Adding upstream version 4:7.4.7.upstream/4%7.4.7upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 611 insertions, 0 deletions

diff --git a/solenv/lockfile/lockfile.c b/solenv/lockfile/lockfile.c
new file mode 100644
index 000000000..52be40b0f
--- /dev/null
+++ b/solenv/lockfile/lockfile.c
@@ -0,0 +1,611 @@
+/*
+ * lockfile.c 	Safely creates a lockfile, also over NFS.
+ *		This file also holds the implementation for
+ *		the Svr4 maillock functions.
+ *
+ *		Copyright (C) Miquel van Smoorenburg and contributors 1997-2021.
+ *
+ *		This library is free software; you can redistribute it and/or
+ *		modify it under the terms of the GNU Library General Public
+ *		License as published by the Free Software Foundation; either
+ *		version 2 of the License, or (at your option) any later version.
+ */
+
+#include "autoconf.h"
+
+#include <sys/types.h>
+#if HAVE_SYS_PARAM_H
+#include <sys/param.h>
+#endif
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include <errno.h>
+#include "lockfile.h"
+#include "maillock.h"
+
+#ifdef HAVE_UTIME
+#include <utime.h>
+#endif
+
+#ifdef LIB
+static char *mlockfile;
+static int  islocked = 0;
+#endif
+
+#ifdef MAILGROUP
+/*
+ *	Get the id of the mailgroup, by statting the helper program.
+ *	If it is setgroup-id, then the group is the mailgroup.
+ */
+static int mailgid()
+{
+	struct stat st;
+
+	if (stat(LOCKPROG, &st) != 0)
+		return (gid_t)-1;
+	if ((st.st_mode & 02000) == 0)
+		return (gid_t)-1;
+	return st.st_gid;
+}
+
+/*
+ *	Is this a lock for a mailbox? Check:
+ *	- is the file in /path/to/USERNAME.lock format
+ *	- is /path/to/USERNAME present and owned by us
+ *	- is /path/to writable by group mail
+ *
+ *	To be safe in a setgid program, chdir() into the lockfile
+ *	directory first, then pass in the basename of the lockfile.
+ */
+#ifdef LIB
+static
+#endif
+int is_maillock(const char *lockfile)
+{
+	struct stat	st;
+	gid_t		gid;
+	char		tmp[1024];
+	char		*p;
+
+	/* remove .lock suffix */
+	strncpy(tmp, lockfile, sizeof(tmp) - 1);
+	tmp[sizeof(tmp) - 1] = 0;
+	if ((p = strrchr(tmp, '.')) == NULL || strcmp(p, ".lock") != 0)
+		return 0;
+	*p = 0;
+
+	/* file to lock must exist, and must be owned by us */
+	if (lstat(tmp, &st) != 0 ||
+	    (st.st_mode & S_IFMT) != S_IFREG || st.st_uid != getuid())
+		return 0;
+
+	/* Directory this file is in must be writable by group mail. */
+	if ((gid = mailgid()) == (gid_t)-1)
+		return 0;
+	if ((p = strrchr(tmp, '/')) != NULL)
+		*p = 0;
+	else
+		strncpy(tmp, ".", sizeof(tmp));
+	if (stat(tmp, &st) != 0 || st.st_gid != gid || (st.st_mode & 0020) == 0)
+		return 0;
+
+	return 1;
+}
+
+#ifdef LIB
+/*
+ *	Call external program to do the actual locking.
+ */
+static int run_helper(char *opt, const char *lockfile, int retries, int flags)
+{
+	sigset_t	set, oldset;
+	char		buf[8];
+	pid_t		pid, n;
+	int		st;
+
+	/*
+	 * Better safe than sorry.
+	 */
+	if (geteuid() == 0)
+		return L_ERROR;
+
+	/*
+	 *	Block SIGCHLD. The main program might have installed
+	 *	handlers we don't want to call.
