/* vi: set sw=4 ts=4: */
/*
 * xxd implementation for busybox
 *
 * Copyright (c) 2017 Denys Vlasenko <vda.linux@gmail.com>
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */
//config:config XXD
//config:	bool "xxd (8.9 kb)"
//config:	default y
//config:	help
//config:	The xxd utility is used to display binary data in a readable
//config:	way that is comparable to the output from most hex editors.

//applet:IF_XXD(APPLET_NOEXEC(xxd, xxd, BB_DIR_USR_BIN, BB_SUID_DROP, xxd))

//kbuild:lib-$(CONFIG_XXD) += hexdump_xxd.o

// $ xxd --version
// xxd V1.10 27oct98 by Juergen Weigert
// $ xxd --help
// Usage:
//       xxd [options] [infile [outfile]]
//    or
//       xxd -r [-s [-]offset] [-c cols] [-ps] [infile [outfile]]
// Options:
//    -a          toggle autoskip: A single '*' replaces nul-lines. Default off.
//    -b          binary digit dump (incompatible with -ps,-i,-r). Default hex.
//    -c cols     format <cols> octets per line. Default 16 (-i: 12, -ps: 30).
//    -E          show characters in EBCDIC. Default ASCII.
//    -e          little-endian dump (incompatible with -ps,-i,-r).
//    -g          number of octets per group in normal output. Default 2 (-e: 4).
//    -i          output in C include file style.
//    -l len      stop after <len> octets.
//    -o off      add <off> to the displayed file position.
//    -ps         output in postscript plain hexdump style.
//    -r          reverse operation: convert (or patch) hexdump into binary.
//    -r -s off   revert with <off> added to file positions found in hexdump.
//    -s [+][-]seek  start at <seek> bytes abs. (or +: rel.) infile offset.
//    -u          use upper case hex letters.

//usage:#define xxd_trivial_usage
//usage:       "[-pri] [-g N] [-c N] [-n LEN] [-s OFS] [-o OFS] [FILE]"
//usage:#define xxd_full_usage "\n\n"
//usage:       "Hex dump FILE (or stdin)\n"
//usage:     "\n	-g N		Bytes per group"
//usage:     "\n	-c N		Bytes per line"
//usage:     "\n	-p		Show only hex bytes, assumes -c30"
//usage:     "\n	-i		C include file style"
// exactly the same help text lines in hexdump and xxd:
//usage:     "\n	-l LENGTH	Show only first LENGTH bytes"
//usage:     "\n	-s OFFSET	Skip OFFSET bytes"
//usage:     "\n	-o OFFSET	Add OFFSET to displayed offset"
//usage:     "\n	-r		Reverse (with -p, assumes no offsets in input)"

#include "libbb.h"
#include "dump.h"

/* This is a NOEXEC applet. Be very careful! */

#define OPT_l (1 << 0)
#define OPT_s (1 << 1)
#define OPT_a (1 << 2)
#define OPT_p (1 << 3)
#define OPT_i (1 << 4)
#define OPT_r (1 << 5)
#define OPT_g (1 << 6)
#define OPT_c (1 << 7)
#define OPT_o (1 << 8)

static void reverse(unsigned opt, const char *filename)
{
	FILE *fp;
	char *buf;

	fp = filename ? xfopen_for_read(filename) : stdin;

	while ((buf = xmalloc_fgetline(fp)) != NULL) {
		char *p;

		p = buf;
		if (!(opt & OPT_p)) {
			/* skip address */
			while (isxdigit(*p)) p++;
			/* NB: for xxd -r, first hex portion is address even without colon */
			/* If it's there, skip it: */
			if (*p == ':') p++;

//TODO: seek (or zero-pad if unseekable) to the address position
//NOTE: -s SEEK value should be added to the address before seeking
		}

		/* Process hex bytes optionally separated by whitespace */
		for (;;) {
			uint8_t val, c;
 nibble1:
			p = skip_whitespace(p);

			c = *p++;
			if (isdigit(c))
				val = c - '0';
			else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
				val = (c|0x20) - ('a' - 10);
			else {
				/* xxd V1.10 is inconsistent here.
				 *  echo -e "31 !3 0a 0a" | xxd -r -p
				 * is "10<a0>" (no <cr>) - "!" is ignored,
				 * but
				 *  echo -e "31 !!343434\n30 0a" | xxd -r -p
				 * is "10<cr>" - "!!" drops rest of the line.
				 * We will ignore all invalid chars:
				 */
				if (c != '\0')
					goto nibble1;
				break;
			}
			val <<= 4;

