changer.c

开源备份软件源码 AMANDA, the Advanced Maryland Automatic Network Disk Archiver, is a backup system that a

/*
 * Amanda, The Advanced Maryland Automatic Network Disk Archiver
 * Copyright (c) 1991-1998 University of Maryland at College Park
 * All Rights Reserved.
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of U.M. not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  U.M. makes no representations about the
 * suitability of this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 *
 * U.M. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL U.M.
 * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Authors: the Amanda Development Team.  Its members are listed in a
 * file named AUTHORS, in the root directory of this distribution.
 */
/*
 * $Id: changer.c,v 1.36 2006/08/24 01:57:16 paddy_s Exp $
 *
 * interface routines for tape changers
 */
#include "amanda.h"
#include "util.h"
#include "conffile.h"
#include "version.h"

#include "changer.h"

/*
 * If we don't have the new-style wait access functions, use our own,
 * compatible with old-style BSD systems at least.  Note that we don't
 * care about the case w_stopval == WSTOPPED since we don't ask to see
 * stopped processes, so should never get them from wait.
 */
#ifndef WEXITSTATUS
#   define WEXITSTATUS(r)       (((union wait *) &(r))->w_retcode)
#   define WTERMSIG(r)          (((union wait *) &(r))->w_termsig)

#   undef  WIFSIGNALED
#   define WIFSIGNALED(r)       (((union wait *) &(r))->w_termsig != 0)
#endif


int changer_debug = 0;
char *changer_resultstr = NULL;

static char *tapechanger = NULL;

/* local functions */
static int changer_command(char *cmd, char *arg);
static int report_bad_resultstr(char *cmd);
static int run_changer_command(char *cmd, char *arg, char **slotstr, char **rest);

int
changer_init(void)
{
    if (tapechanger == NULL)
	tapechanger = getconf_str(CNF_TPCHANGER);
    if (*tapechanger != '\0' && *tapechanger != '/') {
	tapechanger = vstralloc(amlibexecdir, "/", tapechanger, versionsuffix(),
			        NULL);
    }
    return strcmp(tapechanger, "") != 0;
}


static int
report_bad_resultstr(char *cmd)
{
    char *s;

    s = vstrallocf(_("badly formed result from changer command %s: \"%s\""),
		  cmd, changer_resultstr);
    amfree(changer_resultstr);
    changer_resultstr = s;
    return 2;
}

static int
run_changer_command(
    char *	cmd,
    char *	arg,
    char **	slotstr,
    char **	rest)
{
    int exitcode;
    char *result_copy;
    char *slot;
    char *s;
    int ch;

    if (slotstr) {
        *slotstr = NULL;
    }
    if (rest) {
        *rest = NULL;
    }
    exitcode = changer_command(cmd, arg);
    s = changer_resultstr;
    ch = *s++;

    skip_whitespace(s, ch);
    if(ch == '\0') return report_bad_resultstr(cmd);
    slot = s - 1;
    skip_non_whitespace(s, ch);
    s[-1] = '\0';
    if (slotstr) {
        *slotstr = newstralloc(*slotstr, slot);
    }
    s[-1] = (char)ch;

    skip_whitespace(s, ch);
    if (rest) {
        *rest = s - 1;
    }

    if(exitcode) {
	if(ch == '\0') return report_bad_resultstr(cmd);
	result_copy = stralloc(s - 1);
	amfree(changer_resultstr);
	changer_resultstr = result_copy;
	return exitcode;
    }
    return 0;
}

int
changer_reset(
    char **	slotstr)
{
    char *rest;

    return run_changer_command("-reset", (char *) NULL, slotstr, &rest);
}

int
changer_clean(
    char **	slotstr)
{
    char *rest;

    return run_changer_command("-clean", (char *) NULL, slotstr, &rest);
}

int
changer_eject(
    char **	slotstr)
{
    char *rest;

    return run_changer_command("-eject", (char *) NULL, slotstr, &rest);
}

int
changer_loadslot(
    char *inslotstr,
    char **outslotstr,
    char **devicename)
{
    char *rest;
    int rc;

    rc = run_changer_command("-slot", inslotstr, outslotstr, &rest);

    if(rc) return rc;
    if(*rest == '\0') return report_bad_resultstr("-slot");

