Add new program: truncate

* AUTHORS: Register as the author
* NEWS: Mention this change
* README: Add truncate command to list
* src/truncate.c: New command
* src/Makefile.am: Add truncate command to list to build
* src/.gitignore: Add truncate binary to list to ignore
* doc/coreutils.texi (truncate invocation): Add truncate info
* man/Makefile.am: Add truncate man page to list to build
* man/truncate.x: Add truncate man page template
* po/POTFILES.in: Add truncate to list to translate
* tests/Makefile.am: Add truncate tests
* tests/misc/help-version: Add support for new truncate command
* tests/misc/truncate-dangling-symlink: check dangling link ok
* tests/misc/truncate-dir-fail: ensure dirs fail
* tests/misc/truncate-fail-diag: validate messages for missing paths
* tests/misc/truncate-fifo: ensure fifos ignored
* tests/misc/truncate-no-create-missing: ensure -c option honoured
* tests/misc/truncate-overflow: check signed integer overflows
* tests/misc/truncate-owned-by-other: root permissions check
* tests/misc/truncate-parameters: check invalid parameter combinations
* tests/misc/truncate-relative: check invalid relative sizes

3 files changed, 407 insertions, 1 deletions

diff --git a/src/.gitignore b/src/.gitignore
index cee550bc5..ed3111f29 100644
--- a/src/.gitignore
+++ b/src/.gitignore
@@ -91,6 +91,7 @@ timeout
 touch
 tr
 true
+truncate
 tsort
 tty
 uname
diff --git a/src/Makefile.am b/src/Makefile.am
index 97dd33b6d..04c461535 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -39,7 +39,7 @@ EXTRA_PROGRAMS = \
   basename date dirname echo env expr factor false \
   id kill logname pathchk printenv printf pwd \
   runcon seq sleep tee \
-  test timeout true tty whoami yes \
+  test timeout true truncate tty whoami yes \
   base64
 
 bin_PROGRAMS = $(OPTIONAL_BIN_PROGS)
diff --git a/src/truncate.c b/src/truncate.c
new file mode 100644
index 000000000..f3530675e
--- /dev/null
+++ b/src/truncate.c
@@ -0,0 +1,405 @@
+/* truncate -- truncate or extend the length of files.
+   Copyright (C) 2008 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/>.  */
+
+/* Written by Pádraig Brady
+
+   This is backwards compatible with the FreeBSD utility, but is more
+   flexible wrt the size specifications and the use of long options,
+   to better fit the "GNU" environment.
+
+   Note if !defined(HAVE_FTRUNCATE) then the --skip-ftruncate configure flag
+   was specified or we're in a mingw environment. In these cases gnulib
+   emulation will be used and GNULIB_FTRUNCATE is defined. Note if emulation
+   can't even be provided ftruncate() will return EIO.  */
+
+#include <config.h>             /* sets _FILE_OFFSET_BITS=64 etc. */
+#include <stdio.h>
+#include <getopt.h>
+#include <sys/types.h>
+
+#include "system.h"
+#include "error.h"
+#include "posixver.h"
+#include "quote.h"
+#include "xstrtol.h"
+
+/* The official name of this program (e.g., no `g' prefix).  */
+#define PROGRAM_NAME "truncate"
+
+#define AUTHORS proper_name_utf8 ("Padraig Brady", "P\303\241draig Brady")
+
+/* (-c) If true, don't create if not already there */
+static bool no_create;
+
+/* (-o) If true, --size refers to blocks not bytes */
+static bool block_mode;
+
+/* (-r) Reference file to use size from */
+static char const *ref_file;
+
+static struct option const longopts[] = {
+  {"no-create", no_argument, NULL, 'c'},
+  {"io-blocks", no_argument, NULL, 'o'},
+  {"reference", required_argument, NULL, 'r'},
+  {"size", required_argument, NULL, 's'},
+  {GETOPT_HELP_OPTION_DECL},
+  {GETOPT_VERSION_OPTION_DECL},
+  {NULL, 0, NULL, 0}
+};
+
+typedef enum
+{ rm_abs = 0, rm_rel, rm_min, rm_max, rm_rdn, rm_rup } rel_mode_t;
+
+/* Set size to the value of STR, interpreted as a decimal integer,
+   optionally multiplied by various values.
