[nmh] / uip / mhshowsbr.c

/* mhshowsbr.c -- routines to display the contents of MIME messages
 *
 * This code is Copyright (c) 2002, by the authors of nmh.  See the
 * COPYRIGHT file in the root directory of the nmh distribution for
 * complete copyright information.
 */

#include "h/mh.h"
#include "sbr/fmt_new.h"
#include "sbr/concat.h"
#include "sbr/trimcpy.h"
#include "sbr/check_charset.h"
#include "sbr/getcpy.h"
#include "sbr/context_find.h"
#include "sbr/pidstatus.h"
#include "sbr/arglist.h"
#include "sbr/error.h"
#include <fcntl.h>
#include "h/signals.h"
#include "h/mts.h"
#include "h/tws.h"
#include "h/mime.h"
#include "h/mhparse.h"
#include "h/fmt_scan.h"
#include "h/done.h"
#include "h/utils.h"
#include "mhmisc.h"
#include "mhshowsbr.h"
#include "sbr/m_mktemp.h"
#ifdef HAVE_ICONV
#   include <iconv.h>
#endif /* ! HAVE_ICONV */

extern int debugsw;

char *progsw = NULL;

/* flags for moreproc/header display */
int nomore   = 0;
char *formsw = NULL;

/* for output markers and headers */
char *folder = NULL;
char *markerform;
char *headerform;
int headersw = -1;


/*
 * static prototypes
 */
static void show_single_message (CT, char *, int, int, int, struct format *);
static void DisplayMsgHeader (CT, char *, int);
static int show_switch (CT, int, int, int, int, struct format *);
static int show_content (CT, int, int, int, struct format *);
static int show_content_aux2 (CT, int, char *, char *, int, int, int, struct format *);
static int show_text (CT, int, int, struct format *);
static int show_multi (CT, int, int, int, int, struct format *);
static int show_multi_internal (CT, int, int, int, int, struct format *);
static int show_multi_aux (CT, int, char *, struct format *);
static int show_message_rfc822 (CT, int, struct format *);
static int show_external (CT, int, int, int, int, struct format *);
static int parse_display_string (CT, char *, int *, int *, char *, char *,
                                 size_t, int multipart);
static int convert_content_charset (CT, char **);
static struct format *compile_header(char *);
static struct format *compile_marker(char *);
static void output_header (CT, struct format *);
static void output_marker (CT, struct format *, int);
static void free_markercomps (void);
static int pidcheck(int);

/*
 * Components (and list of parameters/components) we care about for the
 * content marker display.
 */

static struct comp *folder_comp = NULL;
static struct comp *part_comp = NULL;
static struct comp *ctype_comp = NULL;
static struct comp *description_comp = NULL;
static struct comp *dispo_comp = NULL;

struct param_comp_list {
    char *param;
    struct comp *comp;
    struct param_comp_list *next;
};

static struct param_comp_list *ctype_pc_list = NULL;
static struct param_comp_list *dispo_pc_list = NULL;


/*
 * Top level entry point to show/display a group of messages
 */

void
show_all_messages(CT *cts, int concat, int textonly, int inlineonly)
{
    CT ct, *ctp;

    /*
     * If form is not specified, then get default form
     * for showing headers of MIME messages.
     */
    if (!formsw)
        formsw = mh_xstrdup(etcpath("mhl.headers"));

    /*
     * If form is "mhl.null", suppress display of header.
     */
    if (!strcmp (formsw, "mhl.null"))
        formsw = NULL;

    for (ctp = cts; *ctp; ctp++) {
        ct = *ctp;

        /* if top-level type is ok, then display message */
        if (type_ok (ct, 1)) {
            /*
             * Compile the content marker format line
             */
            struct format *mfmt = compile_marker(markerform);

            if (headersw) {
                /*
                 * Compile the header format line
                 */
                struct format *hfmt = compile_header(headerform);
                output_header(ct, hfmt);
                fmt_free(hfmt, 0);
            }

            show_single_message (ct, formsw, concat, textonly, inlineonly,
                                 mfmt);
            fmt_free(mfmt, 0);
        }
    }

    /* Reset the format component hashtable, which free's any components which
       it references. */
    fmt_free(NULL, 1);
    free_markercomps();
}


/*
 * Entry point to show/display a single message
 */

static void
show_single_message (CT ct, char *form, int concatsw, int textonly,
                     int inlineonly, struct format *fmt)
{
    sigset_t set, oset;

    int status = OK;

    /* Allow user executable bit so that temporary directories created by
     * the viewer (e.g., lynx) are going to be accessible */
    umask (ct->c_umask & ~(0100));

    /*
     * If you have a format file, then display
     * the message headers.
     */
    if (form)
        DisplayMsgHeader(ct, form, concatsw);

    /* Show the body of the message */
    show_switch (ct, 0, concatsw, textonly, inlineonly, fmt);

    if (ct->c_fp) {
        fclose (ct->c_fp);
        ct->c_fp = NULL;
    }
    if (ct->c_ceclosefnx)
        (*ct->c_ceclosefnx) (ct);

    /* block a few signals */
    sigemptyset (&set);
    sigaddset (&set, SIGHUP);
    sigaddset (&set, SIGINT);
    sigaddset (&set, SIGQUIT);
    sigaddset (&set, SIGTERM);
    sigprocmask (SIG_BLOCK, &set, &oset);

    while (!concatsw && wait (&status) != NOTOK) {
        pidcheck (status);
        continue;
    }

