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Major signal overhaul.  We no longer longjmp all over the place.
Instead, routines responsible to gathering user input (or in some
cases outputting data) catch the signals and set flags as needed.
Because of this some handlers are install without the SA_RESTART
flag so syscalls are not restarted and we can check the flag.  All
signal handlers are now safe.

This should make the flow of control a bit more grokable but the
code is still ugly.

/*	$OpenBSD: fio.c,v 1.19 2001/11/20 20:50:00 millert 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.
 */

#ifndef lint
#if 0
static char sccsid[] = "@(#)fio.c	8.2 (Berkeley) 4/20/95";
#else
static char rcsid[] = "$OpenBSD: fio.c,v 1.19 2001/11/20 20:50:00 millert Exp $";
#endif
#endif /* not lint */

#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.
 */

static volatile sig_atomic_t fiosignal;

/*
 * Wrapper for read() to catch EINTR.
 */
ssize_t
myread(fd, buf, len)
	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(ibuf, offset)
	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)fseek(ibuf, offset, 0);
		/*
		 * 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)fseek(otf, 0L, 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] = linebuf[--count];

		(void)fwrite(linebuf, sizeof(*linebuf), count, otf);
		if (ferror(otf))
			err(1, "/tmp");
		if (count)
			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 = *cp2++) == 0) {
					while (isspace(*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(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(obuf, linebuf, outlf)
	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(ibuf, linebuf, linesize, signo)
	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 interuptible.
	 */
	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(mp)
	struct message *mp;
{

	fflush(otf);
	if (fseek(itf, (long)positionof(mp->m_block, mp->m_offset), 0) < 0)
		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(f, omsgCount)
	FILE *f;
	int omsgCount;
{
	size_t size = (msgCount + 1) * sizeof(struct message);

	if (omsgCount) {
		message = (struct message *)realloc(message, size);
		if (message == 0)
			errx(1, "Insufficient memory for %d messages\n",
			    msgCount);
	} else {
		if (message != 0)
			(void)free(message);
		if ((message = (struct message *)malloc(size)) == NULL)
			errx(1, "Insufficient memory for %d messages",
			    msgCount);
		dot = message;
	}
	size -= (omsgCount + 1) * sizeof(struct message);
	fflush(f);
	(void)lseek(fileno(f), (off_t)sizeof(*message), 0);
	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(mp, f)
	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(name)
	char *name;
{
	struct stat sb;

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

	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()
{

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

/*
 * Unblock and ignore a signal
 */
int
ignoresig(sig, oact, oset)
	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(iob)
	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(name)
	char *name;
{
	char xname[PATHSIZE];
	char cmdbuf[PATHSIZE];		/* also used for file names */
	int pid, l;
	char *cp, *shell;
	int pivec[2];
	struct stat sbuf;
	extern int wait_status;

	/*
	 * 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 (!anyof(name, "~{[*?$`'\"\\"))
		return(name);
	if (pipe(pivec) < 0) {
		warn("pipe");
		return(name);
	}
	(void)snprintf(cmdbuf, sizeof(cmdbuf), "echo %s", name);
	shell = value("SHELL");
	pid = start_command(shell, 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 = myread(pivec[0], xname, PATHSIZE);
	if (l < 0)
		warn("read"); /* report error before errno changes */
	(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)
		return(NULL);
	if (l == 0) {
		fprintf(stderr, "\"%s\": No match.\n", name);
		return(NULL);
	}
	if (l == PATHSIZE) {
		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(name, namelen)
	char *name;
	int namelen;
{
	char *folder;

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

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

	fiosignal = s;
}