[PATCH 1/3] gdbsupport: change scoped_fd::to_file to a free function

[PATCH 1/3] gdbsupport: change scoped_fd::to_file to a free function

[Simon Marchi]

The following patch wants to chagne gdb_fopen_cloexec to return a
scoped_fd.  Doing this causes a cyclic include between scoped_fd.h and
filestuff.h.  scoped_fd.h includes filestuff.h because of the
scoped_fd::to_file method.  To fix that, change scoped_fd::to_file to
be a free function in filestuff.h.

Change-Id: Ic82a48914b2aacee8f14af535b7469245f88b93d
---
 gdb/dwarf2/index-write.c            |  2 +-
 gdb/source.c                        |  2 +-
 gdb/unittests/scoped_fd-selftests.c |  2 +-
 gdbsupport/filestuff.h              | 17 +++++++++++++++++
 gdbsupport/scoped_fd.h              | 13 -------------
 5 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/gdb/dwarf2/index-write.c b/gdb/dwarf2/index-write.c
index 4e00c716d910..59a6aa4264d5 100644
--- a/gdb/dwarf2/index-write.c
+++ b/gdb/dwarf2/index-write.c
@@ -1544,7 +1544,7 @@ struct index_wip_file
     if (out_file_fd.get () == -1)
       perror_with_name (("mkstemp"));
 
-    out_file = out_file_fd.to_file ("wb");
+    out_file = to_file (out_file_fd, "wb");
 
     if (out_file == nullptr)
       error (_("Can't open `%s' for writing"), filename_temp.data ());
diff --git a/gdb/source.c b/gdb/source.c
index 7d1934bd6c9b..0e3308048dc3 100644
--- a/gdb/source.c
+++ b/gdb/source.c
@@ -1620,7 +1620,7 @@ search_command_helper (const char *regex, int from_tty, bool forward)
   if (lseek (desc.get (), (*offsets)[line - 1], 0) < 0)
     perror_with_name (symtab_to_filename_for_display (loc->symtab ()));
 
-  gdb_file_up stream = desc.to_file (FDOPEN_MODE);
+  gdb_file_up stream = to_file (desc, FDOPEN_MODE);
   clearerr (stream.get ());
 
   gdb::def_vector<char> buf;
diff --git a/gdb/unittests/scoped_fd-selftests.c b/gdb/unittests/scoped_fd-selftests.c
index d1803aaf8da2..1a361f00a2e3 100644
--- a/gdb/unittests/scoped_fd-selftests.c
+++ b/gdb/unittests/scoped_fd-selftests.c
@@ -76,7 +76,7 @@ test_to_file ()
 
   unlink (filename);
   
-  gdb_file_up file = sfd.to_file ("rw");
+  gdb_file_up file = to_file (sfd, "rw");
   SELF_CHECK (file != nullptr);
   SELF_CHECK (sfd.get () == -1);
 }
diff --git a/gdbsupport/filestuff.h b/gdbsupport/filestuff.h
index 7f4cfb2388b1..658e1df4e558 100644
--- a/gdbsupport/filestuff.h
+++ b/gdbsupport/filestuff.h
@@ -21,6 +21,7 @@
 
 #include <dirent.h>
 #include <fcntl.h>
+#include "scoped_fd.h"
 
 /* Note all the file descriptors which are open when this is called.
    These file descriptors will not be closed by close_most_fds.  */
@@ -96,6 +97,22 @@ gdb_fopen_cloexec (const std::string &filename, const char *opentype)
   return gdb_fopen_cloexec (filename.c_str (), opentype);
 }
 
+/* Converts FD into a gdb_file_up.
+
+   On success, the file descriptor owned by FD is released, meaning that FD no
+   longer contains nor owns it.  */
+
+static inline
+gdb_file_up to_file (scoped_fd &fd, const char *mode) noexcept
+{
+  gdb_file_up result (fdopen (fd.get (), mode));
+
+  if (result != nullptr)
+    int unused ATTRIBUTE_UNUSED = fd.release ();
+
+  return result;
+}
+
 /* Like 'socketpair', but ensures that the returned file descriptors
    have the close-on-exec flag set.  */
 
diff --git a/gdbsupport/scoped_fd.h b/gdbsupport/scoped_fd.h
index a1aad8493998..a571729c951c 100644
--- a/gdbsupport/scoped_fd.h
+++ b/gdbsupport/scoped_fd.h
@@ -21,7 +21,6 @@
 #define COMMON_SCOPED_FD_H
 