    /* reset the signal mask */
    sigprocmask (SIG_SETMASK, &oset, &set);

    flush_errors ();
}


/*
 * Use the mhlproc to show the header fields
 */

static void
DisplayMsgHeader (CT ct, char *form, int concatsw)
{
    pid_t child_id;
    int vecp;
    char **vec;
    char *file;

    vec = argsplit(mhlproc, &file, &vecp);
    vec[vecp++] = mh_xstrdup("-form");
    vec[vecp++] = mh_xstrdup(form);
    vec[vecp++] = mh_xstrdup("-nobody");
    vec[vecp++] = getcpy(ct->c_file);

    /*
     * If we've specified -(no)moreproc,
     * then just pass that along.
     */
    if (nomore || concatsw) {
        vec[vecp++] = mh_xstrdup("-nomoreproc");
    } else if (progsw) {
        vec[vecp++] = mh_xstrdup("-moreproc");
        vec[vecp++] = mh_xstrdup(progsw);
    }
    vec[vecp] = NULL;

    fflush (stdout);

    child_id = fork();
    switch (child_id) {
    case NOTOK:
        adios ("fork", "unable to");
        /* NOTREACHED */

    case OK:
        execvp (file, vec);
        fprintf (stderr, "unable to exec ");
        perror (mhlproc);
        _exit(1);
        /* NOTREACHED */

    default:
        pidcheck(pidwait(child_id, NOTOK));
        break;
    }

    arglist_free(file, vec);
}


/*
 * Switching routine.  Call the correct routine
 * based on content type.
 */

static int
show_switch (CT ct, int alternate, int concatsw, int textonly, int inlineonly,
             struct format *fmt)
{
    switch (ct->c_type) {
        case CT_MULTIPART:
            return show_multi (ct, alternate, concatsw, textonly,
                               inlineonly, fmt);

        case CT_MESSAGE:
            switch (ct->c_subtype) {
                case MESSAGE_EXTERNAL:
                    return show_external (ct, alternate, concatsw, textonly,
                                          inlineonly, fmt);

                case MESSAGE_RFC822:
                    return show_message_rfc822 (ct, alternate, fmt);

                /*
                 * Treat unknown message types as equivalent to
                 * application/octet-stream for now
                 */
                default:
                    return show_content (ct, alternate, textonly,
                                         inlineonly, fmt);
            }

        case CT_TEXT:
            return show_text (ct, alternate, concatsw, fmt);

        case CT_AUDIO:
        case CT_IMAGE:
        case CT_VIDEO:
        case CT_APPLICATION:
        default:
            return show_content (ct, alternate, textonly, inlineonly, fmt);
    }

    return 0;   /* NOT REACHED */
}


/*
 * Generic method for displaying content
 */

static int
show_content (CT ct, int alternate, int textonly, int inlineonly,
              struct format *fmt)
{
    char *cp;
    CI ci = &ct->c_ctinfo;

    /*
     * If we're here, we are not a text type.  So we don't need to check
     * the content-type.
     */

    if (textonly || (inlineonly && !is_inline(ct))) {
        output_marker(ct, fmt, 1);
        return OK;
    }

    /* Check for invo_name-show-type[/subtype] */
    if ((cp = context_find_by_type ("show", ci->ci_type, ci->ci_subtype)))
        return show_content_aux (ct, alternate, cp, NULL, fmt);

    if ((cp = ct->c_showproc))
        return show_content_aux (ct, alternate, cp, NULL, fmt);

    /* complain if we are not a part of a multipart/alternative */
    if (!alternate)
        content_error (NULL, ct, "don't know how to display content");

    return NOTOK;
}


/*
 * Parse the display string for displaying generic content
 */

int
show_content_aux (CT ct, int alternate, char *cp, char *cracked, struct format *fmt)
{
    int fd;
    int xstdin = 0, xlist = 0;
    char *file = NULL, buffer[NMH_BUFSIZ];

    if (!ct->c_ceopenfnx) {
        if (!alternate)
            content_error (NULL, ct, "don't know how to decode content");

        return NOTOK;
    }

    if ((fd = (*ct->c_ceopenfnx) (ct, &file)) == NOTOK)
        return NOTOK;
    if (ct->c_showproc && !strcmp (ct->c_showproc, "true"))
        return OK;

    if (! strcmp(invo_name, "mhshow")  &&
        ct->c_type == CT_TEXT  &&  ct->c_subtype == TEXT_PLAIN) {
        /* This has to be done after calling c_ceopenfnx, so
           unfortunately the type checks are necessary without
           some code rearrangement.  And to make this really ugly,
           only do it in mhshow, not mhfixmsg, mhn, or mhstore. */
        if (convert_content_charset (ct, &file) == OK) {
            (*ct->c_ceclosefnx) (ct);
            if ((fd = (*ct->c_ceopenfnx) (ct, &file)) == NOTOK)
                return NOTOK;
        } else {
            char *charset = content_charset (ct);
            inform("unable to convert character set%s%s from %s, continuing...",
                      ct->c_partno  ?  " of part "  :  "",
                      FENDNULL(ct->c_partno),
                      charset);
            free (charset);
        }
    }

    if (cracked) {
        strncpy (buffer, cp, sizeof(buffer));
        goto got_command;
    }

    if (parse_display_string (ct, cp, &xstdin, &xlist, file, buffer,
                              sizeof(buffer) - 1, 0)) {
        inform("Buffer overflow constructing show command, continuing...");
        return NOTOK;
    }

got_command:
    return show_content_aux2 (ct, alternate, cracked, buffer,
                              fd, xlist, xstdin, fmt);
}