+	 */
+	sigemptyset(&set);
+	sigaddset(&set, SIGCHLD);
+	sigprocmask(SIG_BLOCK, &set, &oldset);
+
+	/*
+	 *	Fork, execute locking program and wait.
+	 */
+	if ((pid = fork()) < 0)
+		return L_ERROR;
+	if (pid == 0) {
+		/* drop privs */
+		if (setuid(geteuid()) < 0) {
+			perror("setuid");
+			_exit(L_ERROR);
+		}
+		snprintf(buf, sizeof(buf), "%d", retries % 1000);
+		execl(LOCKPROG, LOCKPROG, opt, "-r", buf, "-q",
+			(flags & L_PID) ? "-p" : "-N", lockfile, NULL);
+		_exit(L_ERROR);
+	}
+
+	/*
+	 *	Wait for return status - do something appropriate
+	 *	if program died or returned L_ERROR.
+	 */
+	while ((n = waitpid(pid, &st, 0)) != pid)
+		if (n < 0 && errno != EINTR)
+			break;
+	if (!sigismember(&oldset, SIGCHLD))
+		sigprocmask(SIG_UNBLOCK, &set, NULL);
+	if (n < 0)
+		return L_ERROR;
+	if (!WIFEXITED(st) || WEXITSTATUS(st) == L_ERROR) {
+		errno = EINTR;
+		return L_ERROR;
+	}
+
+	return WEXITSTATUS(st);
+}
+#endif /* LIB*/
+
+#endif /* MAILGROUP */
+
+#define TMPLOCKSTR		".lk"
+#define TMPLOCKSTRSZ		strlen(TMPLOCKSTR)
+#define TMPLOCKPIDSZ		5
+#define TMPLOCKTIMESZ		1
+#define TMPLOCKSYSNAMESZ	23
+#define TMPLOCKFILENAMESZ	(TMPLOCKSTRSZ + TMPLOCKPIDSZ + \
+				 TMPLOCKTIMESZ + TMPLOCKSYSNAMESZ)
+
+static int lockfilename(const char *lockfile, char *tmplock, size_t tmplocksz)
+{
+	char		sysname[256];
+	char		*p;
+
+#ifdef MAXPATHLEN
+	/*
+	 *	Safety measure.
+	 */
+	if (strlen(lockfile) + TMPLOCKFILENAMESZ > MAXPATHLEN) {
+		errno = ENAMETOOLONG;
+		return L_ERROR;
+	}
+#endif
+
+	if (strlen(lockfile) + TMPLOCKFILENAMESZ + 1 > tmplocksz) {
+		errno = EINVAL;
+		return L_ERROR;
+	}
+
+	/*
+	 *	Create a temp lockfile (hopefully unique) and write
+	 *	either our pid/ppid in it, or 0\0 for svr4 compatibility.
+	 */
+	if (gethostname(sysname, sizeof(sysname)) < 0)
+		return L_ERROR;
+	if ((p = strchr(sysname, '.')) != NULL)
+		*p = 0;
+	/* strcpy is safe: length-check above, limited at snprintf below */
+	strcpy(tmplock, lockfile);
+	if ((p = strrchr(tmplock, '/')) == NULL)
+		p = tmplock;
+	else
+		p++;
+	if (snprintf(p, TMPLOCKFILENAMESZ, "%s%0*d%0*x%s", TMPLOCKSTR,
+			TMPLOCKPIDSZ, (int)getpid(),
+			TMPLOCKTIMESZ, (int)time(NULL) & 15,
+			sysname) < 0) {
+		// never happens but gets rid of gcc truncation warning.
+		errno = EOVERFLOW;
+		return L_ERROR;
+	}
+
+	return 0;
+}
+
+/*
+ *	Create a lockfile.