 #include <unistd.h>
-#include "filestuff.h"
 
 /* A smart-pointer-like class to automatically close a file descriptor.  */
 
@@ -63,18 +62,6 @@ class scoped_fd
     return fd;
   }
 
-  /* Like release, but return a gdb_file_up that owns the file
-     descriptor.  On success, this scoped_fd will be released.  On
-     failure, return NULL and leave this scoped_fd in possession of
-     the fd.  */
-  gdb_file_up to_file (const char *mode) noexcept
-  {
-    gdb_file_up result (fdopen (m_fd, mode));
-    if (result != nullptr)
-      m_fd = -1;
-    return result;
-  }
-
   int get () const noexcept
   {
     return m_fd;
-- 
2.32.0

[PATCH 2/3] gdbsupport: make gdb_open_cloexec return scoped_fd

[Simon Marchi]

Make gdb_open_cloexec return a scoped_fd, to encourage using automatic
management of the file descriptor closing.  Except in the most trivial
cases, I changed the callers to just release the fd, which retains their
existing behavior.  That will allow the transition to using scoped_fd
more to go gradually, one caller at a time.

Change-Id: Ife022b403f96e71d5ebb4f1056ef6251b30fe554
---
 gdb/auxv.c                 | 14 ++++++--------
 gdb/corelow.c              |  2 +-
 gdb/darwin-nat.c           |  2 +-
 gdb/gdb_bfd.c              |  2 +-
 gdb/inf-child.c            |  2 +-
 gdb/linux-nat.c            |  2 +-
 gdb/nat/linux-namespaces.c | 13 ++++---------
 gdb/remote-fileio.c        |  2 +-
 gdb/ser-unix.c             |  2 +-
 gdb/solib.c                |  7 ++++---
 gdb/source.c               | 15 +++++++--------
 gdb/top.c                  |  8 +++-----
 gdb/tracefile-tfile.c      |  2 +-
 gdbsupport/filestuff.cc    |  8 ++++----
 gdbsupport/filestuff.h     |  6 +++---
 gdbsupport/scoped_mmap.cc  |  2 +-
 16 files changed, 40 insertions(+), 49 deletions(-)

diff --git a/gdb/auxv.c b/gdb/auxv.c
index 2bcf9f452e3e..120e5c7cc21b 100644
--- a/gdb/auxv.c
+++ b/gdb/auxv.c
@@ -46,23 +46,21 @@ procfs_xfer_auxv (gdb_byte *readbuf,
 		  ULONGEST len,
 		  ULONGEST *xfered_len)
 {
-  int fd;
   ssize_t l;
 
   std::string pathname = string_printf ("/proc/%d/auxv", inferior_ptid.pid ());
-  fd = gdb_open_cloexec (pathname, writebuf != NULL ? O_WRONLY : O_RDONLY, 0);
-  if (fd < 0)
+  scoped_fd fd
+    = gdb_open_cloexec (pathname, writebuf != NULL ? O_WRONLY : O_RDONLY, 0);
+  if (fd.get () < 0)
     return TARGET_XFER_E_IO;
 
   if (offset != (ULONGEST) 0
-      && lseek (fd, (off_t) offset, SEEK_SET) != (off_t) offset)
+      && lseek (fd.get (), (off_t) offset, SEEK_SET) != (off_t) offset)
     l = -1;
   else if (readbuf != NULL)
-    l = read (fd, readbuf, (size_t) len);
+    l = read (fd.get (), readbuf, (size_t) len);
   else
-    l = write (fd, writebuf, (size_t) len);
-
-  (void) close (fd);
+    l = write (fd.get (), writebuf, (size_t) len);
 
   if (l < 0)
     return TARGET_XFER_E_IO;
diff --git a/gdb/corelow.c b/gdb/corelow.c
index eb785a08633a..b2a40b1ed5c8 100644
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -436,7 +436,7 @@ core_target_open (const char *arg, int from_tty)
     flags |= O_RDWR;
   else
     flags |= O_RDONLY;
-  scratch_chan = gdb_open_cloexec (filename.get (), flags, 0);
+  scratch_chan = gdb_open_cloexec (filename.get (), flags, 0).release ();
   if (scratch_chan < 0)
     perror_with_name (filename.get ());
 