/*
 * Routine to actually display the content
 */

static int
show_content_aux2 (CT ct, int alternate, char *cracked, char *buffer,
                   int fd, int xlist, int xstdin, struct format *fmt)
{
    pid_t child_id;
    int vecp;
    char **vec, *file;

    if (debugsw || cracked) {
        fflush (stdout);

        fprintf (stderr, "%s msg %s", cracked ? "storing" : "show",
                 ct->c_file);
        if (ct->c_partno)
            fprintf (stderr, " part %s", ct->c_partno);
        if (cracked)
            fprintf (stderr, " using command (cd %s; %s)\n", cracked, buffer);
        else
            fprintf (stderr, " using command %s\n", buffer);
    }

    if (xlist && fmt) {
        output_marker(ct, fmt, 0);
    }

    /*
     * If the command is a zero-length string, just write the output on
     * stdout.
     */

    if (buffer[0] == '\0') {
        char readbuf[BUFSIZ];
        ssize_t cc;
        char lastchar = '\n';

        if (fd == NOTOK) {
            inform("Cannot use NULL command to display content-type "
                   "%s/%s", ct->c_ctinfo.ci_type, ct->c_ctinfo.ci_subtype);
            return NOTOK;
        }

        while ((cc = read(fd, readbuf, sizeof(readbuf))) > 0) {
            if ((ssize_t) fwrite(readbuf, 1, cc, stdout) < cc) {
                advise ("putline", "fwrite");
            }
            lastchar = readbuf[cc - 1];
        }

        if (cc < 0) {
            advise("read", "while reading text content");
            return NOTOK;
        }

        /*
         * The MIME standards allow content to not have a trailing newline.
         * But because we are (presumably) sending this to stdout, include
         * a newline for text content if the final character was not a
         * newline.  Only do this for mhshow.
         */

        if (strcmp(invo_name, "mhshow") == 0 && ct->c_type == CT_TEXT &&
            ct->c_subtype == TEXT_PLAIN && lastchar != '\n') {
            putchar('\n');
        }

        fflush(stdout);

        return OK;
    }

    vec = argsplit(buffer, &file, &vecp);

    fflush (stdout);

    child_id = fork();
    switch (child_id) {
        case NOTOK:
            advise ("fork", "unable to");
            (*ct->c_ceclosefnx) (ct);
            return NOTOK;

        case OK:
            if (cracked) {
                if (chdir (cracked) < 0) {
                    advise (cracked, "chdir");
                }
            }
            if (!xstdin)
                dup2 (fd, 0);
            close (fd);
            execvp (file, vec);
            fprintf (stderr, "unable to exec ");
            perror (buffer);
            _exit(1);
            /* NOTREACHED */

        default: {
            int status;
            char *display_prog = vecp > 2  &&  vec[2][0] != '\0'
                /* Copy the real display program name.  This relies on the
                   specific construction of vec[] by argsplit(). */
                ?  vec[2]
                :  NULL;

            pidcheck ((status = pidXwait (child_id, display_prog)));

            arglist_free(file, vec);
            if (fd != NOTOK)
                (*ct->c_ceclosefnx) (ct);
            return alternate ? OK : status;
        }
    }
}


/*
 * show content of type "text"
 */

static int
show_text (CT ct, int alternate, int concatsw, struct format *fmt)
{
    char *cp, buffer[BUFSIZ];
    CI ci = &ct->c_ctinfo;

    /* Check for invo_name-show-type[/subtype] */
    if ((cp = context_find_by_type ("show", ci->ci_type, ci->ci_subtype)))
        return show_content_aux (ct, alternate, cp, NULL, fmt);

    /*
     * Use default method if content is text/plain, or if
     * if it is not a text part of a multipart/alternative
     */
    if (!alternate || ct->c_subtype == TEXT_PLAIN) {
        if (concatsw) {
            if (ct->c_termproc)
                snprintf(buffer, sizeof(buffer), "%%lcat");
            else
                snprintf(buffer, sizeof(buffer), "%%l");
        } else
            snprintf (buffer, sizeof(buffer), "%%l%s %%F", progsw ? progsw :
                      moreproc && *moreproc ? moreproc : DEFAULT_PAGER);
        cp = (ct->c_showproc = mh_xstrdup(buffer));
        return show_content_aux (ct, alternate, cp, NULL, fmt);
    }

    return NOTOK;
}


/*
 * show message body of type "multipart"
 */

static int
show_multi (CT ct, int alternate, int concatsw, int textonly, int inlineonly,
            struct format *fmt)
{
    char *cp;
    CI ci = &ct->c_ctinfo;

    /* Check for invo_name-show-type[/subtype] */
    if ((cp = context_find_by_type ("show", ci->ci_type, ci->ci_subtype)))
        return show_multi_aux (ct, alternate, cp, fmt);

    if ((cp = ct->c_showproc)) {
        return show_multi_aux (ct, alternate, cp, fmt);
    }

    /*
     * Use default method to display this multipart content.  Even
     * unknown types are displayable, since they're treated as mixed
     * per RFC 2046.
     */
    return show_multi_internal (ct, alternate, concatsw, textonly,
                                inlineonly, fmt);
}


