gen_init_cpio.c

// SPDX-License-Identifier: GPL-2.0
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string.h>
#include <unistd.h>
#include <time.h>
#include <fcntl.h>
#include <errno.h>
#include <ctype.h>
#include <limits.h>

/*
 * Original work by Jeff Garzik
 *
 * External file lists, symlink, pipe and fifo support by Thayne Harbaugh
 * Hard link support by Luciano Rocha
 */

#define xstr(s) #s
#define str(s) xstr(s)
#define MIN(a, b) ((a) < (b) ? (a) : (b))

static unsigned int offset;
static unsigned int ino = 721;
static time_t default_mtime;
static bool do_csum = false;

struct file_handler {
	const char *type;
	int (*handler)(const char *line);
};

static void push_string(const char *name)
{
	unsigned int name_len = strlen(name) + 1;

	fputs(name, stdout);
	putchar(0);
	offset += name_len;
}

static void push_pad (void)
{
	while (offset & 3) {
		putchar(0);
		offset++;
	}
}

static void push_rest(const char *name)
{
	unsigned int name_len = strlen(name) + 1;
	unsigned int tmp_ofs;

	fputs(name, stdout);
	putchar(0);
	offset += name_len;

	tmp_ofs = name_len + 110;
	while (tmp_ofs & 3) {
		putchar(0);
		offset++;
		tmp_ofs++;
	}
}

static void push_hdr(const char *s)
{
	fputs(s, stdout);
	offset += 110;
}

static void cpio_trailer(void)
{
	char s[256];
	const char name[] = "TRAILER!!!";

	sprintf(s, "%s%08X%08X%08lX%08lX%08X%08lX"
	       "%08X%08X%08X%08X%08X%08X%08X",
		do_csum ? "070702" : "070701", /* magic */
		0,			/* ino */
		0,			/* mode */
		(long) 0,		/* uid */
		(long) 0,		/* gid */
		1,			/* nlink */
		(long) 0,		/* mtime */
		0,			/* filesize */
		0,			/* major */
		0,			/* minor */
		0,			/* rmajor */
		0,			/* rminor */
		(unsigned)strlen(name)+1, /* namesize */
		0);			/* chksum */
	push_hdr(s);
	push_rest(name);

	while (offset % 512) {
		putchar(0);
		offset++;
	}
}

static int cpio_mkslink(const char *name, const char *target,
			 unsigned int mode, uid_t uid, gid_t gid)
{
	char s[256];

	if (name[0] == '/')
		name++;
	sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
	       "%08X%08X%08X%08X%08X%08X%08X",
		do_csum ? "070702" : "070701", /* magic */
		ino++,			/* ino */
		S_IFLNK | mode,		/* mode */
		(long) uid,		/* uid */
		(long) gid,		/* gid */
		1,			/* nlink */
		(long) default_mtime,	/* mtime */
		(unsigned)strlen(target)+1, /* filesize */
		3,			/* major */
		1,			/* minor */
		0,			/* rmajor */
		0,			/* rminor */
		(unsigned)strlen(name) + 1,/* namesize */
		0);			/* chksum */
	push_hdr(s);
	push_string(name);
	push_pad();
	push_string(target);
	push_pad();
	return 0;
}

static int cpio_mkslink_line(const char *line)
{
	char name[PATH_MAX + 1];
	char target[PATH_MAX + 1];
	unsigned int mode;
	int uid;
	int gid;
	int rc = -1;

	if (5 != sscanf(line, "%" str(PATH_MAX) "s %" str(PATH_MAX) "s %o %d %d", name, target, &mode, &uid, &gid)) {
		fprintf(stderr, "Unrecognized dir format '%s'", line);
		goto fail;
	}
	rc = cpio_mkslink(name, target, mode, uid, gid);
 fail:
	return rc;
}

static int cpio_mkgeneric(const char *name, unsigned int mode,
		       uid_t uid, gid_t gid)
{
	char s[256];

	if (name[0] == '/')
		name++;
	sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
	       "%08X%08X%08X%08X%08X%08X%08X",
		do_csum ? "070702" : "070701", /* magic */
		ino++,			/* ino */
		mode,			/* mode */
		(long) uid,		/* uid */
		(long) gid,		/* gid */
		2,			/* nlink */
		(long) default_mtime,	/* mtime */
		0,			/* filesize */
		3,			/* major */
		1,			/* minor */
		0,			/* rmajor */
		0,			/* rminor */
		(unsigned)strlen(name) + 1,/* namesize */
		0);			/* chksum */
	push_hdr(s);
	push_rest(name);
	return 0;
}

