Jan Schaumann <jscha...@netmeister.org> wrote:
> The attached diff adds a flag "-c" (mnemonic "create,
> don't overwrite" or "continue where you left off"):
Ugh, and once more without a race condition.
-Jan
Index: split.1
===================================================================
RCS file: /cvsroot/src/usr.bin/split/split.1,v
retrieving revision 1.16
diff -u -p -r1.16 split.1
--- split.1 30 Jan 2023 15:22:02 -0000 1.16
+++ split.1 12 Feb 2023 21:18:10 -0000
@@ -29,7 +29,7 @@
.\"
.\" @(#)split.1 8.3 (Berkeley) 4/16/94
.\"
-.Dd January 28, 2023
+.Dd February 12, 2023
.Dt SPLIT 1
.Os
.Sh NAME
@@ -37,6 +37,7 @@
.Nd split a file into pieces
.Sh SYNOPSIS
.Nm
+.Op Fl c
.Op Fl a Ar suffix_length
.Oo
.Fl b Ar byte_count Ns Oo Li k|m Oc |
@@ -78,6 +79,9 @@ If
is appended to the number, the file is split into
.Ar byte_count
megabyte pieces.
+.It Fl c
+Continue creating files and do not overwrite existing
+output files.
.It Fl l
Create smaller files
.Ar line_count
@@ -111,6 +115,16 @@ If the
argument is not specified,
.Ql x
is used.
+.Pp
+By default,
+.Nm
+will overwrite any existing output files.
+If the
+.Fl c
+flag is specified,
+.Nm
+will instead continue to generate output file names
+until it finds one that does not already exist.
.Sh STANDARDS
The
.Nm
Index: split.c
===================================================================
RCS file: /cvsroot/src/usr.bin/split/split.c,v
retrieving revision 1.30
diff -u -p -r1.30 split.c
--- split.c 12 Feb 2023 20:43:21 -0000 1.30
+++ split.c 12 Feb 2023 21:18:11 -0000
@@ -56,6 +56,7 @@ __RCSID("$NetBSD: split.c,v 1.30 2023/02
#define DEFLINE 1000 /* Default num lines per file. */
+static int clobber = 1; /* Whether to overwrite existing output files.
*/
static int file_open; /* If a file is open. */
static int ifd = STDIN_FILENO, ofd = -1; /* Input/output file descriptors. */
static char *fname; /* File name prefix. */
@@ -79,7 +80,7 @@ main(int argc, char *argv[])
off_t numlines = 0; /* Line count to split on. */
off_t chunks = 0; /* Number of chunks to split into. */
- while ((ch = getopt(argc, argv, "0123456789b:l:a:n:")) != -1)
+ while ((ch = getopt(argc, argv, "0123456789b:cl:a:n:")) != -1)
switch (ch) {
case '0': case '1': case '2': case '3': case '4':
case '5': case '6': case '7': case '8': case '9':
@@ -115,6 +116,9 @@ main(int argc, char *argv[])
else if (*ep == 'm')
bytecnt *= 1024 * 1024;
break;
+ case 'c': /* Continue, don't overwrite output
files. */
+ clobber = 0;
+ break;
case 'l': /* Line count. */
if (numlines != 0)
usage();
@@ -317,6 +321,11 @@ newfile(void)
static int fnum;
static char *fpnt;
int quot, i;
+ int flags = O_WRONLY | O_CREAT | O_TRUNC;
+
+ if (!clobber) {
+ flags |= O_EXCL;
+ }
if (ofd == -1) {
fpnt = fname + strlen(fname);
@@ -324,6 +333,7 @@ newfile(void)
} else if (close(ofd) != 0)
err(1, "%s", fname);
+again:
quot = fnum;
/* If '-a' is not specified, then we automatically expand the
@@ -364,8 +374,13 @@ newfile(void)
if (quot > 0)
errx(1, "too many files.");
++fnum;
- if ((ofd = open(fname, O_WRONLY | O_CREAT | O_TRUNC, DEFFILEMODE)) < 0)
+
+ if ((ofd = open(fname, flags, DEFFILEMODE)) < 0) {
+ if (!clobber && errno == EEXIST) {
+ goto again;
+ }
err(1, "%s", fname);
+ }
}
static size_t