+   Return -1 on error, 0 on success.
+
+   This supports dd BLOCK size suffixes + lowercase g,t,m for bsd compat
+   Note we don't support dd's b=512, c=1, w=2 or 21x512MiB formats.  */
+static int
+parse_len (char const *str, off_t *size)
+{
+  enum strtol_error e;
+  /* OFF_T_MAX = INTMAX_MAX */
+  e = xstrtoimax (str, NULL, 10, size, "EgGkKmMPtTYZ0");
+  errno = (e == LONGINT_OVERFLOW) ? EOVERFLOW : 0;
+  return (e == LONGINT_OK) ? 0 : -1;
+}
+
+static void
+usage (int status)
+{
+  if (status != EXIT_SUCCESS)
+    fprintf (stderr, _("Try `%s --help' for more information.\n"),
+             program_name);
+  else
+    {
+      printf (_("Usage: %s OPTION... FILE...\n"), program_name);
+      fputs (_("\
+Shrink or extend the size of each FILE to the specified size\n\
+\n\
+A FILE argument that does not exist is created.\n\
+\n\
+If a FILE is larger than the specified size, the extra data is lost.\n\
+If a FILE is shorter, it is extended and the extended part (hole)\n\
+reads as zero bytes.\n\
+\n\
+"), stdout);
+      fputs (_("\
+Mandatory arguments to long options are mandatory for short options too.\n\
+"), stdout);
+      fputs (_("\
+  -c, --no-create        do not create any files\n\
+"), stdout);
+      fputs (_("\
+  -o, --io-blocks        Treat SIZE as number of IO blocks instead of bytes\n\
+"), stdout);
+      fputs (_("\
+  -r, --reference=FILE   use this FILE's size\n\
+  -s, --size=SIZE        use this SIZE\n"), stdout);
+      fputs (HELP_OPTION_DESCRIPTION, stdout);
+      fputs (VERSION_OPTION_DESCRIPTION, stdout);
+      fputs (_("\n\
+SIZE is a number which may be followed by one of the following suffixes:\n\
+KB 1000, K 1024, MB 1000*1000, M 1024*1024, and so on for G, T, P, E, Z, Y.\n\
+"), stdout);
+      fputs (_("\n\
+SIZE may also be prefixed by one of the following modifying characters:\n\
+`+' extend by, `-' reduce by, `<' at most, `>' at least,\n\
+`/' round down to multiple of, `%' round up to multiple of.\n"), stdout);
+      fputs (_("\
+\n\
+Note that the -r and -s options are mutually exclusive.\n\
+"), stdout);
+      emit_bug_reporting_address ();
+    }
+  exit (status);
+}
+
+/* return 1 on error, 0 on success */
+static int
+do_ftruncate (int fd, char const *fname, off_t ssize, rel_mode_t rel_mode)
+{
+  struct stat sb;
+  off_t nsize;
+
+  if ((block_mode || rel_mode) && fstat (fd, &sb) != 0)
+    {
+      error (0, errno, _("cannot fstat %s"), quote (fname));
+      return 1;
+    }
+  if (block_mode)
+    {
+      size_t const blksize = ST_BLKSIZE (sb);
+      if (ssize < OFF_T_MIN / blksize || ssize > OFF_T_MAX / blksize)
+        {
+          error (0, 0,
+                 _("overflow in %" PRIdMAX
+                   " * %zu byte blocks for file %s"), ssize, blksize,
+                 quote (fname));
+          return 1;
+        }
+      ssize *= blksize;
+    }
+  if (rel_mode)
+    {
+      uintmax_t const fsize = sb.st_size;
+
+      if (sb.st_size < 0)
+        {
+          /* Complain only for a regular file, a directory,
+             or a shared memory object, as POSIX 1003.1-2004 specifies
+             ftruncate's behavior only for these file types.  */
+          if (S_ISREG (sb.st_mode) || S_ISDIR (sb.st_mode)
+              || S_TYPEISSHM (&sb))
+            {
+              /* overflow is the only reason I can think
+                 this would ever go negative for the above types */
