paxinc.c

/*
 * Copyright 2003-2024 Gentoo Foundation
 * Distributed under the terms of the GNU General Public License v2
 *
 * Copyright 2005-2012 Ned Ludd        - <solar@gentoo.org>
 * Copyright 2005-2024 Mike Frysinger  - <vapier@gentoo.org>
 */

/* stick common symbols here that are needed by paxinc.h */

#define IN_paxinc
#include "paxinc.h"

char do_reverse_endian;

/* some of this ar code was taken from busybox */

#define AR_MAGIC "!<arch>"
#define AR_MAGIC_SIZE (sizeof(AR_MAGIC)-1) /* dont count null byte */
archive_handle *ar_open_fd(const char *filename, int fd, bool verbose)
{
	static archive_handle ret;
	char buf[AR_MAGIC_SIZE];

	ret.filename = filename;
	ret.fd = fd;
	ret.skip = 0;
	ret.extfn = NULL;
	ret.verbose = verbose;

	if (read(ret.fd, buf, AR_MAGIC_SIZE) != AR_MAGIC_SIZE)
		return NULL;
	if (strncmp(buf, AR_MAGIC, AR_MAGIC_SIZE))
		return NULL;

	return &ret;
}
archive_handle *ar_open(const char *filename, bool verbose)
{
	int fd;
	archive_handle *ret;

	if ((fd=open(filename, O_RDONLY)) == -1)
		errp("%s: could not open", filename);

	ret = ar_open_fd(filename, fd, verbose);
	if (ret == NULL)
		close(fd);

	return ret;
}

static uint64_t ar_read_ascii_number(const char *numstr, size_t ndigits, int base)
{
	/* Largest field ar headers have is 16 bytes. */
	char buf[17];
	char *endp;
	long long ret;

	memcpy(buf, numstr, ndigits);
	buf[ndigits] = '\0';

	ret = strtoll(buf, &endp, base);
	/* Numbers are padded with whitespace. */
	if (*endp != '\0' && *endp != ' ') {
		warn("ar: invalid number: %s", buf);
		ret = 0;
	}

	/*
	 * Unsigned 64-bit numbers use up to 20 digits, and signed 64-bit numbers use
	 * up to 19 digits, but ndigits is always less than that.  So we'd never handle
	 * a number that requires all 64-bits.  If it's negative, it's because the input
	 * was negative e.g. "-1", and none of these fields should ever be negative.
	 */
	if (ret < 0) {
		warn("ar: invalid number: %s", buf);
		ret = 0;
	}

	return ret;
}
#define read_octal_number(s, n) ar_read_ascii_number(s, n, 8)
#define read_decimal_number(s, n) ar_read_ascii_number(s, n, 10)
/* For char[] arrays rather than dynamic pointers. */
#define read_octal_number_fixed(s) read_octal_number(s, sizeof(s))
#define read_decimal_number_fixed(s) read_decimal_number(s, sizeof(s))

archive_member *ar_next(archive_handle *ar)
{
	char *s;
	char *heap_s = NULL;
	ssize_t len = 0;
	static archive_member ret;

	if (ar->skip && lseek(ar->fd, ar->skip, SEEK_CUR) == -1) {
close_and_ret:
		free(heap_s);
		free(ar->extfn);
		close(ar->fd);
		ar->extfn = NULL;
		ar->fd = -1;
		return NULL;
	}

	if (read(ar->fd, ret.buf.raw, sizeof(ret.buf.raw)) != sizeof(ret.buf.raw))
		goto close_and_ret;

	/* ar header starts on an even byte (2 byte aligned)
	 * '\n' is used for padding */
	if (ret.buf.raw[0] == '\n') {
		memmove(ret.buf.raw, ret.buf.raw+1, 59);
		if (read(ar->fd, ret.buf.raw+59, 1) != 1)
			goto close_and_ret;
	}

	if ((ret.buf.formatted.magic[0] != '`') || (ret.buf.formatted.magic[1] != '\n')) {
		/* When dealing with corrupt or random embedded cross-compilers, they might
		 * be abusing the archive format; only complain when in verbose mode. */
		if (ar->verbose)
			warn("%s: invalid ar entry", ar->filename);
		goto close_and_ret;
	}

	/* System V extended filename section. */
	if (ret.buf.formatted.name[0] == '/' && ret.buf.formatted.name[1] == '/') {
		if (ar->extfn != NULL) {
			warn("%s: Duplicate GNU extended filename section", ar->filename);
			goto close_and_ret;
		}
		len = ar->extfn_len = read_decimal_number_fixed(ret.buf.formatted.size);
		ar->extfn = xmalloc(sizeof(char) * (len + 1));
		if (read(ar->fd, ar->extfn, len) != len)
			goto close_and_ret;
		ar->extfn[len--] = '\0';
		for (; len > 0; len--)
			if (ar->extfn[len] == '\n')
				ar->extfn[len] = '\0';
		ar->skip = 0;
		return ar_next(ar);
	}