			/* Works the same with xxd V1.10:
			 *  echo "31 09 32 0a" | xxd -r -p
			 *  echo "31 0 9 32 0a" | xxd -r -p
			 * thus allow whitespace even within the byte:
			 */
 nibble2:
			p = skip_whitespace(p);

			c = *p++;
			if (isdigit(c))
				val |= c - '0';
			else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
				val |= (c|0x20) - ('a' - 10);
			else {
				if (c != '\0') {
					/* "...3<not_hex_char>..." ignores both chars */
					goto nibble1;
				}
				/* Nibbles can join even through newline:
				 * echo -e "31 3\n2 0a" | xxd -r -p
				 * is "12<cr>".
				 */
				free(buf);
				p = buf = xmalloc_fgetline(fp);
				if (!buf)
					break;
				goto nibble2;
			}
			putchar(val);
		}
		free(buf);
	}
	//fclose(fp);
	fflush_stdout_and_exit(EXIT_SUCCESS);
}

static void print_C_style(const char *p, const char *hdr)
{
	printf(hdr, isdigit(p[0]) ? "__" : "");
	while (*p) {
		bb_putchar(isalnum(*p) ? *p : '_');
		p++;
	}
}

int xxd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int xxd_main(int argc UNUSED_PARAM, char **argv)
{
	char buf[80];
	dumper_t *dumper;
	char *opt_l, *opt_s, *opt_o;
	unsigned bytes = 2;
	unsigned cols = 0;
	unsigned opt;
	int r;

	dumper = alloc_dumper();

	opt = getopt32(argv, "^" "l:s:apirg:+c:+o:" "\0" "?1" /* 1 argument max */,
			&opt_l, &opt_s, &bytes, &cols, &opt_o
	);
	argv += optind;

	dumper->dump_vflag = ALL;
//	if (opt & OPT_a)
//		dumper->dump_vflag = SKIPNUL; ..does not exist
	if (opt & OPT_l) {
		dumper->dump_length = xstrtou_range(
				opt_l,
				/*base:*/ 0,
				/*lo:*/ 0, /*hi:*/ INT_MAX
		);
	}
	if (opt & OPT_s) {
		dumper->dump_skip = xstrtoull_range(
				opt_s,
				/*base:*/ 0,
				/*lo:*/ 0, /*hi:*/ OFF_T_MAX
		);
		//BUGGY for /proc/version (unseekable?)
	}

	if (opt & OPT_r) {
		reverse(opt, argv[0]);
	}

	if (opt & OPT_o) {
		/* -o accepts negative numbers too */
		dumper->xxd_displayoff = xstrtoll(opt_o, /*base:*/ 0);
	}

	if (opt & OPT_p) {
		if (cols == 0)
			cols = 30;
		bytes = cols; /* -p ignores -gN */
	} else {
		if (cols == 0)
			cols = (opt & OPT_i) ? 12 : 16;
		if (opt & OPT_i) {
			bytes = 1; // -i ignores -gN
			// output is "  0xXX, 0xXX, 0xXX...", add leading space
			bb_dump_add(dumper, "\" \"");
		} else
			bb_dump_add(dumper, "\"%08.8_ax: \""); // "address: "
	}

	if (bytes < 1 || bytes >= cols) {
		sprintf(buf, "%u/1 \"%%02x\"", cols); // cols * "XX"
		bb_dump_add(dumper, buf);
	}
	else if (bytes == 1) {
		if (opt & OPT_i)
			sprintf(buf, "%u/1 \" 0x%%02x,\"", cols); // cols * " 0xXX,"
//TODO: compat: omit the last comma after the very last byte
		else
			sprintf(buf, "%u/1 \"%%02x \"", cols); // cols * "XX "
		bb_dump_add(dumper, buf);
	}
	else {
/* Format "print byte" with and without trailing space */
#define BS "/1 \"%02x \""
#define B  "/1 \"%02x\""
		unsigned i;
		char *bigbuf = xmalloc(cols * (sizeof(BS)-1));
		char *p = bigbuf;
		for (i = 1; i <= cols; i++) {
			if (i == cols || i % bytes)
				p = stpcpy(p, B);
			else
				p = stpcpy(p, BS);
		}
		// for -g3, this results in B B BS B B BS... B = "xxxxxx xxxxxx .....xx"
		// todo: can be more clever and use
		// one 'bytes-1/1 "%02x"' format instead of many "B B B..." formats
		//bb_error_msg("ADDED:'%s'", bigbuf);
		bb_dump_add(dumper, bigbuf);
		free(bigbuf);
	}

	if (!(opt & (OPT_p|OPT_i))) {
		sprintf(buf, "\"  \"%u/1 \"%%_p\"\"\n\"", cols); // "  ASCII\n"
		bb_dump_add(dumper, buf);
	} else {
		bb_dump_add(dumper, "\"\n\"");
		dumper->xxd_eofstring = "\n";
	}

	if ((opt & OPT_i) && argv[0]) {
		print_C_style(argv[0], "unsigned char %s");
		printf("[] = {\n");
	}
	r = bb_dump_dump(dumper, argv);
	if (r == 0 && (opt & OPT_i) && argv[0]) {
		print_C_style(argv[0], "};\nunsigned int %s");
		printf("_len = %"OFF_FMT"u;\n", dumper->address);
	}
	return r;
}