xen/tools/xs-clients/xenstore_client.c

/*
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file "COPYING" in the main directory of
 * this archive for more details.
 *
 * Copyright (C) 2005 by Christian Limpach
 * Copyright (C) 2005 XenSource Ltd.
 *
 */

#include <assert.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <xenstore.h>

#include <sys/ioctl.h>

#include <xen-tools/xenstore-common.h>

#define PATH_SEP '/'
#define MAX_PATH_LEN 256


enum mode {
    MODE_unknown,
    MODE_chmod,
    MODE_exists,
    MODE_list,
    MODE_ls,
    MODE_read,
    MODE_rm,
    MODE_write,
    MODE_watch,
};

/* Sanitising (quoting) possibly-binary strings. */
struct expanding_buffer {
    char *buf;
    int avail;
};

static char *output_buf = NULL;
static int output_pos = 0;
static struct expanding_buffer ebuf;

static int output_size = 0;

/* Ensure that given expanding buffer has at least min_avail characters. */
static char *expanding_buffer_ensure(struct expanding_buffer *ebuf,
                                     int min_avail)
{
    int want;
    char *got;

    if ( ebuf->avail >= min_avail )
        return ebuf->buf;

    if ( min_avail >= INT_MAX/3 )
        return 0;

    want = ebuf->avail + min_avail + 10;
    got = realloc(ebuf->buf, want);
    if ( !got )
        return 0;

    ebuf->buf = got;
    ebuf->avail = want;
    return ebuf->buf;
}

/* sanitise_value() may return NULL if malloc fails. */
static char *sanitise_value(struct expanding_buffer *ebuf,
                            const char *val, unsigned len)
{
    int used, remain, c;
    unsigned char *ip;

#define ADD(c) (ebuf->buf[used++] = (c))
#define ADDF(f,c) (used += sprintf(ebuf->buf+used, (f), (c)))

    assert(len < INT_MAX/5);

    ip = (unsigned char *)val;
    used = 0;
    remain = len;

    if ( !expanding_buffer_ensure(ebuf, remain + 1) )
        return NULL;

    while ( remain-- > 0 )
    {
        c= *ip++;

        if ( c >= ' ' && c <= '~' && c != '\\' )
        {
            ADD(c);
            continue;
        }

        if ( !expanding_buffer_ensure(ebuf, used + remain + 5) )
            /* for "<used>\\nnn<remain>\0" */
            return 0;

        ADD('\\');
        switch (c)
        {
        case '\t':  ADD('t');   break;
        case '\n':  ADD('n');   break;
        case '\r':  ADD('r');   break;
        case '\\':  ADD('\\');  break;
        default:
            if ( c < 010 ) ADDF("%03o", c);
            else           ADDF("x%02x", c);
        }
    }

    ADD(0);
    assert(used <= ebuf->avail);
    return ebuf->buf;

#undef ADD
#undef ADDF
}

/* *out_len_r on entry is ignored; out must be at least strlen(in)+1 bytes. */
static void unsanitise_value(char *out, unsigned *out_len_r, const char *in)
{
    const char *ip;
    char *op;
    unsigned c;
    int n;

    for ( ip = in, op = out; (c = *ip++); *op++ = c )
    {
        if ( c == '\\' )
        {
            c = *ip++;

#define GETF(f) do                   \
{                                    \
     n = 0;                          \
     sscanf(ip, f "%n", &c, &n);     \
     ip += n;                        \
} while ( 0 )

            switch ( c )
            {
            case 't':           c= '\t';           break;
            case 'n':           c= '\n';           break;
            case 'r':           c= '\r';           break;
            case '\\':          c= '\\';           break;
            case 'x':           GETF("%2x");       break;
            case '0': case '4':
            case '1': case '5':
            case '2': case '6':
            case '3': case '7': --ip; GETF("%3o"); break;
            case 0:             --ip;              break;
            default:;
            }
#undef GETF
        }
    }

