maint: refactor common expand(1) and unexpand(1) code

* src/expand.c, src/unexpand.c: Move global variables from here...
* src/expand-common.h, src/expand-common.c: ... to here.
* src/expand.c, src/unexpand.c: (parse_tab_stops, validate_tab_stops,
next_file): Move identical functions to new module.
(add_tab_stop): Move to new module, including additional code from
'unexpand' (keeping max_column_width) which will have no effect in when
used in 'expand'. Refactor common next-column calculation code
into a new function 'get_next_tab_column'.
* src/local.mk: (src_expand_SOURCES, src_unexpand_SOURCES): Add
'expand-common.c'; (noinst_HEADERS): Add 'expand-common.h'.
* po/POTFILES.in: Add 'expand-common.c'.
* tests/misc/expand.pl: Add more tests.
* tests/misc/unexpand.pl: Likewise.
* TODO: Move conclusions to above test after investigation.

1 files changed, 12 insertions, 218 deletions

diff --git a/src/unexpand.c b/src/unexpand.c
index a75875659..a1317b173 100644
--- a/src/unexpand.c
+++ b/src/unexpand.c
@@ -40,51 +40,16 @@
 #include <sys/types.h>
 #include "system.h"
 #include "error.h"
-#include "fadvise.h"
-#include "quote.h"
 #include "xstrndup.h"
 
+#include "expand-common.h"
+
 /* The official name of this program (e.g., no 'g' prefix).  */
 #define PROGRAM_NAME "unexpand"
 
 #define AUTHORS proper_name ("David MacKenzie")
 
-/* If true, convert blanks even after nonblank characters have been
-   read on the line.  */
-static bool convert_entire_line;
-
-/* If nonzero, the size of all tab stops.  If zero, use 'tab_list' instead.  */
-static size_t tab_size;
-
-/* The maximum distance between tab stops.  */
-static size_t max_column_width;
-
-/* Array of the explicit column numbers of the tab stops;
-   after 'tab_list' is exhausted, the rest of the line is printed
-   unchanged.  The first column is column 0.  */
-static uintmax_t *tab_list;
-
-/* The number of allocated entries in 'tab_list'.  */
-static size_t n_tabs_allocated;
-
-/* The index of the first invalid element of 'tab_list',
-   where the next element can be added.  */
-static size_t first_free_tab;
 
-/* Null-terminated array of input filenames.  */
-static char **file_list;
-
-/* Default for 'file_list' if no files are given on the command line.  */
-static char *stdin_argv[] =
-{
-  (char *) "-", NULL
-};
-
-/* True if we have ever read standard input.  */
-static bool have_read_stdin;
-
-/* The desired exit status.  */
-static int exit_status;
 
 /* For long options that have no equivalent short option, use a
    non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
@@ -134,148 +99,6 @@ Convert blanks in each FILE to tabs, writing to standard output.\n\
   exit (status);
 }
 