diff --git a/gdb/darwin-nat.c b/gdb/darwin-nat.c
index a6790792fb65..eb3b6fa8ef4c 100644
--- a/gdb/darwin-nat.c
+++ b/gdb/darwin-nat.c
@@ -1822,7 +1822,7 @@ may_have_sip ()
 static void
 copy_shell_to_cache (const char *shell, const std::string &new_name)
 {
-  scoped_fd from_fd (gdb_open_cloexec (shell, O_RDONLY, 0));
+  scoped_fd from_fd = gdb_open_cloexec (shell, O_RDONLY, 0);
   if (from_fd.get () < 0)
     error (_("Could not open shell (%s) for reading: %s"),
 	   shell, safe_strerror (errno));
diff --git a/gdb/gdb_bfd.c b/gdb/gdb_bfd.c
index 312442a466e2..c6ff409d49c6 100644
--- a/gdb/gdb_bfd.c
+++ b/gdb/gdb_bfd.c
@@ -541,7 +541,7 @@ gdb_bfd_open (const char *name, const char *target, int fd,
 
   if (fd == -1)
     {
-      fd = gdb_open_cloexec (name, O_RDONLY | O_BINARY, 0);
+      fd = gdb_open_cloexec (name, O_RDONLY | O_BINARY, 0).release ();
       if (fd == -1)
 	{
 	  bfd_set_error (bfd_error_system_call);
diff --git a/gdb/inf-child.c b/gdb/inf-child.c
index f690aa77913f..5084f448c1e0 100644
--- a/gdb/inf-child.c
+++ b/gdb/inf-child.c
@@ -261,7 +261,7 @@ inf_child_target::fileio_open (struct inferior *inf, const char *filename,
       return -1;
     }
 
-  fd = gdb_open_cloexec (filename, nat_flags, nat_mode);
+  fd = gdb_open_cloexec (filename, nat_flags, nat_mode).release ();
   if (fd == -1)
     *target_errno = host_to_fileio_error (errno);
 
diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
index e4d0206eaac8..e4939fb65cbd 100644
--- a/gdb/linux-nat.c
+++ b/gdb/linux-nat.c
@@ -3848,7 +3848,7 @@ linux_proc_xfer_memory_partial_pid (ptid_t ptid,
 		 "/proc/%d/task/%ld/mem", ptid.pid (), ptid.lwp ());
 
       last_proc_mem_file.fd
-	= gdb_open_cloexec (filename, O_RDWR | O_LARGEFILE, 0);
+	= gdb_open_cloexec (filename, O_RDWR | O_LARGEFILE, 0).release ();
 
       if (last_proc_mem_file.fd == -1)
 	{
diff --git a/gdb/nat/linux-namespaces.c b/gdb/nat/linux-namespaces.c
index 0c4fadd49f7b..c5d5eb4ea8ce 100644
--- a/gdb/nat/linux-namespaces.c
+++ b/gdb/nat/linux-namespaces.c
@@ -520,13 +520,8 @@ static ssize_t
 mnsh_handle_open (int sock, const char *filename,
 		  int flags, mode_t mode)
 {
-  int fd = gdb_open_cloexec (filename, flags, mode);
-  ssize_t result = mnsh_return_fd (sock, fd, errno);
-
-  if (fd >= 0)
-    close (fd);
-
-  return result;
+  scoped_fd fd = gdb_open_cloexec (filename, flags, mode);
+  return mnsh_return_fd (sock, fd.get (), errno);
 }
 
 /* Handle a MNSH_REQ_UNLINK message.  Must be async-signal-safe.  */
@@ -901,7 +896,7 @@ linux_mntns_access_fs (pid_t pid)
   if (ns == NULL)
     return MNSH_FS_DIRECT;
 
-  fd = gdb_open_cloexec (linux_ns_filename (ns, pid), O_RDONLY, 0);
+  fd = gdb_open_cloexec (linux_ns_filename (ns, pid), O_RDONLY, 0).release ();
   if (fd < 0)
     return MNSH_FS_ERROR;
 