    *devicename = newstralloc(*devicename, rest);
    return 0;
}


/*
 * This function is somewhat equal to changer_info with one additional
 * parameter, to get information, if the changer is able to search for
 * tapelabels himself. E.g. Barcodereader
 * The changer_script answers with an additional parameter, if it is able
 * to search. This one should be 1, if it is able to search, and 0 if it
 * knows about the extension. If the additional answer is omitted, the
 * changer is not able to search for a tape. 
 */

int
changer_query(
    int *	nslotsp,
    char **	curslotstr,
    int *	backwardsp,
    int *	searchable)
{
    char *rest;
    int rc;

    rc = run_changer_command("-info", (char *) NULL, curslotstr, &rest);
    if(rc) return rc;

    dbprintf(_("changer_query: changer return was %s\n"),rest);
    if (sscanf(rest, "%d %d %d", nslotsp, backwardsp, searchable) != 3) {
      if (sscanf(rest, "%d %d", nslotsp, backwardsp) != 2) {
        return report_bad_resultstr("-info");
      } else {
        *searchable = 0;
      }
    }
    dbprintf(_("changer_query: searchable = %d\n"),*searchable);
    return 0;
}

int
changer_info(
    int *	nslotsp,
    char **	curslotstr,
    int *	backwardsp)
{
    char *rest;
    int rc;

    rc = run_changer_command("-info", (char *) NULL, curslotstr, &rest);
    if(rc) return rc;

    if (sscanf(rest, "%d %d", nslotsp, backwardsp) != 2) {
	return report_bad_resultstr("-info");
    }
    return 0;
}


/* ---------------------------- */

/*
 * This function first uses searchlabel and changer_search, if
 * the library is able to find a tape itself. If it is not, or if 
 * the tape could not be found, then the normal scan is done.
 *
 * See interface documentation in changer.h.
 */

void
changer_find(
     void *	user_data,
     int	(*user_init)(void *, int, int, int, int),
     int	(*user_slot)(void *, int, char *, char *),
     char *	searchlabel)
{
    char *slotstr, *device = NULL, *curslotstr = NULL;
    int nslots, checked, backwards, rc, done, searchable;

    rc = changer_query(&nslots, &curslotstr, &backwards, &searchable);

    if (rc != 0) {
        /* Problem with the changer script. Bail. */
        g_fprintf(stderr, _("Changer problem: %s\n"), changer_resultstr);
        return;
    }

    done = user_init(user_data, rc, nslots, backwards, searchable);
    amfree(curslotstr);
   
    if (searchlabel != NULL)
    {
      dbprintf(_("changer_find: looking for %s changer is searchable = %d\n"),
		searchlabel, searchable);
    } else {
      dbprintf(_("changer_find: looking for NULL changer is searchable = %d\n"),
		searchable);
    }

    if ((searchlabel!=NULL) && searchable && !done){
      rc=changer_search(searchlabel, &curslotstr, &device);
      if(rc == 0)
        done = user_slot(user_data, rc, curslotstr, device);
    }
 
    slotstr = "current";
    checked = 0;

    while(!done && checked < nslots) {
	rc = changer_loadslot(slotstr, &curslotstr, &device);
	if(rc > 0)
	    done = user_slot(user_data, rc, curslotstr, device);
	else if(!done)
	    done = user_slot(user_data, 0,  curslotstr, device);
	amfree(curslotstr);
	amfree(device);

