abuild-tar: new utility to mangle tar files

- ability to embed an checksum inside the tar header for regular
  files (to avoid checksumming at apk installation time)
- way to remove the end-of-archive marker to create concenatable
  .tar.gz:s for signed apks

abuild-tar.c

@@ -0,0 +1,213 @@
+/* abuild-tar.c - A TAR mangling utility for .APK packages
+ *
+ * Copyright (C) 2009 Timo Teräs <timo.teras@iki.fi>
+ * All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation. See http://www.gnu.org/ for details.
+ */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <openssl/evp.h>
+
+#ifndef VERSION
+#define VERSION ""
+#endif
+
+struct tar_header {
+	/* ustar header, Posix 1003.1 */
+	char name[100];     /*   0-99 */
+	char mode[8];       /* 100-107 */
+	char uid[8];        /* 108-115 */
+	char gid[8];        /* 116-123 */
+	char size[12];      /* 124-135 */
+	char mtime[12];     /* 136-147 */
+	char chksum[8];     /* 148-155 */
+	char typeflag;      /* 156-156 */
+	char linkname[100]; /* 157-256 */
+	char magic[8];      /* 257-264 */
+	char uname[32];     /* 265-296 */
+	char gname[32];     /* 297-328 */
+	char devmajor[8];   /* 329-336 */
+	char devminor[8];   /* 337-344 */
+	char prefix[155];   /* 345-499 */
+	char padding[12];   /* 500-512 */
+};
+
+#define GET_OCTAL(s)	get_octal(s, sizeof(s))
+#define PUT_OCTAL(s,v)	put_octal(s, sizeof(s), v)
+
+static inline int dx(int c)
+{
+	if (c >= '0' && c <= '9')
+		return c - '0';
+	if (c >= 'a' && c <= 'f')
+		return c - 'a' + 0xa;
+	if (c >= 'A' && c <= 'F')
+		return c - 'A' + 0xa;
+	return -1;
+}
+
+static int get_octal(char *s, size_t l)
+{
+	unsigned int val;
+	int ch;
+
+	val = 0;
+	while (l && s[0] != 0) {
+		ch = dx(s[0]);
+		if (ch < 0 || ch >= 8)
+			break;
+		val *= 8;
+		val += ch;
+
+		s++;
+		l--;
+	}
+
+	return val;
+}
+
+static void put_octal(char *s, size_t l, size_t value)
+{
+	char *ptr = &s[l - 1];
+
+	*(ptr--) = '\0';
+	while (value != 0 && ptr >= s) {
+		*(ptr--) = '0' + (value % 8);
+		value /= 8;
+	}
+	while (ptr >= s)
+		*(ptr--) = '0';
+}
+
+static int usage(void)
+{
+	fprintf(stderr,
+"abuild-tar " VERSION "\n"
+"\n"
+"usage: abuild-tar [--hash [<algorithm>]] [--no-end]\n"
+"\n"
+"options:\n"
+"  --hash [sha1|md5]	Read tar archive from stdin, precalculate hash for \n"
+"			regular	entries and output tar archive on stdout\n"
+"  --no-end		Remove the end of file tar record\n"
+"\n");
+}
+
+static int do_it(const EVP_MD *md, int cut)
+{
+	struct tar_header hdr;
+	size_t size, aligned_size;
+	void *ptr;
+	int dohash = 0, r;
+	struct {
+		char id[4];
+		uint16_t nid;
+		uint16_t size;
+	} mdinfo;
+
+	if (md != NULL) {
+		memcpy(mdinfo.id, "APK2", 4);
+		mdinfo.nid = EVP_MD_nid(md);
+		mdinfo.size = EVP_MD_size(md);
+	}
+
+	do {
+		if (read(STDIN_FILENO, &hdr, sizeof(hdr)) != sizeof(hdr))
+			return 0;
+
+		if (cut && hdr.name[0] == 0)
+			return 0;
+
+		size = GET_OCTAL(hdr.size);
+		aligned_size = (size + 511) & ~511;
+
+		if (md != NULL)
+			dohash = (hdr.typeflag == '0' || hdr.typeflag == '7');
+		if (dohash) {
+			const unsigned char *src;
+			int chksum, i;
+
+			ptr = malloc(aligned_size);
+			if (read(STDIN_FILENO, ptr, aligned_size) != aligned_size)
+				return 1;
+
+			memcpy(&hdr.linkname[3], &mdinfo, sizeof(mdinfo));
+			EVP_Digest(ptr, size, &hdr.linkname[3+sizeof(mdinfo)],
+				   NULL, md, NULL);
+
+			/* Recalculate checksum */
+			memset(hdr.chksum, ' ', sizeof(hdr.chksum));
+			src = (const unsigned char *) &hdr;
+			for (i = chksum = 0; i < sizeof(hdr); i++)
+				chksum += src[i];
+			put_octal(hdr.chksum, sizeof(hdr.chksum)-1, chksum);
+		}
+
+		if (write(STDOUT_FILENO, &hdr, sizeof(hdr)) != sizeof(hdr))
+			return 2;
+
+		if (dohash) {
+			if (write(STDOUT_FILENO, ptr, aligned_size) != aligned_size)
+				return 2;
+			free(ptr);
+		} else if (aligned_size != 0) {
+			r = splice(STDIN_FILENO, NULL, STDOUT_FILENO, NULL,
+				   aligned_size, 0);
+			if (r == -1) {
+				while (aligned_size > 0) {
+					if (read(STDIN_FILENO, &hdr, sizeof(hdr)) != sizeof(hdr))
+						return 1;
+					if (write(STDOUT_FILENO, &hdr, sizeof(hdr)) != sizeof(hdr))
+						return 2;
+					aligned_size -= sizeof(hdr);
+				}
+			} else if (r != aligned_size)
+				return 2;
+		}
+	} while (1);
+}
+
+int main(int argc, char **argv)
+{
+	static int cut = 0;
+	static const struct option options[] = {
+		{ "hash", optional_argument },
+		{ "no-end", no_argument, &cut, 1 },
+		{ NULL }
+	};
+	const EVP_MD *md = NULL;
+	char *digest = NULL;
+	int ndx;
+
+	OpenSSL_add_all_algorithms();
+	ENGINE_load_builtin_engines();
+	ENGINE_register_all_complete();
+
+	while (getopt_long(argc, argv, "", options, &ndx) != -1) {
+		if (ndx == 0)
+			digest = optarg ? optarg : "sha1";
+	}
+
+	fprintf(stderr, "digest: %s, cut: %d\n", digest, cut);
+
+	if (digest == NULL && cut == 0)
+		return usage();
+	if (isatty(STDIN_FILENO))
+		return usage();
+
+	if (digest != NULL) {
+		md = EVP_get_digestbyname(digest);
+		if (md == NULL)
+			return usage();
+	}
+
+	return do_it(md, cut);
+}