source: MondoRescue/branches/3.2/mindi-busybox/findutils/xargs.c@ 3232

/* vi: set sw=4 ts=4: */
/*
 * Mini xargs implementation for busybox
 *
 * (C) 2002,2003 by Vladimir Oleynik <dzo@simtreas.ru>
 *
 * Special thanks
 * - Mark Whitley and Glenn McGrath for stimulus to rewrite :)
 * - Mike Rendell <michael@cs.mun.ca>
 * and David MacKenzie <djm@gnu.ai.mit.edu>.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 *
 * xargs is described in the Single Unix Specification v3 at
 * http://www.opengroup.org/onlinepubs/007904975/utilities/xargs.html
 */

//config:config XARGS
//config:   bool "xargs"
//config:   default y
//config:   help
//config:     xargs is used to execute a specified command for
//config:     every item from standard input.
//config:
//config:config FEATURE_XARGS_SUPPORT_CONFIRMATION
//config:   bool "Enable -p: prompt and confirmation"
//config:   default y
//config:   depends on XARGS
//config:   help
//config:     Support -p: prompt the user whether to run each command
//config:     line and read a line from the terminal.
//config:
//config:config FEATURE_XARGS_SUPPORT_QUOTES
//config:   bool "Enable single and double quotes and backslash"
//config:   default y
//config:   depends on XARGS
//config:   help
//config:     Support quoting in the input.
//config:
//config:config FEATURE_XARGS_SUPPORT_TERMOPT
//config:   bool "Enable -x: exit if -s or -n is exceeded"
//config:   default y
//config:   depends on XARGS
//config:   help
//config:     Support -x: exit if the command size (see the -s or -n option)
//config:     is exceeded.
//config:
//config:config FEATURE_XARGS_SUPPORT_ZERO_TERM
//config:   bool "Enable -0: NUL-terminated input"
//config:   default y
//config:   depends on XARGS
//config:   help
//config:     Support -0: input items are terminated by a NUL character
//config:     instead of whitespace, and the quotes and backslash
//config:     are not special.

//applet:IF_XARGS(APPLET_NOEXEC(xargs, xargs, BB_DIR_USR_BIN, BB_SUID_DROP, xargs))

//kbuild:lib-$(CONFIG_XARGS) += xargs.o

#include "libbb.h"

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


//#define dbg_msg(...) bb_error_msg(__VA_ARGS__)
#define dbg_msg(...) ((void)0)


#ifdef TEST
# ifndef ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
#  define ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION 1
# endif
# ifndef ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
#  define ENABLE_FEATURE_XARGS_SUPPORT_QUOTES 1
# endif
# ifndef ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
#  define ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT 1
# endif
# ifndef ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
#  define ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM 1
# endif
#endif


struct globals {
    char **args;
    const char *eof_str;
    int idx;
} FIX_ALIASING;
#define G (*(struct globals*)&bb_common_bufsiz1)
#define INIT_G() do { \
    G.eof_str = NULL; /* need to clear by hand because we are NOEXEC applet */ \
} while (0)


/*
 * This function has special algorithm.
 * Don't use fork and include to main!
 */
static int xargs_exec(void)
{
    int status;

    status = spawn_and_wait(G.args);
    if (status < 0) {
        bb_simple_perror_msg(G.args[0]);
        return errno == ENOENT ? 127 : 126;
    }
    if (status == 255) {
        bb_error_msg("%s: exited with status 255; aborting", G.args[0]);
        return 124;
    }
    if (status >= 0x180) {
        bb_error_msg("%s: terminated by signal %d",
            G.args[0], status - 0x180);
        return 125;
    }
    if (status)
        return 123;
    return 0;
}

/* In POSIX/C locale isspace is only these chars: "\t\n\v\f\r" and space.
 * "\t\n\v\f\r" happen to have ASCII codes 9,10,11,12,13.
 */
#define ISSPACE(a) ({ unsigned char xargs__isspace = (a) - 9; xargs__isspace == (' ' - 9) || xargs__isspace <= (13 - 9); })

static void store_param(char *s)
{
    /* Grow by 256 elements at once */
    if (!(G.idx & 0xff)) { /* G.idx == N*256 */
        /* Enlarge, make G.args[(N+1)*256 - 1] last valid idx */
        G.args = xrealloc(G.args, sizeof(G.args[0]) * (G.idx + 0x100));
    }
    G.args[G.idx++] = s;
}

