From: Baptiste Daroussin <bapt@FreeBSD.org>
Date: Fri, 2 Dec 2022 12:55:17 +0000 (+0100)
Subject: locking: use a more portable mechanism
X-Git-Tag: RELEASE_1_4_0a1~3
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2af27b24d181bdbc71193268fceeffb59f792524;p=thirdparty%2Fmlmmj.git

locking: use a more portable mechanism
---

diff --git a/include/utils.h b/include/utils.h
index f94d59ca..f2d68942 100644
--- a/include/utils.h
+++ b/include/utils.h
@@ -24,6 +24,7 @@
 
 #include <sys/file.h>
 #include <stdint.h>
+#include <stdbool.h>
 
 #include <time.h>
 #include <fcntl.h>
@@ -35,36 +36,4 @@ uintmax_t strtouim(const char *, uintmax_t, uintmax_t, const char **);
 void exec_or_die(const char *arg, ...);
 int exec_and_wait(const char *arg, ...);
 time_t strtotimet(const char *np, const char **errpp);
-
-static inline int open_locked(const char *path, int flags, mode_t mode) {
-#ifdef O_EXLOCK
-	flags |= O_EXLOCK;
-	return (open(path, flags, mode));
-#else
-	int fd = open(path, flags, mode);
-	if (fd != -1) {
-		if (flock(fd, LOCK_EX) == -1) {
-			close(fd);
-			fd = -1;
-		}
-	}
-	return (fd);
-#endif
-}
-
-static inline int openat_locked(int dfd, const char *path, int flags, mode_t mode) {
-#ifdef O_EXLOCK
-	flags |= O_EXLOCK;
-	return (openat(dfd, path, flags, mode));
-#else
-	int fd = openat(dfd, path, flags, mode);
-	if (fd != -1) {
-		if (flock(fd, LOCK_EX) == -1) {
-			close(fd);
-			fd = -1;
-		}
-	}
-	return (fd);
-#endif
-}
-
+bool lock(int fd, bool write);
diff --git a/src/incindexfile.c b/src/incindexfile.c
index 96d3798f..ac522021 100644
--- a/src/incindexfile.c
+++ b/src/incindexfile.c
@@ -49,8 +49,8 @@ int incindexfile(const char *listdir)
 	const char *errstr;
 
 	xasprintf(&indexfilename, "%s/index", listdir);
-	fd = open_locked(indexfilename, O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
-	if(fd == -1) {
+	fd = open(indexfilename, O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
+	if(fd == -1 && !lock(fd, true)) {
 		free(indexfilename);
 		log_error(LOG_ARGS, "Error opening index file");
 		return 0;
diff --git a/src/log_oper.c b/src/log_oper.c
index 1e27f79d..82ab11dc 100644
--- a/src/log_oper.c
+++ b/src/log_oper.c
@@ -65,8 +65,8 @@ int log_oper(const char *prefix, const char *basename, const char *fmt, ...)
 		free(tmp);
 	}
 	
-	fd = open_locked(logfilename, O_RDWR|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR);
-	if(fd < 0) {
+	fd = open(logfilename, O_RDWR|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR);
+	if(fd < 0 && !lock(fd, true)) {
 		log_error(LOG_ARGS, "Could not open %s", logfilename);
 		free(logfilename);
 		return -1;
diff --git a/src/mlmmj-maintd.c b/src/mlmmj-maintd.c
index 74481e22..1ab7ad2b 100644
--- a/src/mlmmj-maintd.c
+++ b/src/mlmmj-maintd.c
@@ -602,8 +602,8 @@ run_digests(int dfd, const char *mlmmjsend, const char *listdir, int logfd)
 	digestinterval = ctrltimet(dfd, "digestinterval", DIGESTINTERVAL);
 	digestmaxmails = ctrllong(listdir, "digestmaxmail", DIGESTMAXMAILS);
 
-	fd = openat_locked(dfd, "lastdigest", O_RDWR|O_CREAT, S_IRUSR | S_IWUSR);
-	if (fd < 0) {
+	fd = openat(dfd, "lastdigest", O_RDWR|O_CREAT, S_IRUSR | S_IWUSR);
+	if (fd < 0 && !lock(fd, true)) {
 		log(" - Could not open or create 'lastdigest': %s\n",
 		    strerror(errno));
 		return (false);
diff --git a/src/mlmmj-send.c b/src/mlmmj-send.c
index 93488c7f..dd8d0af4 100644
--- a/src/mlmmj-send.c
+++ b/src/mlmmj-send.c
@@ -919,7 +919,8 @@ int main(int argc, char **argv)
 	
