Imported Upstream version 8.24upstream/8.24upstream

1 files changed, 22 insertions, 38 deletions

diff --git a/src/cat.c b/src/cat.c
index 8aef79fa..948f1341 100644
--- a/src/cat.c
+++ b/src/cat.c
@@ -1,5 +1,5 @@
 /* cat -- concatenate files and print on the standard output.
-   Copyright (C) 1988-2014 Free Software Foundation, Inc.
+   Copyright (C) 1988-2015 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
@@ -90,7 +90,12 @@ Usage: %s [OPTION]... [FILE]...\n\
 "),
               program_name);
       fputs (_("\
-Concatenate FILE(s), or standard input, to standard output.\n\
+Concatenate FILE(s) to standard output.\n\
+"), stdout);
+
+      emit_stdin_note ();
+
+      fputs (_("\
 \n\
   -A, --show-all           equivalent to -vET\n\
   -b, --number-nonblank    number nonempty output lines, overrides -n\n\
@@ -107,10 +112,6 @@ Concatenate FILE(s), or standard input, to standard output.\n\
 "), stdout);
       fputs (HELP_OPTION_DESCRIPTION, stdout);
       fputs (VERSION_OPTION_DESCRIPTION, stdout);
-      fputs (_("\
-\n\
-With no FILE, or when FILE is -, read standard input.\n\
-"), stdout);
       printf (_("\
 \n\
 Examples:\n\
@@ -118,7 +119,7 @@ Examples:\n\
   %s        Copy standard input to standard output.\n\
 "),
               program_name, program_name);
-      emit_ancillary_info ();
+      emit_ancillary_info (PROGRAM_NAME);
     }
   exit (status);
 }
@@ -239,7 +240,7 @@ cat (
   /* Pointer to the next character in the input buffer.  */
   char *bpin;
 
-  /* Pointer to the first non-valid byte in the input buffer, i.e. the
+  /* Pointer to the first non-valid byte in the input buffer, i.e., the
      current end of the buffer.  */
   char *eob;
 
@@ -365,7 +366,7 @@ cat (
               /* It was a real (not a sentinel) newline.  */
 
               /* Was the last line empty?
-                 (i.e. have two or more consecutive newlines been read?)  */
+                 (i.e., have two or more consecutive newlines been read?)  */
 
               if (++newlines > 0)
                 {
@@ -422,7 +423,7 @@ cat (
          which means that the buffer is empty or that a proper newline
          has been found.  */
 
-      /* If quoting, i.e. at least one of -v, -e, or -t specified,
+      /* If quoting, i.e., at least one of -v, -e, or -t specified,
          scan for chars that need conversion.  */
       if (show_nonprinting)
         {
@@ -527,8 +528,8 @@ main (int argc, char **argv)
   /* I-node number of the output.  */
   ino_t out_ino;
 
-  /* True if the output file should not be the same as any input file.  */
-  bool check_redirection = true;
+  /* True if the output is a regular file.  */
+  bool out_isreg;
 
   /* Nonzero if we have ever read standard input.  */
   bool have_read_stdin = false;
@@ -637,25 +638,9 @@ main (int argc, char **argv)
     error (EXIT_FAILURE, errno, _("standard output"));
 
   outsize = io_blksize (stat_buf);
-  /* Input file can be output file for non-regular files.
-     fstat on pipes returns S_IFSOCK on some systems, S_IFIFO
-     on others, so the checking should not be done for those types,
-     and to allow things like cat < /dev/tty > /dev/tty, checking
-     is not done for device files either.  */
-
-  if (S_ISREG (stat_buf.st_mode))
-    {
-      out_dev = stat_buf.st_dev;
-      out_ino = stat_buf.st_ino;
-    }
-  else
-    {
-      check_redirection = false;
-#ifdef lint  /* Suppress 'used before initialized' warning.  */
-      out_dev = 0;
-      out_ino = 0;
-#endif
-    }
+  out_dev = stat_buf.st_dev;
+  out_ino = stat_buf.st_ino;
+  out_isreg = S_ISREG (stat_buf.st_mode) != 0;
 
   if (! (number || show_ends || squeeze_blank))
     {
@@ -704,14 +689,13 @@ main (int argc, char **argv)
 
       fdadvise (input_desc, 0, 0, FADVISE_SEQUENTIAL);
 
-      /* Compare the device and i-node numbers of this input file with
-         the corresponding values of the (output file associated with)
-         stdout, and skip this input file if they coincide.  Input
-         files cannot be redirected to themselves.  */
+      /* Don't copy a nonempty regular file to itself, as that would
+         merely exhaust the output device.  It's better to catch this
+         error earlier rather than later.  */
 
-      if (check_redirection
+      if (out_isreg
           && stat_buf.st_dev == out_dev && stat_buf.st_ino == out_ino
-          && (input_desc != STDIN_FILENO))
+          && lseek (input_desc, 0, SEEK_CUR) < stat_buf.st_size)
         {
           error (0, 0, _("%s: input file is output file"), infile);
           ok = false;
@@ -780,5 +764,5 @@ main (int argc, char **argv)
   if (have_read_stdin && close (STDIN_FILENO) < 0)
     error (EXIT_FAILURE, errno, _("closing standard input"));
 
-  exit (ok ? EXIT_SUCCESS : EXIT_FAILURE);
+  return ok ? EXIT_SUCCESS : EXIT_FAILURE;
 }