/* process[0]_stdin:
 * Read characters into buf[n_max_chars+1], and when parameter delimiter
 * is seen, store the address of a new parameter to args[].
 * If reading discovers that last chars do not form the complete
 * parameter, the pointer to the first such "tail character" is returned.
 * (buf has extra byte at the end to accomodate terminating NUL
 * of "tail characters" string).
 * Otherwise, the returned pointer points to NUL byte.
 * On entry, buf[] may contain some "seed chars" which are to become
 * the beginning of the first parameter.
 */

#if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
static char* FAST_FUNC process_stdin(int n_max_chars, int n_max_arg, char *buf)
{
#define NORM      0
#define QUOTE     1
#define BACKSLASH 2
#define SPACE     4
    char q = '\0';             /* quote char */
    char state = NORM;
    char *s = buf;             /* start of the word */
    char *p = s + strlen(buf); /* end of the word */

    buf += n_max_chars;        /* past buffer's end */

    /* "goto ret" is used instead of "break" to make control flow
     * more obvious: */

    while (1) {
        int c = getchar();
        if (c == EOF) {
            if (p != s)
                goto close_word;
            goto ret;
        }
        if (state == BACKSLASH) {
            state = NORM;
            goto set;
        }
        if (state == QUOTE) {
            if (c != q)
                goto set;
            q = '\0';
            state = NORM;
        } else { /* if (state == NORM) */
            if (ISSPACE(c)) {
                if (p != s) {
 close_word:
                    state = SPACE;
                    c = '\0';
                    goto set;
                }
            } else {
                if (c == '\\') {
                    state = BACKSLASH;
                } else if (c == '\'' || c == '"') {
                    q = c;
                    state = QUOTE;
                } else {
 set:
                    *p++ = c;
                }
            }
        }
        if (state == SPACE) {   /* word's delimiter or EOF detected */
            if (q) {
                bb_error_msg_and_die("unmatched %s quote",
                    q == '\'' ? "single" : "double");
            }
            /* A full word is loaded */
            if (G.eof_str) {
                if (strcmp(s, G.eof_str) == 0) {
                    while (getchar() != EOF)
                        continue;
                    p = s;
                    goto ret;
                }
            }
            store_param(s);
            dbg_msg("args[]:'%s'", s);
            s = p;
            n_max_arg--;
            if (n_max_arg == 0) {
                goto ret;
            }
            state = NORM;
        }
        if (p == buf) {
            goto ret;
        }
    }
 ret:
    *p = '\0';
    /* store_param(NULL) - caller will do it */
    dbg_msg("return:'%s'", s);
    return s;
}
#else
/* The variant does not support single quotes, double quotes or backslash */
static char* FAST_FUNC process_stdin(int n_max_chars, int n_max_arg, char *buf)
{
    char *s = buf;             /* start of the word */
    char *p = s + strlen(buf); /* end of the word */

    buf += n_max_chars;        /* past buffer's end */

    while (1) {
        int c = getchar();
        if (c == EOF) {
            if (p == s)
                goto ret;
        }
        if (c == EOF || ISSPACE(c)) {
            if (p == s)
                continue;
            c = EOF;
        }
        *p++ = (c == EOF ? '\0' : c);
        if (c == EOF) { /* word's delimiter or EOF detected */
            /* A full word is loaded */
            if (G.eof_str) {
                if (strcmp(s, G.eof_str) == 0) {
                    while (getchar() != EOF)
                        continue;
                    p = s;
                    goto ret;
                }
            }
            store_param(s);
            dbg_msg("args[]:'%s'", s);
            s = p;
            n_max_arg--;
            if (n_max_arg == 0) {
                goto ret;
            }
        }
        if (p == buf) {
            goto ret;
        }
    }
 ret:
    *p = '\0';
    /* store_param(NULL) - caller will do it */
    dbg_msg("return:'%s'", s);
    return s;
}
#endif /* FEATURE_XARGS_SUPPORT_QUOTES */

#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
static char* FAST_FUNC process0_stdin(int n_max_chars, int n_max_arg, char *buf)
{
    char *s = buf;             /* start of the word */
    char *p = s + strlen(buf); /* end of the word */

    buf += n_max_chars;        /* past buffer's end */

    while (1) {
        int c = getchar();
        if (c == EOF) {
            if (p == s)
                goto ret;
            c = '\0';
        }
        *p++ = c;
        if (c == '\0') {   /* word's delimiter or EOF detected */
            /* A full word is loaded */
            store_param(s);
            dbg_msg("args[]:'%s'", s);
            s = p;
            n_max_arg--;
            if (n_max_arg == 0) {
                goto ret;
            }
        }
        if (p == buf) {
            goto ret;
        }
    }
 ret:
    *p = '\0';
    /* store_param(NULL) - caller will do it */
    dbg_msg("return:'%s'", s);
    return s;
}
#endif /* FEATURE_XARGS_SUPPORT_ZERO_TERM */