-/* Add tab stop TABVAL to the end of 'tab_list'.  */
-
-static void
-add_tab_stop (uintmax_t tabval)
-{
-  uintmax_t prev_column = first_free_tab ? tab_list[first_free_tab - 1] : 0;
-  uintmax_t column_width = prev_column <= tabval ? tabval - prev_column : 0;
-
-  if (first_free_tab == n_tabs_allocated)
-    tab_list = X2NREALLOC (tab_list, &n_tabs_allocated);
-  tab_list[first_free_tab++] = tabval;
-
-  if (max_column_width < column_width)
-    {
-      if (SIZE_MAX < column_width)
-        error (EXIT_FAILURE, 0, _("tabs are too far apart"));
-      max_column_width = column_width;
-    }
-}
-
-/* Add the comma or blank separated list of tab stops STOPS
-   to the list of tab stops.  */
-
-static void
-parse_tab_stops (char const *stops)
-{
-  bool have_tabval = false;
-  uintmax_t tabval IF_LINT ( = 0);
-  char const *num_start IF_LINT ( = NULL);
-  bool ok = true;
-
-  for (; *stops; stops++)
-    {
-      if (*stops == ',' || isblank (to_uchar (*stops)))
-        {
-          if (have_tabval)
-            add_tab_stop (tabval);
-          have_tabval = false;
-        }
-      else if (ISDIGIT (*stops))
-        {
-          if (!have_tabval)
-            {
-              tabval = 0;
-              have_tabval = true;
-              num_start = stops;
-            }
-
-          /* Detect overflow.  */
-          if (!DECIMAL_DIGIT_ACCUMULATE (tabval, *stops - '0', uintmax_t))
-            {
-              size_t len = strspn (num_start, "0123456789");
-              char *bad_num = xstrndup (num_start, len);
-              error (0, 0, _("tab stop is too large %s"), quote (bad_num));
-              free (bad_num);
-              ok = false;
-              stops = num_start + len - 1;
-            }
-        }
-      else
-        {
-          error (0, 0, _("tab size contains invalid character(s): %s"),
-                 quote (stops));
-          ok = false;
-          break;
-        }
-    }
-
-  if (!ok)
-    exit (EXIT_FAILURE);
-
-  if (have_tabval)
-    add_tab_stop (tabval);
-}
-
-/* Check that the list of tab stops TABS, with ENTRIES entries,
-   contains only nonzero, ascending values.  */
-
-static void
-validate_tab_stops (uintmax_t const *tabs, size_t entries)
-{
-  uintmax_t prev_tab = 0;
-  size_t i;
-
-  for (i = 0; i < entries; i++)
-    {
-      if (tabs[i] == 0)
-        error (EXIT_FAILURE, 0, _("tab size cannot be 0"));
-      if (tabs[i] <= prev_tab)
-        error (EXIT_FAILURE, 0, _("tab sizes must be ascending"));
-      prev_tab = tabs[i];
-    }
-}
-
-/* Close the old stream pointer FP if it is non-NULL,
-   and return a new one opened to read the next input file.
-   Open a filename of '-' as the standard input.
-   Return NULL if there are no more input files.  */
-
-static FILE *
-next_file (FILE *fp)
-{
-  static char *prev_file;
-  char *file;
-
-  if (fp)
-    {
-      if (ferror (fp))
-        {
-          error (0, errno, "%s", quotef (prev_file));
-          exit_status = EXIT_FAILURE;
-        }
-      if (STREQ (prev_file, "-"))
-        clearerr (fp);		/* Also clear EOF.  */
-      else if (fclose (fp) != 0)
-        {
-          error (0, errno, "%s", quotef (prev_file));
-          exit_status = EXIT_FAILURE;
-        }
-    }
-
-  while ((file = *file_list++) != NULL)
-    {
-      if (STREQ (file, "-"))
-        {
-          have_read_stdin = true;
-          fp = stdin;
-        }
-      else
-        fp = fopen (file, "r");
-      if (fp)
-        {
-          prev_file = file;
-          fadvise (fp, FADVISE_SEQUENTIAL);
-          return fp;
-        }
-      error (0, errno, "%s", quotef (file));
-      exit_status = EXIT_FAILURE;
-    }
-  return NULL;
-}
-
 /* Change blanks to tabs, writing to stdout.
    Read each file in 'file_list', in order.  */
 
@@ -344,28 +167,13 @@ unexpand (void)
 
               if (blank)
                 {
-                  if (next_tab_column <= column)
-                    {
-                      if (tab_size)
-                        next_tab_column =
-                          column + (tab_size - column % tab_size);
-                      else
-                        while (true)
-                          if (tab_index == first_free_tab)
-                            {
-                              convert = false;
-                              break;
-                            }
-                          else
-                            {
-                              uintmax_t tab = tab_list[tab_index++];
-                              if (column < tab)
-                                {
-                                  next_tab_column = tab;
-                                  break;
-                                }
-                            }
-                    }
+                  bool last_tab IF_LINT (=0);
+
+                  next_tab_column = get_next_tab_column (column, &tab_index,
+                                                         &last_tab);
+
+                  if (last_tab)
+                    convert = false;
 
                   if (convert)
                     {
@@ -464,12 +272,6 @@ main (int argc, char **argv)
 
   atexit (close_stdout);
 
-  have_read_stdin = false;
-  exit_status = EXIT_SUCCESS;
-  convert_entire_line = false;
-  tab_list = NULL;
-  first_free_tab = 0;
-
   while ((c = getopt_long (argc, argv, ",0123456789at:", longopts, NULL))
          != -1)
     {
@@ -512,21 +314,13 @@ main (int argc, char **argv)
   if (have_tabval)
     add_tab_stop (tabval);
 
-  validate_tab_stops (tab_list, first_free_tab);
-
-  if (first_free_tab == 0)
-    tab_size = max_column_width = 8;
-  else if (first_free_tab == 1)
-    tab_size = tab_list[0];
-  else
-    tab_size = 0;
+  finalize_tab_stops ();
 
-  file_list = (optind < argc ? &argv[optind] : stdin_argv);
+  set_file_list ( (optind < argc) ? &argv[optind] : NULL);
 
   unexpand ();
 
-  if (have_read_stdin && fclose (stdin) != 0)
-    error (EXIT_FAILURE, errno, "-");
+  cleanup_file_list_stdin ();
 
   return exit_status;
 }