@@ -968,7 +963,7 @@ linux_mntns_open_cloexec (pid_t pid, const char *filename,
     return -1;
 
   if (access == MNSH_FS_DIRECT)
-    return gdb_open_cloexec (filename, flags, mode);
+    return gdb_open_cloexec (filename, flags, mode).release ();
 
   gdb_assert (access == MNSH_FS_HELPER);
 
diff --git a/gdb/remote-fileio.c b/gdb/remote-fileio.c
index 9765093a7235..20ec0f215aae 100644
--- a/gdb/remote-fileio.c
+++ b/gdb/remote-fileio.c
@@ -425,7 +425,7 @@ remote_fileio_func_open (remote_target *remote, char *buf)
 	}
     }
 
-  fd = gdb_open_cloexec (pathname, flags, mode);
+  fd = gdb_open_cloexec (pathname, flags, mode).release ();
   if (fd < 0)
     {
       remote_fileio_return_errno (remote, -1);
diff --git a/gdb/ser-unix.c b/gdb/ser-unix.c
index 96d024eea3d9..597032afe896 100644
--- a/gdb/ser-unix.c
+++ b/gdb/ser-unix.c
@@ -75,7 +75,7 @@ static int hardwire_setstopbits (struct serial *, int);
 static int
 hardwire_open (struct serial *scb, const char *name)
 {
-  scb->fd = gdb_open_cloexec (name, O_RDWR, 0);
+  scb->fd = gdb_open_cloexec (name, O_RDWR, 0).release ();
   if (scb->fd < 0)
     return -1;
 
diff --git a/gdb/solib.c b/gdb/solib.c
index 317f7eb485e2..a89ce6831e73 100644
--- a/gdb/solib.c
+++ b/gdb/solib.c
@@ -255,7 +255,8 @@ solib_find_1 (const char *in_pathname, int *fd, bool is_solib)
     }
 
   /* Now see if we can open it.  */
-  found_file = gdb_open_cloexec (temp_pathname.get (), O_RDONLY | O_BINARY, 0);
+  found_file = gdb_open_cloexec (temp_pathname.get (),
+				 O_RDONLY | O_BINARY, 0).release ();
 
   /* If the search in gdb_sysroot failed, and the path name has a
      drive spec (e.g, c:/foo), try stripping ':' from the drive spec,
@@ -276,7 +277,7 @@ solib_find_1 (const char *in_pathname, int *fd, bool is_solib)
 				   in_pathname + 2, (char *) NULL));
 
       found_file = gdb_open_cloexec (temp_pathname.get (),
-				     O_RDONLY | O_BINARY, 0);
+				     O_RDONLY | O_BINARY, 0).release ();
       if (found_file < 0)
 	{
 	  /* If the search in gdb_sysroot still failed, try fully
@@ -290,7 +291,7 @@ solib_find_1 (const char *in_pathname, int *fd, bool is_solib)
 				       in_pathname + 2, (char *) NULL));
 
 	  found_file = gdb_open_cloexec (temp_pathname.get (),
-					 O_RDONLY | O_BINARY, 0);
+					 O_RDONLY | O_BINARY, 0).release ();
 	}
     }
 
diff --git a/gdb/source.c b/gdb/source.c
index 0e3308048dc3..c57e96d49be7 100644
--- a/gdb/source.c
+++ b/gdb/source.c
@@ -818,7 +818,7 @@ openp (const char *path, openp_flags opts, const char *string,
 	{
 	  filename = (char *) alloca (strlen (string) + 1);
 	  strcpy (filename, string);
-	  fd = gdb_open_cloexec (filename, mode, 0);
+	  fd = gdb_open_cloexec (filename, mode, 0).release ();
 	  if (fd >= 0)
 	    goto done;
 	  last_errno = errno;
@@ -910,7 +910,7 @@ openp (const char *path, openp_flags opts, const char *string,
 
       if (is_regular_file (filename, &reg_file_errno))
 	{
-	  fd = gdb_open_cloexec (filename, mode, 0);
+	  fd = gdb_open_cloexec (filename, mode, 0).release ();
 	  if (fd >= 0)
 	    break;
 	  last_errno = errno;
@@ -1046,7 +1046,6 @@ find_and_open_source (const char *filename,
 {
   char *path = source_path;
   const char *p;
-  int result;
 
   /* Quick way out if we already know its full name.  */
 
@@ -1061,11 +1060,11 @@ find_and_open_source (const char *filename,
       if (rewritten_fullname != NULL)
 	*fullname = std::move (rewritten_fullname);
 