#if ENABLE_FEATURE_XARGS_SUPPORT_CONFIRMATION
/* Prompt the user for a response, and
   if the user responds affirmatively, return true;
   otherwise, return false. Uses "/dev/tty", not stdin. */
static int xargs_ask_confirmation(void)
{
    FILE *tty_stream;
    int c, savec;

    tty_stream = xfopen_for_read(CURRENT_TTY);
    fputs(" ?...", stderr);
    fflush_all();
    c = savec = getc(tty_stream);
    while (c != EOF && c != '\n')
        c = getc(tty_stream);
    fclose(tty_stream);
    return (savec == 'y' || savec == 'Y');
}
#else
# define xargs_ask_confirmation() 1
#endif

//usage:#define xargs_trivial_usage
//usage:       "[OPTIONS] [PROG ARGS]"
//usage:#define xargs_full_usage "\n\n"
//usage:       "Run PROG on every item given by stdin\n"
//usage:    IF_FEATURE_XARGS_SUPPORT_CONFIRMATION(
//usage:     "\n    -p  Ask user whether to run each command"
//usage:    )
//usage:     "\n    -r  Don't run command if input is empty"
//usage:    IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(
//usage:     "\n    -0  Input is separated by NUL characters"
//usage:    )
//usage:     "\n    -t  Print the command on stderr before execution"
//usage:     "\n    -e[STR] STR stops input processing"
//usage:     "\n    -n N    Pass no more than N args to PROG"
//usage:     "\n    -s N    Pass command line of no more than N bytes"
//usage:    IF_FEATURE_XARGS_SUPPORT_TERMOPT(
//usage:     "\n    -x  Exit if size is exceeded"
//usage:    )
//usage:#define xargs_example_usage
//usage:       "$ ls | xargs gzip\n"
//usage:       "$ find . -name '*.c' -print | xargs rm\n"

/* Correct regardless of combination of CONFIG_xxx */
enum {
    OPTBIT_VERBOSE = 0,
    OPTBIT_NO_EMPTY,
    OPTBIT_UPTO_NUMBER,
    OPTBIT_UPTO_SIZE,
    OPTBIT_EOF_STRING,
    OPTBIT_EOF_STRING1,
    IF_FEATURE_XARGS_SUPPORT_CONFIRMATION(OPTBIT_INTERACTIVE,)
    IF_FEATURE_XARGS_SUPPORT_TERMOPT(     OPTBIT_TERMINATE  ,)
    IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(   OPTBIT_ZEROTERM   ,)

    OPT_VERBOSE     = 1 << OPTBIT_VERBOSE    ,
    OPT_NO_EMPTY    = 1 << OPTBIT_NO_EMPTY   ,
    OPT_UPTO_NUMBER = 1 << OPTBIT_UPTO_NUMBER,
    OPT_UPTO_SIZE   = 1 << OPTBIT_UPTO_SIZE  ,
    OPT_EOF_STRING  = 1 << OPTBIT_EOF_STRING , /* GNU: -e[<param>] */
    OPT_EOF_STRING1 = 1 << OPTBIT_EOF_STRING1, /* SUS: -E<param> */
    OPT_INTERACTIVE = IF_FEATURE_XARGS_SUPPORT_CONFIRMATION((1 << OPTBIT_INTERACTIVE)) + 0,
    OPT_TERMINATE   = IF_FEATURE_XARGS_SUPPORT_TERMOPT(     (1 << OPTBIT_TERMINATE  )) + 0,
    OPT_ZEROTERM    = IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(   (1 << OPTBIT_ZEROTERM   )) + 0,
};
#define OPTION_STR "+trn:s:e::E:" \
    IF_FEATURE_XARGS_SUPPORT_CONFIRMATION("p") \
    IF_FEATURE_XARGS_SUPPORT_TERMOPT(     "x") \
    IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(   "0")

int xargs_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int xargs_main(int argc, char **argv)
{
    int i;
    int child_error = 0;
    char *max_args;
    char *max_chars;
    char *buf;
    unsigned opt;
    int n_max_chars;
    int n_max_arg;
#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
    char* FAST_FUNC (*read_args)(int, int, char*) = process_stdin;
#else
#define read_args process_stdin
#endif

    INIT_G();

#if ENABLE_DESKTOP && ENABLE_LONG_OPTS
    /* For example, Fedora's build system uses --no-run-if-empty */
    applet_long_options =
        "no-run-if-empty\0" No_argument "r"
        ;
#endif
    opt = getopt32(argv, OPTION_STR, &max_args, &max_chars, &G.eof_str, &G.eof_str);

