[unix-history] / usr / src / undoc / v6mail.c

/*
 * v6mail
 */
#include <sysexits.h>

#include <sys/param.h>
#include <sys/stat.h>
#include <sys/dir.h>
#include <sys/times.h>
#include <ctype.h>
#include <errno.h>
#include <pwd.h>
#include <signal.h>

char	*ctime(), *index(), *rindex(), *ctime(), *strcpy(), *getlogin();
char	*mktemp();
struct	passwd *getpwnam(), *getpwuid();
time_t	time();
struct	utmp *getutmp();
char	*getdate();
int	errno;

#include <stdio.h>

#define MAILMODE 0644
#define MSGSCMD "/usr/ucb/msgs"
#define MAILDIR "/usr/spool/mail"

char	lettmp[]  = "/tmp/MaXXXXX";	/* keep letter before sending it */
char	preptmp[] = "/tmp/mbXXXXX";	/* if prepending msg, use this file */
int	chew;				/* if true, strip extra from lines */
int	dflag;				/* if true, don't call sendmail */
char	shopcnt[30] = "0";		/* hop count parameter for rmt mail */
int	errs;				/* no of errs in sending */
char	deleteonly;			/* if true, just delete mailbox */
char 	remname[50];			/* if non-empty, from line extra */

main(argc, argv)
	int argc;
	char **argv;
{
	register int myuid;
	int delexit();
	char namebuf[128], *sn = NULL, logindir[60];
	struct passwd *pwd;

	(void) mktemp(lettmp);
	(void) mktemp(preptmp);
	(void) unlink(lettmp);
	(void) unlink(preptmp);
	myuid = getuid();
	logindir[0] = 0;
	sn = getlogin();
	if (sn == NULL || *sn == 0 || *sn == ' ') {
		pwd = getpwuid(myuid);		/* will read passwd file */
		if (pwd != NULL){
			sn = pwd->pw_name;
			(void) strcpy(logindir, pwd->pw_dir);
		}
		if (sn == NULL) {
			fprintf(stderr, "Who are you?\n");
			delexit(EX_OSFILE);
		}
	}
	(void) strcpy(namebuf, sn);
	if (argc < 2)
		goto hitit;
	for (argc--, argv++; argc > 0 && argv[0][0] == '-'; argc--, argv++)
	switch (argv[0][1]) {

	case 'y':
	case 'n':
		argc++, argv--;
hitit:
		printmail(argc, argv, namebuf, logindir);
		delexit(EX_OK);

	case 'r':	/* one-arg -r--   -r addr */
		if (argc < 2)
			continue;
		/* ignore -r if not network or root */
		if (strcmp("network", namebuf) == 0 || myuid == 0 ||
/*###86 [lint] index arg. 1 used inconsistently v6mail.c(86) :: v6mail.c(244)%%%*/
/*###86 [lint] index arg. 2 used inconsistently v6mail.c(86) :: v6mail.c(244)%%%*/
		    strcmp("uucp", namebuf) == 0 || index('!', argv[1])) {
			(void) strcpy(namebuf, argv[1]);
			chew++;		/* eat From lines */
		}
		else
			(void) strcpy(remname, argv[1]);
		argc--, argv++;
		continue;

	case 'h':	/* hop count - used by network */
		if (argc < 2)
			continue;
		(void) strcpy(shopcnt, argv[1]);
		argc--, argv++;
		continue;

	case 'd':	/* really deliver this message */
		dflag++;
		continue;

	case 'D':	/* only delete the invokers mailbox */
		deleteonly++;
		goto hitit;		/* delete mail box, thats all */
	}
	/* if we are already ignoring signals, catch sigint */
	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
		(void) signal(SIGINT, delexit);
	argc++, argv--;
	bulkmail(argc, argv, namebuf);
	delexit(EX_OK);
}

printmail(argc, argv, name, logindir)
	int argc;
	char **argv;
	char *name, *logindir;
{
	register int c;
	FILE *fdin;
	char sfnmail[60], mbox[120];
	struct stat stb;

