[src/trunk]: src/usr.bin/split auto-extend suffix length if required

[jschauma <jschauma%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/8acd2269f5ec
branches:  trunk
changeset: 373303:8acd2269f5ec
user:      jschauma <jschauma%NetBSD.org@localhost>
date:      Mon Jan 30 15:22:02 2023 +0000

description:
auto-extend suffix length if required

If the input cannot be split into the number of files resulting from the
default suffix length, automatically extend the suffix length rather than
bailing out with 'too many files'.

Suffixes are extended such that the resulting files continue to sort
lexically and "cat *" would reproduce the input.  For example, splitting
a 1M lines file into (default) 1000 lines per file would yield files
named 'xaa', 'xab', ..., 'xyy', 'xyz', 'xzaaa', 'xzaab', ..., 'xzanl'.

If '-a' is specified, the suffix length is not auto-extended.

This behavior matches GNU sort(1) since around version 8.16.

diffstat:

 usr.bin/split/split.1 |  11 ++++++++---
 usr.bin/split/split.c |  38 ++++++++++++++++++++++++++++++++++++--
 2 files changed, 44 insertions(+), 5 deletions(-)

diffs (105 lines):

diff -r 95bee298176e -r 8acd2269f5ec usr.bin/split/split.1
--- a/usr.bin/split/split.1     Mon Jan 30 13:45:26 2023 +0000
+++ b/usr.bin/split/split.1     Mon Jan 30 15:22:02 2023 +0000
@@ -1,4 +1,4 @@
-.\"    $NetBSD: split.1,v 1.15 2007/05/31 01:35:35 jschauma Exp $
+.\"    $NetBSD: split.1,v 1.16 2023/01/30 15:22:02 jschauma Exp $
 .\"
 .\" Copyright (c) 1990, 1991, 1993, 1994
 .\"    The Regents of the University of California.  All rights reserved.
@@ -29,7 +29,7 @@
 .\"
 .\"    @(#)split.1     8.3 (Berkeley) 4/16/94
 .\"
-.Dd May 28, 2007
+.Dd January 28, 2023
 .Dt SPLIT 1
 .Os
 .Sh NAME
@@ -99,7 +99,12 @@
 .Dq Li a-z .
 If
 .Fl a
-is not specified, two letters are used as the suffix.
+is not specified, two letters are used as the initial
+suffix.
+If the output does not fit into the resulting number
+of files, then the suffix length is automatically
+extended as needed such that all output files continue
+to sort in lexical order.
 .Pp
 If the
 .Ar name
diff -r 95bee298176e -r 8acd2269f5ec usr.bin/split/split.c
--- a/usr.bin/split/split.c     Mon Jan 30 13:45:26 2023 +0000
+++ b/usr.bin/split/split.c     Mon Jan 30 15:22:02 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: split.c,v 1.28 2023/01/27 19:39:04 jschauma Exp $      */
+/*     $NetBSD: split.c,v 1.29 2023/01/30 15:22:02 jschauma Exp $      */
 
 /*
  * Copyright (c) 1987, 1993, 1994
@@ -39,7 +39,7 @@
 #if 0
 static char sccsid[] = "@(#)split.c    8.3 (Berkeley) 4/25/94";
 #endif
-__RCSID("$NetBSD: split.c,v 1.28 2023/01/27 19:39:04 jschauma Exp $");
+__RCSID("$NetBSD: split.c,v 1.29 2023/01/30 15:22:02 jschauma Exp $");
 #endif /* not lint */
 
 #include <sys/param.h>
@@ -60,6 +60,7 @@
 static int ifd = STDIN_FILENO, ofd = -1; /* Input/output file descriptors. */
 static char *fname;            /* File name prefix. */
 static size_t sfxlen = 2;      /* Suffix length. */
+static int autosfx = 1;                /* Whether to auto-extend the suffix length. */
 
 static void newfile(void);
 static void split1(off_t, int) __dead;
@@ -120,6 +121,7 @@
                            (sfxlen = (size_t)strtoul(optarg, &ep, 10)) == 0 ||
                            *ep != '\0')
                                errx(1, "%s: illegal suffix length.", optarg);
+                       autosfx = 0;
                        break;
                case 'n':               /* Chunks. */
                        if (!isdigit((unsigned char)optarg[0]) ||
@@ -323,6 +325,38 @@
                err(1, "%s", fname);
 
        quot = fnum;
+
+       /* If '-a' is not specified, then we automatically expand the
+        * suffix length to accomodate splitting all input.  We do this
+        * by moving the suffix pointer (fpnt) forward and incrementing
+        * sfxlen by one, thereby yielding an additional two characters
+        * and allowing all output files to sort such that 'cat *' yields
+        * the input in order.  I.e., the order is '... xyy xyz xzaaa
+        * xzaab ... xzyzy, xzyzz, xzzaaaa, xzzaaab' and so on. */
+       if (autosfx && (fpnt[0] == 'y') && (strspn(fpnt+1, "z") == strlen(fpnt+1))) {
+               if ((fname = realloc(fname, strlen(fname) + sfxlen + 2 + 1)) == NULL)
+                       err(EXIT_FAILURE, NULL);
+                       /* NOTREACHED */
+
+               fpnt = fname + strlen(fname) - sfxlen;
+               fpnt[sfxlen + 2] = '\0';
+
+               fpnt[0] = 'z';
+               fpnt[1] = 'a';
+
+               /*  Basename | Suffix
+                *  before:
+                *  x        | yz
+                *  after:
+                *  xz       | a.. */
+               fpnt++;
+               sfxlen++;
+
+               /* Reset so we start back at all 'a's in our extended suffix. */
+               quot = 0;
+               fnum = 0;
+       }
+
        for (i = sfxlen - 1; i >= 0; i--) {
                fpnt[i] = quot % 26 + 'a';
                quot = quot / 26;