/*
 * show message body of subtypes of multipart that
 * we understand directly (mixed, alternate, etc...)
 */

static int
show_multi_internal (CT ct, int alternate, int concatsw, int textonly,
                     int inlineonly, struct format *fmt)
{
    int alternating, nowalternate, result;
    struct multipart *m = (struct multipart *) ct->c_ctparams;
    struct part *part;
    bool request_matched;
    bool display_success;
    bool mult_alt_done;
    int ret;
    CT p;

    alternating = 0;
    nowalternate = alternate;

    if (ct->c_subtype == MULTI_ALTERNATE) {
        nowalternate = 1;
        alternating  = 1;
    }

    /*
     * alternate   -> we are a part inside a multipart/alternative
     * alternating -> we are a multipart/alternative
     */

    result = NOTOK;
    request_matched = false;
    display_success = false;
    mult_alt_done = false;

    for (part = m->mp_parts; part; part = part->mp_next) {
        p = part->mp_part;

        /* while looking for the right displayable alternative, we
         * use a looser search criterion than we do after finding it.
         * specifically, while still looking, part_ok() will match
         * "parent" parts (e.g.  "-part 2" where 2 is a high-level
         * multipart).  after finding it, we use part_exact() to only
         * choose a part that was requested explicitly.
         */
        if ((part_exact(p) && type_ok(p, 1)) ||
                (!mult_alt_done && part_ok (p) && type_ok (p, 1))) {

            int inneresult;

            inneresult = show_switch (p, nowalternate, concatsw, textonly,
                                      inlineonly, fmt);
            switch (inneresult) {
                case NOTOK:  /* hard display error */
                    request_matched = true;
                    if (alternate && !alternating) {
                        result = NOTOK;
                        goto out;
                    }
                    continue;

                case DONE:  /* found no match on content type */
                    continue;

                case OK:  /* display successful */
                    request_matched = true;
                    display_success = true;
                    result = OK;

                    /* if we got success on a sub-part of
                     * multipart/alternative, we're done, unless
                     * there's a chance an explicit part should be
                     * matched later in the alternatives.  */
                    if (alternating) {
                        mult_alt_done = true;
                    } else if (alternate) {
                        alternate = nowalternate = 0;
                    }
                    continue;
            }
            break;
        }
    }

    /* we're supposed to be displaying at least something from a
     * multipart/alternative.  if we've had parts to consider, and
     * we've had no success, then we should complain.  we shouldn't
     * complain if none of the parts matched any -part or -type option.
     */
    if (alternating && request_matched && !display_success) {
        /* if we're ourselves an alternate.  don't complain yet. */
        if (!alternate)
            content_error (NULL, ct, "don't know how to display any of the contents");
        result = NOTOK;
    }

out:
    /* if no parts matched what was requested, there can't have been
     * any display errors.  we report DONE rather than OK. */
    ret = request_matched ? result : DONE;
    return ret;
}


/*
 * Parse display string for multipart content
 * and use external program to display it.
 */

static int
show_multi_aux (CT ct, int alternate, char *cp, struct format *fmt)
{
    /* xstdin is only used in the call to parse_display_string():
       its value is ignored in the function. */
    int xstdin = 0, xlist = 0;
    char *file = NULL, buffer[BUFSIZ];
    struct multipart *m = (struct multipart *) ct->c_ctparams;
    struct part *part;
    CT p;

    for (part = m->mp_parts; part; part = part->mp_next) {
        p = part->mp_part;

        if (!p->c_ceopenfnx) {
            if (!alternate)
                content_error (NULL, p, "don't know how to decode content");
            return NOTOK;
        }

        if (p->c_storage == NULL) {
            if ((*p->c_ceopenfnx) (p, &file) == NOTOK)
                return NOTOK;

            p->c_storage = mh_xstrdup(FENDNULL(file));

            if (p->c_showproc && !strcmp (p->c_showproc, "true"))
                return OK;
            (*p->c_ceclosefnx) (p);
        }
    }

    if (parse_display_string (ct, cp, &xstdin, &xlist, file,
                              buffer, sizeof(buffer) - 1, 1)) {
        inform("Buffer overflow constructing show command, continuing...");
        return NOTOK;
    }

    return show_content_aux2 (ct, alternate, NULL, buffer, NOTOK, xlist, 0, fmt);
}


/*
 * show content of type "message/rfc822"
 */

static int
show_message_rfc822 (CT ct, int alternate, struct format *fmt)
{
    char *cp;
    CI ci = &ct->c_ctinfo;

    /* Check for invo_name-show-type[/subtype] */
    if ((cp = context_find_by_type ("show", ci->ci_type, ci->ci_subtype)))
        return show_content_aux (ct, alternate, cp, NULL, fmt);

    if ((cp = ct->c_showproc))
        return show_content_aux (ct, alternate, cp, NULL, fmt);

    /* default method for message/rfc822 */
    if (ct->c_subtype == MESSAGE_RFC822) {
        cp = (ct->c_showproc = mh_xstrdup("%pshow -file %F"));
        return show_content_aux (ct, alternate, cp, NULL, fmt);
    }