	checked += 1;
	slotstr = "next";
    }
}

/* ---------------------------- */

void
changer_current(
    void *	user_data,
    int		(*user_init)(void *, int, int, int, int),
    int		(*user_slot)(void *, int, char *, char *))
{
    char *device = NULL, *curslotstr = NULL;
    int nslots, backwards, rc, done, searchable;

    rc = changer_query(&nslots, &curslotstr, &backwards, &searchable);
    done = user_init(user_data, rc, nslots, backwards, searchable);
    amfree(curslotstr);

    rc = changer_loadslot("current", &curslotstr, &device);
    if(rc > 0) {
	done = user_slot(user_data, rc, curslotstr, device);
    } else if(!done) {
	done = user_slot(user_data, 0,  curslotstr, device);
    }
    amfree(curslotstr);
    amfree(device);
}

/* ---------------------------- */

static int
changer_command(
     char *cmd,
     char *arg)
{
    int fd[2];
    amwait_t wait_exitcode = 1;
    int exitcode;
    char *cmdstr;
    pid_t pid, changer_pid = 0;
    int fd_to_close[4], *pfd_to_close = fd_to_close;

    cmdstr = vstralloc(tapechanger, " ",
		       cmd, arg ? " " : "", 
		       arg ? arg : "",
		       NULL);

    if(changer_debug) {
	g_fprintf(stderr, _("changer: opening pipe to: %s\n"), cmdstr);
	fflush(stderr);
    }

    amfree(changer_resultstr);

    if(socketpair(AF_UNIX, SOCK_STREAM, 0, fd) == -1) {
	changer_resultstr = vstrallocf(
				_("<error> could not create pipe for \"%s\": %s"),
				cmdstr, strerror(errno));
	exitcode = 2;
	goto failed;
    }

    /* make sure fd[0] > 2  && fd[1] > 2 */
    pfd_to_close = fd_to_close;
    while(fd[0] <= 2) {
	int a = dup(fd[0]);
	*pfd_to_close++ = fd[0];
	fd[0] = a;
    }
    while(fd[1] <= 2) {
	int a = dup(fd[1]);
	*pfd_to_close++ = fd[1];
	fd[1] = a;
    }
    while (pfd_to_close > fd_to_close) {
	close(*--pfd_to_close);
    }

    if(fd[0] < 0 || fd[0] >= (int)FD_SETSIZE) {
	changer_resultstr = vstrallocf(
			_("<error> could not create pipe for \"%s\":"
			"socketpair 0: descriptor %d out of range ( 0 .. %d)"),
			cmdstr, fd[0], (int)FD_SETSIZE-1);
	exitcode = 2;
	goto done;
    }
    if(fd[1] < 0 || fd[1] >= (int)FD_SETSIZE) {
	changer_resultstr = vstrallocf(
			_("<error> could not create pipe for \"%s\":"
			"socketpair 1: descriptor %d out of range ( 0 .. %d)"),
			cmdstr, fd[1], (int)FD_SETSIZE-1);
	exitcode = 2;
	goto done;
    }

    switch(changer_pid = fork()) {
    case -1:
	changer_resultstr = vstrallocf(
			_("<error> could not fork for \"%s\": %s"),
			cmdstr, strerror(errno));
	exitcode = 2;
	goto done;
    case 0:
	debug_dup_stderr_to_debug();
	if(dup2(fd[1], 1) == -1) {
	    changer_resultstr = vstrallocf(
			_("<error> could not open pipe to \"%s\": %s"),
			cmdstr, strerror(errno));
	    (void)fullwrite(fd[1], changer_resultstr, strlen(changer_resultstr));
	    exit(1);
	}
	aclose(fd[0]);
	aclose(fd[1]);
	if(config_dir && chdir(config_dir) == -1) {
	    changer_resultstr = vstrallocf(
			_("<error> could not cd to \"%s\": %s"),
			config_dir, strerror(errno));
	    (void)fullwrite(STDOUT_FILENO, changer_resultstr, strlen(changer_resultstr));
	    exit(1);
	}
	safe_fd(-1, 0);
	if(arg) {
	    execle(tapechanger, tapechanger, cmd, arg, (char *)NULL,
		   safe_env());
	} else {
	    execle(tapechanger, tapechanger, cmd, (char *)NULL, safe_env());
	}
	changer_resultstr = vstrallocf(
			_("<error> could not exec \"%s\": %s"),
			tapechanger, strerror(errno));
	(void)fullwrite(STDOUT_FILENO, changer_resultstr, strlen(changer_resultstr));
	exit(1);
    default:
	aclose(fd[1]);
    }