	(void) sprintf(sfnmail, "%s/%s", MAILDIR, name);
	if (deleteonly) {
		remove(sfnmail);
		return;
	}
	fdin = fopen(sfnmail, "r");
	if (fdin < 0 || fstat(fileno(fdin), &stb) < 0 || stb.st_size == 0) {
		printf("No mail.\n");
		return;
	}
	if (stb.st_nlink > 1) {
		printf("%s: Too many links.\n", sfnmail);
		return;
	}
	(void) getput(fdin, stdout);
	(void) fclose(fdin);
	(void) fflush(stdout);
	c = 'y';
	if (argc < 2) {
		if (isatty(0)) {
			printf("Save (y or n) ?"); (void) fflush(stdout);
			c = getchar();
		}
	} else
		c = argv[1][1];
	switch (c) {

	default:
		delexit(EX_OK);
		/*NOTREACHED*/

	case 'x':
		return;

	case 'y':
		(void) sprintf(mbox, "%s/mbox", logindir);
		if (writeable(mbox)) {
			perror(mbox);
			return;
		}
		printf("Saving mail in %s.\n", mbox);
		if (append(sfnmail, mbox, getuid(), getgid()) == 0)
			return;
		/* fall into... */

	case 'n':
		remove(sfnmail);
		return;
	}
}

bulkmail(argc, argv, from)
	char **argv, *from;
{
	char linebuf[BUFSIZ];
	FILE *fdout;

	if (dflag == 0) {
		argv[0] = "sendmail";
		argv[argc] = 0;
		execv("/usr/lib/sendmail", argv);
		perror("/usr/lib/sendmail");
		_exit(1);
	}
	fdout = fopen(lettmp, "w");
	if (fdout == NULL) {
		perror(lettmp);
		delexit(EX_OSFILE);
	}

	/*
	 * If delivering mail from the network via mail -r,
	 * Strip the leading line and throw it away, as long
	 * as it begins with "From ..." (and preserve the date if poss.)
	 */
	if (chew) {
		if (fgets(linebuf, BUFSIZ, stdin) == 0)
			goto skip;
		if (!strncmp(linebuf, "From ", 5) != 0)
			printfromline(fdout, getdate(linebuf), from);
		else {
			printfromline(fdout, (char *)0, from);
			fprintf(fdout, "%s", linebuf);
		}
	} else
		printfromline(fdout, (char *)0, from);
skip:
	if (remname[0])
		fprintf(fdout, "(from %s)\n", remname);
	if (getput(stdin, fdout) == 0)
		delexit(EX_OSERR);
	putc('\n', fdout);
	(void) fclose(fdout);
	while (--argc > 0)
		sendto(*++argv);
	delexit(errs);
}

printfromline(fdout, date, from)
	FILE *fdout;
	char *date, *from;
{
	time_t t;

	if (date == NULL) {
		t = time((time_t *)0);
		date = ctime(&t);
	}
	fprintf(fdout, "From %s  %s", from, date);
}

/* look over linebuf and return ptr to date, NULL if error */
char *
getdate(linebuf)
	char *linebuf;
{
	register char *s = linebuf;

/*###244 [lint] index arg. 2 used inconsistently v6mail.c(86) :: v6mail.c(244)%%%*/
/*###244 [lint] index arg. 1 used inconsistently v6mail.c(86) :: v6mail.c(244)%%%*/
	while (s = index(' ', s))
		if (!strncmp(s, " Sun ", 5) ||
		    !strncmp(s, " Mon ", 5) ||
		    !strncmp(s, " Tue ", 5) ||
		    !strncmp(s, " Wed ", 5) ||
		    !strncmp(s, " Thu ", 5) ||
		    !strncmp(s, " Fri ", 5) ||
		    !strncmp(s, " Sat ", 5))
			return (s + 1);
	return (0);
}

int	saved = 0;

sendto(person)
	char *person;
{
	char mailboxname[BUFSIZ];
	struct passwd *pwd;