    /* -E ""? You may wonder why not just omit -E?
     * This is used for portability:
     * old xargs was using "_" as default for -E / -e */
    if ((opt & OPT_EOF_STRING1) && G.eof_str[0] == '\0')
        G.eof_str = NULL;

    if (opt & OPT_ZEROTERM)
        IF_FEATURE_XARGS_SUPPORT_ZERO_TERM(read_args = process0_stdin);

    argv += optind;
    argc -= optind;
    if (!argv[0]) {
        /* default behavior is to echo all the filenames */
        *--argv = (char*)"echo";
        argc++;
    }

    /* -s NUM default. fileutils-4.4.2 uses 128k, but I heasitate
     * to use such a big value - first need to change code to use
     * growable buffer instead of fixed one.
     */
    n_max_chars = 32 * 1024;
    /* Make smaller if system does not allow our default value.
     * The Open Group Base Specifications Issue 6:
     * "The xargs utility shall limit the command line length such that
     * when the command line is invoked, the combined argument
     * and environment lists (see the exec family of functions
     * in the System Interfaces volume of IEEE Std 1003.1-2001)
     * shall not exceed {ARG_MAX}-2048 bytes".
     */
    {
        long arg_max = 0;
#if defined _SC_ARG_MAX
        arg_max = sysconf(_SC_ARG_MAX) - 2048;
#elif defined ARG_MAX
        arg_max = ARG_MAX - 2048;
#endif
        if (arg_max > 0 && n_max_chars > arg_max)
            n_max_chars = arg_max;
    }
    if (opt & OPT_UPTO_SIZE) {
        n_max_chars = xatou_range(max_chars, 1, INT_MAX);
    }
    /* Account for prepended fixed arguments */
    {
        size_t n_chars = 0;
        for (i = 0; argv[i]; i++) {
            n_chars += strlen(argv[i]) + 1;
        }
        n_max_chars -= n_chars;
    }
    /* Sanity check */
    if (n_max_chars <= 0) {
        bb_error_msg_and_die("can't fit single argument within argument list size limit");
    }

    buf = xzalloc(n_max_chars + 1);

    n_max_arg = n_max_chars;
    if (opt & OPT_UPTO_NUMBER) {
        n_max_arg = xatou_range(max_args, 1, INT_MAX);
        /* Not necessary, we use growable args[]: */
        /* if (n_max_arg > n_max_chars) n_max_arg = n_max_chars */
    }

    /* Allocate pointers for execvp */
    /* We can statically allocate (argc + n_max_arg + 1) elements
     * and do not bother with resizing args[], but on 64-bit machines
     * this results in args[] vector which is ~8 times bigger
     * than n_max_chars! That is, with n_max_chars == 20k,
     * args[] will take 160k (!), which will most likely be
     * almost entirely unused.
     */
    /* See store_param() for matching 256-step growth logic */
    G.args = xmalloc(sizeof(G.args[0]) * ((argc + 0xff) & ~0xff));

    /* Store the command to be executed, part 1 */
    for (i = 0; argv[i]; i++)
        G.args[i] = argv[i];

    while (1) {
        char *rem;

        G.idx = argc;
        rem = read_args(n_max_chars, n_max_arg, buf);
        store_param(NULL);

        if (!G.args[argc]) {
            if (*rem != '\0')
                bb_error_msg_and_die("argument line too long");
            if (opt & OPT_NO_EMPTY)
                break;
        }
        opt |= OPT_NO_EMPTY;

        if (opt & (OPT_INTERACTIVE | OPT_VERBOSE)) {
            const char *fmt = " %s" + 1;
            char **args = G.args;
            for (i = 0; args[i]; i++) {
                fprintf(stderr, fmt, args[i]);
                fmt = " %s";
            }
            if (!(opt & OPT_INTERACTIVE))
                bb_putchar_stderr('\n');
        }

        if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
            child_error = xargs_exec();
        }

        if (child_error > 0 && child_error != 123) {
            break;
        }

        overlapping_strcpy(buf, rem);
    } /* while */

    if (ENABLE_FEATURE_CLEAN_UP) {
        free(G.args);
        free(buf);
    }

    return child_error;
}


#ifdef TEST

const char *applet_name = "debug stuff usage";

void bb_show_usage(void)
{
    fprintf(stderr, "Usage: %s [-p] [-r] [-t] -[x] [-n max_arg] [-s max_chars]\n",
        applet_name);
    exit(EXIT_FAILURE);
}

int main(int argc, char **argv)
{
    return xargs_main(argc, argv);
}
#endif /* TEST */