/*      $OpenBSD: fio.c,v 1.39 2022/12/26 19:16:01 jmc Exp $    */
/*      $NetBSD: fio.c,v 1.8 1997/07/07 22:57:55 phil Exp $     */

/*
 * Copyright (c) 1980, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "rcv.h"

#include <unistd.h>
#include <paths.h>
#include <errno.h>
#include <glob.h>
#include "extern.h"

/*
 * Mail -- a mail program
 *
 * File I/O.
 */

static volatile sig_atomic_t fiosignal;

/*
 * Wrapper for read() to catch EINTR.
 */
static ssize_t
myread(int fd, char *buf, int len)
{
        ssize_t nread;

        while ((nread = read(fd, buf, len)) == -1 && errno == EINTR)
                ;
        return(nread);
}

/*
 * Set up the input pointers while copying the mail file into /tmp.
 */
void
setptr(FILE *ibuf, off_t offset)
{
        int c, count;
        char *cp, *cp2;
        struct message this;
        FILE *mestmp;
        int maybe, inhead, omsgCount;
        char linebuf[LINESIZE], pathbuf[PATHSIZE];

        /* Get temporary file. */
        (void)snprintf(pathbuf, sizeof(pathbuf), "%s/mail.XXXXXXXXXX", tmpdir);
        if ((c = mkstemp(pathbuf)) == -1 || (mestmp = Fdopen(c, "r+")) == NULL)
                err(1, "can't open %s", pathbuf);
        (void)rm(pathbuf);

        if (offset == 0) {
                msgCount = 0;
        } else {
                /* Seek into the file to get to the new messages */
                (void)fseeko(ibuf, offset, SEEK_SET);
                /*
                 * We need to make "offset" a pointer to the end of
                 * the temp file that has the copy of the mail file.
                 * If any messages have been edited, this will be
                 * different from the offset into the mail file.
                 */
                (void)fseeko(otf, (off_t)0, SEEK_END);
                offset = ftell(otf);
        }
        omsgCount = msgCount;
        maybe = 1;
        inhead = 0;
        this.m_flag = MUSED|MNEW;
        this.m_size = 0;
        this.m_lines = 0;
        this.m_block = 0;
        this.m_offset = 0;
        for (;;) {
                if (fgets(linebuf, sizeof(linebuf), ibuf) == NULL) {
                        if (append(&this, mestmp))
                                err(1, "temporary file");
                        makemessage(mestmp, omsgCount);
                        return;
                }
                count = strlen(linebuf);
                /*
                 * Transforms lines ending in <CR><LF> to just <LF>.
                 * This allows mail to be able to read Eudora mailboxes
                 * that reside on a DOS partition.
                 */
                if (count >= 2 && linebuf[count-1] == '\n' &&
                    linebuf[count - 2] == '\r') {
                        linebuf[count - 2] = '\n';
                        linebuf[count - 1] = '\0';
                        count--;
                }

                (void)fwrite(linebuf, sizeof(*linebuf), count, otf);
                if (ferror(otf))
                        err(1, "%s", pathbuf);
                if (count && linebuf[count - 1] == '\n')
                        linebuf[count - 1] = '\0';
                if (maybe && linebuf[0] == 'F' && ishead(linebuf)) {
                        msgCount++;
                        if (append(&this, mestmp))
                                err(1, "temporary file");
                        this.m_flag = MUSED|MNEW;
                        this.m_size = 0;
                        this.m_lines = 0;
                        this.m_block = blockof(offset);
                        this.m_offset = offsetof(offset);
                        inhead = 1;
                } else if (linebuf[0] == 0) {
                        inhead = 0;
                } else if (inhead) {
                        for (cp = linebuf, cp2 = "status";; cp++) {
                                if ((c = (unsigned char)*cp2++) == 0) {
                                        while (isspace((unsigned char)*cp++))
                                                ;
                                        if (cp[-1] != ':')
                                                break;
                                        while ((c = (unsigned char)*cp++) != '\0')
                                                if (c == 'R')
                                                        this.m_flag |= MREAD;
                                                else if (c == 'O')
                                                        this.m_flag &= ~MNEW;
                                        inhead = 0;
                                        break;
                                }
                                if (*cp != c && *cp != toupper(c))
                                        break;
                        }
                }
                offset += count;
                this.m_size += count;
                this.m_lines++;
                maybe = linebuf[0] == 0;
        }
}

/*
 * Drop the passed line onto the passed output buffer.
 * If a write error occurs, return -1, else the count of
 * characters written, including the newline if requested.
 */
int
putline(FILE *obuf, char *linebuf, int outlf)
{
        int c;

        c = strlen(linebuf);
        (void)fwrite(linebuf, sizeof(*linebuf), c, obuf);
        if (outlf) {
                (void)putc('\n', obuf);
                c++;
        }
        if (ferror(obuf))
                return(-1);
        return(c);
}