+ */
+static int lockfile_create_save_tmplock(const char *lockfile,
+		char *tmplock, size_t tmplocksz,
+		volatile char **xtmplock,
+        int retries, int flags, const struct lockargs_s_ *args)
+{
+	struct stat	st, st1;
+	char		pidbuf[40];
+	pid_t		pid = 0;
+	int		sleeptime = 0;
+	int		statfailed = 0;
+	int		fd;
+	int		i, e, pidlen;
+	int		dontsleep = 1;
+	int		tries = retries + 1;
+
+	/* process optional flags that have arguments */
+	if (flags & L_INTERVAL_D_) {
+		sleeptime = args->interval;
+	}
+
+	/* decide which PID to write to the lockfile */
+	if (flags & L_PID)
+		pid = getpid();
+	if (flags & L_PPID) {
+		pid = getppid();
+		if (pid == 1) {
+			/* orphaned */
+			return L_ORPHANED;
+		}
+	}
+	pidlen = snprintf(pidbuf, sizeof(pidbuf), "%d\n", pid);
+	if (pidlen < 0 || pidlen > (int) sizeof(pidbuf) - 1) {
+		errno = EOVERFLOW;
+		return L_ERROR;
+	}
+
+	/* create temporary lockfile */
+	if ((i = lockfilename(lockfile, tmplock, tmplocksz)) != 0)
+		return i;
+	if (xtmplock)
+		*xtmplock = tmplock;
+	fd = open(tmplock, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0644);
+	if (fd < 0) {
+		/* permission denied? perhaps try suid helper */
+#if defined(LIB) && defined(MAILGROUP)
+		if (errno == EACCES && is_maillock(lockfile))
+			return run_helper("-l", lockfile, retries, flags);
+#endif
+		return L_TMPLOCK;
+	}
+	i = write(fd, pidbuf, pidlen);
+	e = errno;
+
+	if (close(fd) != 0) {
+		e = errno;
+		i = -1;
+	}
+	if (i != pidlen) {
+		unlink(tmplock);
+		tmplock[0] = 0;
+		errno = i < 0 ? e : EAGAIN;
+		return L_TMPWRITE;
+	}
+
+	/*
+	 *	Now try to link the temporary lock to the lock.
+	 */
+	for (i = 0; i < tries && tries > 0; i++) {
+		if (!dontsleep) {
+			if (!(flags & L_INTERVAL_D_))
+				sleeptime += 5;
+
+			if (sleeptime > 5) sleeptime = 5;
+#ifdef LIB
+			sleep(sleeptime);
+#else
+			if ((e = check_sleep(sleeptime, flags)) != 0) {
+				unlink(tmplock);
+				tmplock[0] = 0;
+				return e;
+			}
+#endif
+		}
+		dontsleep = 0;
+
+
+		/*
+		 *	Now lock by linking the tempfile to the lock.
+		 *
+		 *	KLUDGE: some people say the return code of
+		 *	link() over NFS can't be trusted.
+		 *	EXTRA FIX: the value of the nlink field
+		 *	can't be trusted (may be cached).
+		 */
+		(void)!link(tmplock, lockfile);
+
+		if (lstat(tmplock, &st1) < 0) {
+			tmplock[0] = 0;
+			return L_ERROR; /* Can't happen */
+		}
+
+		if (lstat(lockfile, &st) < 0) {
+			if (statfailed++ > 5) {
+				/*
+				 *	Normally, this can't happen; either
+				 *	another process holds the lockfile or
+				 *	we do. So if this error pops up
+				 *	repeatedly, just exit...
+				 */
+				e = errno;
+				(void)unlink(tmplock);
+				tmplock[0] = 0;
+				errno = e;
+				return L_MAXTRYS;
+			}
+			continue;
+		}
+
+		/*
+		 *	See if we got the lock.
+		 */
+		if (st.st_rdev == st1.st_rdev &&
+		    st.st_ino  == st1.st_ino) {
+			(void)unlink(tmplock);
+			tmplock[0] = 0;
+			return L_SUCCESS;
+		}
+		statfailed = 0;
+
+		/*
+		 *	If there is a lockfile and it is invalid,
+		 *	remove the lockfile.
