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authorRich Felker <dalias@aerifal.cx>2020-11-23 19:44:19 -0500
committerRich Felker <dalias@aerifal.cx>2020-11-23 19:44:19 -0500
commite2fa720be7024cce4fc489f3877476d35da48ee2 (patch)
tree624a4b85cc7aacccc9a359eaf0ffc00a614ffddf /src/unistd/readlink.c
parentc17cda6d61bc24d5bb51b0837d951da063a1fba5 (diff)
downloadmusl-e2fa720be7024cce4fc489f3877476d35da48ee2.tar.gz
work around linux bug in readlink syscall with zero buffer size
linux fails with EINVAL when a zero buffer size is passed to the syscall. this is non-conforming because POSIX already defines EINVAL with a significantly different meaning: the target is not a symlink. since the request is semantically valid, patch it up by using a dummy buffer of length one, and truncating the return value to zero if it succeeds.
Diffstat (limited to 'src/unistd/readlink.c')
-rw-r--r--src/unistd/readlink.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/src/unistd/readlink.c b/src/unistd/readlink.c
index a152d524..32f4537f 100644
--- a/src/unistd/readlink.c
+++ b/src/unistd/readlink.c
@@ -4,9 +4,16 @@
ssize_t readlink(const char *restrict path, char *restrict buf, size_t bufsize)
{
+ char dummy[1];
+ if (!bufsize) {
+ buf = dummy;
+ bufsize = 1;
+ }
#ifdef SYS_readlink
- return syscall(SYS_readlink, path, buf, bufsize);
+ int r = __syscall(SYS_readlink, path, buf, bufsize);
#else
- return syscall(SYS_readlinkat, AT_FDCWD, path, buf, bufsize);
+ int r = __syscall(SYS_readlinkat, AT_FDCWD, path, buf, bufsize);
#endif
+ if (buf == dummy && r > 0) r = 0;
+ return __syscall_ret(r);
}