	if (index('/', person)) {
		if (!writeable(person)) {
			perror(person);
			return;
		}
		lock(person);
		(void) append(lettmp, person, -1, -1);
		unlock();
		return;
	}
	pwd = getpwnam(person);
	if (pwd) {
		(void) sprintf(mailboxname, "%s/%s", MAILDIR, person);
		lock(mailboxname);
		(void) append(lettmp, mailboxname, pwd->pw_uid, pwd->pw_gid);
		unlock();
		return;
	}
	fprintf(stderr, "Can't send to %s.\n", person);
	errs++;
	if (!isatty(0) || saved)
		return;
	saved++;
	if (!writeable("dead.letter")) {
		perror("dead.letter");
		return;
	}
	printf("Letter saved in 'dead.letter'\n");
	(void) append(lettmp, "dead.letter", getuid(), getgid());
}

#include <sys/socket.h>
#include <net/in.h>

struct sockaddr_in biffaddr = { AF_INET, IPPORT_BIFFUDP };

append(from, to, uid, gid)
	char *from, *to;
	int uid, gid;
{
	register FILE *fdin, *fdout;
	int ret;
	struct stat stb;
	char *cp, buf[100]; int f;

	if (stat(to, &stb) >= 0 && (stb.st_mode&S_IFMT) != S_IFREG) {
		fprintf(stderr, "Not a plain file: %s\n", to);
		goto fail;
	}
	fdout = fopen(to, "a");
	if (fdout == NULL) {
		perror(to);
		goto fail;
	}
	if (uid != -1) {
		(void) chown(to, uid, gid);
		(void) chmod(to, MAILMODE);
	}
	if ((fdin = fopen(from, "r")) == NULL) {
		perror(from);
		return (0);
	}
	cp = rindex(to, '/');
	if (cp) {
		char *host = "localhost";
		biffaddr.sin_addr.s_addr = rhost(&host);
#if vax || pdp11
		biffaddr.sin_port =
		    (biffaddr.sin_port<<8) | ((biffaddr.sin_port>>8) & 0xff);
#endif
		f = socket(SOCK_DGRAM, 0, 0, 0);
		(void) sprintf(buf, "%s@%d\n", cp+1, ftell(fdout)); 
	}
	ret = getput(fdin, fdout);
	(void) fclose(fdin);
	(void) fclose(fdout);
	if (cp && f >= 0) {
		send(f, &biffaddr, buf, strlen(buf)+1);
		(void) close(f);
	}
	return (ret);
fail:
	errs++;
	return (0);
}

delexit(status)
	int status;
{

	(void) unlink(lettmp);
	(void) unlink(preptmp);
	exit(status);
}

getput(fdin, fdout)
	register FILE *fdin, *fdout;
{
	register int c;

	while ((c = getc(fdin)) != EOF) {
		errno = 0;
		putc(c, fdout);
		if (errno) {
			perror("mail");
			return (0);
		}
	}
	return (1);
}

writeable(name)
	char *name;
{
	struct stat stb;
	char *cp;
	int ok;

	if (stat(name, &stb) < 0) {
		cp = rindex(name, '/');
		if (cp)
			*cp = 0;
		ok = access(cp ? "." : name, 2) == 0;
		if (cp)
			*cp = '/';
		return (ok);
	}
	return (access(name, 2) == 0);
}

char	locktmp[30];				/* Usable lock temporary */
char	curlock[50];				/* Last used name of lock */
int	locked;					/* To note that we locked it */

/*
 * Lock the specified mail file by setting the file mailfile.lock.
 * We must, of course, be careful to unlink the lock file by a call
 * to unlock before we stop.  The algorithm used here is to see if
 * the lock exists, and if it does, to check its modify time.  If it
 * is older than 30 seconds, we assume error and set our own file.
 * Otherwise, we wait for 5 seconds and try again.
 */
lock(file)
	char *file;
{
	register int f;
	struct stat statbuf;
	time_t curtime;