+              error (0, 0, _("%s has unusable, apparently negative size"),
+                     quote (fname));
+              return 1;
+            }
+          return 0;
+        }
+
+      if (rel_mode == rm_min)
+        nsize = MAX (fsize, ssize);
+      else if (rel_mode == rm_max)
+        nsize = MIN (fsize, ssize);
+      else if (rel_mode == rm_rdn)
+        /* 0..ssize-1 -> 0 */
+        nsize = (fsize / ssize) * ssize;
+      else if (rel_mode == rm_rup)
+        /* 1..ssize -> ssize */
+        {
+          /* Here ssize>=1 && fsize>=0 */
+          uintmax_t const overflow = ((fsize + ssize - 1) / ssize) * ssize;
+          if (overflow > OFF_T_MAX)
+            {
+              error (0, 0, _("overflow rounding up size of file %s"),
+                     quote (fname));
+              return 1;
+            }
+          nsize = overflow;
+        }
+      else
+        {
+          if (ssize > OFF_T_MAX - (off_t)fsize)
+            {
+              error (0, 0, _("overflow extending size of file %s"),
+                     quote (fname));
+              return 1;
+            }
+          nsize = fsize + ssize;
+        }
+    }
+  else
+    nsize = ssize;
+  if (nsize < 0)
+    nsize = 0;
+
+  if (ftruncate (fd, nsize) == -1)      /* note updates mtime & ctime */
+    {
+      /* Complain only when ftruncate fails on a regular file, a
+         directory, or a shared memory object, as POSIX 1003.1-2004
+         specifies ftruncate's behavior only for these file types.
+         For example, do not complain when Linux 2.4 ftruncate
+         fails on /dev/fd0.  */
+      int const ftruncate_errno = errno;
+      if (fstat (fd, &sb) != 0)
+        {
+          error (0, errno, _("cannot fstat %s"), quote (fname));
+          return 1;
+        }
+      else if (S_ISREG (sb.st_mode) || S_ISDIR (sb.st_mode)
+               || S_TYPEISSHM (&sb))
+        {
+          error (0, ftruncate_errno,
+                 _("truncating %s at %" PRIdMAX " bytes"), quote (fname),
+                 nsize);
+          return 1;
+        }
+      return 0;
+    }
+
+  return 0;
+}
+
+int
+main (int argc, char **argv)
+{
+  bool got_size = false;
+  off_t size;
+  rel_mode_t rel_mode = rm_abs;
+  mode_t omode;
+  int c, errors = 0, fd = -1, oflags;
+  char const *fname;
+
+  initialize_main (&argc, &argv);
+  set_program_name (argv[0]);
+  setlocale (LC_ALL, "");
+  bindtextdomain (PACKAGE, LOCALEDIR);
+  textdomain (PACKAGE);
+
+  atexit (close_stdout);
+
+  while ((c = getopt_long (argc, argv, "cor:s:", longopts, NULL)) != -1)
+    {
+      switch (c)
+        {
+        case 'c':
+          no_create = true;
+          break;
+
+        case 'o':
+          block_mode = true;
+          break;
+
+        case 'r':
+          ref_file = optarg;
+          break;
+
+        case 's':
+          switch (*optarg)
+            {
+            case '<':
+              rel_mode = rm_max;
+              optarg++;
+              break;
+            case '>':
+              rel_mode = rm_min;
+              optarg++;
+              break;
+            case '/':
+              rel_mode = rm_rdn;
+              optarg++;
+              break;
+            case '%':
+              rel_mode = rm_rup;
+              optarg++;
+              break;
+            }
+          if (*optarg == '+' || *optarg == '-')
+            {
+              if (rel_mode)
+                {