    *op = 0;

    if ( out_len_r )
        *out_len_r = op - out;
}

/* make sure there is at least 'len' more space in output_buf */
static void expand_buffer(size_t len)
{
    if (output_pos + len > output_size) {
        output_size += len + 1024;
        output_buf = realloc(output_buf, output_size);
        if (output_buf == NULL)
            err(1, "malloc");
    }
}

static void
output(const char *fmt, ...) {
    va_list ap;
    int len;
    char buf[1];

    va_start(ap, fmt);
    len = vsnprintf(buf, 1, fmt, ap);
    if (len < 0)
	err(1, "output");
    va_end(ap);
    expand_buffer(len + 1);
    va_start(ap, fmt);
    if (vsnprintf(&output_buf[output_pos], len + 1, fmt, ap) != len)
	err(1, "output");
    va_end(ap);
    output_pos += len;
}

static void
output_raw(const char *data, int len)
{
    expand_buffer(len);
    memcpy(&output_buf[output_pos], data, len);
    output_pos += len;
}

static void
usage(int err_val, enum mode mode, int incl_mode, const char *progname)
{
    const char *mstr = NULL;

    switch (mode) {
    case MODE_unknown:
	errx(err_val, "Usage: %s <mode> [-h] [...]", progname);
    case MODE_read:
	mstr = incl_mode ? "read " : "";
	errx(err_val, "Usage: %s %s[-h] [-p] [-R] key [...]", progname, mstr);
    case MODE_write:
	mstr = incl_mode ? "write " : "";
	errx(err_val, "Usage: %s %s[-h] [-R] key value [...]", progname, mstr);
    case MODE_rm:
	mstr = incl_mode ? "rm " : "";
	errx(err_val, "Usage: %s %s[-h] [-t] key [...]", progname, mstr);
    case MODE_exists:
	mstr = incl_mode ? "exists " : "";
	errx(err_val, "Usage: %s %s[-h] key", progname, mstr);
    case MODE_list:
	mstr = mstr ? : incl_mode ? "list " : "";
	errx(err_val, "Usage: %s %s[-h] [-p] key [...]", progname, mstr);
    case MODE_ls:
	mstr = mstr ? : incl_mode ? "ls " : "";
	errx(err_val, "Usage: %s %s[-h] [-f] [-p] [path]", progname, mstr);
    case MODE_chmod:
	mstr = incl_mode ? "chmod " : "";
	errx(err_val, "Usage: %s %s[-h] [-u] [-r] key <mode [modes...]>", progname, mstr);
    case MODE_watch:
	mstr = incl_mode ? "watch " : "";
	errx(err_val, "Usage: %s %s[-h] [-n NR] key", progname, mstr);
    }
}


static int
do_rm(char *path, struct xs_handle *xsh, xs_transaction_t xth)
{
    if (xs_rm(xsh, xth, path)) {
        return 0;
    }
    else {
        warnx("could not remove path %s", path);
        return 1;
    }
}

#define STRING_MAX XENSTORE_ABS_PATH_MAX+1024
static int max_width = 80;
static int desired_width = 60;
static int show_whole_path = 0;

#define TAG " = \"...\""
#define TAG_LEN strlen(TAG)

#define MIN(a, b) (((a) < (b))? (a) : (b))

static void do_ls(struct xs_handle *h, char *path, int cur_depth, int show_perms)
{
    char **e;
    char *newpath, *val;
    int newpath_len;
    int i;
    unsigned int num, len;

    e = xs_directory(h, XBT_NULL, path, &num);
    if (e == NULL) {
        if (cur_depth && errno == ENOENT) {
            /* If a node disappears while recursing, silently move on. */
            return;
        }

        err(1, "xs_directory (%s)", path);
    }

    newpath = malloc(STRING_MAX);
    if (!newpath)
      err(1, "malloc in do_ls");

    for (i = 0; i<num; i++) {
        char buf[MAX_STRLEN(unsigned int)+1];
        struct xs_permissions *perms;
        unsigned int nperms;
        int linewid;

        /* Compose fullpath */
        newpath_len = snprintf(newpath, STRING_MAX, "%s%s%s", path,
                path[strlen(path)-1] == '/' ? "" : "/", 
                e[i]);

        /* Print indent and path basename */
        linewid = 0;
        if (show_whole_path) {
            fputs(newpath, stdout);
        } else {
            for (; linewid<cur_depth; linewid++) {
                putchar(' ');
            }
            linewid += printf("%.*s",
                              (int) (max_width - TAG_LEN - linewid), e[i]);
        }

	/* Fetch value */
        if ( newpath_len < STRING_MAX ) {
            val = xs_read(h, XBT_NULL, newpath, &len);
        }
        else {
            /* Path was truncated and thus invalid */
            val = NULL;
            len = 0;
        }