	if (locked)
		return;
	(void) sprintf(curlock, "%s%s", file, ".lock");
	(void) sprintf(locktmp, "%s/tmXXXXXX", MAILDIR);
	(void) mktemp(locktmp);
	(void) unlink(locktmp);
	for (;;) {
		f = lock1(locktmp, curlock);
		if (f == 0) {
			locked = 1;
			return;
		}
		if (stat(curlock, &statbuf) < 0)
			return;
		(void) time(&curtime);
		if (curtime < statbuf.st_mtime + 30) {
			sleep(5);
			continue;
		}
		(void) unlink(curlock);
	}
}

unlock()
{

	if (locked)
		(void) unlink(curlock);
	locked = 0;
}

/*
 * Attempt to set the lock by creating the temporary file,
 * then doing a link/unlink.  If it fails, return -1 else 0
 */
lock1(tempfile, name)
	char tempfile[], name[];
{
	int fno;

	fno = creat(tempfile, 0400);
	if (fno < 0)
		return (-1);
	(void) close(fno);
	if (link(tempfile, name) < 0) {
		(void) unlink(tempfile);
		return (-1);
	}
	(void) unlink(tempfile);
	return (0);
}

remove(sfn)
	char *sfn;
{
	int i;

	if (unlink(sfn) < 0) {
		i = creat(sfn, MAILMODE);
		if (i >= 0)
			(void) close(i);
	}
}
Commit	Line	Data
6baee9a1 C	1	/*
	2	* v6mail
	3	*/
	4	#include <sysexits.h>
	5
	6	#include <sys/param.h>
	7	#include <sys/stat.h>
	8	#include <sys/dir.h>
	9	#include <sys/times.h>
	10	#include <ctype.h>
	11	#include <errno.h>
	12	#include <pwd.h>
	13	#include <signal.h>
	14
	15	char ctime(), index(), rindex(), ctime(), strcpy(), getlogin();
	16	char *mktemp();
	17	struct passwd getpwnam(), getpwuid();
	18	time_t time();
	19	struct utmp *getutmp();
	20	char *getdate();
	21	int errno;
	22
	23	#include <stdio.h>
	24
	25	#define MAILMODE 0644
	26	#define MSGSCMD "/usr/ucb/msgs"
	27	#define MAILDIR "/usr/spool/mail"
	28
	29	char lettmp[] = "/tmp/MaXXXXX"; /* keep letter before sending it */
	30	char preptmp[] = "/tmp/mbXXXXX"; /* if prepending msg, use this file */
	31	int chew; /* if true, strip extra from lines */
	32	int dflag; /* if true, don't call sendmail */
	33	char shopcnt[30] = "0"; /* hop count parameter for rmt mail */
	34	int errs; /* no of errs in sending */
	35	char deleteonly; /* if true, just delete mailbox */
	36	char remname[50]; /* if non-empty, from line extra */
	37
	38	main(argc, argv)
	39	int argc;
	40	char **argv;
	41	{
	42	register int myuid;
	43	int delexit();
	44	char namebuf[128], *sn = NULL, logindir[60];
	45	struct passwd *pwd;
	46
	47	(void) mktemp(lettmp);
	48	(void) mktemp(preptmp);
	49	(void) unlink(lettmp);
	50	(void) unlink(preptmp);
	51	myuid = getuid();
	52	logindir[0] = 0;
	53	sn = getlogin();
	54	if (sn == NULL \|\| sn == 0 \|\| sn == ' ') {
	55	pwd = getpwuid(myuid); /* will read passwd file */
	56	if (pwd != NULL){
	57	sn = pwd->pw_name;
	58	(void) strcpy(logindir, pwd->pw_dir);
	59	}
	60	if (sn == NULL) {
	61	fprintf(stderr, "Who are you?\n");
	62	delexit(EX_OSFILE);
	63	}
	64	}
65	(void) strcpy(namebuf, sn);
66	if (argc < 2)
67	goto hitit;
68	for (argc--, argv++; argc > 0 && argv[0][0] == '-'; argc--, argv++)
69	switch (argv[0][1]) {
70
71	case 'y':
72	case 'n':
73	argc++, argv--;
74	hitit:
75	printmail(argc, argv, namebuf, logindir);
