/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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 <sys/file.h>
#include <sys/wait.h>

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

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

extern int wait_status;

/*
 * 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;
        char linebuf[LINESIZE], pathbuf[PATHSIZE];
        int omsgCount;

        /* 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 = ftello(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))
                                errx(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.
                 */
                if (count >= 2 && linebuf[count - 1] == '\n' &&
                    linebuf[count - 2] == '\r') {
                        count--;
                        linebuf[count - 1] = '\n';
                }

                (void)fwrite(linebuf, sizeof(*linebuf), count, otf);
                if (ferror(otf))
                        errx(1, "/tmp");
                if (count)
                        linebuf[count - 1] = '\0';
                if (maybe && linebuf[0] == 'F' && ishead(linebuf)) {
                        msgCount++;
                        if (append(&this, mestmp))
                                errx(1, "temporary file");
                        this.m_flag = MUSED|MNEW;
                        this.m_size = 0;
                        this.m_lines = 0;
                        this.m_block = blockof(offset);
                        this.m_offset = boffsetof(offset);
                        inhead = 1;
                } else if (linebuf[0] == 0) {
                        inhead = 0;
                } else if (inhead) {
                        for (cp = linebuf, cp2 = "status";; cp++) {
                                if ((c = *cp2++) == '\0') {
                                        while (isspace((unsigned char)*cp++))
                                                ;
                                        if (cp[-1] != ':')
                                                break;
                                        while ((c = *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((unsigned char)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) {
                fprintf(obuf, "\n");
                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 n;

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

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

        (void)fflush(otf);
        if (fseeko(itf,
                   positionof(mp->m_block, mp->m_offset), SEEK_SET) < 0)
                err(1, "fseeko");
        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 = (struct message *)realloc(message, size);
        if (nmessage == NULL)
                errx(1, "Insufficient memory for %d messages\n",
                    msgCount);
        if (omsgCount == 0 || message == NULL)
                dot = nmessage;
        else
                dot = nmessage + (dot - message);
        message = nmessage;
        size -= (omsgCount + 1) * sizeof(struct message);
        (void)fflush(f);
        (void)lseek(fileno(f), (off_t)sizeof(*message), 0);
        if (read(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 a file, but only if the file is a plain file.
 */
int
rm(char *name)
{
        struct stat sb;

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

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

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

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

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

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

        if (fstat(fileno(iob), &sbuf) < 0)
                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)
{
        char xname[PATHSIZE];
        char cmdbuf[PATHSIZE];          /* also used for file names */
        int pid, l;
        char *cp, *sh;
        int pivec[2];
        struct stat sbuf;

        /*
         * 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) {
                        printf("No previous file\n");
                        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 != NULL &&
            (name[1] == '/' || name[1] == '\0')) {
                (void)snprintf(xname, sizeof(xname), "%s%s", homedir, name + 1);
                name = savestr(xname);
        }
        if (!strpbrk(name, "~{[*?$`'\"\\"))
                return (savestr(name));
        if (pipe(pivec) < 0) {
                warn("pipe");
                return (NULL);
        }
        (void)snprintf(cmdbuf, sizeof(cmdbuf), "echo %s", name);
        if ((sh = value("SHELL")) == NULL)
                sh = _PATH_CSHELL;
        pid = start_command(sh, 0, -1, pivec[1], "-c", cmdbuf, NULL);
        if (pid < 0) {
                (void)close(pivec[0]);
                (void)close(pivec[1]);
                return (NULL);
        }
        (void)close(pivec[1]);
        l = read(pivec[0], xname, BUFSIZ);
        (void)close(pivec[0]);
        if (wait_child(pid) < 0 && WIFSIGNALED(wait_status) &&
            WTERMSIG(wait_status) != SIGPIPE) {
                fprintf(stderr, "\"%s\": Expansion failed.\n", name);
                return (NULL);
        }
        if (l < 0) {
                warn("read");
                return (NULL);
        }
        if (l == 0) {
                fprintf(stderr, "\"%s\": No match.\n", name);
                return (NULL);
        }
        if (l == BUFSIZ) {
                fprintf(stderr, "\"%s\": Expansion buffer overflow.\n", name);
                return (NULL);
        }
        xname[l] = '\0';
        for (cp = &xname[l-1]; *cp == '\n' && cp > xname; cp--)
                ;
        cp[1] = '\0';
        if (strchr(xname, ' ') && stat(xname, &sbuf) < 0) {
                fprintf(stderr, "\"%s\": Ambiguous.\n", name);
                return (NULL);
        }
        return (savestr(xname));
}

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

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