        /* Print value */
        if (val == NULL) {
            printf(":\n");
        }
        else {
            if (max_width < (linewid + len + TAG_LEN)) {
                printf(" = \"%.*s\\...\"",
                       (int)(max_width - TAG_LEN - linewid),
		       sanitise_value(&ebuf, val, len));
            }
            else {
                linewid += printf(" = \"%s\"",
				  sanitise_value(&ebuf, val, len));
                if (show_perms) {
                    putchar(' ');
                    for (linewid++;
                         linewid < MIN(desired_width, max_width);
                         linewid++)
                        putchar((linewid & 1)? '.' : ' ');
                }
            }
        }
        free(val);

        if (show_perms) {
            perms = xs_get_permissions(h, XBT_NULL, newpath, &nperms);
            if (perms == NULL) {
                warn("\ncould not access permissions for %s", e[i]);
            }
            else {
                int i;
                fputs("  (", stdout);
                for (i = 0; i < nperms; i++) {
                    if (i)
                        putchar(',');
                    xenstore_perm_to_string(perms+i, buf, sizeof(buf));
                    fputs(buf, stdout);
                }
                putchar(')');
            }
        }

        putchar('\n');
            
        do_ls(h, newpath, cur_depth+1, show_perms); 
    }
    free(e);
    free(newpath);
}

static void
do_chmod(char *path, struct xs_permissions *perms, int nperms, int upto,
	 int recurse, struct xs_handle *xsh, xs_transaction_t xth)
{
    int ret;

    if (!path[0])
	return;

    ret = xs_set_permissions(xsh, xth, path, perms, nperms);
    if (!ret)
	err(1, "Error occurred setting permissions on '%s'", path);

    if (upto) {
	/* apply same permissions to all parent entries: */
	char *path_sep_ptr = strrchr(path, PATH_SEP);
	if (!path_sep_ptr)
	    errx(1, "Unable to locate path separator '%c' in '%s'",
		 PATH_SEP, path);
	
	*path_sep_ptr = '\0'; /* truncate path */
	
	do_chmod(path, perms, nperms, 1, 0, xsh, xth);

	*path_sep_ptr = PATH_SEP;
    }

    if (recurse) {
	char buf[MAX_PATH_LEN];

	/* apply same permissions to all child entries: */
	unsigned int xsval_n;
	char **xsval = xs_directory(xsh, xth, path, &xsval_n);

	if (xsval) {
	    int i;
	    for (i = 0; i < xsval_n; i++) {
		snprintf(buf, MAX_PATH_LEN, "%s/%s", path, xsval[i]);

		do_chmod(buf, perms, nperms, 0, 1, xsh, xth);
	    }

	    free(xsval);
	}
    }
}

static void
do_watch(struct xs_handle *xsh, int max_events)
{
    int count = 0;
    char **vec = NULL;

    for ( count = 0; max_events == -1 || count < max_events; count++ ) {
	unsigned int num;

	vec = xs_read_watch(xsh, &num);
	if (vec == NULL)
	    continue;

	printf("%s\n", vec[XS_WATCH_PATH]);
	fflush(stdout);
	free(vec);
    }
}

static int
perform(enum mode mode, int optind, int argc, char **argv, struct xs_handle *xsh,
        xs_transaction_t xth, int prefix, int tidy, int upto, int recurse, int nr_watches,
        int raw, int depth)
{
    switch (mode) {
    case MODE_ls:
	if (optind == argc)
	{
	    optind=0;
	    argc=1;
	    argv[0] = "/";
	}
	break;
    default:
	break;
    }

    while (optind < argc) {
        switch (mode) {
        case MODE_unknown:
            /* CANNOT BE REACHED */
            errx(1, "invalid mode %d", mode);
        case MODE_read: {
            unsigned len;
            char *val = xs_read(xsh, xth, argv[optind], &len);
            if (val == NULL) {
                warnx("couldn't read path %s", argv[optind]);
                return 1;
            }
            if (prefix)
                output("%s: ", argv[optind]);
            if (raw)
                output_raw(val, len);
            else
                output("%s\n", sanitise_value(&ebuf, val, len));
            free(val);
            optind++;
            break;
        }
        case MODE_write: {
            char *val_spec = argv[optind + 1];
            char *val;
            unsigned len;
            if (raw) {
                val = val_spec;
                len = strlen(val_spec);
            } else {
                expanding_buffer_ensure(&ebuf, strlen(val_spec)+1);
                unsanitise_value(ebuf.buf, &len, val_spec);
                val = ebuf.buf;
            }
            if (!xs_write(xsh, xth, argv[optind], val, len)) {
                warnx("could not write path %s", argv[optind]);
                return 1;
            }
            optind += 2;
        } break;
        case MODE_rm: {
            /* Remove the specified path.  If the tidy flag is set, then also
               remove any containing directories that are both empty and have no
               value attached, and repeat, recursing all the way up to the root if
               necessary.
            */

            char *slash, *path = argv[optind];

            if (tidy) {
                /* Copy path, because we can't modify argv because we will need it
                   again if xs_transaction_end gives us EAGAIN. */
                char *p = malloc(strlen(path) + 1);
                if (!p)
                    return 1;
                strcpy(p, path);
                path = p;

            again:
                if (do_rm(path, xsh, xth)) {
                    free(path);
                    return 1;
                }

                slash = strrchr(p, '/');
                if (slash) {
                    char *val;
                    unsigned len;
                    *slash = '\0';
                    val = xs_read(xsh, xth, p, &len);
                    if (val && len == 0) {
                        unsigned int num;
                        char ** list = xs_directory(xsh, xth, p, &num);