-      result = gdb_open_cloexec (fullname->get (), OPEN_MODE, 0);
-      if (result >= 0)
+      scoped_fd result = gdb_open_cloexec (fullname->get (), OPEN_MODE, 0);
+      if (result.get () >= 0)
 	{
 	  *fullname = gdb_realpath (fullname->get ());
-	  return scoped_fd (result);
+	  return result;
 	}
 
       /* Didn't work -- free old one, try again.  */
@@ -1109,8 +1108,8 @@ find_and_open_source (const char *filename,
     filename = rewritten_filename.get ();
 
   /* Try to locate file using filename.  */
-  result = openp (path, OPF_SEARCH_IN_PATH | OPF_RETURN_REALPATH, filename,
-		  OPEN_MODE, fullname);
+  int result = openp (path, OPF_SEARCH_IN_PATH | OPF_RETURN_REALPATH, filename,
+		      OPEN_MODE, fullname);
   if (result < 0 && dirname != NULL)
     {
       /* Remove characters from the start of PATH that we don't need when
diff --git a/gdb/top.c b/gdb/top.c
index 6e0f43d2fd92..e2b00d1242a5 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -335,13 +335,11 @@ ui::~ui ()
 static gdb_file_up
 open_terminal_stream (const char *name)
 {
-  int fd;
-
-  fd = gdb_open_cloexec (name, O_RDWR | O_NOCTTY, 0);
-  if (fd < 0)
+  scoped_fd fd = gdb_open_cloexec (name, O_RDWR | O_NOCTTY, 0);
+  if (fd.get () < 0)
     perror_with_name  (_("opening terminal failed"));
 
-  return gdb_file_up (fdopen (fd, "w+"));
+  return to_file (fd, "w+");
 }
 
 /* Implementation of the "new-ui" command.  */
diff --git a/gdb/tracefile-tfile.c b/gdb/tracefile-tfile.c
index 33ce86bbe238..e1534826c5fe 100644
--- a/gdb/tracefile-tfile.c
+++ b/gdb/tracefile-tfile.c
@@ -475,7 +475,7 @@ tfile_target_open (const char *arg, int from_tty)
 
   flags = O_BINARY | O_LARGEFILE;
   flags |= O_RDONLY;
-  scratch_chan = gdb_open_cloexec (filename.get (), flags, 0);
+  scratch_chan = gdb_open_cloexec (filename.get (), flags, 0).release ();
   if (scratch_chan < 0)
     perror_with_name (filename.get ());
 
diff --git a/gdbsupport/filestuff.cc b/gdbsupport/filestuff.cc
index 6ea2ad842d5d..2975a0e6a990 100644
--- a/gdbsupport/filestuff.cc
+++ b/gdbsupport/filestuff.cc
@@ -306,13 +306,13 @@ socket_mark_cloexec (int fd)
 
 /* See filestuff.h.  */
 
-int
+scoped_fd
 gdb_open_cloexec (const char *filename, int flags, unsigned long mode)
 {
-  int fd = open (filename, flags | O_CLOEXEC, mode);
+  scoped_fd fd (open (filename, flags | O_CLOEXEC, mode));
 
-  if (fd >= 0)
-    maybe_mark_cloexec (fd);
+  if (fd.get () >= 0)
+    maybe_mark_cloexec (fd.get ());
 
   return fd;
 }
diff --git a/gdbsupport/filestuff.h b/gdbsupport/filestuff.h
index 658e1df4e558..a75312544191 100644
--- a/gdbsupport/filestuff.h
+++ b/gdbsupport/filestuff.h
@@ -47,8 +47,8 @@ extern void close_most_fds (void);
 /* Like 'open', but ensures that the returned file descriptor has the
    close-on-exec flag set.  */
 
-extern int gdb_open_cloexec (const char *filename, int flags,
-			     /* mode_t */ unsigned long mode);
+extern scoped_fd gdb_open_cloexec (const char *filename, int flags,
+				   /* mode_t */ unsigned long mode);
 
 /* Like mkstemp, but ensures that the file descriptor is
    close-on-exec.  */
@@ -63,7 +63,7 @@ gdb_mkostemp_cloexec (char *name_template, int flags = 0)
 /* Convenience wrapper for the above, which takes the filename as an
    std::string.  */
 
