libshare: nfs: commonify nfs_{init,fini}_tmpfile(), nfs_disable_share()

Also open the temp file cloexec

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Wilson <gwilson@delphix.com>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes openzfs#11886

lib/libshare/libshare_impl.h

@@ -24,6 +24,8 @@
  * Copyright (c) 2011 Gunnar Beutner
  * Copyright (c) 2019, 2020 by Delphix. All rights reserved.
  */
+#ifndef _LIBSPL_LIBSHARE_IMPL_H
+#define	_LIBSPL_LIBSHARE_IMPL_H
 
 typedef struct sa_share_fsinfo {
 	char *shareopts;
@@ -59,3 +61,5 @@ typedef struct sa_fstype {
 } sa_fstype_t;
 
 sa_fstype_t *register_fstype(const char *name, const sa_share_ops_t *ops);
+
+#endif /* _LIBSPL_LIBSHARE_IMPL_H */

lib/libshare/nfs.c

@@ -22,8 +22,11 @@
 
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/file.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <errno.h>
+#include <libshare.h>
 #include "nfs.h"
 
 
@@ -71,3 +74,77 @@ nfs_exports_unlock(const char *name)
 	(void) close(nfs_lock_fd);
 	nfs_lock_fd = -1;
 }
+
+__attribute__((visibility("hidden"))) char *
+nfs_init_tmpfile(const char *prefix, const char *mdir)
+{
+	char *tmpfile = NULL;
+	struct stat sb;
+
+	if (mdir != NULL &&
+	    stat(mdir, &sb) < 0 &&
+	    mkdir(mdir, 0755) < 0) {
+		fprintf(stderr, "failed to create %s: %s\n",
+		    mdir, strerror(errno));
+		return (NULL);
+	}
+
+	if (asprintf(&tmpfile, "%s.XXXXXXXX", prefix) == -1) {
+		fprintf(stderr, "Unable to allocate temporary file\n");
+		return (NULL);
+	}
+
+	int fd = mkostemp(tmpfile, O_CLOEXEC);
+	if (fd == -1) {
+		fprintf(stderr, "Unable to create temporary file: %s",
+		    strerror(errno));
+		free(tmpfile);
+		return (NULL);
+	}
+	close(fd);
+	return (tmpfile);
+}
+
+__attribute__((visibility("hidden"))) int
+nfs_fini_tmpfile(const char *exports, char *tmpfile)
+{
+	if (rename(tmpfile, exports) == -1) {
+		fprintf(stderr, "Unable to rename %s: %s\n", tmpfile,
+		    strerror(errno));
+		unlink(tmpfile);
+		free(tmpfile);
+		return (SA_SYSTEM_ERR);
+	}
+	free(tmpfile);
+	return (SA_OK);
+}
+
+__attribute__((visibility("hidden"))) int
+nfs_disable_share_impl(const char *lockfile, const char *exports,
+    const char *expdir, sa_share_impl_t impl_share)
+{
+	int error;
+	char *filename;
+
+	if ((filename = nfs_init_tmpfile(exports, expdir)) == NULL)
+		return (SA_SYSTEM_ERR);
+
+	error = nfs_exports_lock(lockfile);
+	if (error != 0) {
+		unlink(filename);
+		free(filename);
+		return (error);
+	}
+
+	error = nfs_copy_entries(filename, impl_share->sa_mountpoint);
+	if (error != SA_OK) {
+		unlink(filename);
+		free(filename);
+		nfs_exports_unlock(lockfile);
+		return (error);
+	}
+
+	error = nfs_fini_tmpfile(exports, filename);
+	nfs_exports_unlock(lockfile);
+	return (error);
+}

lib/libshare/nfs.h

@@ -24,9 +24,18 @@
  * Copyright (c) 2011 Gunnar Beutner
  */
 
+#include "libshare_impl.h"
+
 #define	FILE_HEADER		"# !!! DO NOT EDIT THIS FILE MANUALLY !!!\n\n"
 
