build: support building all tools in a single binary

Add the --enable-single-binary option to the configure file.
When enabled, this option builds a single binary file containing
the selected tools.  Which tool gets executed depends on the value
of argv[0] which can be set implicitly through symlinks to the
single program.

This setup reduces significantly the size of a complete coreutils
install, since code from lib/libcoreutils.a is not duplicated in
every one of the more than 100 binaries.  Runtime overhead is
increased due to more dynamic libraries being loaded, and extra
initialization being performed for all utils.  Also initially
a larger binary is loaded from storage, though this is usually
alleviated due to caching and lazy mmaping of unused blocks,
and in fact the single binary should have better caching
characteristics.

Comparing the size of the individual versus single binary on x86_64:
  $ cd src
  $ size coreutils
  $ size -t $(../build-aux/gen-lists-of-programs.sh --list-progs |
              grep -Ev '(coreutils|libstdbuf)') | tail -n1
     text    data     bss     dec     hex filename
  1097416    5388   88432 1191236  122d44 src/coreutils
  4901010  124964  163768 5189742  4f306e (TOTALS)

Storage requirements are reduced similarly:
  $ cd src
  $ du -h coreutils
  $ du -ch $(../build-aux/gen-lists-of-programs.sh --list-progs |
             grep -Ev '(coreutils|libstdbuf)') | tail -n1
  1.2M    coreutils
  5.3M    total

When installing, the makefile will create either symlinks or
shebangs based on the --enable-single-binary setting, for
each configured tool. In this way, all the tools are still
callable individually, but they are all implemented by the same
"coreutils" binary installed on the same directory.

* .gitignore: Add new generated files.
* Makefile.am: New rules to generate build-aux/gen-single-binary.sh
  and install symlinks.
* NEWS: Mention the new feature.
* README: Add "coreutils" to the list of utils.
* bootstrap.conf: Regenerate src/single-binary.mk
* build-aux/gen-lists-of-programs.sh: New --list-progs option.
* build-aux/gen-single-binary.sh: Regenerate
* configure.ac: New --enable-single-binary option and other variables.
Disallow --enable-single-binary=symlinks with --program-prefix et. al.
* man/coreutils.x: Manpage hook.
* man/local.mk: Add manpage hook and fix dependencies.
* src/coreutils.c: Multicall implementation.
* src/local.mk: New rules for the single binary option.
* tests/local.mk: Add $single_binary_progs to support
require_built_() from init.cfg
* tests/misc/env.sh: Avoid the use of symlink to echo.
* tests/misc/help-version.sh: Add exception for coreutils.
* tests/install/basic-1.sh: Really avoid using ginstall strip
functionality if there is an issue with the independent strip command.
* src/kill.c: Changes to call exit() in main.
* src/readlink.c: Likewise.
* src/shuf.c: Likewise.
* src/timeout.c: Likewise.
* src/truncate.c: Likewise.