enum generic_types {
	GT_DIR,
	GT_PIPE,
	GT_SOCK
};

struct generic_type {
	const char *type;
	mode_t mode;
};

static const struct generic_type generic_type_table[] = {
	[GT_DIR] = {
		.type = "dir",
		.mode = S_IFDIR
	},
	[GT_PIPE] = {
		.type = "pipe",
		.mode = S_IFIFO
	},
	[GT_SOCK] = {
		.type = "sock",
		.mode = S_IFSOCK
	}
};

static int cpio_mkgeneric_line(const char *line, enum generic_types gt)
{
	char name[PATH_MAX + 1];
	unsigned int mode;
	int uid;
	int gid;
	int rc = -1;

	if (4 != sscanf(line, "%" str(PATH_MAX) "s %o %d %d", name, &mode, &uid, &gid)) {
		fprintf(stderr, "Unrecognized %s format '%s'",
			line, generic_type_table[gt].type);
		goto fail;
	}
	mode |= generic_type_table[gt].mode;
	rc = cpio_mkgeneric(name, mode, uid, gid);
 fail:
	return rc;
}

static int cpio_mkdir_line(const char *line)
{
	return cpio_mkgeneric_line(line, GT_DIR);
}

static int cpio_mkpipe_line(const char *line)
{
	return cpio_mkgeneric_line(line, GT_PIPE);
}

static int cpio_mksock_line(const char *line)
{
	return cpio_mkgeneric_line(line, GT_SOCK);
}

static int cpio_mknod(const char *name, unsigned int mode,
		       uid_t uid, gid_t gid, char dev_type,
		       unsigned int maj, unsigned int min)
{
	char s[256];

	if (dev_type == 'b')
		mode |= S_IFBLK;
	else
		mode |= S_IFCHR;

	if (name[0] == '/')
		name++;
	sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
	       "%08X%08X%08X%08X%08X%08X%08X",
		do_csum ? "070702" : "070701", /* magic */
		ino++,			/* ino */
		mode,			/* mode */
		(long) uid,		/* uid */
		(long) gid,		/* gid */
		1,			/* nlink */
		(long) default_mtime,	/* mtime */
		0,			/* filesize */
		3,			/* major */
		1,			/* minor */
		maj,			/* rmajor */
		min,			/* rminor */
		(unsigned)strlen(name) + 1,/* namesize */
		0);			/* chksum */
	push_hdr(s);
	push_rest(name);
	return 0;
}

static int cpio_mknod_line(const char *line)
{
	char name[PATH_MAX + 1];
	unsigned int mode;
	int uid;
	int gid;
	char dev_type;
	unsigned int maj;
	unsigned int min;
	int rc = -1;

	if (7 != sscanf(line, "%" str(PATH_MAX) "s %o %d %d %c %u %u",
			 name, &mode, &uid, &gid, &dev_type, &maj, &min)) {
		fprintf(stderr, "Unrecognized nod format '%s'", line);
		goto fail;
	}
	rc = cpio_mknod(name, mode, uid, gid, dev_type, maj, min);
 fail:
	return rc;
}

static int cpio_mkfile_csum(int fd, unsigned long size, uint32_t *csum)
{
	while (size) {
		unsigned char filebuf[65536];
		ssize_t this_read;
		size_t i, this_size = MIN(size, sizeof(filebuf));

		this_read = read(fd, filebuf, this_size);
		if (this_read <= 0 || this_read > this_size)
			return -1;

		for (i = 0; i < this_read; i++)
			*csum += filebuf[i];

		size -= this_read;
	}
	/* seek back to the start for data segment I/O */
	if (lseek(fd, 0, SEEK_SET) < 0)
		return -1;

	return 0;
}

static int cpio_mkfile(const char *name, const char *location,
			unsigned int mode, uid_t uid, gid_t gid,
			unsigned int nlinks)
{
	char s[256];
	struct stat buf;
	unsigned long size;
	int file = -1;
	int retval;
	int rc = -1;
	int namesize;
	unsigned int i;
	uint32_t csum = 0;

	mode |= S_IFREG;

	file = open (location, O_RDONLY);
	if (file < 0) {
		fprintf (stderr, "File %s could not be opened for reading\n", location);
		goto error;
	}

	retval = fstat(file, &buf);
	if (retval) {
		fprintf(stderr, "File %s could not be stat()'ed\n", location);
		goto error;
	}

	if (buf.st_mtime > 0xffffffff) {
		fprintf(stderr, "%s: Timestamp exceeds maximum cpio timestamp, clipping.\n",
			location);
		buf.st_mtime = 0xffffffff;
	}