76	delexit(EX_OK);
77
78	case 'r': /* one-arg -r-- -r addr */
79	if (argc < 2)
80	continue;
81	/* ignore -r if not network or root */
82	if (strcmp("network", namebuf) == 0 \|\| myuid == 0 \|\|
83	/###86 [lint] index arg. 1 used inconsistently v6mail.c(86) :: v6mail.c(244)%%%/
84	/###86 [lint] index arg. 2 used inconsistently v6mail.c(86) :: v6mail.c(244)%%%/
85	strcmp("uucp", namebuf) == 0 \|\| index('!', argv[1])) {
86	(void) strcpy(namebuf, argv[1]);
87	chew++; /* eat From lines */
88	}
89	else
90	(void) strcpy(remname, argv[1]);
91	argc--, argv++;
92	continue;
93
94	case 'h': /* hop count - used by network */
95	if (argc < 2)
96	continue;
97	(void) strcpy(shopcnt, argv[1]);
98	argc--, argv++;
99	continue;
100
101	case 'd': /* really deliver this message */
102	dflag++;
103	continue;
104
105	case 'D': /* only delete the invokers mailbox */
106	deleteonly++;
107	goto hitit; /* delete mail box, thats all */
108	}
109	/* if we are already ignoring signals, catch sigint */
110	if (signal(SIGINT, SIG_IGN) != SIG_IGN)
111	(void) signal(SIGINT, delexit);
112	argc++, argv--;
113	bulkmail(argc, argv, namebuf);
114	delexit(EX_OK);
115	}
116
117	printmail(argc, argv, name, logindir)
118	int argc;
119	char **argv;
120	char name, logindir;
121	{
122	register int c;
123	FILE *fdin;
124	char sfnmail[60], mbox[120];
125	struct stat stb;
126
127	(void) sprintf(sfnmail, "%s/%s", MAILDIR, name);
128	if (deleteonly) {
129	remove(sfnmail);
130	return;
131	}
132	fdin = fopen(sfnmail, "r");
133	if (fdin < 0 \|\| fstat(fileno(fdin), &stb) < 0 \|\| stb.st_size == 0) {
134	printf("No mail.\n");
135	return;
136	}
137	if (stb.st_nlink > 1) {
138	printf("%s: Too many links.\n", sfnmail);
139	return;
140	}
141	(void) getput(fdin, stdout);
142	(void) fclose(fdin);
143	(void) fflush(stdout);
144	c = 'y';
145	if (argc < 2) {
146	if (isatty(0)) {
147	printf("Save (y or n) ?"); (void) fflush(stdout);
148	c = getchar();
149	}
150	} else
151	c = argv[1][1];
152	switch (c) {
153
154	default:
155	delexit(EX_OK);
156	/NOTREACHED/
157
158	case 'x':
159	return;
160
161	case 'y':
162	(void) sprintf(mbox, "%s/mbox", logindir);
163	if (writeable(mbox)) {
164	perror(mbox);
165	return;
166	}
167	printf("Saving mail in %s.\n", mbox);
168	if (append(sfnmail, mbox, getuid(), getgid()) == 0)
169	return;
170	/* fall into... */
171
172	case 'n':
173	remove(sfnmail);
174	return;
175	}
176	}
177
178	bulkmail(argc, argv, from)
179	char *argv, from;
180	{
181	char linebuf[BUFSIZ];
182	FILE *fdout;
183
184	if (dflag == 0) {
185	argv[0] = "sendmail";
186	argv[argc] = 0;
187	execv("/usr/lib/sendmail", argv);
188	perror("/usr/lib/sendmail");
189	_exit(1);
190	}
191	fdout = fopen(lettmp, "w");
192	if (fdout == NULL) {
193	perror(lettmp);
194	delexit(EX_OSFILE);
195	}
196
197	/*
198	* If delivering mail from the network via mail -r,
199	* Strip the leading line and throw it away, as long
200	* as it begins with "From ..." (and preserve the date if poss.)
201	*/
202	if (chew) {
203	if (fgets(linebuf, BUFSIZ, stdin) == 0)
204	goto skip;
