Allow the user to specify a number of files for processing.

Declare have_read_stdin

Variable declaration

Notes

If standard input is read, then the file is not opened by name. Most of the time, files are opened and closed by name. This is part of a scheme that fakes out stdin handling so that it looks like a named file to the rest of sort.

Segment Source

 199: /* Nonzero if any of the input files are the standard input. */
 200: static int have_read_stdin;
 201: 

Minus indicates stdin

Segment Element

Code insertion

 340:   if (strcmp (file, "-") == 0)
 341:     {
 342:       fp = stdin;
 343:     }
 344:   else
 345:     {

Segment Element

Code insertion

 352:     }

Segment Element

Code insertion

 354:   if (fp == stdin)
 355:     have_read_stdin = 1;

Check each input file

Notes

The whole check routine is really just a wrapper where the Modes concern can control mulitple checkfp() calls.

Segment Element

Argument modification

1495: check (char **files, int nfiles)

Segment Element

Variable declaration

1497:   int i, disorders = 0;

Segment Element

Code insertion

1500:   for (i = 0; i < nfiles; ++i)
1501:     {
1502:       fp = xfopen (files[i], "r");

Segment Element

Code insertion

1508:     }

Sort and merge the list of input files

Notes

This part of SrcSpec has significant overlap with LargeFile support. They both use the merge() routine to generate the final results, though the each create intermediates for different reasons.

Segment Element

Parameter modification

1556: sort (char **files, int nfiles, FILE *ofp)

Segment Element

Variable declaration

1562:   FILE *fp, *tfp;

Segment Element

Variable declaration

1563:   struct tempnode *node;
1564:   int n_temp_files = 0;
1565:   char **tempfiles;
1566: 

Segment Element

Code insertion

1573:   while (nfiles--)
1574:     {
1575:       fp = xfopen (*files++, "r");

Segment Element

Code insertion

1591:               ++n_temp_files;
1592:               tfp = xtmpfopen (tempname ());

Segment Element

Argument modification

1598:                 write_bytes (lines.lines[i].text, lines.lines[i].length, tfp);
1599:                 putc (eolchar, tfp);

Segment Element

Code insertion

1601:           if (tfp != ofp)
1602:             xfclose (tfp);

Segment Element

Code insertion

1604:       xfclose (fp);
1605:     }
1606: 

Segment Element

Code insertion

1611:   if (n_temp_files)
1612:     {
1613:       tempfiles = (char **) xmalloc (n_temp_files * sizeof (char *));
1614:       i = n_temp_files;
1615:       for (node = temphead.next; i > 0; node = node->next)
1616:         tempfiles[--i] = node->name;
1617:       merge (tempfiles, n_temp_files, ofp);
1618:       free ((char *) tempfiles);
1619:     }

Define input list variables

Variable definition

Notes

The handling of the "minus" variable is a bit inconsistant. First, it is only a coincidence that the same symbol is used for both <stdin> and <stdout>. This works only because they never share the same role. (Note that there is no standard way to redirect to <stderr>). Also, OutSpec uses "minus" sometimes, and the literal dash ("-") at other times.

Segment Source

1721:   int checkonly = 0, mergeonly = 0, nfiles = 0;
1722:   char *minus = "-", *outfile = minus, **files, *tmp;

Initialize have_read_stdin

Code insertion

Segment Source

1735:   have_read_stdin = 0;

Allocate space for file list

Code insertion

Notes

This works only because the first argv entry is never an input file specification. Otherwise, at line 2021, there is a potential for under-allocated file list.

Segment Source

1776:   files = (char **) xmalloc (sizeof (char *) * argc);
1777: 

Build input file list

Code insertion

Segment Source

2019:       else                      /* Not an option. */
2020:         {
2021:           files[nfiles++] = argv[i];
2022:         }

Default to stdin

Code insertion

If no input is specified on the command line, cause stdin to be used as the input file.

Notes

This establishes a default for the input list.

Segment Source

2051:   if (nfiles == 0)
2052:     {
2053:       nfiles = 1;
2054:       files = −
2055:     }
2056: 

Check each input file

Argument modification

Segment Source

2061:       exit (check (files, nfiles) == 0 ? 0 : 1);

Sort each input file

Argument modification

Segment Source

2128:     sort (files, nfiles, ofp);

Close stdin if it was used.

Code insertion

Segment Source

2139:   if (have_read_stdin && fclose (stdin) == EOF)
2140:     error (SORT_FAILURE, errno, outfile);