    /* complain if we are not a part of a multipart/alternative */
    if (!alternate)
        content_error (NULL, ct, "don't know how to display content");

    return NOTOK;
}


/*
 * Show content of type "message/external".
 *
 * THE ERROR CHECKING IN THIS ONE IS NOT DONE YET.
 */

static int
show_external (CT ct, int alternate, int concatsw, int textonly, int inlineonly,
               struct format *fmt)
{
    struct exbody *e = (struct exbody *) ct->c_ctparams;
    CT p = e->eb_content;

    if (!type_ok (p, 0))
        return OK;

    return show_switch (p, alternate, concatsw, textonly, inlineonly, fmt);
}


static int
parse_display_string (CT ct, char *cp, int *xstdin, int *xlist,
                      char *file, char *buffer, size_t buflen,
                      int multipart)
{
    int len;
    bool quoted = false;
    char *bp = buffer, *pp;
    CI ci = &ct->c_ctinfo;

    bp[0] = bp[buflen] = '\0';

    for ( ; *cp && buflen > 0; cp++) {
        if (*cp == '%') {
            pp = bp;

            switch (*++cp) {
            case 'a':
                /* insert parameters from Content-Type field */
            {
                PM pm;
                char *s = "";

                for (pm = ci->ci_first_pm; pm; pm = pm->pm_next) {
                    snprintf (bp, buflen, "%s%s=\"%s\"", s, pm->pm_name,
                              get_param_value(pm, '?'));
                    len = strlen (bp);
                    bp += len;
                    buflen -= len;
                    s = " ";
                }
            }
            break;

            case 'd':
                /* insert content description */
                if (ct->c_descr) {
                    char *s;

                    s = trimcpy (ct->c_descr);
                    strncpy (bp, s, buflen);
                    free (s);
                }
                break;

            case 'e':
                /* no longer implemented */
                break;

            case 'F':
                /* %f, and stdin is terminal not content */
                *xstdin = 1;
                /* FALLTHRU */

            case 'f':
                if (multipart) {
                    /* insert filename(s) containing content */
                    struct multipart *m = (struct multipart *) ct->c_ctparams;
                    struct part *part;
                    char *s = "";
                    CT p;

                    for (part = m->mp_parts; part; part = part->mp_next) {
                        p = part->mp_part;

                        snprintf (bp, buflen, "%s%s", s, p->c_storage);
                        len = strlen (bp);
                        bp += len;
                        buflen -= len;
                        s = " ";
                    }
                } else {
                    /* insert filename containing content */
                    snprintf (bp, buflen, "%s", file);

                    /*
                     * Old comments below are left here for posterity.
                     * This was/is tricky.
                     */
                    /* since we've quoted the file argument, set things up
                     * to look past it, to avoid problems with the quoting
                     * logic below.  (I know, I should figure out what's
                     * broken with the quoting logic, but..)
                     */
                    /*
                     * Here's the email that submitted the patch with
                     * the comment above:
                     *   https://www.mail-archive.com/nmh-workers@mhost.com/
                     *     msg00288.html
                     * I can't tell from that exactly what was broken,
                     * beyond misquoting of the filename.  The profile
                     * had appearances of %F both with and without quotes.
                     * The unquoted ones should have been quoted by the
                     * code below.
                     * The fix was to always quote the filename.  But
                     * that broke '%F' because it expanded to ''filename''.
                     */
                    /*
                     * Old comments above are left here for posterity.
                     * The quoting below should work properly now.
                     */
                }
                break;

            case 'p':
                /* No longer supported */
                /* FALLTHRU */

            case 'l':
                /* display listing prior to displaying content */
                *xlist = 1;
                break;

            case 's':
                /* insert subtype of content */
                strncpy (bp, ci->ci_subtype, buflen);
                break;

            case '%':
                /* insert character % */
                goto raw;

            case '{' : {
                const char *closing_brace = strchr(cp, '}');

                if (closing_brace) {
                    const size_t param_len = closing_brace - cp - 1;
                    char *param = mh_xmalloc(param_len + 1);
                    char *value;

                    (void) strncpy(param, cp + 1, param_len);
                    param[param_len] = '\0';
                    value = get_param(ci->ci_first_pm, param, '?', 0);
                    free(param);

                    cp += param_len + 1; /* Skip both braces, too. */

                    if (value) {
                        /* %{param} is set in the Content-Type header.
                           After the break below, quote it if necessary. */
                        (void) strncpy(bp, value, buflen);
                        free(value);
                    } else {
                        /* %{param} not found, so skip it completely.  cp
                           was advanced above. */
                        continue;
                    }
                } else {
                    /* This will get confused if there are multiple %{}'s,
                       but its real purpose is to avoid doing bad things
                       above if a closing brace wasn't found. */
                    inform("no closing brace for display string escape %s, continuing...",
                             cp);
                }
                break;
            }

            default:
                *bp++ = *--cp;
                *bp = '\0';
                buflen--;
                continue;
            }
            len = strlen (bp);
            bp += len;
            buflen -= len;
            *bp = '\0';

