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-rw-r--r--src/libstore/platform/darwin.cc17
1 files changed, 16 insertions, 1 deletions
diff --git a/src/libstore/platform/darwin.cc b/src/libstore/platform/darwin.cc
index 1b591fde3..1f7e9be23 100644
--- a/src/libstore/platform/darwin.cc
+++ b/src/libstore/platform/darwin.cc
@@ -56,12 +56,27 @@ void DarwinLocalStore::findPlatformRoots(UncheckedRoots & unchecked)
while (fdBufSize > fds.size() * sizeof(struct proc_fdinfo)) {
// Reserve some extra size so we don't fail too much
fds.resize((fdBufSize + fdBufSize / 8) / sizeof(struct proc_fdinfo));
+ errno = 0;
fdBufSize = proc_pidinfo(
pid, PROC_PIDLISTFDS, 0, fds.data(), fds.size() * sizeof(struct proc_fdinfo)
);
+ // errno == 0???! Yes, seriously. This is because macOS has a
+ // broken syscall wrapper for proc_pidinfo that has no way of
+ // dealing with the system call successfully returning 0. It
+ // takes the -1 error result from the errno-setting syscall
+ // wrapper and turns it into a 0 result. But what if the system
+ // call actually returns 0? Then you get an errno of success.
+ //
+ // https://github.com/apple-opensource/xnu/blob/4f43d4276fc6a87f2461a3ab18287e4a2e5a1cc0/libsyscall/wrappers/libproc/libproc.c#L100-L110
+ // https://git.lix.systems/lix-project/lix/issues/446#issuecomment-5483
+ // FB14695751
if (fdBufSize <= 0) {
- throw SysError("Listing pid %1% file descriptors", pid);
+ if (errno == 0) {
+ break;
+ } else {
+ throw SysError("Listing pid %1% file descriptors", pid);
+ }
}
}
fds.resize(fdBufSize / sizeof(struct proc_fdinfo));