1 files changed, 205 insertions, 0 deletions

diff --git a/src/coreutils.c b/src/coreutils.c
new file mode 100644
index 000000000..c459b1d62
--- /dev/null
+++ b/src/coreutils.c
@@ -0,0 +1,205 @@
+/* Copyright (C) 2014 Free Software Foundation, Inc.
+
+   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/>.  */
+
+/* coreutils.c aggregates the functionality of every other tool into a single
+   binary multiplexed by the value of argv[0]. This is enabled by passing
+   --enable-single-binary to configure.
+
+   Written by Alex Deymo <deymo@chromium.org>.  */
+
+#include <config.h>
+#include <getopt.h>
+#include <stdio.h>
+#if HAVE_PRCTL
+# include <sys/prctl.h>
+#endif
+
+#include "system.h"
+#include "error.h"
+#include "quote.h"
+
+#ifdef SINGLE_BINARY
+/* Declare the main function on each one of the selected tools.  This name
+   needs to match the one passed as CFLAGS on single-binary.mk (generated
+   by gen-single-binary.sh). */
+# define SINGLE_BINARY_PROGRAM(prog_name_str, main_name) \
+  int _single_binary_main_##main_name (int, char**) ATTRIBUTE_NORETURN;
+# include "coreutils.h"
+# undef SINGLE_BINARY_PROGRAM
+#endif
+
+/* The official name of this program (e.g., no 'g' prefix).  */
+#define PROGRAM_NAME "coreutils"
+
+#define AUTHORS \
+  proper_name ("Alex Deymo")
+
+void
+launch_program (const char *prog_name, int prog_argc, char **prog_argv);
+
+static struct option const long_options[] =
+{
+  {GETOPT_HELP_OPTION_DECL},
+  {GETOPT_VERSION_OPTION_DECL},
+  {NULL, 0, NULL, 0}
+};
+
+
+void
+usage (int status)
+{
+  if (status != EXIT_SUCCESS)
+    emit_try_help ();
+  else
+    {
+      printf (_("\
+Usage: %s --coreutils-prog=PROGRAM_NAME [PARAMETERS]... \n"),
+              program_name);
+      fputs (_("\
+Execute the PROGRAM_NAME built-in program with the given PARAMETERS.\n\
+\n"), stdout);
+      fputs (HELP_OPTION_DESCRIPTION, stdout);
+      fputs (VERSION_OPTION_DESCRIPTION, stdout);
+
+      printf ("\n\
+Built-in programs:\n"
+#ifdef SINGLE_BINARY
+/* XXX: Ideally we#d like to present "install" here, not "ginstall".  */
+# define SINGLE_BINARY_PROGRAM(prog_name_str, main_name) " " prog_name_str
+# include "coreutils.h"
+# undef SINGLE_BINARY_PROGRAM
+#endif
+  "\n");
+
+      printf (_("\
+\n\
+Use: '%s --coreutils-prog=PROGRAM_NAME --help' for individual program help.\n"),
+              program_name);
+      emit_ancillary_info ();
+    }
+  exit (status);
+}
+
+void
+launch_program (const char *prog_name, int prog_argc, char **prog_argv)
+{
+  int (*prog_main)(int, char **) = NULL;
+
+  /* Ensure that at least one parameter was passed.  */
+  if (!prog_argc || !prog_argv || !prog_argv[0] || !prog_name)
+    return;
+
+#ifdef SINGLE_BINARY
+  if (false);
+  /* Lookup the right main program.  */
+# define SINGLE_BINARY_PROGRAM(prog_name_str, main_name) \
+  else if (STREQ (prog_name_str, prog_name)) \
+    prog_main = _single_binary_main_##main_name;
+# include "coreutils.h"
+# undef SINGLE_BINARY_PROGRAM
+#endif
+
+  if (! prog_main)
+    return;
+
+#if HAVE_PRCTL && defined PR_SET_NAME
+  /* Not being able to set the program name is not a fatal error.  */
+  prctl (PR_SET_NAME, prog_argv[0]);
+#endif
+#if HAVE_PRCTL && defined PR_SET_MM_ARG_START
+  /* Shift the beginning of the command line to prog_argv[0] (if set) so
+     /proc/pid/cmdline reflects the right value.  */
+  prctl (PR_SET_MM_ARG_START, prog_argv[0]);
+#endif
+
+  exit ((*prog_main) (prog_argc, prog_argv));
+}
+
+int
+main (int argc, char **argv)
+{
+  char *prog_name = last_component (argv[0]);
+  int optc;
+
+  /* Map external name to internal name.  */
+  char ginstall[] = "ginstall";
+  if (STREQ (prog_name, "install"))
+    prog_name = ginstall;
+
+  /* If this program is called directly as "coreutils" or if the value of
+     argv[0] is an unknown tool (which "coreutils" is), we proceed and parse
+     the options.  */
+  launch_program (prog_name, argc, argv);
+
+  /* No known program was selected via argv[0].  Try parsing the first
+     argument as --coreutils-prog=PROGRAM to determine the program.  The
+     invocation for this case should be:
+       path/to/coreutils --coreutils-prog=someprog someprog ...
+     The third argument is what the program will see as argv[0].  */
+
+  if (argc >= 2)
+    {
+      size_t nskip = 0;
+      char *arg_name = NULL;
+
+      /* If calling coreutils directly, the "script" name isn't passed.
+         Distinguish the two cases with a -shebang suffix.  */
+      if (STRPREFIX (argv[1], "--coreutils-prog="))
+        {
+          nskip = 1;
+          arg_name = prog_name = argv[1] + strlen ("--coreutils-prog=");
+        }
+      else if (STRPREFIX (argv[1], "--coreutils-prog-shebang="))
+        {
+          nskip = 2;
+          prog_name = argv[1] + strlen ("--coreutils-prog-shebang=");
+          if (argc >= 3)
+            arg_name = last_component (argv[2]);
+          else
+            arg_name = prog_name;
+        }
+
+      if (nskip)
+        {
+          argv[nskip] = arg_name; /* XXX: Discards any specified path.  */
+          launch_program (prog_name, argc - nskip, argv + nskip);
+          error (EXIT_FAILURE, 0, _("unknown program %s"), quote (prog_name));
+        }
+    }
+
+  /* No known program was selected.  From here on, we behave like any other
+     coreutils program.  */
+  initialize_main (&argc, &argv);
+  set_program_name (argv[0]);
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+  atexit (close_stdout);
+
+  if ((optc = getopt_long (argc, argv, "", long_options, NULL)) != -1)
+    switch (optc)
+      {
+      case_GETOPT_HELP_CHAR;
+
+      case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
+      }
+
+  /* Only print the error message when no options have been passed
+     to coreutils.  */
+  if (optind == 1 && prog_name && !STREQ (prog_name, "coreutils"))
+    error (0, 0, _("unknown program %s"), quote (prog_name));
+
+  usage (EXIT_FAILURE);
+}