            /* Did we actually insert something? */
            if (bp != pp) {
                /* Insert single quote if not inside quotes already */
                if (!quoted && buflen) {
                    len = strlen (pp);
                    memmove (pp + 1, pp, len+1);
                    *pp++ = '\'';
                    buflen--;
                    bp++;
                    quoted = true;
                }
                /* Escape existing quotes */
                while ((pp = strchr (pp, '\'')) && buflen > 3) {
                    len = strlen (pp++);
                    if (quoted) {
                        /* Quoted.  Let this quote close that quoting.
                           Insert an escaped quote to replace it and
                           another quote to reopen quoting, which will be
                           closed below. */
                        memmove (pp + 2, pp, len);
                        *pp++ = '\\';
                        *pp++ = '\'';
                        buflen -= 2;
                        bp += 2;
                        quoted = false;
                    } else {
                        /* Not quoted.  This should not be reached with
                           the current code, but handle the condition
                           in case the code changes.  Just escape the
                           quote. */
                        memmove (pp, pp-1, len+1);
                        *(pp++-1) = '\\';
                        buflen--;
                        bp++;
                    }
                }
                /* If pp is still set, that means we ran out of space. */
                if (pp)
                    buflen = 0;
                /* Close quoting. */
                if (quoted && buflen) {
                    /* See if we need to close the quote by looking
                       for an odd number of unescaped close quotes in
                       the remainder of the display string. */
                    int found_quote = 0, escaped = 0;
                    char *c;

                    for (c = cp+1; *c; ++c) {
                        if (*c == '\\') {
                            escaped = ! escaped;
                        } else {
                            if (escaped) {
                                escaped = 0;
                            } else {
                                if (*c == '\'') {
                                    found_quote = ! found_quote;
                                }
                            }
                        }
                    }
                    if (! found_quote) {
                        *bp++ = '\'';
                        buflen--;
                        quoted = false;
                    }
                }
            }
        } else {
raw:
            *bp++ = *cp;
            buflen--;

            if (*cp == '\'')
                quoted = !quoted;
        }

        *bp = '\0';
    }

    if (buflen <= 0 ||
        (ct->c_termproc && buflen <= strlen(ct->c_termproc))) {
        /* content_error would provide a more useful error message
         * here, except that if we got overrun, it probably would
         * too.
         */
        return NOTOK;
    }

    /* use charset string to modify display method */
    if (ct->c_termproc) {
        char term[BUFSIZ];

        strncpy (term, buffer, sizeof(term));
        snprintf (buffer, buflen, ct->c_termproc, term);
    }

    return OK;
}


int
convert_charset (CT ct, char *dest_charset, int *message_mods)
{
    char *src_charset = content_charset (ct);
    int status = OK;

    if (strcasecmp (src_charset, dest_charset)) {
#ifdef HAVE_ICONV
        iconv_t conv_desc = NULL;
        char *dest;
        int fd = -1;
        char **file = NULL;
        FILE **fp = NULL;
        size_t begin;
        size_t end;
        bool opened_input_file = false;
        char src_buffer[BUFSIZ];
        size_t dest_buffer_size = BUFSIZ;
        char *dest_buffer = mh_xmalloc(dest_buffer_size);
        HF hf;
        char *tempfile;
        int fromutf8 = !strcasecmp(src_charset, "UTF-8");

        if ((conv_desc = iconv_open (dest_charset, src_charset)) ==
            (iconv_t) -1) {
            inform("Can't convert %s to %s", src_charset, dest_charset);
            free (src_charset);
            return NOTOK;
        }

        if ((tempfile = m_mktemp2 (NULL, invo_name, &fd, NULL)) == NULL) {
            die("unable to create temporary file in %s",
                   get_temp_dir());
        }
        dest = mh_xstrdup(tempfile);

        if (ct->c_cefile.ce_file) {
            file = &ct->c_cefile.ce_file;
            fp = &ct->c_cefile.ce_fp;
            begin = end = 0;
        } else if (ct->c_file) {
            file = &ct->c_file;
            fp = &ct->c_fp;
            begin = (size_t) ct->c_begin;
            end = (size_t) ct->c_end;
        } /* else no input file: shouldn't happen */

        if (file  &&  *file  &&  fp) {
            if (! *fp) {
                if ((*fp = fopen (*file, "r")) == NULL) {
                    advise (*file, "unable to open for reading");
                    status = NOTOK;
                } else {
                    opened_input_file = true;
                }
            }
        }

        if (fp  &&  *fp) {
            size_t inbytes;
            size_t bytes_to_read =
                end > 0 && end > begin  ?  end - begin  :  sizeof src_buffer;

            fseeko (*fp, begin, SEEK_SET);
            while ((inbytes = fread (src_buffer, 1,
                                     min (bytes_to_read, sizeof src_buffer),
                                     *fp)) > 0) {
                ICONV_CONST char *ib = src_buffer;
                char *ob = dest_buffer;
                size_t outbytes = dest_buffer_size;
                size_t outbytes_before = outbytes;

                if (end > 0) bytes_to_read -= inbytes;

iconv_start:
                if (iconv (conv_desc, &ib, &inbytes, &ob, &outbytes) ==
                    (size_t) -1) {
                    if (errno == E2BIG) {
                        /*
                         * Bump up the buffer by at least a factor of 2
                         * over what we need.
                         */
                        size_t bumpup = inbytes * 2, ob_off = ob - dest_buffer;
                        dest_buffer_size += bumpup;
                        dest_buffer = mh_xrealloc(dest_buffer,
                                                  dest_buffer_size);
                        ob = dest_buffer + ob_off;
                        outbytes += bumpup;
                        outbytes_before += bumpup;
                        goto iconv_start;
                    }
                    if (errno == EINVAL) {
                        /* middle of multi-byte sequence */
                        if (write (fd, dest_buffer, outbytes_before - outbytes) < 0) {
                            advise (dest, "write");
                        }
                        fseeko (*fp, -inbytes, SEEK_CUR);
                        if (end > 0) bytes_to_read += inbytes;
                        /* inform("convert_charset: EINVAL"); */
                        continue;
                    }
                    if (errno == EILSEQ) {
                        /* invalid multi-byte sequence */
                        if (fromutf8) {
                            for (++ib, --inbytes;
                                 inbytes > 0 &&
                                        (((unsigned char) *ib) & 0xc0) == 0x80;
                                 ++ib, --inbytes)
                                continue;
                        } else {
                            ib++; inbytes--; /* skip it */
                        }
                        (*ob++) = '?'; outbytes --;
                        /* inform("convert_charset: EILSEQ"); */
                        goto iconv_start;
                    }
                    inform("convert_charset: errno = %d", errno);
                    status = NOTOK;
                    break;
                }