205	if (!strncmp(linebuf, "From ", 5) != 0)
206	printfromline(fdout, getdate(linebuf), from);
207	else {
208	printfromline(fdout, (char *)0, from);
209	fprintf(fdout, "%s", linebuf);
210	}
211	} else
212	printfromline(fdout, (char *)0, from);
213	skip:
214	if (remname[0])
215	fprintf(fdout, "(from %s)\n", remname);
216	if (getput(stdin, fdout) == 0)
217	delexit(EX_OSERR);
218	putc('\n', fdout);
219	(void) fclose(fdout);
220	while (--argc > 0)
221	sendto(*++argv);
222	delexit(errs);
223	}
224
225	printfromline(fdout, date, from)
226	FILE *fdout;
227	char date, from;
228	{
229	time_t t;
230
231	if (date == NULL) {
232	t = time((time_t *)0);
233	date = ctime(&t);
234	}
235	fprintf(fdout, "From %s %s", from, date);
236	}
237
238	/* look over linebuf and return ptr to date, NULL if error */
239	char *
240	getdate(linebuf)
241	char *linebuf;
242	{
243	register char *s = linebuf;
244
245	/###244 [lint] index arg. 2 used inconsistently v6mail.c(86) :: v6mail.c(244)%%%/
246	/###244 [lint] index arg. 1 used inconsistently v6mail.c(86) :: v6mail.c(244)%%%/
247	while (s = index(' ', s))
248	if (!strncmp(s, " Sun ", 5) \|\|
249	!strncmp(s, " Mon ", 5) \|\|
250	!strncmp(s, " Tue ", 5) \|\|
251	!strncmp(s, " Wed ", 5) \|\|
252	!strncmp(s, " Thu ", 5) \|\|
253	!strncmp(s, " Fri ", 5) \|\|
254	!strncmp(s, " Sat ", 5))
255	return (s + 1);
256	return (0);
257	}
258
259	int saved = 0;
260
261	sendto(person)
262	char *person;
263	{
264	char mailboxname[BUFSIZ];
265	struct passwd *pwd;
266
267	if (index('/', person)) {
268	if (!writeable(person)) {
269	perror(person);
270	return;
271	}
272	lock(person);
273	(void) append(lettmp, person, -1, -1);
274	unlock();
275	return;
276	}
277	pwd = getpwnam(person);
278	if (pwd) {
279	(void) sprintf(mailboxname, "%s/%s", MAILDIR, person);
280	lock(mailboxname);
281	(void) append(lettmp, mailboxname, pwd->pw_uid, pwd->pw_gid);
282	unlock();
283	return;
284	}
285	fprintf(stderr, "Can't send to %s.\n", person);
286	errs++;
287	if (!isatty(0) \|\| saved)
288	return;
289	saved++;
290	if (!writeable("dead.letter")) {
291	perror("dead.letter");
292	return;
293	}
294	printf("Letter saved in 'dead.letter'\n");
295	(void) append(lettmp, "dead.letter", getuid(), getgid());
296	}
297
298	#include <sys/socket.h>
299	#include <net/in.h>
300
301	struct sockaddr_in biffaddr = { AF_INET, IPPORT_BIFFUDP };
302
303	append(from, to, uid, gid)
304	char from, to;
305	int uid, gid;
306	{
307	register FILE fdin, fdout;
308	int ret;
309	struct stat stb;
310	char *cp, buf[100]; int f;
311
312	if (stat(to, &stb) >= 0 && (stb.st_mode&S_IFMT) != S_IFREG) {
313	fprintf(stderr, "Not a plain file: %s\n", to);
314	goto fail;
315	}
316	fdout = fopen(to, "a");
317	if (fdout == NULL) {
318	perror(to);
319	goto fail;
320	}
321	if (uid != -1) {
322	(void) chown(to, uid, gid);
323	(void) chmod(to, MAILMODE);
324	}
325	if ((fdin = fopen(from, "r")) == NULL) {
326	perror(from);
327	return (0);
328	}
329	cp = rindex(to, '/');
330	if (cp) {
331	char *host = "localhost";
332	biffaddr.sin_addr.s_addr = rhost(&host);