	if (buf.st_size > 0xffffffff) {
		fprintf(stderr, "%s: Size exceeds maximum cpio file size\n",
			location);
		goto error;
	}

	if (do_csum && cpio_mkfile_csum(file, buf.st_size, &csum) < 0) {
		fprintf(stderr, "Failed to checksum file %s\n", location);
		goto error;
	}

	size = 0;
	for (i = 1; i <= nlinks; i++) {
		/* data goes on last link */
		if (i == nlinks)
			size = buf.st_size;

		if (name[0] == '/')
			name++;
		namesize = strlen(name) + 1;
		sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
		       "%08lX%08X%08X%08X%08X%08X%08X",
			do_csum ? "070702" : "070701", /* magic */
			ino,			/* ino */
			mode,			/* mode */
			(long) uid,		/* uid */
			(long) gid,		/* gid */
			nlinks,			/* nlink */
			(long) buf.st_mtime,	/* mtime */
			size,			/* filesize */
			3,			/* major */
			1,			/* minor */
			0,			/* rmajor */
			0,			/* rminor */
			namesize,		/* namesize */
			size ? csum : 0);	/* chksum */
		push_hdr(s);
		push_string(name);
		push_pad();

		while (size) {
			unsigned char filebuf[65536];
			ssize_t this_read;
			size_t this_size = MIN(size, sizeof(filebuf));

			this_read = read(file, filebuf, this_size);
			if (this_read <= 0 || this_read > this_size) {
				fprintf(stderr, "Can not read %s file\n", location);
				goto error;
			}

			if (fwrite(filebuf, this_read, 1, stdout) != 1) {
				fprintf(stderr, "writing filebuf failed\n");
				goto error;
			}
			offset += this_read;
			size -= this_read;
		}
		push_pad();

		name += namesize;
	}
	ino++;
	rc = 0;

error:
	if (file >= 0)
		close(file);
	return rc;
}

static char *cpio_replace_env(char *new_location)
{
	char expanded[PATH_MAX + 1];
	char *start, *end, *var;

	while ((start = strstr(new_location, "${")) &&
	       (end = strchr(start + 2, '}'))) {
		*start = *end = 0;
		var = getenv(start + 2);
		snprintf(expanded, sizeof expanded, "%s%s%s",
			 new_location, var ? var : "", end + 1);
		strcpy(new_location, expanded);
	}

	return new_location;
}

static int cpio_mkfile_line(const char *line)
{
	char name[PATH_MAX + 1];
	char *dname = NULL; /* malloc'ed buffer for hard links */
	char location[PATH_MAX + 1];
	unsigned int mode;
	int uid;
	int gid;
	int nlinks = 1;
	int end = 0, dname_len = 0;
	int rc = -1;

	if (5 > sscanf(line, "%" str(PATH_MAX) "s %" str(PATH_MAX)
				"s %o %d %d %n",
				name, location, &mode, &uid, &gid, &end)) {
		fprintf(stderr, "Unrecognized file format '%s'", line);
		goto fail;
	}
	if (end && isgraph(line[end])) {
		int len;
		int nend;

		dname = malloc(strlen(line));
		if (!dname) {
			fprintf (stderr, "out of memory (%d)\n", dname_len);
			goto fail;
		}

		dname_len = strlen(name) + 1;
		memcpy(dname, name, dname_len);

		do {
			nend = 0;
			if (sscanf(line + end, "%" str(PATH_MAX) "s %n",
					name, &nend) < 1)
				break;
			len = strlen(name) + 1;
			memcpy(dname + dname_len, name, len);
			dname_len += len;
			nlinks++;
			end += nend;
		} while (isgraph(line[end]));
	} else {
		dname = name;
	}
	rc = cpio_mkfile(dname, cpio_replace_env(location),
	                 mode, uid, gid, nlinks);
 fail:
	if (dname_len) free(dname);
	return rc;
}