+                  error (0, 0, _("multiple relative modifiers specified"));
+                  /* Note other combinations are flagged as invalid numbers */
+                  usage (EXIT_FAILURE);
+                }
+              rel_mode = rm_rel;
+            }
+          if (parse_len (optarg, &size) == -1)
+            error (EXIT_FAILURE, errno, _("invalid number %s"),
+                   quote (optarg));
+          /* Rounding to multiple of 0 is nonsensical */
+          if ((rel_mode == rm_rup || rel_mode == rm_rdn) && size == 0)
+            error (EXIT_FAILURE, 0, _("division by zero"));
+          got_size = true;
+          break;
+
+        case_GETOPT_HELP_CHAR;
+
+        case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);
+
+        default:
+          usage (EXIT_FAILURE);
+        }
+    }
+
+  argv += optind;
+  argc -= optind;
+
+  /* must specify either size or reference file */
+  if ((ref_file && got_size) || (!ref_file && !got_size))
+    {
+      error (0, 0, _("You must specify one of %s or %s"),
+             quote_n (0, "--size"), quote_n (1, "--reference"));
+      usage (EXIT_FAILURE);
+    }
+  /* block_mode without size is not valid */
+  if (block_mode && !got_size)
+    {
+      error (0, 0, _("%s was specified but %s was not"),
+             quote_n (0, "--io-blocks"), quote_n (1, "--size"));
+      usage (EXIT_FAILURE);
+    }
+  /* must specify at least 1 file */
+  if (argc < 1)
+    {
+      error (0, 0, _("missing file operand"));
+      usage (EXIT_FAILURE);
+    }
+
+  if (ref_file)
+    {
+      struct stat sb;
+      if (stat (ref_file, &sb) != 0)
+        error (EXIT_FAILURE, errno, _("cannot stat %s"), quote (ref_file));
+      size = sb.st_size;
+    }
+
+  oflags = O_WRONLY | (no_create ? 0 : O_CREAT) | O_NONBLOCK;
+  omode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
+
+  while ((fname = *argv++) != NULL)
+    {
+      if ((fd = open (fname, oflags, omode)) == -1)
+        {
+          /* `truncate -s0 -c no-such-file`  shouldn't gen error
+             `truncate -s0 no-such-dir/file` should gen ENOENT error
+             `truncate -s0 no-such-dir/` should gen EISDIR error
+             `truncate -s0 .` should gen EISDIR error */
+          if (!(no_create && errno == ENOENT))
+            {
+              int const open_errno = errno;
+              struct stat sb;
+              if (stat (fname, &sb) == 0)
+                {
+                  /* Complain only for a regular file, a directory,
+                     or a shared memory object, as POSIX 1003.1-2004 specifies
+                     ftruncate's behavior only for these file types.  */
+                  if (!S_ISREG (sb.st_mode) && !S_ISDIR (sb.st_mode)
+                      && !S_TYPEISSHM (&sb))
+                    continue;
+                }
+              error (0, open_errno, _("cannot open %s for writing"),
+                     quote (fname));
+              errors++;
+            }
+          continue;
+        }
+
+
+      if (fd != -1)
+        {
+          errors += do_ftruncate (fd, fname, size, rel_mode);
+          if (close (fd) != 0)
+            {
+              error (0, errno, _("closing %s"), quote (fname));
+              errors++;
+            }
+        }
+    }
+
+  return errors ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+/*
+ * Local variables:
+ *  indent-tabs-mode: nil
+ * End:
+ */