/*
 * Read up a line from the specified input into the line
 * buffer.  Return the number of characters read.  Do not
 * include the newline (or carriage return) at the end.
 */
int
readline(FILE *ibuf, char *linebuf, int linesize, int *signo)
{
        struct sigaction act;
        struct sigaction savetstp;
        struct sigaction savettou;
        struct sigaction savettin;
        struct sigaction saveint;
        struct sigaction savehup;
        sigset_t oset;
        int n;

        /*
         * Setup signal handlers if the caller asked us to catch signals.
         * Note that we do not restart system calls since we need the
         * read to be interruptible.
         */
        if (signo) {
                fiosignal = 0;
                sigemptyset(&act.sa_mask);
                act.sa_flags = 0;
                act.sa_handler = fioint;
                if (sigaction(SIGINT, NULL, &saveint) == 0 &&
                    saveint.sa_handler != SIG_IGN) {
                        (void)sigaction(SIGINT, &act, &saveint);
                        (void)sigprocmask(SIG_UNBLOCK, &intset, &oset);
                }
                if (sigaction(SIGHUP, NULL, &savehup) == 0 &&
                    savehup.sa_handler != SIG_IGN)
                        (void)sigaction(SIGHUP, &act, &savehup);
                (void)sigaction(SIGTSTP, &act, &savetstp);
                (void)sigaction(SIGTTOU, &act, &savettou);
                (void)sigaction(SIGTTIN, &act, &savettin);
        }

        clearerr(ibuf);
        if (fgets(linebuf, linesize, ibuf) == NULL) {
                if (ferror(ibuf))
                        clearerr(ibuf);
                n = -1;
        } else {
                n = strlen(linebuf);
                if (n > 0 && linebuf[n - 1] == '\n')
                        linebuf[--n] = '\0';
                if (n > 0 && linebuf[n - 1] == '\r')
                        linebuf[--n] = '\0';
        }

        if (signo) {
                (void)sigprocmask(SIG_SETMASK, &oset, NULL);
                (void)sigaction(SIGINT, &saveint, NULL);
                (void)sigaction(SIGHUP, &savehup, NULL);
                (void)sigaction(SIGTSTP, &savetstp, NULL);
                (void)sigaction(SIGTTOU, &savettou, NULL);
                (void)sigaction(SIGTTIN, &savettin, NULL);
                *signo = fiosignal;
        }

        return(n);
}

/*
 * Return a file buffer all ready to read up the
 * passed message pointer.
 */
FILE *
setinput(struct message *mp)
{

        fflush(otf);
        if (fseek(itf, (long)positionof(mp->m_block, mp->m_offset), SEEK_SET)
            == -1)
                err(1, "fseek");
        return(itf);
}

/*
 * Take the data out of the passed ghost file and toss it into
 * a dynamically allocated message structure.
 */
void
makemessage(FILE *f, int omsgCount)
{
        size_t size;
        struct message *nmessage;

        size = (msgCount + 1) * sizeof(struct message);
        nmessage = realloc(message, size);
        if (nmessage == 0)
                err(1, "realloc");
        if (omsgCount == 0 || message == NULL)
                dot = nmessage;
        else
                dot = nmessage + (dot - message);
        message = nmessage;
        size -= (omsgCount + 1) * sizeof(struct message);
        fflush(f);
        (void)lseek(fileno(f), (off_t)sizeof(*message), SEEK_SET);
        if (myread(fileno(f), (void *) &message[omsgCount], size) != size)
                errx(1, "Message temporary file corrupted");
        message[msgCount].m_size = 0;
        message[msgCount].m_lines = 0;
        (void)Fclose(f);
}

/*
 * Append the passed message descriptor onto the temp file.
 * If the write fails, return 1, else 0
 */
int
append(struct message *mp, FILE *f)
{

        return(fwrite((char *) mp, sizeof(*mp), 1, f) != 1);
}

/*
 * Delete or truncate a file, but only if the file is a plain file.
 */
int
rm(char *name)
{
        struct stat sb;

        if (stat(name, &sb) == -1)
                return(-1);
        if (!S_ISREG(sb.st_mode)) {
                errno = EISDIR;
                return(-1);
        }
        if (unlink(name) == -1) {
                if (errno == EPERM)
                        return(truncate(name, (off_t)0));
                else
                        return(-1);
        }
        return(0);
}

static int sigdepth;            /* depth of holdsigs() */
static sigset_t nset, oset;
/*
 * Hold signals SIGHUP, SIGINT, and SIGQUIT.
 */
void
holdsigs(void)
{

        if (sigdepth++ == 0) {
                sigemptyset(&nset);
                sigaddset(&nset, SIGHUP);
                sigaddset(&nset, SIGINT);
                sigaddset(&nset, SIGQUIT);
                sigprocmask(SIG_BLOCK, &nset, &oset);
        }
}

