source: MondoRescue/branches/stable/mindi-busybox/findutils/xargs.c@ 1770

/* vi: set sw=4 ts=4: */
/*
 * Mini xargs implementation for busybox
 * Options are supported: "-prtx -n max_arg -s max_chars -e[ouf_str]"
 *
 * (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 the GPL v2 or later, see the file LICENSE in this tarball.
 *
 * xargs is described in the Single Unix Specification v3 at
 * http://www.opengroup.org/onlinepubs/007904975/utilities/xargs.html
 *
 */

#include "libbb.h"

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


/* COMPAT:  SYSV version defaults size (and has a max value of) to 470.
   We try to make it as large as possible. */
#if !defined(ARG_MAX) && defined(_SC_ARG_MAX)
#define ARG_MAX sysconf (_SC_ARG_MAX)
#endif
#ifndef ARG_MAX
#define ARG_MAX 470
#endif


#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

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

    status = spawn_and_wait(args);
    if (status < 0) {
        bb_perror_msg("%s", args[0]);
        return errno == ENOENT ? 127 : 126;
    }
    if (status == 255) {
        bb_error_msg("%s: exited with status 255; aborting", args[0]);
        return 124;
    }
/* Huh? I think we won't see this, ever. We don't wait with WUNTRACED!
    if (WIFSTOPPED(status)) {
        bb_error_msg("%s: stopped by signal %d",
            args[0], WSTOPSIG(status));
        return 125;
    }
*/
    if (status >= 1000) {
        bb_error_msg("%s: terminated by signal %d",
            args[0], status - 1000);
        return 125;
    }
    if (status)
        return 123;
    return 0;
}


typedef struct xlist_t {
    struct xlist_t *link;
    size_t length;
    char xstr[1];
} xlist_t;

static smallint eof_stdin_detected;

#define ISBLANK(c) ((c) == ' ' || (c) == '\t')
#define ISSPACE(c) (ISBLANK(c) || (c) == '\n' || (c) == '\r' \
            || (c) == '\f' || (c) == '\v')

#if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
static xlist_t *process_stdin(xlist_t *list_arg,
    const char *eof_str, size_t mc, char *buf)
{
#define NORM      0
#define QUOTE     1
#define BACKSLASH 2
#define SPACE     4

    char *s = NULL;         /* start word */
    char *p = NULL;         /* pointer to end word */
    char q = '\0';          /* quote char */
    char state = NORM;
    char eof_str_detected = 0;
    size_t line_l = 0;      /* size loaded args line */
    int c;                  /* current char */
    xlist_t *cur;
    xlist_t *prev;

    prev = cur = list_arg;
    while (1) {
        if (!cur) break;
        prev = cur;
        line_l += cur->length;
        cur = cur->link;
    }

    while (!eof_stdin_detected) {
        c = getchar();
        if (c == EOF) {
            eof_stdin_detected = 1;
            if (s)
                goto unexpected_eof;
            break;
        }
        if (eof_str_detected)
            continue;
        if (state == BACKSLASH) {
            state = NORM;
            goto set;
        } else if (state == QUOTE) {
            if (c != q)
                goto set;
            q = '\0';
            state = NORM;
        } else { /* if (state == NORM) */
            if (ISSPACE(c)) {
                if (s) {
 unexpected_eof:
                    state = SPACE;
                    c = '\0';
                    goto set;
                }
            } else {
                if (s == NULL)
                    s = p = buf;
                if (c == '\\') {
                    state = BACKSLASH;
                } else if (c == '\'' || c == '"') {
                    q = c;
                    state = QUOTE;
                } else {
 set:
                    if ((size_t)(p - buf) >= mc)
                        bb_error_msg_and_die("argument line too long");
                    *p++ = c;
                }
            }
        }
        if (state == SPACE) {   /* word's delimiter or EOF detected */
            if (q) {
                bb_error_msg_and_die("unmatched %s quote",
                    q == '\'' ? "single" : "double");
            }
            /* word loaded */
            if (eof_str) {
                eof_str_detected = (strcmp(s, eof_str) == 0);
            }
            if (!eof_str_detected) {
                size_t length = (p - buf);
                /* Dont xzalloc - it can be quite big */
                cur = xmalloc(offsetof(xlist_t, xstr) + length);
                cur->link = NULL;
                cur->length = length;
                memcpy(cur->xstr, s, length);
                if (prev == NULL) {
                    list_arg = cur;
                } else {
                    prev->link = cur;
                }
                prev = cur;
                line_l += length;
                if (line_l > mc) {
                    /* stop memory usage :-) */
                    break;
                }
            }
            s = NULL;
            state = NORM;
        }
    }
    return list_arg;
}
#else
/* The variant does not support single quotes, double quotes or backslash */
static xlist_t *process_stdin(xlist_t *list_arg,
        const char *eof_str, size_t mc, char *buf)
{

