Prevent the situation where errno is set by function A, then function B
is called (which is typically _(), but could be anything else) and it
overwrites errno, then errno is checked by the caller.

errno is a horrific API, and we need to be careful to save its value as
soon as a function call (which might set it) returns. i.e. Follow the
pattern:
  int errsv, ret;
  ret = some_call_which_might_set_errno ();
  errsv = errno;

  if (ret < 0)
    puts (strerror (errsv));

This patch implements that pattern throughout GLib. There might be a few
places in the test code which still use errno directly. They should be
ported as necessary. It doesn’t modify all the call sites like this:
  if (some_call_which_might_set_errno () && errno == ESOMETHING)
since the refactoring involved is probably more harmful than beneficial
there. It does, however, refactor other call sites regardless of whether
they were originally buggy.

https://bugzilla.gnome.org/show_bug.cgi?id=785577

https://bugzilla.gnome.org/show_bug.cgi?id=711751

2004-11-01  Matthias Clasen  <mclasen@redhat.com>

	* glib/gconvert.c:
	* glib/gdebug.h
	* glib/gutils.c
	* gobject/gtype.c
	* gthread/gthread-posix.c
	* tests/timeloop-closure.c
	* tests/timeloop.c: Fix sparse warnings.  (#157014, Kjartan Maraas)

2002-07-04  Sebastian Wilhelmi  <wilhelmi@ira.uka.de>

	* tests/*.c: Added #undef G_DISABLE_ASSERT and #undef G_LOG_DOMAIN
	throughout the files, which didn't already have them. (#87312)

Wed Jun 20 12:00:54 2001  Owen Taylor  <otaylor@redhat.com>

        Changes for 64-bit cleanliness, loosely based on patch
	from Mark Murnane.

	* gconvert.c (g_convert/g_convert_with_fallback): Remove
	workarounds for since-fixed GNU libc bugs. Minor
	doc fix.

	* gconvert.[ch]: Change gint to gsize/gssize as
	appropriate.

	* gconvert.c (g_locale/filename_to/from_utf8): Fix incorrect
	computation of bytes_read / bytes_written.

	* gfileutils.[ch] (g_file_get_contents): Make length
	out parameter 'gsize *len'.

	* ghook.c (g_hook_compare_ids): Don't compare a
	and b as 'a - b'.

	* gmacros.h (GSIZE_TO_POINTER): Add GPOINTER_TO_SIZE,
	GSIZE_TO_POINTER.

	* gmain.c (g_timeout_prepare): Rewrite to avoid
	overflows. (Fixes bug when system clock skews
	backwards more than 24 days.)

	* gmarkup.[ch]: Make lengths passed to callbacks
	gsize, length for g_markup_parse-context_parse(),
	g_markup_escape_text() gssize.

	* gmessages.[ch] (g_printf_string_upper_bound): Change
	return value to gsize.

	* gmessages.c (printf_string_upper_bound): Remove
	a ridiculous use of 'inline' on a 300 line function.

	* gstring.[ch]: Represent size of string as a gsize,
	not gint. Make parameters to functions take gsize,
	or gssize where -1 is allowed.

	* gstring.c (g_string_erase): Make
	g_string_erase (string, pos, -1) a synonym for
	g_string_truncate for consistency with other G*
	APIs.

	* gstrfuncs.[ch]: Make all functions taking a string
	length, take a gsize, or gssize if -1 is allowed.
	(g_strstr_len, g_strrstr_len). Also fix some boundary
	conditions in g_str[r]str[_len].

	* gutf8.c tests/unicode-encoding.c: Make parameters that
	are byte lengths gsize, gssize as appropriate. Make
	character offsets, other counts, glong.

	* gasyncqueue.c gcompletion.c
          timeloop.c timeloop-basic.c gutils.c gspawn.c.
	Small 64 bit cleanliness fixups.

	* glist.c (g_list_sort2, g_list_sort_real): Fix functions
	that should have been static.

	* gdate.c (g_date_fill_parse_tokens): Fix extra
	declaration that was shadowing another.

	* tests/module-test.c: Include string.h

Mon Jun 18 15:43:29 2001  Owen Taylor  <otaylor@redhat.com>

	* gutf8.c (g_get_charset): Make argument
	G_CONST_RETURN char **.

Mon Mar 26 14:14:53 2001  Owen Taylor  <otaylor@redhat.com>

	* Makefile.am (INCLUDES): -DG_DISABLE_DEPRECATED

	* gmain.h timeloop.c: Surround the cruftiest stuff with
	#ifndef G_DISABLE_DEPRECATED.

	* gcompat.h gdate.h: Move compat defines back to
	gdate.h, surround with #ifndef G_DISABLE_DEPRECATED.
	Remove gcompat.h.

Sat Mar 17 19:54:51 2001  Owen Taylor  <otaylor@redhat.com>

        * timeloop.c: Reorder headers to make FreeBSD happy.

Tue Dec  5 12:23:04 2000  Owen Taylor  <otaylor@redhat.com>

        * gmain.[hc]: Major change in API for creating sources
	to handle multiple main loops (GMainContext *).

	GSources are now exposed as GSource * and implemented
	with structure derivation.

	* giochannel.[ch]: Changed vtable for GIOChannel to correspond
	to the new mainloop API, add g_io_channel_create_watch().

	* gtypes.h: Move GTimeVal here.

	* gthread.h: Remove gmain.h include to avoid circularity.

        * giounix.c: Update for new GMain API.

	* giowin32.c: Update for new GMain API. (No check for
	proper compilation or working.)

	* timeloop.c timeloop-basic.c: A benchmarking program for
	the main loop comparing the main loop against a
	hand-written (timeloop-basic.c) variant.

	* tests/mainloop-test.c: New torture test of mainloop.

	* docs/Changes-2.0.txt: Started. Added text about
	changes to GMain.

	* gmain.c (g_main_add_poll_unlocked): Initial fd->revents
	to zero. (#8482, Benjamin Kahn)