/* vi: set sw=4 ts=4: */
/*
 * cat implementation for busybox
 *
 * Copyright (C) 2003  Manuel Novoa III  <mjn3@codepoet.org>
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */
//config:config CAT
//config:       bool "cat (5.6 kb)"
//config:       default y
//config:       help
//config:       cat is used to concatenate files and print them to the standard
//config:       output. Enable this option if you wish to enable the 'cat' utility.
//config:
//config:config FEATURE_CATN
//config:       bool "Enable -n and -b options"
//config:       default y
//config:       depends on CAT
//config:       help
//config:       -n numbers all output lines while -b numbers nonempty output lines.
//config:
//config:config FEATURE_CATV
//config:       bool "cat -v[etA]"
//config:       default y
//config:       depends on CAT
//config:       help
//config:       Display nonprinting characters as escape sequences

//applet:IF_CAT(APPLET(cat, BB_DIR_BIN, BB_SUID_DROP))

//kbuild:lib-$(CONFIG_CAT) += cat.o

/* BB_AUDIT SUSv3 compliant */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/cat.html */

//usage:#if ENABLE_FEATURE_CATN || ENABLE_FEATURE_CATV
//usage:#define cat_trivial_usage
//usage:       "[-" IF_FEATURE_CATN("nb") IF_FEATURE_CATV("vteA") "] [FILE]..."
//usage:#else
//usage:#define cat_trivial_usage
//usage:       "[FILE]..."
//usage:#endif
//usage:#define cat_full_usage "\n\n"
//usage:       "Print FILEs to stdout\n"
//usage:        IF_FEATURE_CATN(
//usage:     "\n        -n      Number output lines"
//usage:     "\n        -b      Number nonempty lines"
//usage:        )
//usage:        IF_FEATURE_CATV(
//usage:     "\n        -v      Show nonprinting characters as ^x or M-x"
//usage:     "\n        -t      ...and tabs as ^I"
//usage:     "\n        -e      ...and end lines with $"
//usage:     "\n        -A      Same as -vte"
//usage:        )
/*
  Longopts not implemented yet:
      --number-nonblank    number nonempty output lines, overrides -n
      --number             number all output lines
      --show-nonprinting   use ^ and M- notation, except for LFD and TAB
      --show-all           equivalent to -vet
  Not implemented yet:
  -E, --show-ends          display $ at end of each line (-e sans -v)
  -T, --show-tabs          display TAB characters as ^I (-t sans -v)
  -s, --squeeze-blank      suppress repeated empty output lines
*/
//usage:
//usage:#define cat_example_usage
//usage:       "$ cat /proc/uptime\n"
//usage:       "110716.72 17.67"

#include "libbb.h"
#include "common_bufsiz.h"

#if ENABLE_FEATURE_CATV
/*
 * cat -v implementation for busybox
 *
 * Copyright (C) 2006 Rob Landley <rob@landley.net>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
/* Rob had "cat -v" implemented as a separate applet, catv.
 * See "cat -v considered harmful" at
 * http://cm.bell-labs.com/cm/cs/doc/84/kp.ps.gz
 * From USENIX Summer Conference Proceedings, 1983
 * """
 * The talk reviews reasons for UNIX's popularity and shows, using UCB cat
 * as a primary example, how UNIX has grown fat. cat isn't for printing
 * files with line numbers, it isn't for compressing multiple blank lines,
 * it's not for looking at non-printing ASCII characters, it's for
 * concatenating files.
 * We are reminded that ls isn't the place for code to break a single column
 * into multiple ones, and that mailnews shouldn't have its own more
 * processing or joke encryption code.
 * """
 *
 * I agree with the argument. Unfortunately, this ship has sailed (1983...).
 * There are dozens of Linux distros and each of them has "cat" which supports -v.
 * It's unrealistic for us to "reeducate" them to use our, incompatible way
 * to achieve "cat -v" effect. The actual effect would be "users pissed off
 * by gratuitous incompatibility".
 */
#define CAT_OPT_e (1<<0)
#define CAT_OPT_t (1<<1)
#define CAT_OPT_v (1<<2)
/* -A occupies bit (1<<3) */
#define CAT_OPT_n ((1<<4) * ENABLE_FEATURE_CATN)
#define CAT_OPT_b ((1<<5) * ENABLE_FEATURE_CATN)
static int catv(unsigned opts, char **argv)
{
        int retval = EXIT_SUCCESS;
        int fd;
#if ENABLE_FEATURE_CATN
        bool eol_seen = (opts & (CAT_OPT_n|CAT_OPT_b));
        unsigned eol_char = (eol_seen ? '\n' : 0x100);
        unsigned skip_num_on = (opts & CAT_OPT_b) ? '\n' : 0x100;
        unsigned lineno = 0;
#endif