-static inline int
+static inline scoped_fd
 gdb_open_cloexec (const std::string &filename, int flags,
 		  /* mode_t */ unsigned long mode)
 {
diff --git a/gdbsupport/scoped_mmap.cc b/gdbsupport/scoped_mmap.cc
index c76fb77b72d3..598b3280381f 100644
--- a/gdbsupport/scoped_mmap.cc
+++ b/gdbsupport/scoped_mmap.cc
@@ -27,7 +27,7 @@
 scoped_mmap
 mmap_file (const char *filename)
 {
-  scoped_fd fd (gdb_open_cloexec (filename, O_RDONLY, 0));
+  scoped_fd fd = gdb_open_cloexec (filename, O_RDONLY, 0);
   if (fd.get () < 0)
     perror_with_name (("open"));
 
-- 
2.32.0

[PATCH 3/3] gdbsupport: make gdb_mkostemp_cloexec return a scoped_fd

[Simon Marchi]

This encourages the callers to use automatic file descriptor management.

Change-Id: I137a81df6f3607b457e28c35aafde8ed6f3a3344
---
 gdb/darwin-nat.c                      | 2 +-
 gdb/dwarf2/index-write.c              | 4 ++--
 gdb/unittests/scoped_fd-selftests.c   | 6 +++---
 gdb/unittests/scoped_mmap-selftests.c | 9 +++++----
 gdbsupport/filestuff.h                | 4 ++--
 5 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/gdb/darwin-nat.c b/gdb/darwin-nat.c
index eb3b6fa8ef4c..a90ba8675b3c 100644
--- a/gdb/darwin-nat.c
+++ b/gdb/darwin-nat.c
@@ -1833,7 +1833,7 @@ copy_shell_to_cache (const char *shell, const std::string &new_name)
 	   new_dir.c_str (), safe_strerror (errno));
 
   gdb::char_vector temp_name = make_temp_filename (new_name);
-  scoped_fd to_fd (gdb_mkostemp_cloexec (&temp_name[0]));
+  scoped_fd to_fd = gdb_mkostemp_cloexec (&temp_name[0]);
   gdb::unlinker unlink_file_on_error (temp_name.data ());
 
   if (to_fd.get () < 0)
diff --git a/gdb/dwarf2/index-write.c b/gdb/dwarf2/index-write.c
index 59a6aa4264d5..6cec5c25ef42 100644
--- a/gdb/dwarf2/index-write.c
+++ b/gdb/dwarf2/index-write.c
@@ -1539,8 +1539,8 @@ struct index_wip_file
 
     filename_temp = make_temp_filename (filename);
 
-    scoped_fd out_file_fd (gdb_mkostemp_cloexec (filename_temp.data (),
-						 O_BINARY));
+    scoped_fd out_file_fd = gdb_mkostemp_cloexec (filename_temp.data (),
+						  O_BINARY);
     if (out_file_fd.get () == -1)
       perror_with_name (("mkstemp"));
 
diff --git a/gdb/unittests/scoped_fd-selftests.c b/gdb/unittests/scoped_fd-selftests.c
index 1a361f00a2e3..5aa0e4e7a198 100644
--- a/gdb/unittests/scoped_fd-selftests.c
+++ b/gdb/unittests/scoped_fd-selftests.c
@@ -32,7 +32,7 @@ static void
 test_destroy ()
 {
   char filename[] = "scoped_fd-selftest-XXXXXX";
-  int fd = gdb_mkostemp_cloexec (filename);
+  int fd = gdb_mkostemp_cloexec (filename).release ();
   SELF_CHECK (fd >= 0);
 
   unlink (filename);
@@ -51,7 +51,7 @@ static void
 test_release ()
 {
   char filename[] = "scoped_fd-selftest-XXXXXX";
-  int fd = gdb_mkostemp_cloexec (filename);
+  int fd = gdb_mkostemp_cloexec (filename).release ();
   SELF_CHECK (fd >= 0);
 
   unlink (filename);
@@ -71,7 +71,7 @@ test_to_file ()
 {
   char filename[] = "scoped_fd-selftest-XXXXXX";
 
