gen_init_cpio: support -o <output_file> parameter

This is another preparatory change to allow for reflink-optimized
cpio archives with file data written / cloned via copy_file_range().
The output file is truncated prior to write, so that it maps to
usr/gen_initramfs.sh usage. It may make sense to offer an append option
in future, for easier archive concatenation.

Signed-off-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Link: https://lore.kernel.org/r/20250819032607.28727-3-ddiss@suse.de
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
This commit is contained in:
David Disseldorp 2025-08-19 13:05:45 +10:00 committed by Nathan Chancellor
parent 1400227773
commit ae18b94099
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GPG Key ID: 1D6B269171C01A96
1 changed files with 16 additions and 4 deletions

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@ -1,4 +1,5 @@
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
@ -110,7 +111,7 @@ static int cpio_trailer(void)
push_pad(padlen(offset, 512)) < 0)
return -1;
return 0;
return fsync(outfd);
}
static int cpio_mkslink(const char *name, const char *target,
@ -532,7 +533,7 @@ static int cpio_mkfile_line(const char *line)
static void usage(const char *prog)
{
fprintf(stderr, "Usage:\n"
"\t%s [-t <timestamp>] [-c] <cpio_list>\n"
"\t%s [-t <timestamp>] [-c] [-o <output_file>] <cpio_list>\n"
"\n"
"<cpio_list> is a file containing newline separated entries that\n"
"describe the files to be included in the initramfs archive:\n"
@ -569,7 +570,8 @@ static void usage(const char *prog)
"as mtime for symlinks, directories, regular and special files.\n"
"The default is to use the current time for all files, but\n"
"preserve modification time for regular files.\n"
"-c: calculate and store 32-bit checksums for file data.\n",
"-c: calculate and store 32-bit checksums for file data.\n"
"<output_file>: write cpio to this file instead of stdout\n",
prog);
}
@ -611,7 +613,7 @@ int main (int argc, char *argv[])
default_mtime = time(NULL);
while (1) {
int opt = getopt(argc, argv, "t:ch");
int opt = getopt(argc, argv, "t:cho:");
char *invalid;
if (opt == -1)
@ -630,6 +632,16 @@ int main (int argc, char *argv[])
case 'c':
do_csum = true;
break;
case 'o':
outfd = open(optarg,
O_WRONLY | O_CREAT | O_LARGEFILE | O_TRUNC,
0600);
if (outfd < 0) {
fprintf(stderr, "failed to open %s\n", optarg);
usage(argv[0]);
exit(1);
}
break;
case 'h':
case '?':
usage(argv[0]);