+		 */
+		if (lockfile_check(lockfile, flags) == -1) {
+			if (unlink(lockfile) < 0 && errno != ENOENT) {
+				/*
+				 *	we failed to unlink the stale
+				 *	lockfile, give up.
+				 */
+				return L_RMSTALE;
+			}
+			dontsleep = 1;
+			/*
+			 *	If the lockfile was invalid, then the first
+			 *	try wasn't valid either - make sure we
+			 *	try at least once more.
+			 */
+			if (tries == 1) tries++;
+		}
+
+	}
+	(void)unlink(tmplock);
+	tmplock[0] = 0;
+	errno = EAGAIN;
+	return L_MAXTRYS;
+}
+
+#ifdef LIB
+static
+#endif
+int lockfile_create_set_tmplock(const char *lockfile, volatile char **xtmplock, int retries, int flags, const struct lockargs_s_ *args)
+{
+	char *tmplock;
+	int r, e;
+	size_t l;
+
+	l = strlen(lockfile)+TMPLOCKFILENAMESZ+1;
+	if ((tmplock = (char *)malloc(l)) == NULL)
+		return L_ERROR;
+	tmplock[0] = 0;
+	r = lockfile_create_save_tmplock(lockfile,
+						tmplock, l, xtmplock, retries, flags, args);
+	if (xtmplock)
+		*xtmplock = NULL;
+	e = errno;
+	free(tmplock);
+	errno = e;
+	return r;
+}
+
+#ifdef LIB
+int lockfile_create(const char *lockfile, int retries, int flags)
+{
+	/* check against unknown flags */
+	if (flags & ~(L_PID|L_PPID)) {
+		errno = EINVAL;
+		return L_ERROR;
+	}
+	return lockfile_create_set_tmplock(lockfile, NULL, retries, flags, NULL);
+}
+
+#ifdef STATIC
+int lockfile_create2(const char *lockfile, int retries,
+		int flags, struct lockargs_s_ *args, int args_sz)
+{
+
+	#define FLAGS_WITH_ARGS (L_INTERVAL_D_)
+	#define KNOWN_FLAGS (L_PID|L_PPID|L_INTERVAL_D_)
+
+	/* check if size is the same (version check) */
+	if (args != NULL && sizeof(struct lockargs_s_) != args_sz) {
+		errno = EINVAL;
+		return L_ERROR;
+	}
+	/* some flags _must_ have a non-null args */
+	if (args == NULL && (flags & FLAGS_WITH_ARGS)) {
+		errno = EINVAL;
+		return L_ERROR;
+	}
+	/* check against unknown flags */
+	if (flags & ~KNOWN_FLAGS) {
+		errno = EINVAL;
+		return L_ERROR;
+	}
+	return lockfile_create_set_tmplock(lockfile, NULL, retries, flags, args);
+}
+#endif
+
+#endif
+
+/*
+ *	See if a valid lockfile is present.
+ *	Returns 0 if so, -1 if not.
+ */
+int lockfile_check(const char *lockfile, int flags)
+{
+	struct stat	st, st2;
+	char		buf[16];
+	time_t		now;
+	pid_t		pid;
+	int		fd, len, r;
+
+	if (stat(lockfile, &st) < 0)
+		return -1;
+
+	/*
+	 *	Get the contents and mtime of the lockfile.
+	 */
+	time(&now);
+	pid = 0;
+	if ((fd = open(lockfile, O_RDONLY)) >= 0) {
+		/*
+		 *	Try to use 'atime after read' as now, this is
+		 *	the time of the filesystem. Should not get
+		 *	confused by 'atime' or 'noatime' mount options.