333	#if vax \|\| pdp11
334	biffaddr.sin_port =
335	(biffaddr.sin_port<<8) \| ((biffaddr.sin_port>>8) & 0xff);
336	#endif
337	f = socket(SOCK_DGRAM, 0, 0, 0);
338	(void) sprintf(buf, "%s@%d\n", cp+1, ftell(fdout));
339	}
340	ret = getput(fdin, fdout);
341	(void) fclose(fdin);
342	(void) fclose(fdout);
343	if (cp && f >= 0) {
344	send(f, &biffaddr, buf, strlen(buf)+1);
345	(void) close(f);
346	}
347	return (ret);
348	fail:
349	errs++;
350	return (0);
351	}
352
353	delexit(status)
354	int status;
355	{
356
357	(void) unlink(lettmp);
358	(void) unlink(preptmp);
359	exit(status);
360	}
361
362	getput(fdin, fdout)
363	register FILE fdin, fdout;
364	{
365	register int c;
366
367	while ((c = getc(fdin)) != EOF) {
368	errno = 0;
369	putc(c, fdout);
370	if (errno) {
371	perror("mail");
372	return (0);
373	}
374	}
375	return (1);
376	}
377
378	writeable(name)
379	char *name;
380	{
381	struct stat stb;
382	char *cp;
383	int ok;
384
385	if (stat(name, &stb) < 0) {
386	cp = rindex(name, '/');
387	if (cp)
388	*cp = 0;
389	ok = access(cp ? "." : name, 2) == 0;
390	if (cp)
391	*cp = '/';
392	return (ok);
393	}
394	return (access(name, 2) == 0);
395	}
396
397	char locktmp[30]; /* Usable lock temporary */
398	char curlock[50]; /* Last used name of lock */
399	int locked; /* To note that we locked it */
400
401	/*
402	* Lock the specified mail file by setting the file mailfile.lock.
403	* We must, of course, be careful to unlink the lock file by a call
404	* to unlock before we stop. The algorithm used here is to see if
405	* the lock exists, and if it does, to check its modify time. If it
406	* is older than 30 seconds, we assume error and set our own file.
407	* Otherwise, we wait for 5 seconds and try again.
408	*/
409	lock(file)
410	char *file;
411	{
412	register int f;
413	struct stat statbuf;
414	time_t curtime;
415
416	if (locked)
417	return;
418	(void) sprintf(curlock, "%s%s", file, ".lock");
419	(void) sprintf(locktmp, "%s/tmXXXXXX", MAILDIR);
420	(void) mktemp(locktmp);
421	(void) unlink(locktmp);
422	for (;;) {
423	f = lock1(locktmp, curlock);
424	if (f == 0) {
425	locked = 1;
426	return;
427	}
428	if (stat(curlock, &statbuf) < 0)
429	return;
430	(void) time(&curtime);
431	if (curtime < statbuf.st_mtime + 30) {
432	sleep(5);
433	continue;
434	}
435	(void) unlink(curlock);
436	}
437	}
438
439	unlock()
440	{
441
442	if (locked)
443	(void) unlink(curlock);
444	locked = 0;
445	}
446
447	/*
448	* Attempt to set the lock by creating the temporary file,
449	* then doing a link/unlink. If it fails, return -1 else 0
450	*/
451	lock1(tempfile, name)
452	char tempfile[], name[];
453	{
454	int fno;
455
456	fno = creat(tempfile, 0400);
457	if (fno < 0)
458	return (-1);
459	(void) close(fno);
460	if (link(tempfile, name) < 0) {
461	(void) unlink(tempfile);
462	return (-1);
463	}
464	(void) unlink(tempfile);
465	return (0);
466	}
467
468	remove(sfn)
469	char *sfn;
470	{
471	int i;
472
473	if (unlink(sfn) < 0) {
474	i = creat(sfn, MAILMODE);
475	if (i >= 0)
476	(void) close(i);
477	}
478	}