work around linux bug in readlink syscall with zero buffer size

[musl] / src / unistd / readlinkat.c

diff --git a/src/unistd/readlinkat.c b/src/unistd/readlinkat.c
index 9af45cd..f79d3d1 100644 (file)
--- a/src/unistd/readlinkat.c
+++ b/src/unistd/readlinkat.c
@@ -3,5 +3,12 @@
 
 ssize_t readlinkat(int fd, const char *restrict path, char *restrict buf, size_t bufsize)
 {
-       return syscall(SYS_readlinkat, fd, path, buf, bufsize);
+       char dummy[1];
+       if (!bufsize) {
+               buf = dummy;
+               bufsize = 1;
+       }
+       int r = __syscall(SYS_readlinkat, fd, path, buf, bufsize);
+       if (buf == dummy && r > 0) r = 0;
+       return __syscall_ret(r);
 }