static void usage(const char *prog)
{
	fprintf(stderr, "Usage:\n"
		"\t%s [-t <timestamp>] [-c] <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"
		"\n"
		"# a comment\n"
		"file <name> <location> <mode> <uid> <gid> [<hard links>]\n"
		"dir <name> <mode> <uid> <gid>\n"
		"nod <name> <mode> <uid> <gid> <dev_type> <maj> <min>\n"
		"slink <name> <target> <mode> <uid> <gid>\n"
		"pipe <name> <mode> <uid> <gid>\n"
		"sock <name> <mode> <uid> <gid>\n"
		"\n"
		"<name>       name of the file/dir/nod/etc in the archive\n"
		"<location>   location of the file in the current filesystem\n"
		"             expands shell variables quoted with ${}\n"
		"<target>     link target\n"
		"<mode>       mode/permissions of the file\n"
		"<uid>        user id (0=root)\n"
		"<gid>        group id (0=root)\n"
		"<dev_type>   device type (b=block, c=character)\n"
		"<maj>        major number of nod\n"
		"<min>        minor number of nod\n"
		"<hard links> space separated list of other links to file\n"
		"\n"
		"example:\n"
		"# A simple initramfs\n"
		"dir /dev 0755 0 0\n"
		"nod /dev/console 0600 0 0 c 5 1\n"
		"dir /root 0700 0 0\n"
		"dir /sbin 0755 0 0\n"
		"file /sbin/kinit /usr/src/klibc/kinit/kinit 0755 0 0\n"
		"\n"
		"<timestamp> is time in seconds since Epoch that will be used\n"
		"as mtime for symlinks, special files and directories. The default\n"
		"is to use the current time for these entries.\n"
		"-c: calculate and store 32-bit checksums for file data.\n",
		prog);
}

static const struct file_handler file_handler_table[] = {
	{
		.type    = "file",
		.handler = cpio_mkfile_line,
	}, {
		.type    = "nod",
		.handler = cpio_mknod_line,
	}, {
		.type    = "dir",
		.handler = cpio_mkdir_line,
	}, {
		.type    = "slink",
		.handler = cpio_mkslink_line,
	}, {
		.type    = "pipe",
		.handler = cpio_mkpipe_line,
	}, {
		.type    = "sock",
		.handler = cpio_mksock_line,
	}, {
		.type    = NULL,
		.handler = NULL,
	}
};

#define LINE_SIZE (2 * PATH_MAX + 50)

int main (int argc, char *argv[])
{
	FILE *cpio_list;
	char line[LINE_SIZE];
	char *args, *type;
	int ec = 0;
	int line_nr = 0;
	const char *filename;

	default_mtime = time(NULL);
	while (1) {
		int opt = getopt(argc, argv, "t:ch");
		char *invalid;

		if (opt == -1)
			break;
		switch (opt) {
		case 't':
			default_mtime = strtol(optarg, &invalid, 10);
			if (!*optarg || *invalid) {
				fprintf(stderr, "Invalid timestamp: %s\n",
						optarg);
				usage(argv[0]);
				exit(1);
			}
			break;
		case 'c':
			do_csum = true;
			break;
		case 'h':
		case '?':
			usage(argv[0]);
			exit(opt == 'h' ? 0 : 1);
		}
	}

	/*
	 * Timestamps after 2106-02-07 06:28:15 UTC have an ascii hex time_t
	 * representation that exceeds 8 chars and breaks the cpio header
	 * specification.
	 */
	if (default_mtime > 0xffffffff) {
		fprintf(stderr, "ERROR: Timestamp too large for cpio format\n");
		exit(1);
	}

	if (argc - optind != 1) {
		usage(argv[0]);
		exit(1);
	}
	filename = argv[optind];
	if (!strcmp(filename, "-"))
		cpio_list = stdin;
	else if (!(cpio_list = fopen(filename, "r"))) {
		fprintf(stderr, "ERROR: unable to open '%s': %s\n\n",
			filename, strerror(errno));
		usage(argv[0]);
		exit(1);
	}

	while (fgets(line, LINE_SIZE, cpio_list)) {
		int type_idx;
		size_t slen = strlen(line);

		line_nr++;

		if ('#' == *line) {
			/* comment - skip to next line */
			continue;
		}

		if (! (type = strtok(line, " \t"))) {
			fprintf(stderr,
				"ERROR: incorrect format, could not locate file type line %d: '%s'\n",
				line_nr, line);
			ec = -1;
			break;
		}

		if ('\n' == *type) {
			/* a blank line */
			continue;
		}

		if (slen == strlen(type)) {
			/* must be an empty line */
			continue;
		}

		if (! (args = strtok(NULL, "\n"))) {
			fprintf(stderr,
				"ERROR: incorrect format, newline required line %d: '%s'\n",
				line_nr, line);
			ec = -1;
		}

		for (type_idx = 0; file_handler_table[type_idx].type; type_idx++) {
			int rc;
			if (! strcmp(line, file_handler_table[type_idx].type)) {
				if ((rc = file_handler_table[type_idx].handler(args))) {
					ec = rc;
					fprintf(stderr, " line %d\n", line_nr);
				}
				break;
			}
		}

		if (NULL == file_handler_table[type_idx].type) {
			fprintf(stderr, "unknown file type line %d: '%s'\n",
				line_nr, line);
		}
	}
	if (ec == 0)
		cpio_trailer();

	exit(ec);
}