                if (write (fd, dest_buffer, outbytes_before - outbytes) < 0) {
                    advise (dest, "write");
                }
            }

            if (opened_input_file) {
                fclose (*fp);
                *fp = NULL;
            }
        }

        iconv_close (conv_desc);
        close (fd);

        if (status == OK) {
            /* Replace the decoded file with the converted one. */
            if (ct->c_cefile.ce_file) {
                if (ct->c_cefile.ce_unlink) {
                    (void) m_unlink (ct->c_cefile.ce_file);
                }
                free (ct->c_cefile.ce_file);
            }
            ct->c_cefile.ce_file = dest;
            ct->c_cefile.ce_unlink = 1;

            ++*message_mods;

            /* Update ct->c_ctline. */
            if (ct->c_ctline) {
                char *ctline = concat(" ", ct->c_ctinfo.ci_type, "/",
                                      ct->c_ctinfo.ci_subtype, NULL);
                char *outline;

                replace_param(&ct->c_ctinfo.ci_first_pm,
                              &ct->c_ctinfo.ci_last_pm, "charset",
                              dest_charset, 0);
                outline = output_params(LEN(TYPE_FIELD) + 1 + strlen(ctline),
                                        ct->c_ctinfo.ci_first_pm, NULL, 0);
                if (outline) {
                    ctline = add(outline, ctline);
                    free(outline);
                }

                free (ct->c_ctline);
                ct->c_ctline = ctline;
            } /* else no CT line, which is odd */

            /* Update Content-Type header field. */
            for (hf = ct->c_first_hf; hf; hf = hf->next) {
                if (! strcasecmp (TYPE_FIELD, hf->name)) {
                    char *ctline = concat (ct->c_ctline, "\n", NULL);

                    free (hf->value);
                    hf->value = ctline;
                    break;
                }
            }
        } else {
            (void) m_unlink (dest);
        }
        free(dest_buffer);
#else  /* ! HAVE_ICONV */
        NMH_UNUSED (message_mods);

        inform("Can't convert %s to %s without iconv", src_charset,
                dest_charset);
        errno = ENOSYS;
        status = NOTOK;
#endif /* ! HAVE_ICONV */
    }

    free (src_charset);
    return status;
}


static int
convert_content_charset (CT ct, char **file)
{
    int status = OK;

#ifdef HAVE_ICONV
    /* Using current locale, see if the content needs to be converted. */

    /* content_charset() cannot return NULL. */
    char *src_charset = content_charset (ct);

    if (! check_charset (src_charset, strlen (src_charset))) {
        int unused = 0;

        char *dest_charset = getcpy (get_charset ());

        if (convert_charset (ct, dest_charset, &unused) == 0) {
            *file = ct->c_cefile.ce_file;
        } else {
            status = NOTOK;
        }

        free (dest_charset);
    }
    free (src_charset);
#else  /* ! HAVE_ICONV */
    NMH_UNUSED (ct);
    NMH_UNUSED (file);
#endif /* ! HAVE_ICONV */

    return status;
}

/*
 * Compile our format string and save any parameters we care about.
 */

#define DEFAULT_HEADER "[ Message %{folder}%<{folder}:%>%(msg) ]"
#define DEFAULT_MARKER "[ part %{part} - %{content-type} - " \
                       "%<{description}%{description}" \
                         "%?{cdispo-filename}%{cdispo-filename}" \
                         "%|%{ctype-name}%>  " \
                       "%(kilo(size))B %<(unseen)\\(suppressed\\)%> ]"

static struct format *
compile_header(char *form)
{
    struct format *fmt;
    char *fmtstring;
    struct comp *comp = NULL;
    unsigned int bucket;

    fmtstring = new_fs(form, NULL, DEFAULT_HEADER);

    (void) fmt_compile(fmtstring, &fmt, 0);
    free_fs();

    while ((comp = fmt_nextcomp(comp, &bucket)) != NULL) {
        if (strcasecmp(comp->c_name, "folder") == 0) {
            folder_comp = comp;
        }
    }

    return fmt;
}

static struct format *
compile_marker(char *form)
{
    struct format *fmt;
    char *fmtstring;
    struct comp *comp = NULL;
    unsigned int bucket;
    struct param_comp_list *pc_entry;

    fmtstring = new_fs(form, NULL, DEFAULT_MARKER);

    (void) fmt_compile(fmtstring, &fmt, 0);
    free_fs();

