AT_SYMLINK_FOLLOW) {
+ WARN_ONCE("linkat() does not support AT_SYMLINK_FOLLOW\n");
+ errno = EINVAL;
+ return -1;
+ }
+
+ if (!oldpath || !newpath) {
+ errno = EINVAL;
+ return -1;
+ }
+
+ if (newpath[0] == '/' || newdirfd == AT_FDCWD) {
+ return vfs_fun_at2(olddirfd, oldpath, [newpath](const char *path) {
+ return link(path, newpath);
+ });
+ } else {
+ char absolute_newpath[PATH_MAX];
+ auto error = vfs_fun_at(newdirfd, newpath, [&absolute_newpath](const char *absolute_path) {
+ strlcpy(absolute_newpath, absolute_path, PATH_MAX);
+ return 0;
+ });
+
+ if (error) {
+ return error;
+ } else {
+ return vfs_fun_at2(olddirfd, oldpath, [absolute_newpath](const char *path) {
+ return link(path, absolute_newpath);
+ });
+ }
+ }
+}

TRACEPOINT(trace_vfs_symlink, "oldpath=%s, newpath=%s", const char*, const char*);
TRACEPOINT(trace_vfs_symlink_ret, "");