os_open: impl mch_open with libuv. ref #133

- use return value instead of open_req.result
- libuv uv_fs_open() returns `-errno` instead of always -1
- libuv always sets open_req.result to the return value, _except_ for OOM
  where it only sets the return value. So always use the return value.
- replace calls to mch_open macro.
- update call sites expecting -1 error

src/nvim/eval.c

@@ -8317,7 +8317,7 @@ static void f_filereadable(typval_T *argvars, typval_T *rettv)
 # define O_NONBLOCK 0
 #endif
   p = get_tv_string(&argvars[0]);
-  if (*p && !os_isdir(p) && (fd = mch_open((char *)p,
+  if (*p && !os_isdir(p) && (fd = os_open((char *)p,
                                   O_RDONLY | O_NONBLOCK, 0)) >= 0) {
     n = TRUE;
     close(fd);

src/nvim/ex_cmds.c

@@ -1575,19 +1575,19 @@ void write_viminfo(char_u *file, int forceit)
     if (tempname != NULL) {
       int fd;
 
-      /* Use mch_open() to be able to use O_NOFOLLOW and set file
+      /* Use os_open() to be able to use O_NOFOLLOW and set file
        * protection:
        * Unix: same as original file, but strip s-bit.  Reset umask to
        * avoid it getting in the way.
        * Others: r&w for user only. */
 # ifdef UNIX
       umask_save = umask(0);
-      fd = mch_open((char *)tempname,
+      fd = os_open((char *)tempname,
           O_CREAT|O_EXCL|O_WRONLY|O_NOFOLLOW,
           (int)((old_info.stat.st_mode & 0777) | 0600));
       (void)umask(umask_save);
 # else
-      fd = mch_open((char *)tempname,
+      fd = os_open((char *)tempname,
           O_CREAT|O_EXCL|O_WRONLY|O_NOFOLLOW, 0600);
 # endif
       if (fd < 0)

src/nvim/ex_cmds2.c

@@ -2372,9 +2372,9 @@ int source_level(void *cookie)
  */
 static FILE *fopen_noinh_readbin(char *filename)
 {
-  int fd_tmp = mch_open(filename, O_RDONLY, 0);
+  int fd_tmp = os_open(filename, O_RDONLY, 0);
 
-  if (fd_tmp == -1)
+  if (fd_tmp < 0)
     return NULL;
 
 # ifdef HAVE_FD_CLOEXEC

src/nvim/fileio.c

@@ -428,7 +428,7 @@ readfile (
 #ifdef UNIX
     /*
      * On Unix it is possible to read a directory, so we have to
-     * check for it before the mch_open().
+     * check for it before os_open().
      */
     perm = os_getperm(fname);
     if (perm >= 0 && !S_ISREG(perm)                 /* not a regular file ... */
@@ -507,13 +507,13 @@ readfile (
   if (!read_buffer && !read_stdin) {
     if (!newfile || readonlymode) {
       file_readonly = TRUE;
-    } else if ((fd = mch_open((char *)fname, O_RDWR, 0)) < 0) {
+    } else if ((fd = os_open((char *)fname, O_RDWR, 0)) < 0) {
       // opening in readwrite mode failed => file is readonly
       file_readonly = TRUE;
     }
     if (file_readonly == TRUE) {
       // try to open readonly
-      fd = mch_open((char *)fname, O_RDONLY, 0);
+      fd = os_open((char *)fname, O_RDONLY, 0);
     }
   }
 
@@ -696,9 +696,7 @@ readfile (
     if (!read_stdin && (curbuf != old_curbuf
                         || (using_b_ffname && (old_b_ffname != curbuf->b_ffname))
                         || (using_b_fname && (old_b_fname != curbuf->b_fname))
-                        || (fd =
+                        || (fd = os_open((char *)fname, O_RDONLY, 0)) < 0)) {
-                              mch_open((char *)fname, O_RDONLY,
-                                  0)) < 0)) {
       --no_wait_return;
       msg_scroll = msg_save;
       if (fd < 0)
@@ -2157,9 +2155,9 @@ readfile_charconvert (
     if (eval_charconvert(fenc, enc_utf8 ? (char_u *)"utf-8" : p_enc,
             fname, tmpname) == FAIL)
       errmsg = (char_u *)_("Conversion with 'charconvert' failed");
-    if (errmsg == NULL && (*fdp = mch_open((char *)tmpname,
+    if (errmsg == NULL && (*fdp = os_open((char *)tmpname, O_RDONLY, 0)) < 0) {
-                               O_RDONLY, 0)) < 0)
       errmsg = (char_u *)_("can't read output of 'charconvert'");
+    }
   }
 