    int c;                  /* current char */
    char eof_str_detected = 0;
    char *s = NULL;         /* start word */
    char *p = NULL;         /* pointer to end word */
    size_t line_l = 0;      /* size loaded args line */
    xlist_t *cur;
    xlist_t *prev;

    prev = cur = list_arg;
    while (1) {
        if (!cur) break;
        prev = cur;
        line_l += cur->length;
        cur = cur->link;
    }

    while (!eof_stdin_detected) {
        c = getchar();
        if (c == EOF) {
            eof_stdin_detected = 1;
        }
        if (eof_str_detected)
            continue;
        if (c == EOF || ISSPACE(c)) {
            if (s == NULL)
                continue;
            c = EOF;
        }
        if (s == NULL)
            s = p = buf;
        if ((p - buf) >= mc)
            bb_error_msg_and_die("argument line too long");
        *p++ = (c == EOF ? '\0' : c);
        if (c == EOF) { /* word's delimiter or EOF detected */
            /* word loaded */
            if (eof_str) {
                eof_str_detected = (strcmp(s, eof_str) == 0);
            }
            if (!eof_str_detected) {
                size_t length = (p - buf);
                /* Dont xzalloc - it can be quite big */
                cur = xmalloc(offsetof(xlist_t, xstr) + length);
                cur->link = NULL;
                cur->length = length;
                memcpy(cur->xstr, s, length);
                if (prev == NULL) {
                    list_arg = cur;
                } else {
                    prev->link = cur;
                }
                prev = cur;
                line_l += length;
                if (line_l > mc) {
                    /* stop memory usage :-) */
                    break;
                }
                s = NULL;
            }
        }
    }
    return list_arg;
}
#endif /* FEATURE_XARGS_SUPPORT_QUOTES */


#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(CURRENT_TTY, "r");
    fputs(" ?...", stderr);
    fflush(stderr);
    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 /* FEATURE_XARGS_SUPPORT_CONFIRMATION */

#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
static xlist_t *process0_stdin(xlist_t *list_arg,
        const char *eof_str ATTRIBUTE_UNUSED, size_t mc, char *buf)
{
    int c;                  /* current char */
    char *s = NULL;         /* start word */
    char *p = NULL;         /* pointer to end word */
    size_t line_l = 0;      /* size loaded args line */
    xlist_t *cur;
    xlist_t *prev;

    prev = cur = list_arg;
    while (1) {
        if (!cur) break;
        prev = cur;
        line_l += cur->length;
        cur = cur->link;
    }

    while (!eof_stdin_detected) {
        c = getchar();
        if (c == EOF) {
            eof_stdin_detected = 1;
            if (s == NULL)
                break;
            c = '\0';
        }
        if (s == NULL)
            s = p = buf;
        if ((size_t)(p - buf) >= mc)
            bb_error_msg_and_die("argument line too long");
        *p++ = c;
        if (c == '\0') {   /* word's delimiter or EOF detected */
            /* word loaded */
            size_t length = (p - buf);
            /* Dont xzalloc - it can be quite big */
            cur = xmalloc(offsetof(xlist_t, xstr) + length);
            cur->link = NULL;
            cur->length = length;
            memcpy(cur->xstr, s, length);
            if (prev == NULL) {
                list_arg = cur;
            } else {
                prev->link = cur;
            }
            prev = cur;
            line_l += length;
            if (line_l > mc) {
                /* stop memory usage :-) */
                break;
            }
            s = NULL;
        }
    }
    return list_arg;
}
#endif /* FEATURE_XARGS_SUPPORT_ZERO_TERM */

