Make findRuntimeRoots() more resilient to disappearing processes

I saw this random failure in https://hydra.nixos.org/build/211811692:

  error: opening /proc/15307/fd: No such process

while running nix-collect-garbage in a readfile-context.sh. This is
because we're not handling ESRCH errors reading /proc/<pid>/fd. So
just move the read inside the try/catch where we do handle it.
This commit is contained in:
Eelco Dolstra 2023-03-09 16:44:51 +01:00
parent c44750982d
commit 4f3a4b732c

View file

@ -371,29 +371,29 @@ void LocalStore::findRuntimeRoots(Roots & roots, bool censor)
while (errno = 0, ent = readdir(procDir.get())) { while (errno = 0, ent = readdir(procDir.get())) {
checkInterrupt(); checkInterrupt();
if (std::regex_match(ent->d_name, digitsRegex)) { if (std::regex_match(ent->d_name, digitsRegex)) {
readProcLink(fmt("/proc/%s/exe" ,ent->d_name), unchecked);
readProcLink(fmt("/proc/%s/cwd", ent->d_name), unchecked);
auto fdStr = fmt("/proc/%s/fd", ent->d_name);
auto fdDir = AutoCloseDir(opendir(fdStr.c_str()));
if (!fdDir) {
if (errno == ENOENT || errno == EACCES)
continue;
throw SysError("opening %1%", fdStr);
}
struct dirent * fd_ent;
while (errno = 0, fd_ent = readdir(fdDir.get())) {
if (fd_ent->d_name[0] != '.')
readProcLink(fmt("%s/%s", fdStr, fd_ent->d_name), unchecked);
}
if (errno) {
if (errno == ESRCH)
continue;
throw SysError("iterating /proc/%1%/fd", ent->d_name);
}
fdDir.reset();
try { try {
readProcLink(fmt("/proc/%s/exe" ,ent->d_name), unchecked);
readProcLink(fmt("/proc/%s/cwd", ent->d_name), unchecked);
auto fdStr = fmt("/proc/%s/fd", ent->d_name);
auto fdDir = AutoCloseDir(opendir(fdStr.c_str()));
if (!fdDir) {
if (errno == ENOENT || errno == EACCES)
continue;
throw SysError("opening %1%", fdStr);
}
struct dirent * fd_ent;
while (errno = 0, fd_ent = readdir(fdDir.get())) {
if (fd_ent->d_name[0] != '.')
readProcLink(fmt("%s/%s", fdStr, fd_ent->d_name), unchecked);
}
if (errno) {
if (errno == ESRCH)
continue;
throw SysError("iterating /proc/%1%/fd", ent->d_name);
}
fdDir.reset();
auto mapFile = fmt("/proc/%s/maps", ent->d_name); auto mapFile = fmt("/proc/%s/maps", ent->d_name);
auto mapLines = tokenizeString<std::vector<std::string>>(readFile(mapFile), "\n"); auto mapLines = tokenizeString<std::vector<std::string>>(readFile(mapFile), "\n");
for (const auto & line : mapLines) { for (const auto & line : mapLines) {