+		 */
+		len = 0;
+		if (fstat(fd, &st) == 0 &&
+		    (len = read(fd, buf, sizeof(buf))) >= 0 &&
+		    fstat(fd, &st2) == 0 &&
+		    st.st_atime != st2.st_atime)
+			now = st.st_atime;
+		close(fd);
+		if (len > 0 && (flags & (L_PID|L_PPID))) {
+			buf[len] = 0;
+			pid = atoi(buf);
+		}
+	}
+
+	if (pid > 0) {
+		/*
+		 *	If we have a pid, see if the process
+		 *	owning the lockfile is still alive.
+		 */
+		r = kill(pid, 0);
+		if (r == 0 || errno == EPERM)
+			return 0;
+		if (r < 0 && errno == ESRCH)
+			return -1;
+		/* EINVAL - FALLTHRU */
+	}
+
+	/*
+	 *	Without a pid in the lockfile, the lock
+	 *	is valid if it is newer than 5 mins.
+	 */
+
+	if (now < st.st_mtime + 300)
+		return 0;
+
+	return -1;
+}
+
+/*
+ *	Remove a lock.
+ */
+int lockfile_remove(const char *lockfile)
+{
+	if (unlink(lockfile) < 0) {
+#if defined(LIB) && defined(MAILGROUP)
+		if (errno == EACCES && is_maillock(lockfile))
+			return run_helper("-u", lockfile, 0, 0);
+#endif
+		return errno == ENOENT ? 0 : -1;
+	}
+	return 0;
+}
+
+/*
+ *	Touch a lock.
+ */
+int lockfile_touch(const char *lockfile)
+{
+#ifdef HAVE_UTIME
+	return utime(lockfile, NULL);
+#else
+	return utimes(lockfile, NULL);
+#endif
+}
+
+#ifdef LIB
+/*
+ *	Lock a mailfile. This looks a lot like the SVR4 function.
+ *	Arguments: lusername, retries.
+ */
+int maillock(const char *name, int retries)
+{
+	char		*p, *mail;
+	char		*newlock;
+	int		i, e;
+	int             len, newlen;
+
+	if (islocked) return 0;
+
+#ifdef MAXPATHLEN
+	if (strlen(name) + sizeof(MAILDIR) + 6 > MAXPATHLEN) {
+		errno = ENAMETOOLONG;
+		return L_NAMELEN;
+	}
+#endif
+
+	/*
+	 *	If $MAIL is for the same username as "name"
+	 *	then use $MAIL instead.
+	 */
+
+	len = strlen(name)+strlen(MAILDIR)+6;
+	mlockfile = (char *)malloc(len);
+	if (!mlockfile)
+		return L_ERROR;
+	sprintf(mlockfile, "%s%s.lock", MAILDIR, name);
+	if ((mail = getenv("MAIL")) != NULL) {
+		if ((p = strrchr(mail, '/')) != NULL)
+			p++;
+		else
+			p = mail;
+		if (strcmp(p, name) == 0) {
+			newlen = strlen(mail)+6;
+#ifdef MAXPATHLEN
+			if (newlen > MAXPATHLEN) {
+				errno = ENAMETOOLONG;
+				return L_NAMELEN;
+			}
+#endif
+			if (newlen > len) {
+				newlock = (char *)realloc (mlockfile, newlen);
+				if (newlock == NULL) {
+					e = errno;
+					free (mlockfile);
+					mlockfile = NULL;
+					errno = e;
+					return L_ERROR;
+				}
+				mlockfile = newlock;
+			}
+			sprintf(mlockfile, "%s.lock", mail);
+		}
+	}
+	i = lockfile_create(mlockfile, retries, 0);
+	if (i == 0) islocked = 1;
+
+	return i;
+}
+
+void mailunlock(void)
+{
+	if (!islocked) return;
+	lockfile_remove(mlockfile);
+	free (mlockfile);
+	islocked = 0;
+}
+
+void touchlock(void)
+{
+	lockfile_touch(mlockfile);
+}
+#endif
+