        BUILD_BUG_ON(CAT_OPT_e != VISIBLE_ENDLINE);
        BUILD_BUG_ON(CAT_OPT_t != VISIBLE_SHOW_TABS);
#if 0 /* These consts match, we can just pass "opts" to visible() */
        if (opts & CAT_OPT_e)
                flags |= VISIBLE_ENDLINE;
        if (opts & CAT_OPT_t)
                flags |= VISIBLE_SHOW_TABS;
#endif

#define read_buf bb_common_bufsiz1
        setup_common_bufsiz();
        do {
                fd = open_or_warn_stdin(*argv);
                if (fd < 0) {
                        retval = EXIT_FAILURE;
                        continue;
                }
                for (;;) {
                        int i, res;

                        res = read(fd, read_buf, COMMON_BUFSIZE);
                        if (res < 0)
                                retval = EXIT_FAILURE;
                        if (res <= 0)
                                break;
                        for (i = 0; i < res; i++) {
                                unsigned char c = read_buf[i];
                                char buf[sizeof("M-^c")];
#if ENABLE_FEATURE_CATN
                                if (eol_seen && c != skip_num_on)
                                        printf("%6u  ", ++lineno);
                                eol_seen = (c == eol_char);
#endif
                                visible(c, buf, opts);
                                fputs(buf, stdout);
                        }
                }
                if (ENABLE_FEATURE_CLEAN_UP && fd)
                        close(fd);
        } while (*++argv);

        fflush_stdout_and_exit(retval);
}
#undef CAT_OPT_n
#undef CAT_OPT_b
#endif

int cat_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int cat_main(int argc UNUSED_PARAM, char **argv)
{
#if ENABLE_FEATURE_CATV || ENABLE_FEATURE_CATN
        unsigned opts;

        opts =
#endif
        getopt32(argv, IF_FEATURE_CATV("^")
                /* -u is ignored ("unbuffered") */
                IF_FEATURE_CATV("etvA")IF_FEATURE_CATN("nb")"u"
                IF_FEATURE_CATV("\0" "Aetv" /* -A == -vet */)
        );
        argv += optind;

        /* Read from stdin if there's nothing else to do. */
        if (!argv[0])
                *--argv = (char*)"-";

#if ENABLE_FEATURE_CATV
        if (opts & 7)
                return catv(opts, argv);
        opts >>= 4;
#endif

#if ENABLE_FEATURE_CATN
# define CAT_OPT_n (1<<0)
# define CAT_OPT_b (1<<1)
        if (opts & (CAT_OPT_n|CAT_OPT_b)) { /* -n or -b */
                struct number_state ns;
                int exitcode;

                ns.width = 6;
                ns.start = 1;
                ns.inc = 1;
                ns.sep = "\t";
                ns.empty_str = "\n";
                ns.all = !(opts & CAT_OPT_b); /* -n without -b */
                ns.nonempty = (opts & CAT_OPT_b); /* -b (with or without -n) */
                exitcode = EXIT_SUCCESS;
                do {
                        exitcode |= print_numbered_lines(&ns, *argv);
                } while (*++argv);
                fflush_stdout_and_exit(exitcode);
        }
        /*opts >>= 2;*/
#endif

        return bb_cat(argv);
}