   if (errmsg != NULL) {
@@ -2174,8 +2172,9 @@ readfile_charconvert (
   }
 
   /* If the input file is closed, open it (caller should check for error). */
-  if (*fdp < 0)
+  if (*fdp < 0) {
-    *fdp = mch_open((char *)fname, O_RDONLY, 0);
+    *fdp = os_open((char *)fname, O_RDONLY, 0);
+  }
 
   return tmpname;
 }
@@ -2737,7 +2736,7 @@ buf_write (
             break;
           }
         }
-        fd = mch_open((char *)IObuff,
+        fd = os_open((char *)IObuff,
             O_CREAT|O_WRONLY|O_EXCL|O_NOFOLLOW, perm);
         if (fd < 0)             /* can't write in directory */
           backup_copy = TRUE;
@@ -2791,8 +2790,7 @@ buf_write (
     else
       backup_ext = p_bex;
 
-    if (backup_copy
+    if (backup_copy && (fd = os_open((char *)fname, O_RDONLY, 0)) >= 0) {
-        && (fd = mch_open((char *)fname, O_RDONLY, 0)) >= 0) {
       int bfd;
       char_u      *copybuf, *wp;
       int some_error = FALSE;
@@ -2890,7 +2888,7 @@ buf_write (
           os_remove((char *)backup);
           /* Open with O_EXCL to avoid the file being created while
            * we were sleeping (symlink hacker attack?) */
-          bfd = mch_open((char *)backup,
+          bfd = os_open((char *)backup,
               O_WRONLY|O_CREAT|O_EXCL|O_NOFOLLOW,
               perm & 0777);
           if (bfd < 0) {
@@ -3194,7 +3192,7 @@ nobackup:
    * (this may happen when the user reached his quotum for number of files).
    * Appending will fail if the file does not exist and forceit is FALSE.
    */
-  while ((fd = mch_open((char *)wfname, O_WRONLY | (append
+  while ((fd = os_open((char *)wfname, O_WRONLY | (append
                                                               ? (forceit ? (
                                                                    O_APPEND |
                                                                    O_CREAT) :
@@ -3515,8 +3513,8 @@ restore_backup:
           MSG(_(e_interr));
           out_flush();
         }
-        if ((fd = mch_open((char *)backup, O_RDONLY, 0)) >= 0) {
+        if ((fd = os_open((char *)backup, O_RDONLY, 0)) >= 0) {
-          if ((write_info.bw_fd = mch_open((char *)fname,
+          if ((write_info.bw_fd = os_open((char *)fname,
                    O_WRONLY | O_CREAT | O_TRUNC,
                    perm & 0777)) >= 0) {
             /* copy the file. */
@@ -3646,7 +3644,7 @@ restore_backup:
       int empty_fd;
 
       if (org == NULL
-          || (empty_fd = mch_open(org,
+          || (empty_fd = os_open(org,
                   O_CREAT | O_EXCL | O_NOFOLLOW,
                   perm < 0 ? 0666 : (perm & 0777))) < 0)
         EMSG(_("E206: patchmode: can't touch empty original file"));
@@ -4615,7 +4613,7 @@ int vim_rename(char_u *from, char_u *to)
   /* For systems that support ACL: get the ACL from the original file. */
   acl = mch_get_acl(from);
 #endif
-  fd_in = mch_open((char *)from, O_RDONLY, 0);
+  fd_in = os_open((char *)from, O_RDONLY, 0);
   if (fd_in == -1) {
 #ifdef HAVE_ACL
     mch_free_acl(acl);
@@ -4624,7 +4622,7 @@ int vim_rename(char_u *from, char_u *to)
   }
 
   /* Create the new file with same permissions as the original. */
-  fd_out = mch_open((char *)to,
+  fd_out = os_open((char *)to,
       O_CREAT|O_EXCL|O_WRONLY|O_NOFOLLOW, (int)perm);
   if (fd_out == -1) {
     close(fd_in);
@@ -4660,7 +4658,7 @@ int vim_rename(char_u *from, char_u *to)
     errmsg = _("E210: Error reading \"%s\"");
     to = from;
   }
-#ifndef UNIX        /* for Unix mch_open() already set the permission */
+#ifndef UNIX        /* for Unix os_open() already set the permission */
   os_setperm(to, perm);
 #endif
 #ifdef HAVE_ACL

src/nvim/macros.h

@@ -108,13 +108,12 @@
 #endif
 
 #  define mch_fopen(n, p)       fopen((n), (p))
-#   define mch_open(n, m, p)    open((n), (m), (p))
 
-/* mch_open_rw(): invoke mch_open() with third argument for user R/W. */
+/* mch_open_rw(): invoke os_open() with third argument for user R/W. */
 #if defined(UNIX)  /* open in rw------- mode */
-# define mch_open_rw(n, f)      mch_open((n), (f), (mode_t)0600)
+# define mch_open_rw(n, f)      os_open((n), (f), (mode_t)0600)
 #else
-#  define mch_open_rw(n, f)     mch_open((n), (f), 0)
+#  define mch_open_rw(n, f)     os_open((n), (f), 0)
 #endif
 
