zircon/system/core/bootsvc/bootfs-service.cc

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "bootfs-service.h"

#include <fcntl.h>
#include <lib/bootfs/parser.h>
#include <sys/stat.h>
#include <zircon/compiler.h>
#include <zircon/process.h>
#include <zircon/processargs.h>
#include <zircon/status.h>

#include <utility>

#include <fbl/algorithm.h>
#include <fs/vfs_types.h>
#include <launchpad/launchpad.h>

#include "util.h"

namespace bootsvc {

zx_status_t BootfsService::Create(async_dispatcher_t* dispatcher, fbl::RefPtr<BootfsService>* out) {
  auto svc = fbl::AdoptRef(new BootfsService());

  zx_status_t status = memfs::Vfs::Create("<root>", UINT64_MAX, &svc->vfs_, &svc->root_);
  if (status != ZX_OK) {
    return status;
  }

  svc->vfs_->SetDispatcher(dispatcher);
  *out = std::move(svc);
  return ZX_OK;
}

zx_status_t BootfsService::AddBootfs(zx::vmo bootfs_vmo) {
  bootfs::Parser parser;
  zx_status_t status = parser.Init(zx::unowned_vmo(bootfs_vmo));
  if (status != ZX_OK) {
    return status;
  }

  // Load all of the entries in the bootfs into the FS
  status = parser.Parse([this, &bootfs_vmo](const zbi_bootfs_dirent_t* entry) -> zx_status_t {
    PublishUnownedVmo(entry->name, bootfs_vmo, entry->data_off, entry->data_len);
    return ZX_OK;
  });
  // Add this VMO to our list of parts even on failure, since we may have
  // added a file
  owned_vmos_.push_back(std::move(bootfs_vmo));
  return status;
}

zx_status_t BootfsService::CreateRootConnection(zx::channel* out) {
  return CreateVnodeConnection(vfs_.get(), root_, fs::Rights::ReadExec(), out);
}

zx_status_t BootfsService::Open(const char* path, zx::vmo* vmo, size_t* size) {
  auto open_result = vfs_->Open(root_, path, fs::VnodeConnectionOptions::ReadOnly().set_no_remote(),
                                fs::Rights::ReadOnly(), 0);
  if (open_result.is_error()) {
    return open_result.error();
  }
  ZX_ASSERT(open_result.is_ok());
  fbl::RefPtr<fs::Vnode> node = std::move(open_result.ok().vnode);
  fs::VnodeRepresentation info;
  zx_status_t status = node->GetNodeInfo(fs::Rights::ReadOnly(), &info);
  if (status != ZX_OK) {
    return status;
  }

  if (!info.is_memory()) {
    return ZX_ERR_WRONG_TYPE;
  }
  fs::VnodeRepresentation::Memory& memory = info.memory();
  ZX_ASSERT(memory.offset == 0);

  *vmo = std::move(memory.vmo);
  *size = memory.length;
  return ZX_OK;
}

BootfsService::~BootfsService() {
  auto callback = [parts(std::move(owned_vmos_))](zx_status_t status) mutable {
    // Bootfs uses multiple Vnodes which may share a reference to a single VMO.
    // Since the lifetime of the VMOs are coupled with the BootfsService, all
    // connections to these Vnodes must be terminated (with Shutdown) before
    // we can safely close the VMOs
    parts.reset();
  };
  vfs_->Shutdown(std::move(callback));
}

zx_status_t BootfsService::PublishVmo(const char* path, zx::vmo vmo, zx_off_t off, size_t len) {
  zx_status_t status = PublishUnownedVmo(path, vmo, off, len);
  if (status != ZX_OK) {
    return status;
  }
  owned_vmos_.push_back(std::move(vmo));
  return ZX_OK;
}

zx_status_t BootfsService::PublishUnownedVmo(const char* path, const zx::vmo& vmo, zx_off_t off,
                                             size_t len) {
  ZX_ASSERT(root_ != nullptr);
  fbl::RefPtr<memfs::VnodeDir> vnb(root_);
  zx_status_t r;
  if ((path[0] == '/') || (path[0] == 0))
    return ZX_ERR_INVALID_ARGS;
  for (;;) {
    const char* nextpath = strchr(path, '/');
    if (nextpath == nullptr) {
      if (path[0] == 0) {
        return ZX_ERR_INVALID_ARGS;
      }
      return vfs_->CreateFromVmo(vnb.get(), fbl::StringPiece(path, strlen(path)), vmo.get(), off,
                                 len);
    } else {
      if (nextpath == path) {
        return ZX_ERR_INVALID_ARGS;
      }

      fbl::RefPtr<fs::Vnode> out;
      r = vnb->Lookup(&out, fbl::StringPiece(path, nextpath - path));
      if (r == ZX_ERR_NOT_FOUND) {
        r = vnb->Create(&out, fbl::StringPiece(path, nextpath - path), S_IFDIR);
      }

      if (r < 0) {
        return r;
      }
      vnb = fbl::RefPtr<memfs::VnodeDir>::Downcast(std::move(out));
      path = nextpath + 1;
    }
  }
}

void BootfsService::PublishStartupVmos(uint8_t type, const char* debug_type_name) {
  constexpr char kVmoSubdir[] = "kernel/";
  constexpr size_t kVmoSubdirLen = sizeof(kVmoSubdir) - 1;

  for (uint16_t i = 0; true; ++i) {
    zx::vmo owned_vmo(zx_take_startup_handle(PA_HND(type, i)));
    if (!owned_vmo.is_valid()) {
      break;
    }
    // We use an unowned VMO here so we can have some finer control over
    // whether the handle is closed.   This is safe since |owned_vmo| will
    // never be closed before |vmo|.
    zx::unowned_vmo vmo(owned_vmo);

    // The first vDSO is the default vDSO.  Since we've taken the startup
    // handle, launchpad won't find it on its own.  So point launchpad at
    // it instead of closing it.
    const bool is_default_vdso = (type == PA_VMO_VDSO && i == 0);
    if (is_default_vdso) {
      launchpad_set_vdso_vmo(owned_vmo.release());
    }

    // The vDSO VMOs have names like "vdso/default", so those
    // become VMO files at "/boot/kernel/vdso/default".
    char name[kVmoSubdirLen + ZX_MAX_NAME_LEN] = {};
    memcpy(name, kVmoSubdir, kVmoSubdirLen);
    size_t size;
    zx_status_t status =
        vmo->get_property(ZX_PROP_NAME, name + kVmoSubdirLen, sizeof(name) - kVmoSubdirLen);
    if (status != ZX_OK) {
      printf("bootsvc: vmo.get_property on %s %u: %s\n", debug_type_name, i,
             zx_status_get_string(status));
      continue;
    }
    status = vmo->get_size(&size);
    if (status != ZX_OK) {
      printf("bootsvc: vmo.get_size on %s %u: %s\n", debug_type_name, i,
             zx_status_get_string(status));
      continue;
    }
    if (size == 0) {
      // empty vmos do not get installed
      continue;
    }

    if (!strcmp(name + kVmoSubdirLen, "crashlog")) {
      // the crashlog has a special home
      strcpy(name, kLastPanicFilePath);
    }

    if (owned_vmo.is_valid()) {
      status = PublishVmo(name, std::move(owned_vmo), 0, size);
    } else {
      status = PublishUnownedVmo(name, *vmo, 0, size);
    }
    if (status != ZX_OK) {
      printf("bootsvc: failed to add %s %u to filesystem as %s: %s\n", debug_type_name, i, name,
             zx_status_get_string(status));
      continue;
    }
  }
}

}  // namespace bootsvc