-  ::scoped_fd sfd (gdb_mkostemp_cloexec (filename));
+  ::scoped_fd sfd = gdb_mkostemp_cloexec (filename);
   SELF_CHECK (sfd.get () >= 0);
 
   unlink (filename);
diff --git a/gdb/unittests/scoped_mmap-selftests.c b/gdb/unittests/scoped_mmap-selftests.c
index 92a821d14b31..76d6c417ad05 100644
--- a/gdb/unittests/scoped_mmap-selftests.c
+++ b/gdb/unittests/scoped_mmap-selftests.c
@@ -89,11 +89,12 @@ static void
 test_normal ()
 {
   char filename[] = "scoped_mmapped_file-selftest-XXXXXX";
-  int fd = gdb_mkostemp_cloexec (filename);
-  SELF_CHECK (fd >= 0);
+  {
+    scoped_fd fd = gdb_mkostemp_cloexec (filename);
+    SELF_CHECK (fd.get () >= 0);
 
-  SELF_CHECK (write (fd, "Hello!", 7) == 7);
-  close (fd);
+    SELF_CHECK (write (fd.get (), "Hello!", 7) == 7);
+  }
 
   gdb::unlinker unlink_test_file (filename);
 
diff --git a/gdbsupport/filestuff.h b/gdbsupport/filestuff.h
index a75312544191..de71ec90647c 100644
--- a/gdbsupport/filestuff.h
+++ b/gdbsupport/filestuff.h
@@ -53,11 +53,11 @@ extern scoped_fd gdb_open_cloexec (const char *filename, int flags,
 /* Like mkstemp, but ensures that the file descriptor is
    close-on-exec.  */
 
-static inline int
+static inline scoped_fd
 gdb_mkostemp_cloexec (char *name_template, int flags = 0)
 {
   /* gnulib provides a mkostemp replacement if needed.  */
-  return mkostemp (name_template, flags | O_CLOEXEC);
+  return scoped_fd (mkostemp (name_template, flags | O_CLOEXEC));
 }
 
 /* Convenience wrapper for the above, which takes the filename as an
-- 
2.32.0

Re: [PATCH 1/3] gdbsupport: change scoped_fd::to_file to a free function

[Tom Tromey]

Simon> The following patch wants to chagne gdb_fopen_cloexec to return a

"change"
Also I think that should be gdb_mkostemp_cloexec?

Simon> scoped_fd.  Doing this causes a cyclic include between scoped_fd.h and
Simon> filestuff.h.  scoped_fd.h includes filestuff.h because of the
Simon> scoped_fd::to_file method.  To fix that, change scoped_fd::to_file to
Simon> be a free function in filestuff.h.

I guess that, while I don't really object, it seems like it would be
better to break the dependency some other way.  For instance would
introducing a new header that only declares gdb_file_up work?  The idea
behind this is not to let the oddities of C++ header file management
influence how the code itself is spelled -- that seems like a kind of
inversion to me.  Going along with this is the idea that a method is the
clearest way to write to_file.  These are all opinions of course, maybe
there's a reason to prefer a free function.

Tom

Re: [PATCH 1/3] gdbsupport: change scoped_fd::to_file to a free function

[Simon Marchi]

On 2021-07-30 09:47, Tom Tromey wrote:
> Simon> The following patch wants to chagne gdb_fopen_cloexec to return a
> 
> "change"
> Also I think that should be gdb_mkostemp_cloexec?

Both, actually.

> 
> Simon> scoped_fd.  Doing this causes a cyclic include between scoped_fd.h and
> Simon> filestuff.h.  scoped_fd.h includes filestuff.h because of the
> Simon> scoped_fd::to_file method.  To fix that, change scoped_fd::to_file to
> Simon> be a free function in filestuff.h.
> 
> I guess that, while I don't really object, it seems like it would be
> better to break the dependency some other way.  For instance would
> introducing a new header that only declares gdb_file_up work?  The idea
> behind this is not to let the oddities of C++ header file management
> influence how the code itself is spelled -- that seems like a kind of
> inversion to me.  Going along with this is the idea that a method is the
> clearest way to write to_file.  These are all opinions of course, maybe
> there's a reason to prefer a free function.

There's three way to do this:

 - scoped_fd::to_file method
 - gdb_file::from_fd static method
 - a free function

I never know which is best, which object should know about the other
one, or if no object should no about the other (and hence use a free
function).

But I agree with you here.  See the updated 1/3 patch below.

Patch 2 changes trivially to update the includes and a to_file call.