                        if (list) {
                            free(list);
                            if (num == 0){
                                free(val);
                                goto again;
                            }
                        }
                    }
                    free(val);
                }

                free(path);
            }
            else {
                if (do_rm(path, xsh, xth)) {
                    return 1;
                }
            }

            optind++;
            break;
        }
        case MODE_exists: {
            char *val = xs_read(xsh, xth, argv[optind], NULL);
            if (val == NULL) {
                return 1;
            }
            free(val);
            optind++;
            break;
        }
        case MODE_list: {
            unsigned int i, num;
            char **list = xs_directory(xsh, xth, argv[optind], &num);
            const char *pref = argv[optind];

            if (list == NULL) {
                warnx("could not list path %s", argv[optind]);
                return 1;
            }
            if (prefix && !strcmp(pref, "/"))
                pref = "";
            for (i = 0; i < num; i++) {
                if (prefix)
                    output("%s/", pref);
                output("%s\n", list[i]);
            }
            free(list);
            optind++;
            break;
        }
        case MODE_ls: {
            do_ls(xsh, argv[optind], 0, prefix);
            optind++;
            break;
        }
        case MODE_chmod: {
            /* save path pointer: */
            char *path = argv[optind++];
            int nperms = argc - optind;
            struct xs_permissions perms[nperms];
            int i;
            for (i = 0; argv[optind]; optind++, i++)
            {
                perms[i].id = atoi(argv[optind]+1);

                switch (argv[optind][0])
                {
                case 'n':
                    perms[i].perms = XS_PERM_NONE;
                    break;
                case 'r':
                    perms[i].perms = XS_PERM_READ;
                    break;
                case 'w':
                    perms[i].perms = XS_PERM_WRITE;
                    break;
                case 'b':
                    perms[i].perms = XS_PERM_READ | XS_PERM_WRITE;
                    break;
                default:
                    errx(1, "Invalid permission specification: '%c'",
                         argv[optind][0]);
                }
            }

            do_chmod(path, perms, nperms, upto, recurse, xsh, xth);
            break;
        }
        case MODE_watch: {
            for (; argv[optind]; optind++) {
                const char *w = argv[optind];

                if (depth < 0 && !xs_watch(xsh, w, w))
                    errx(1, "Unable to add watch on %s\n", w);
                if (depth >= 0 && !xs_watch_depth(xsh, w, w, depth))
                    errx(1, "Unable to add watch on %s with depth %d\n", w,
                         depth);
            }
            do_watch(xsh, nr_watches);
        }
        }
    }

    return 0;
}

static enum mode lookup_mode(const char *m)
{
    if (strcmp(m, "read") == 0)
	return MODE_read;
    else if (strcmp(m, "chmod") == 0)
	return MODE_chmod;
    else if (strcmp(m, "exists") == 0)
	return MODE_exists;
    else if (strcmp(m, "list") == 0)
	return MODE_list;
    else if (strcmp(m, "ls") == 0)
	return MODE_ls;
    else if (strcmp(m, "rm") == 0)
	return MODE_rm;
    else if (strcmp(m, "write") == 0)
	return MODE_write;
    else if (strcmp(m, "read") == 0)
	return MODE_read;
    else if (strcmp(m, "watch") == 0)
	return MODE_watch;

    errx(1, "unknown mode %s\n", m);
    return 0;
}

int
main(int argc, char **argv)
{
    struct xs_handle *xsh;
    xs_transaction_t xth = XBT_NULL;
    int ret = 0;
    int prefix = 0;
    int tidy = 0;
    int upto = 0;
    int recurse = 0;
    int nr_watches = -1;
    int transaction;
    int raw = 0;
    int depth = -1;
    struct winsize ws;
    enum mode mode;

    const char *_command = strrchr(argv[0], '/');
    const char *command = _command ? &_command[1] : argv[0];
    int switch_argv = -1; /* which element of argv did we switch on */