 #ifdef STARTUPTIME

src/nvim/memline.c

@@ -440,7 +440,7 @@ void ml_setname(buf_T *buf)
   }
 
   if (mfp->mf_fd == -1) {           /* need to (re)open the swap file */
-    mfp->mf_fd = mch_open((char *)mfp->mf_fname, O_RDWR, 0);
+    mfp->mf_fd = os_open((char *)mfp->mf_fname, O_RDWR, 0);
     if (mfp->mf_fd < 0) {
       /* could not (re)open the swap file, what can we do???? */
       EMSG(_("E301: Oops, lost the swap file!!!"));
@@ -1517,7 +1517,7 @@ static time_t swapfile_info(char_u *fname)
   /*
    * print the original file name
    */
-  fd = mch_open((char *)fname, O_RDONLY, 0);
+  fd = os_open((char *)fname, O_RDONLY, 0);
   if (fd >= 0) {
     if (read_eintr(fd, &b0, sizeof(b0)) == sizeof(b0)) {
       if (STRNCMP(b0.b0_version, "VIM 3.0", 7) == 0) {
@@ -3329,7 +3329,7 @@ findswapname (
          * Try to read block 0 from the swap file to get the original
          * file name (and inode number).
          */
-        fd = mch_open((char *)fname, O_RDONLY, 0);
+        fd = os_open((char *)fname, O_RDONLY, 0);
         if (fd >= 0) {
           if (read_eintr(fd, &b0, sizeof(b0)) == sizeof(b0)) {
             /*

src/nvim/os/fs.c

@@ -11,6 +11,7 @@
 #include "nvim/misc2.h"
 #include "nvim/path.h"
 #include "nvim/strings.h"
+#include "nvim/log.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "os/fs.c.generated.h"
@@ -150,6 +151,24 @@ static bool is_executable_in_path(const char_u *name)
   return false;
 }
 
+/// Opens or creates a file and returns a non-negative integer representing
+/// the lowest-numbered unused file descriptor, for use in subsequent system
+/// calls (read, write, lseek, fcntl, etc.). If the operation fails, `-errno`
+/// is returned, and no file is created or modified.
+///
+/// @param flags bitwise OR of flags defined in <fcntl.h>
+/// @param mode permissions for the newly-created file (IGNORED if 'flags' is
+/// not `O_CREAT` or `O_TMPFILE`)
+/// @return file descriptor, or negative `errno` on failure
+int os_open(const char* path, int flags, int mode)
+{
+  uv_fs_t open_req;
+  int r = uv_fs_open(uv_default_loop(), &open_req, path, flags, mode, NULL);
+  uv_fs_req_cleanup(&open_req);
+  //`r` is the same as open_req.result, except when OOM. So just use `r`.
+  return r;
+}
+
 /// Get stat information for a file.
 ///
 /// @return OK on success, FAIL if a failure occurred.
@@ -291,7 +310,7 @@ int os_remove(const char *path)
 
 /// Get the file information for a given path
 ///
-/// @param file_descriptor File descriptor of the file.
+/// @param path Path to the file.
 /// @param[out] file_info Pointer to a FileInfo to put the information in.
 /// @return `true` on success, `false` for failure.
 bool os_get_file_info(const char *path, FileInfo *file_info)

src/nvim/undo.c

@@ -1045,7 +1045,7 @@ void u_write_undo(char_u *name, int forceit, buf_T *buf, char_u *hash)
   if (os_file_exists(file_name)) {
     if (name == NULL || !forceit) {
       /* Check we can read it and it's an undo file. */
-      fd = mch_open((char *)file_name, O_RDONLY, 0);
+      fd = os_open((char *)file_name, O_RDONLY, 0);
       if (fd < 0) {
         if (name != NULL || p_verbose > 0) {
           if (name == NULL)
@@ -1089,7 +1089,7 @@ void u_write_undo(char_u *name, int forceit, buf_T *buf, char_u *hash)
     goto theend;
   }
 
-  fd = mch_open((char *)file_name,
+  fd = os_open((char *)file_name,
       O_CREAT|O_WRONLY|O_EXCL|O_NOFOLLOW, perm);
   if (fd < 0) {
     EMSG2(_(e_not_open), file_name);