From 7a281de194629ba00546c2d34cc41d2f77ccc5b3 Mon Sep 17 00:00:00 2001
From: Simon Marchi <simon.marchi@polymtl.ca>
Date: Thu, 22 Jul 2021 11:34:57 -0400
Subject: [PATCH] gdbsupport: move gdb_file_up to its own file

The following patches wants to change gdb_fopen_cloexec and
gdb_mkostemp_cloexec to return a scoped_fd.  Doing this causes a cyclic
include between scoped_fd.h and filestuff.h, that both want to include
each other.  scoped_fd.h includes filestuff.h because of the
scoped_fd::to_file method's return value.  filestuff.h would then
include scoped_fd.h for gdb_fopen_cloexec's and gdb_mkostemp_cloexec's
return values.

To fix that, move gdb_file_up to its own file, gdb_file.h.

Change-Id: Ic82a48914b2aacee8f14af535b7469245f88b93d
---
 gdbsupport/filestuff.h | 13 +------------
 gdbsupport/gdb_file.h  | 37 +++++++++++++++++++++++++++++++++++++
 gdbsupport/scoped_fd.h |  2 +-
 3 files changed, 39 insertions(+), 13 deletions(-)
 create mode 100644 gdbsupport/gdb_file.h

diff --git a/gdbsupport/filestuff.h b/gdbsupport/filestuff.h
index 7f4cfb2388b1..aa15f89aa920 100644
--- a/gdbsupport/filestuff.h
+++ b/gdbsupport/filestuff.h
@@ -21,6 +21,7 @@
 
 #include <dirent.h>
 #include <fcntl.h>
+#include "gdb_file.h"
 
 /* Note all the file descriptors which are open when this is called.
    These file descriptors will not be closed by close_most_fds.  */
@@ -69,18 +70,6 @@ gdb_open_cloexec (const std::string &filename, int flags,
   return gdb_open_cloexec (filename.c_str (), flags, mode);
 }
 
-struct gdb_file_deleter
-{
-  void operator() (FILE *file) const
-  {
-    fclose (file);
-  }
-};
-
-/* A unique pointer to a FILE.  */
-
-typedef std::unique_ptr<FILE, gdb_file_deleter> gdb_file_up;
-
 /* Like 'fopen', but ensures that the returned file descriptor has the
    close-on-exec flag set.  */
 
diff --git a/gdbsupport/gdb_file.h b/gdbsupport/gdb_file.h
new file mode 100644
index 000000000000..2f5b399f6e87
--- /dev/null
+++ b/gdbsupport/gdb_file.h
@@ -0,0 +1,37 @@
+/* gdb_file_up, an RAII wrapper around FILE.
+   Copyright (C) 2021 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef GDBSUPPORT_GDB_FILE
+#define GDBSUPPORT_GDB_FILE
+
+#include <memory>
+#include <stdio.h>
+
+struct gdb_file_deleter
+{
+  void operator() (FILE *file) const
+  {
+    fclose (file);
+  }
+};
+
+/* A unique pointer to a FILE.  */
+
+typedef std::unique_ptr<FILE, gdb_file_deleter> gdb_file_up;
+
+#endif
diff --git a/gdbsupport/scoped_fd.h b/gdbsupport/scoped_fd.h
index a1aad8493998..f16e811a2cef 100644
--- a/gdbsupport/scoped_fd.h
+++ b/gdbsupport/scoped_fd.h
@@ -21,7 +21,7 @@
 #define COMMON_SCOPED_FD_H
 
 #include <unistd.h>
-#include "filestuff.h"
+#include "gdb_file.h"
 
 /* A smart-pointer-like class to automatically close a file descriptor.  */
 
-- 
2.33.0

Re: [PATCH 1/3] gdbsupport: change scoped_fd::to_file to a free function

[Tom Tromey]

>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:

Simon> But I agree with you here.  See the updated 1/3 patch below.

Looks good to me, thank you.

Tom

Re: [PATCH 1/3] gdbsupport: change scoped_fd::to_file to a free function

[Simon Marchi]

On 2021-09-30 13:48, Tom Tromey wrote:
>>>>>> "Simon" == Simon Marchi via Gdb-patches <gdb-patches@sourceware.org> writes:
> 
> Simon> But I agree with you here.  See the updated 1/3 patch below.
> 
> Looks good to me, thank you.
> 
> Tom
> 

Thanks, pushed.

Simon