    if((changer_resultstr = areads(fd[0])) == NULL) {
	if (errno == 0) {
	    changer_resultstr = vstrallocf(
			_("<error> could not read result from \"%s\": Premature end of file, see %s"),
			tapechanger, dbfn());
	} else {
	    changer_resultstr = vstrallocf(
			_("<error> could not read result from \"%s\": %s"),
			tapechanger, strerror(errno));
	}
    }

    while(1) {
	if ((pid = wait(&wait_exitcode)) == -1) {
	    if(errno == EINTR) {
		continue;
	    } else {
		changer_resultstr = vstrallocf(
			_("<error> wait for \"%s\" failed: %s"),
			tapechanger, strerror(errno));
		exitcode = 2;
		goto done;
	    }
	} else if (pid != changer_pid) {
	    changer_resultstr = vstrallocf(
			_("<error> wait for \"%s\" returned unexpected pid %ld"),
			tapechanger, (long)pid);
	    exitcode = 2;
	    goto done;
	} else {
	    break;
	}
    }

    /* mark out-of-control changers as fatal error */
    if(WIFSIGNALED(wait_exitcode)) {
	changer_resultstr = newvstrallocf(changer_resultstr,
			_("<error> %s (got signal %d)"),
			changer_resultstr, WTERMSIG(wait_exitcode));
	exitcode = 2;
    } else {
	exitcode = WEXITSTATUS(wait_exitcode);
    }

done:
    aclose(fd[0]);
    aclose(fd[1]);

failed:
    if (exitcode != 0) {
        dbprintf(_("changer: got exit: %d str: %s\n"), exitcode, changer_resultstr); 
    }

    amfree(cmdstr);

    return exitcode;
}


/*
 * This function commands the changerscript to look for a tape named
 * searchlabel. If is found, the changerscript answers with the device,
 * in which the tape can be accessed.
 */

int
changer_search(
    char *	searchlabel,
    char **	outslotstr,
    char **	devicename)
{
    char *rest;
    int rc;

    dbprintf("changer_search: %s\n",searchlabel);
    rc = run_changer_command("-search", searchlabel, outslotstr, &rest);
    if(rc) return rc;

    if(*rest == '\0') return report_bad_resultstr("-search");

    *devicename = newstralloc(*devicename, rest);
    return 0;
}


/*
 * Because barcodelabel are short, and may not be the same as the 
 * amandalabels, the changerscript should be informed, which tapelabel
 * is associated with a tape. This function should be called after 
 * giving a label for a tape. (Maybe also, when the label and the associated
 * slot is known. e.g. during library scan.
 */

int
changer_label(
    char *	slotsp, 
    char *	labelstr)
{
    int rc;
    char *rest=NULL;
    char *slotstr;
    char *curslotstr = NULL;
    int nslots, backwards, searchable;

    dbprintf(_("changer_label: %s for slot %s\n"),labelstr,slotsp);
    rc = changer_query(&nslots, &curslotstr, &backwards,&searchable);
    amfree(curslotstr);

    if ((rc == 0) && (searchable == 1)){
	dbprintf(_("changer_label: calling changer -label %s\n"),labelstr);
	rc = run_changer_command("-label", labelstr, &slotstr, &rest);
	amfree(slotstr);
    }

    if(rc) return rc;

    return 0;
}