    if (strncmp(command, "xenstore-", strlen("xenstore-")) == 0)
    {
	switch_argv = 0;
	command = command + strlen("xenstore-");
    }
    else if (argc < 2)
	usage(1, MODE_unknown, 0, argv[0]);
    else
    {
	command = argv[1];
	switch_argv = 1;
    }

    mode = lookup_mode(command);

    while (1) {
	int c, index = 0;
	static struct option long_options[] = {
	    {"help",    0, 0, 'h'},
	    {"flat",    0, 0, 'f'}, /* MODE_ls */
	    {"prefix",  0, 0, 'p'}, /* MODE_read || MODE_list || MODE_ls */
	    {"tidy",    0, 0, 't'}, /* MODE_rm */
	    {"upto",    0, 0, 'u'}, /* MODE_chmod */
	    {"recurse", 0, 0, 'r'}, /* MODE_chmod */
	    {"number",  1, 0, 'n'}, /* MODE_watch */
	    {"raw",     0, 0, 'R'}, /* MODE_read || MODE_write */
	    {"depth",   1, 0, 'd'}, /* MODE_watch */
	    {0, 0, 0, 0}
	};

	c = getopt_long(argc - switch_argv, argv + switch_argv, "hfspturn:Rd:",
			long_options, &index);
	if (c == -1)
	    break;

	switch (c) {
	case 'h':
	    usage(0, mode, switch_argv, argv[0]);
	    /* NOTREACHED */
        case 'f':
	    if ( mode == MODE_ls ) {
		max_width = INT_MAX/2;
		desired_width = 0;
		show_whole_path = 1;
	    } else {
		usage(1, mode, switch_argv, argv[0]);
	    }
            break;
	case 'p':
	    if ( mode == MODE_read || mode == MODE_list || mode == MODE_ls )
		prefix = 1;
	    else
		usage(1, mode, switch_argv, argv[0]);
	    break;
	case 't':
	    if ( mode == MODE_rm )
		tidy = 1;
	    else
		usage(1, mode, switch_argv, argv[0]);
	    break;
	case 'u':
	    if ( mode == MODE_chmod )
		upto = 1;
	    else
		usage(1, mode, switch_argv, argv[0]);
	    break;
	case 'r':
	    if ( mode == MODE_chmod )
		recurse = 1;
	    else
		usage(1, mode, switch_argv, argv[0]);
	    break;
	case 'n':
	    if ( mode == MODE_watch )
		nr_watches = atoi(optarg);
	    else
		usage(1, mode, switch_argv, argv[0]);
	    break;
	case 'R':
	    if ( mode == MODE_read || mode == MODE_write )
		raw = 1;
	    else
		usage(1, mode, switch_argv, argv[0]);
	    break;
	case 'd':
	    if ( mode == MODE_watch )
		depth = atoi(optarg);
	    else
		usage(1, mode, switch_argv, argv[0]);
	    break;
	}
    }

    switch (mode) {
    case MODE_ls:
	break;
    case MODE_write:
	if ((argc - switch_argv - optind) % 2 == 1) {
	    usage(1, mode, switch_argv, argv[0]);
	    /* NOTREACHED */
	}
	/* DROP-THRU */
    default:
	if (optind == argc - switch_argv) {
	    usage(1, mode, switch_argv, argv[0]);
	    /* NOTREACHED */
	}
    }

    switch (mode) {
    case MODE_read:
	transaction = (argc - switch_argv - optind) > 1;
	break;
    case MODE_write:
	transaction = (argc - switch_argv - optind) > 2;
	break;
    case MODE_ls:
    case MODE_watch:
	transaction = 0;
	break;
    default:
	transaction = 1;
	break;
    }

    if ( mode == MODE_ls )
    {
	memset(&ws, 0, sizeof(ws));
	ret = ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws);
	if (!ret)
	    max_width = ws.ws_col - 2;
    }

    xsh = xs_open(0);
    if (xsh == NULL) err(1, "xs_open");

again:
    if (transaction) {
	xth = xs_transaction_start(xsh);
	if (xth == XBT_NULL)
	    errx(1, "couldn't start transaction");
    }

    ret = perform(mode, optind, argc - switch_argv, argv + switch_argv, xsh, xth, prefix, tidy, upto, recurse, nr_watches, raw, depth);

    if (transaction && !xs_transaction_end(xsh, xth, ret)) {
	if (ret == 0 && errno == EAGAIN) {
	    output_pos = 0;
	    goto again;
	}
	errx(1, "couldn't end transaction");
    }

    if (output_pos)
        fwrite(output_buf, 1, output_pos, stdout);

    free(output_buf);
    free(ebuf.buf);

    if (xsh)
        xs_close(xsh);

    return ret;
}