    /*
     * Things we care about:
     *
     * part             - Part name (e.g., 1.1)
     * content-type     - Content-Type
     * description      - Content-Description
     * disposition      - Content-Disposition (inline, attachment)
     * ctype-<param>    - Content-Type parameter
     * cdispo-<param>   - Content-Disposition parameter
     */

    while ((comp = fmt_nextcomp(comp, &bucket)) != NULL) {
        if (strcasecmp(comp->c_name, "part") == 0) {
            part_comp = comp;
        } else if (strcasecmp(comp->c_name, "content-type") == 0) {
            ctype_comp = comp;
        } else if (strcasecmp(comp->c_name, "description") == 0) {
            description_comp = comp;
        } else if (strcasecmp(comp->c_name, "disposition") == 0) {
            dispo_comp = comp;
        } else if (strncasecmp(comp->c_name, "ctype-", 6) == 0 &&
                   strlen(comp->c_name) > 6) {
            NEW(pc_entry);
            pc_entry->param = mh_xstrdup(comp->c_name + 6);
            pc_entry->comp = comp;
            pc_entry->next = ctype_pc_list;
            ctype_pc_list = pc_entry;
        } else if (strncasecmp(comp->c_name, "cdispo-", 7) == 0 &&
                   strlen(comp->c_name) > 7) {
            NEW(pc_entry);
            pc_entry->param = mh_xstrdup(comp->c_name + 7);
            pc_entry->comp = comp;
            pc_entry->next = dispo_pc_list;
            dispo_pc_list = pc_entry;
        }
    }

    return fmt;
}

/*
 * Output on stdout an appropriate marker for this content, using mh-format
 */

static void
output_header(CT ct, struct format *fmt)
{
    charstring_t outbuf = charstring_create (BUFSIZ);
    int dat[5] = { 0 };
    char *endp;
    int message = 0;

    if (folder_comp)
        folder_comp->c_text = getcpy(folder);

    if (ct->c_file && *ct->c_file) {
        message = strtol(ct->c_file, &endp, 10);
        if (*endp) message = 0;
        dat[0] = message;
    }

    /* it would be nice to populate dat[2], for %(size) here,
     * but it's not available.  it might also be nice to know
     * if the message originally had any mime parts or not -- but
     * there's also no record of that.  (except for MIME-version:)
     */

    fmt_scan(fmt, outbuf, BUFSIZ, dat, NULL);

    fputs(charstring_buffer (outbuf), stdout);
    charstring_free (outbuf);

    fmt_freecomptext();
}

static void
output_marker(CT ct, struct format *fmt, int hidden)
{
    charstring_t outbuf = charstring_create (BUFSIZ);
    struct param_comp_list *pcentry;
    int partsize;
    int message = 0;
    char *endp;
    int dat[5] = { 0 };

    /*
     * Grab any items we care about.
     */

    if (ctype_comp && ct->c_ctinfo.ci_type) {
        ctype_comp->c_text = concat(ct->c_ctinfo.ci_type, "/",
                                    ct->c_ctinfo.ci_subtype, NULL);
    }

    if (part_comp && ct->c_partno) {
        part_comp->c_text = mh_xstrdup(ct->c_partno);
    }

    if (description_comp && ct->c_descr) {
        description_comp->c_text = mh_xstrdup(ct->c_descr);
    }

    if (dispo_comp && ct->c_dispo_type) {
        dispo_comp->c_text = mh_xstrdup(ct->c_dispo_type);
    }

    for (pcentry = ctype_pc_list; pcentry != NULL; pcentry = pcentry->next) {
        pcentry->comp->c_text = get_param(ct->c_ctinfo.ci_first_pm,
                                          pcentry->param, '?', 0);
    }

    for (pcentry = dispo_pc_list; pcentry != NULL; pcentry = pcentry->next) {
        pcentry->comp->c_text = get_param(ct->c_dispo_first,
                                          pcentry->param, '?', 0);
    }

    if (ct->c_cesizefnx)
        partsize = (*ct->c_cesizefnx) (ct);
    else
        partsize = ct->c_end - ct->c_begin;

    if (ct->c_file && *ct->c_file) {
        message = strtol(ct->c_file, &endp, 10);
        if (*endp) message = 0;
        dat[0] = message;
    }
    dat[2] = partsize;

    /* make the part's hidden aspect available by overloading the
     * %(unseen) function.  make the part's size available via %(size).
     * see comments in h/fmt_scan.h.
     */
    dat[4] = hidden;

    fmt_scan(fmt, outbuf, BUFSIZ, dat, NULL);

    fputs(charstring_buffer (outbuf), stdout);
    charstring_free (outbuf);

    fmt_freecomptext();
}

/*
 * Reset (and free) any of the saved marker text
 */

static void
free_markercomps(void)
{
    struct param_comp_list *pc_entry, *pc2;

    folder_comp = NULL;
    part_comp = NULL;
    ctype_comp = NULL;
    description_comp = NULL;
    dispo_comp = NULL;

    for (pc_entry = ctype_pc_list; pc_entry != NULL; ) {
        free(pc_entry->param);
        pc2 = pc_entry->next;
        free(pc_entry);
        pc_entry = pc2;
    }

    for (pc_entry = dispo_pc_list; pc_entry != NULL; ) {
        free(pc_entry->param);
        pc2 = pc_entry->next;
        free(pc_entry);
        pc_entry = pc2;
    }
}

/*
 * Exit if the display process returned with a nonzero exit code, or terminated
 * with a SIGQUIT signal.
 */

static int
pidcheck (int status)
{
    if ((status & 0xff00) == 0xff00 || (status & 0x007f) != SIGQUIT)
        return status;

    fflush (stdout);
    fflush (stderr);
    done (1);
    return 1;
}