/* Correct regardless of combination of CONFIG_xxx */
enum {
    OPTBIT_VERBOSE = 0,
    OPTBIT_NO_EMPTY,
    OPTBIT_UPTO_NUMBER,
    OPTBIT_UPTO_SIZE,
    OPTBIT_EOF_STRING,
    USE_FEATURE_XARGS_SUPPORT_CONFIRMATION(OPTBIT_INTERACTIVE,)
    USE_FEATURE_XARGS_SUPPORT_TERMOPT(     OPTBIT_TERMINATE  ,)
    USE_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 ,
    OPT_INTERACTIVE = USE_FEATURE_XARGS_SUPPORT_CONFIRMATION((1<<OPTBIT_INTERACTIVE)) + 0,
    OPT_TERMINATE   = USE_FEATURE_XARGS_SUPPORT_TERMOPT(     (1<<OPTBIT_TERMINATE  )) + 0,
    OPT_ZEROTERM    = USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   (1<<OPTBIT_ZEROTERM   )) + 0,
};
#define OPTION_STR "+trn:s:e::" \
    USE_FEATURE_XARGS_SUPPORT_CONFIRMATION("p") \
    USE_FEATURE_XARGS_SUPPORT_TERMOPT(     "x") \
    USE_FEATURE_XARGS_SUPPORT_ZERO_TERM(   "0")

int xargs_main(int argc, char **argv);
int xargs_main(int argc, char **argv)
{
    char **args;
    int i, n;
    xlist_t *list = NULL;
    xlist_t *cur;
    int child_error = 0;
    char *max_args, *max_chars;
    int n_max_arg;
    size_t n_chars = 0;
    long orig_arg_max;
    const char *eof_str = "_";
    unsigned opt;
    size_t n_max_chars;
#if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
    xlist_t* (*read_args)(xlist_t*, const char*, size_t, char*) = process_stdin;
#else
#define read_args process_stdin
#endif

    opt = getopt32(argv, OPTION_STR, &max_args, &max_chars, &eof_str);

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

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

    orig_arg_max = ARG_MAX;
    if (orig_arg_max == -1)
        orig_arg_max = LONG_MAX;
    orig_arg_max -= 2048;   /* POSIX.2 requires subtracting 2048 */

    if (opt & OPT_UPTO_SIZE) {
        n_max_chars = xatoul_range(max_chars, 1, orig_arg_max);
        for (i = 0; i < argc; i++) {
            n_chars += strlen(*argv) + 1;
        }
        if (n_max_chars < n_chars) {
            bb_error_msg_and_die("cannot fit single argument within argument list size limit");
        }
        n_max_chars -= n_chars;
    } else {
        /* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which
           have it at 1 meg).  Things will work fine with a large ARG_MAX but it
           will probably hurt the system more than it needs to; an array of this
           size is allocated.  */
        if (orig_arg_max > 20 * 1024)
            orig_arg_max = 20 * 1024;
        n_max_chars = orig_arg_max;
    }
    max_chars = xmalloc(n_max_chars);

    if (opt & OPT_UPTO_NUMBER) {
        n_max_arg = xatoul_range(max_args, 1, INT_MAX);
    } else {
        n_max_arg = n_max_chars;
    }

    while ((list = read_args(list, eof_str, n_max_chars, max_chars)) != NULL ||
        !(opt & OPT_NO_EMPTY))
    {
        opt |= OPT_NO_EMPTY;
        n = 0;
        n_chars = 0;
#if ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
        for (cur = list; cur;) {
            n_chars += cur->length;
            n++;
            cur = cur->link;
            if (n_chars > n_max_chars || (n == n_max_arg && cur)) {
                if (opt & OPT_TERMINATE)
                    bb_error_msg_and_die("argument list too long");
                break;
            }
        }
#else
        for (cur = list; cur; cur = cur->link) {
            n_chars += cur->length;
            n++;
            if (n_chars > n_max_chars || n == n_max_arg) {
                break;
            }
        }
#endif /* FEATURE_XARGS_SUPPORT_TERMOPT */

        /* allocate pointers for execvp:
           argc*arg, n*arg from stdin, NULL */
        args = xzalloc((n + argc + 1) * sizeof(char *));

        /* store the command to be executed
           (taken from the command line) */
        for (i = 0; i < argc; i++)
            args[i] = argv[i];
        /* (taken from stdin) */
        for (cur = list; n; cur = cur->link) {
            args[i++] = cur->xstr;
            n--;
        }

        if (opt & (OPT_INTERACTIVE | OPT_VERBOSE)) {
            for (i = 0; args[i]; i++) {
                if (i)
                    fputc(' ', stderr);
                fputs(args[i], stderr);
            }
            if (!(opt & OPT_INTERACTIVE))
                fputc('\n', stderr);
        }
        if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
            child_error = xargs_exec(args);
        }

        /* clean up */
        for (i = argc; args[i]; i++) {
            cur = list;
            list = list->link;
            free(cur);
        }
        free(args);
        if (child_error > 0 && child_error != 123) {
            break;
        }
    }
    if (ENABLE_FEATURE_CLEAN_UP)
        free(max_chars);
    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(1);
}

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