path: root/src/nvim/os/fs.c

// This is an open source non-commercial project. Dear PVS-Studio, please check
// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com

// fs.c -- filesystem access
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdbool.h>
#include <stddef.h>

#include "auto/config.h"

#ifdef HAVE_SYS_UIO_H
# include <sys/uio.h>
#endif

#include <uv.h>

#include "nvim/ascii.h"
#include "nvim/assert.h"
#include "nvim/memory.h"
#include "nvim/message.h"
#include "nvim/option.h"
#include "nvim/os/os.h"
#include "nvim/os/os_defs.h"
#include "nvim/path.h"
#include "nvim/strings.h"

#ifdef WIN32
# include "nvim/mbyte.h"  // for utf8_to_utf16, utf16_to_utf8
#endif

#ifdef INCLUDE_GENERATED_DECLARATIONS
# include "os/fs.c.generated.h"
#endif

#define RUN_UV_FS_FUNC(ret, func, ...) \
  do { \
    bool did_try_to_free = false; \
uv_call_start: {} \
    uv_fs_t req; \
    fs_loop_lock(); \
    ret = func(&fs_loop, &req, __VA_ARGS__); \
    uv_fs_req_cleanup(&req); \
    fs_loop_unlock(); \
    if (ret == UV_ENOMEM && !did_try_to_free) { \
      try_to_free_memory(); \
      did_try_to_free = true; \
      goto uv_call_start; \
    } \
  } while (0)

// Many fs functions from libuv return that value on success.
static const int kLibuvSuccess = 0;
static uv_loop_t fs_loop;
static uv_mutex_t fs_loop_mutex;

// Initialize the fs module
void fs_init(void)
{
  uv_loop_init(&fs_loop);
  uv_mutex_init_recursive(&fs_loop_mutex);
}

/// TODO(bfredl): some of these operations should
/// be possible to do the private libuv loop of the
/// thread, instead of contending the global fs loop
void fs_loop_lock(void)
{
  uv_mutex_lock(&fs_loop_mutex);
}

void fs_loop_unlock(void)
{
  uv_mutex_unlock(&fs_loop_mutex);
}

/// Changes the current directory to `path`.
///
/// @return 0 on success, or negative error code.
int os_chdir(const char *path)
  FUNC_ATTR_NONNULL_ALL
{
  if (p_verbose >= 5) {
    verbose_enter();
    smsg("chdir(%s)", path);
    verbose_leave();
  }
  return uv_chdir(path);
}

/// Get the name of current directory.
///
/// @param buf Buffer to store the directory name.
/// @param len Length of `buf`.
/// @return `OK` for success, `FAIL` for failure.
int os_dirname(char_u *buf, size_t len)
  FUNC_ATTR_NONNULL_ALL
{
  int error_number;
  if ((error_number = uv_cwd((char *)buf, &len)) != kLibuvSuccess) {
    STRLCPY(buf, uv_strerror(error_number), len);
    return FAIL;
  }
  return OK;
}

/// Check if the given path is a directory and not a symlink to a directory.
/// @return `true` if `name` is a directory and NOT a symlink to a directory.
///         `false` if `name` is not a directory or if an error occurred.
bool os_isrealdir(const char *name)
  FUNC_ATTR_NONNULL_ALL
{
  uv_fs_t request;
  fs_loop_lock();
  if (uv_fs_lstat(&fs_loop, &request, name, NULL) != kLibuvSuccess) {
    fs_loop_unlock();
    return false;
  }
  fs_loop_unlock();
  if (S_ISLNK(request.statbuf.st_mode)) {
    return false;
  } else {
    return S_ISDIR(request.statbuf.st_mode);
  }
}

/// Check if the given path exists and is a directory.
///
/// @return `true` if `name` is a directory.
bool os_isdir(const char_u *name)
  FUNC_ATTR_NONNULL_ALL
{
  int32_t mode = os_getperm((const char *)name);
  if (mode < 0) {
    return false;
  }

  if (!S_ISDIR(mode)) {
    return false;
  }

  return true;
}

/// Check what `name` is:
/// @return NODE_NORMAL: file or directory (or doesn't exist)
///         NODE_WRITABLE: writable device, socket, fifo, etc.
///         NODE_OTHER: non-writable things
int os_nodetype(const char *name)
  FUNC_ATTR_NONNULL_ALL
{
#ifndef WIN32  // Unix
  uv_stat_t statbuf;
  if (0 != os_stat(name, &statbuf)) {
    return NODE_NORMAL;  // File doesn't exist.
  }
  // uv_handle_type does not distinguish BLK and DIR.
  //    Related: https://github.com/joyent/libuv/pull/1421
  if (S_ISREG(statbuf.st_mode) || S_ISDIR(statbuf.st_mode)) {
    return NODE_NORMAL;
  }
  if (S_ISBLK(statbuf.st_mode)) {  // block device isn't writable
    return NODE_OTHER;
  }
  // Everything else is writable?
  // buf_write() expects NODE_WRITABLE for char device /dev/stderr.
  return NODE_WRITABLE;
#else  // Windows
  // Edge case from Vim os_win32.c:
  // We can't open a file with a name "\\.\con" or "\\.\prn", trying to read
  // from it later will cause Vim to hang. Thus return NODE_WRITABLE here.
  if (STRNCMP(name, "\\\\.\\", 4) == 0) {
    return NODE_WRITABLE;
  }

  // Vim os_win32.c:mch_nodetype does (since 7.4.015):
  //    wn = enc_to_utf16(name, NULL);
  //    hFile = CreatFile(wn, ...)
  // to get a HANDLE. Whereas libuv just calls _get_osfhandle() on the fd we
  // give it. But uv_fs_open later calls fs__capture_path which does a similar
  // utf8-to-utf16 dance and saves us the hassle.

  // macOS: os_open(/dev/stderr) would return UV_EACCES.
  int fd = os_open(name, O_RDONLY
# ifdef O_NONBLOCK