	s = ret.buf.formatted.name;
	if (s[0] == '#' && s[1] == '1' && s[2] == '/') {
		/* BSD extended filename, always in use on Darwin */
		len = read_decimal_number(s + 3, sizeof(ret.buf.formatted.name) - 3);
		if (len <= (ssize_t)sizeof(ret.buf.formatted.name)) {
			if (read(ar->fd, ret.buf.formatted.name, len) != len)
				goto close_and_ret;
		} else {
			s = heap_s = xmalloc(sizeof(char) * (len + 1));
			if (read(ar->fd, s, len) != len)
				goto close_and_ret;
			s[len] = '\0';
		}
	} else if (s[0] == '/' && s[1] >= '0' && s[1] <= '9') {
		/* GNU extended filename */
		if (ar->extfn == NULL) {
			warn("%s: GNU extended filename without special data section", ar->filename);
			goto close_and_ret;
		}
		/* NB: We NUL terminated extfn above when reading it. */
		int64_t off = read_decimal_number(s + 1, sizeof(ret.buf.formatted.name) - 1);
		if (off >= ar->extfn_len) {
			warn("%s: GNU extended filename has invalid offset", ar->filename);
			goto close_and_ret;
		}
		s = ar->extfn + off;
	}

	snprintf(ret.name, sizeof(ret.name), "%s:%s", ar->filename, s);
	free(heap_s);
	ret.name[sizeof(ret.name) - 1] = '\0';
	if ((s=strchr(ret.name+strlen(ar->filename), '/')) != NULL)
		*s = '\0';
	ret.date = read_decimal_number_fixed(ret.buf.formatted.date);
	ret.uid = read_decimal_number_fixed(ret.buf.formatted.uid);
	ret.gid = read_decimal_number_fixed(ret.buf.formatted.gid);
	ret.mode = read_octal_number_fixed(ret.buf.formatted.mode);
	ret.size = read_decimal_number_fixed(ret.buf.formatted.size);
	ar->skip = ret.size - len;

	return &ret;
}

/* Convert file perms into octal string */
const char *strfileperms(const char *fname)
{
	struct stat st;
	static char buf[8];

	if (stat(fname, &st) == -1)
		return "";

	snprintf(buf, sizeof(buf), "%o", st.st_mode);

	return buf + 2;
}

/* Color helpers */
#define COLOR(c,b) "\e[" c ";" b "m"
const char *NORM   = COLOR("00", "00");
const char *RED    = COLOR("31", "01");
const char *YELLOW = COLOR("33", "01");

void color_init(bool disable)
{
	if (!disable) {
		const char *nocolor = getenv("NOCOLOR");
		if (nocolor)
			disable = !strcmp(nocolor, "yes") || !strcmp(nocolor, "true");
	}
	if (disable)
		NORM = RED = YELLOW = "";
}

/* File system helpers. */
int root_fd = AT_FDCWD;

FILE *fopenat_r(int dir_fd, const char *path)
{
	int fd = openat(dir_fd, path, O_RDONLY|O_CLOEXEC);
	if (fd == -1)
		return NULL;
	return fdopen(fd, "re");
}

const char *root_rel_path(const char *path)
{
	/*
	 * openat() will ignore the dirfd if path starts with
	 * a /, so consume all of that noise
	 *
	 * XXX: we don't handle relative paths like ../ that
	 * break out of the --root option, but for now, just
	 * don't do that :P.
	 */
	if (root_fd != AT_FDCWD) {
		while (*path == '/')
			++path;
		if (*path == '\0')
			path = ".";
	}

	return path;
}

void pax_usage(
	const char *header,
	const char *args,
	const char *parse_flags,
	const struct option long_opts[],
	const char * const opts_help[],
	int status)
{
	const char a_arg[] = "<arg>";
	size_t a_arg_len = strlen(a_arg) + 2;
	size_t i;
	int optlen;

	printf("* %s\n\n"
	       "Usage: %s [options] %s\n\n", header, argv0, args);
	printf("Options: -[%s]\n", parse_flags);

	/* Prescan the --long opt length to auto-align. */
	optlen = 0;
	for (i = 0; long_opts[i].name; ++i) {
		int l = strlen(long_opts[i].name);
		if (long_opts[i].has_arg == a_argument)
			l += a_arg_len;
		optlen = max(l, optlen);
	}
	/* Use some reasonable min width. */
	optlen = max(20, optlen);

	for (i = 0; long_opts[i].name; ++i) {
		/* First output the short flag if it has one. */
		if (long_opts[i].val > '~')
			printf("      ");
		else
			printf("  -%c, ", long_opts[i].val);

		/* Then the long flag. */
		if (long_opts[i].has_arg == no_argument)
			printf("--%-*s", optlen, long_opts[i].name);
		else
			printf("--%s %s %*s", long_opts[i].name, a_arg,
				(int)(optlen - strlen(long_opts[i].name) - a_arg_len), "");

		/* Finally the help text. */
		printf("* %s\n", opts_help[i]);
	}

	printf("\nFor more information, see the %s(1) manpage.\n", argv0);
	exit(status);
}