/*
 * Release signals SIGHUP, SIGINT, and SIGQUIT.
 */
void
relsesigs(void)
{

        if (--sigdepth == 0)
                sigprocmask(SIG_SETMASK, &oset, NULL);
}

/*
 * Unblock and ignore a signal
 */
int
ignoresig(int sig, struct sigaction *oact, sigset_t *oset)
{
        struct sigaction act;
        sigset_t nset;
        int error;

        sigemptyset(&act.sa_mask);
        act.sa_flags = SA_RESTART;
        act.sa_handler = SIG_IGN;
        error = sigaction(sig, &act, oact);

        if (error == 0) {
                sigemptyset(&nset);
                sigaddset(&nset, sig);
                (void)sigprocmask(SIG_UNBLOCK, &nset, oset);
        } else if (oset != NULL)
                (void)sigprocmask(SIG_BLOCK, NULL, oset);

        return(error);
}

/*
 * Determine the size of the file possessed by
 * the passed buffer.
 */
off_t
fsize(FILE *iob)
{
        struct stat sbuf;

        if (fstat(fileno(iob), &sbuf) == -1)
                return(0);
        return(sbuf.st_size);
}

/*
 * Evaluate the string given as a new mailbox name.
 * Supported meta characters:
 *      %       for my system mail box
 *      %user   for user's system mail box
 *      #       for previous file
 *      &       invoker's mbox file
 *      +file   file in folder directory
 *      any shell meta character
 * Return the file name as a dynamic string.
 */
char *
expand(char *name)
{
        const int flags = GLOB_BRACE|GLOB_TILDE|GLOB_NOSORT;
        char xname[PATHSIZE];
        char cmdbuf[PATHSIZE];          /* also used for file names */
        char *match = NULL;
        glob_t names;

        /*
         * The order of evaluation is "%" and "#" expand into constants.
         * "&" can expand into "+".  "+" can expand into shell meta characters.
         * Shell meta characters expand into constants.
         * This way, we make no recursive expansion.
         */
        switch (*name) {
        case '%':
                findmail(name[1] ? name + 1 : myname, xname, sizeof(xname));
                return(savestr(xname));
        case '#':
                if (name[1] != 0)
                        break;
                if (prevfile[0] == 0) {
                        puts("No previous file");
                        return(NULL);
                }
                return(savestr(prevfile));
        case '&':
                if (name[1] == 0 && (name = value("MBOX")) == NULL)
                        name = "~/mbox";
                /* fall through */
        }
        if (name[0] == '+' && getfold(cmdbuf, sizeof(cmdbuf)) >= 0) {
                (void)snprintf(xname, sizeof(xname), "%s/%s", cmdbuf, name + 1);
                name = savestr(xname);
        }
        /* catch the most common shell meta character */
        if (name[0] == '~' && homedir && (name[1] == '/' || name[1] == '\0')) {
                (void)snprintf(xname, sizeof(xname), "%s%s", homedir, name + 1);
                name = savestr(xname);
        }
        if (strpbrk(name, "~{[*?\\") == NULL)
                return(savestr(name));

        /* XXX - does not expand environment variables. */
        switch (glob(name, flags, NULL, &names)) {
        case 0:
                if (names.gl_pathc == 1)
                        match = savestr(names.gl_pathv[0]);
                else
                        fprintf(stderr, "\"%s\": Ambiguous.\n", name);
                break;
        case GLOB_NOSPACE:
                fprintf(stderr, "\"%s\": Out of memory.\n", name);
                break;
        case GLOB_NOMATCH:
                fprintf(stderr, "\"%s\": No match.\n", name);
                break;
        default:
                fprintf(stderr, "\"%s\": Expansion failed.\n", name);
                break;
        }
        globfree(&names);
        return(match);
}

/*
 * Determine the current folder directory name.
 */
int
getfold(char *name, int namelen)
{
        char *folder;

        if ((folder = value("folder")) == NULL)
                return(-1);
        if (*folder == '/')
                strlcpy(name, folder, namelen);
        else
                (void)snprintf(name, namelen, "%s/%s", homedir ? homedir : ".",
                    folder);
        return(0);
}

/*
 * Return the name of the dead.letter file.
 */
char *
getdeadletter(void)
{
        char *cp;

        if ((cp = value("DEAD")) == NULL || (cp = expand(cp)) == NULL)
                cp = expand("~/dead.letter");
        else if (*cp != '/') {
                char buf[PATHSIZE];

                (void)snprintf(buf, sizeof(buf), "~/%s", cp);
                cp = expand(buf);
        }
        return(cp);
}

/*
 * Signal handler used by readline() to catch SIGINT, SIGHUP, SIGTSTP,
 * SIGTTOU, SIGTTIN.
 */
void
fioint(int s)
{

        fiosignal = s;
}