 	/* initialize file with mail to send */
 
-	if((mailfd = open_locked(mailfilename, O_RDWR, 0644)) < 0) {
+	if((mailfd = open(mailfilename, O_RDWR, 0644)) < 0 &&
+	    !lock(mailfd, true)) {
 	        log_error(LOG_ARGS, "Could not open '%s'", mailfilename);
 		exit(EXIT_FAILURE);
 	}
diff --git a/src/mlmmj-sub.c b/src/mlmmj-sub.c
index 4c24c379..b72bb5e9 100644
--- a/src/mlmmj-sub.c
+++ b/src/mlmmj-sub.c
@@ -569,9 +569,9 @@ static void subscribe_type(char *listdir, char *listaddr, char *listdelim,
 	
 	subfilename = concatstr(3, listdir, subdir, chstr);
 
-	subfilefd = open_locked(subfilename, O_RDWR|O_CREAT|O_APPEND,
+	subfilefd = open(subfilename, O_RDWR|O_CREAT|O_APPEND,
 				S_IRUSR|S_IWUSR|groupwritable);
-	if(subfilefd == -1) {
+	if(subfilefd == -1 && !lock(subfilefd, true)) {
 		log_error(LOG_ARGS, "Could not open '%s'", subfilename);
 		exit(EXIT_FAILURE);
 	}
diff --git a/src/mlmmj.c b/src/mlmmj.c
index 2100f26b..c9d76974 100644
--- a/src/mlmmj.c
+++ b/src/mlmmj.c
@@ -187,9 +187,11 @@ unsubscribe(int listfd, const char *address, enum subtype typesub)
 		    strcmp(dp->d_name, "..") == 0)
 			continue;
 
-		rfd = openat_locked(fd, dp->d_name, O_RDONLY, 0644);
+		rfd = openat(fd, dp->d_name, O_RDONLY, 0644);
 		if (rfd == -1)
 			continue;
+		if (!lock(rfd, false))
+			continue;
 
 		if (fstat(rfd, &st) == -1) {
 			log_err("Impossible to determine the size of %s/%s: %s",
@@ -255,9 +257,9 @@ unsubscribe(int listfd, const char *address, enum subtype typesub)
 		}
 
 		xasprintf(&wrname, "%s.new", dp->d_name);
-		wfd = openat_locked(fd, wrname, O_RDWR|O_CREAT|O_TRUNC,
+		wfd = openat(fd, wrname, O_RDWR|O_CREAT|O_TRUNC,
 		    S_IRUSR|S_IWUSR|groupwritable);
-		if (wfd == -1) {
+		if (wfd == -1 && !lock(wfd, true)) {
 			log_err("Could not open '%s/%s': %s", subdir, wrname,
 			    strerror(errno));
 			munmap(start, st.st_size);
diff --git a/src/utils.c b/src/utils.c
index cab6f7bb..6b0677a4 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -20,6 +20,7 @@
  * IN THE SOFTWARE.
  */
 
+#include <fcntl.h>
 #include <sys/wait.h>
 #include <sys/param.h>
 
@@ -28,6 +29,7 @@
 #include <errno.h>
 #include <inttypes.h>
 #include <spawn.h>
+#include <stdbool.h>
 #include <unistd.h>
 
 #include "xmalloc.h"
@@ -179,3 +181,25 @@ exec_and_wait(const char *arg, ...)
 
 	return (WEXITSTATUS(pstat));
 }
+
+bool
+lock(int fd, bool wr)
+{
+	struct flock lck;
+	int r;
+
+	if (fd == -1)
+		return (false);
+	lck.l_type = wr ? F_WRLCK : F_RDLCK;
+	lck.l_whence = SEEK_SET;
+	lck.l_start = 0;
+	lck.l_len = 0;
+	do {
+		r = fcntl(fd, F_SETLKW, &lck);
+	} while (r < 0 && errno != EINTR);
+	if (r == -1) {
+		close(fd);
+		return (false);
+	}
+	return (true);
+}