On Wed, 1 Sep 2021 12:51:15 GMT, Florian Weimer <fwei...@openjdk.org> wrote:
>> Hi, >> Please help me review the change to enhance getting time zone ID from >> /etc/localtime on linux. >> >> We use `realpath` instead of `readlink` to obtain the link name of >> /etc/localtime, because `readlink` can only read the value of a symbolic of >> link, not the canonicalized absolute pathname. >> >> For example, the value of /etc/localtime is >> "../usr/share/zoneinfo//Asia/Shanghai", then the linkbuf obtained by >> `readlink` is "../usr/share/zoneinfo//Asia/Shanghai", and then the call of >> `getZoneName(linkbuf)` will get "/Asia/Shanghai", not "Asia/Shanghai", which >> consider as invalid in `ZoneInfoFile.getZoneInfo()`. Using `realpath`, you >> can get “/usr/share/zoneinfo/Asia/Shanghai“ directly from “/etc/localtime“. >> >> Thanks, >> wuyan > > src/java.base/unix/native/libjava/TimeZone_md.c line 292: > >> 290: /* canonicalize the path */ >> 291: char resolvedpath[PATH_MAX + 1]; >> 292: char *path = realpath(DEFAULT_ZONEINFO_FILE, resolvedpath); > > You really should use `realpath` with `NULL` as the second argument, to avoid > any risk of buffer overflow. Future C library headers may warn about non-null > arguments here. Ok, Thanks. I will refer to the implementation of `os::Posix::realpath` to fix it if we still use `realpath`. https://github.com/openjdk/jdk/blob/5245c1cf0260a78ca5f8ab4e7d13107f21faf071/src/hotspot/os/posix/os_posix.cpp#L805 ------------- PR: https://git.openjdk.java.net/jdk/pull/5327