 void libshare_nfs_init(void);
 
 int nfs_exports_lock(const char *name);
 void nfs_exports_unlock(const char *name);
+
+char *nfs_init_tmpfile(const char *prefix, const char *mdir);
+int nfs_fini_tmpfile(const char *exports, char *tmpfile);
+
+int nfs_copy_entries(char *filename, const char *mountpoint);
+int nfs_disable_share_impl(const char *lockfile, const char *exports,
+    const char *expdir, sa_share_impl_t impl_share);

lib/libshare/os/freebsd/nfs.c

@@ -143,47 +143,11 @@ translate_opts(const char *shareopts)
 	return (newopts);
 }
 
-static char *
-nfs_init_tmpfile(void)
-{
-	char *tmpfile = NULL;
-
-	if (asprintf(&tmpfile, "%s%s", ZFS_EXPORTS_FILE, ".XXXXXXXX") == -1) {
-		fprintf(stderr, "Unable to allocate buffer for temporary "
-		    "file name\n");
-		return (NULL);
-	}
-
-	int fd = mkstemp(tmpfile);
-	if (fd == -1) {
-		fprintf(stderr, "Unable to create temporary file: %s",
-		    strerror(errno));
-		free(tmpfile);
-		return (NULL);
-	}
-	close(fd);
-	return (tmpfile);
-}
-
-static int
-nfs_fini_tmpfile(char *tmpfile)
-{
-	if (rename(tmpfile, ZFS_EXPORTS_FILE) == -1) {
-		fprintf(stderr, "Unable to rename %s: %s\n", tmpfile,
-		    strerror(errno));
-		unlink(tmpfile);
-		free(tmpfile);
-		return (SA_SYSTEM_ERR);
-	}
-	free(tmpfile);
-	return (SA_OK);
-}
-
 /*
  * This function copies all entries from the exports file to "filename",
  * omitting any entries for the specified mountpoint.
  */
-static int
+__attribute__((visibility("hidden"))) int
 nfs_copy_entries(char *filename, const char *mountpoint)
 {
 	int error = SA_OK;
@@ -234,7 +198,7 @@ nfs_enable_share(sa_share_impl_t impl_share)
 	char *filename = NULL;
 	int error;
 
-	if ((filename = nfs_init_tmpfile()) == NULL)
+	if ((filename = nfs_init_tmpfile(ZFS_EXPORTS_FILE, NULL)) == NULL)
 		return (SA_SYSTEM_ERR);
 
 	error = nfs_exports_lock(ZFS_EXPORTS_LOCK);
@@ -283,38 +247,16 @@ nfs_enable_share(sa_share_impl_t impl_share)
 		nfs_exports_unlock(ZFS_EXPORTS_LOCK);
 		return (SA_SYSTEM_ERR);
 	}
-	error = nfs_fini_tmpfile(filename);
+	error = nfs_fini_tmpfile(ZFS_EXPORTS_FILE, filename);
 	nfs_exports_unlock(ZFS_EXPORTS_LOCK);
 	return (error);
 }
 
 static int
 nfs_disable_share(sa_share_impl_t impl_share)
 {
-	int error;
-	char *filename = NULL;
-
-	if ((filename = nfs_init_tmpfile()) == NULL)
-		return (SA_SYSTEM_ERR);
-
-	error = nfs_exports_lock(ZFS_EXPORTS_LOCK);
-	if (error != 0) {
-		unlink(filename);
-		free(filename);
-		return (error);
-	}
-
-	error = nfs_copy_entries(filename, impl_share->sa_mountpoint);
-	if (error != SA_OK) {
-		unlink(filename);
-		free(filename);
-		nfs_exports_unlock(ZFS_EXPORTS_LOCK);
-		return (error);
-	}
-
-	error = nfs_fini_tmpfile(filename);
-	nfs_exports_unlock(ZFS_EXPORTS_LOCK);
-	return (error);
+	return (nfs_disable_share_impl(
+	    ZFS_EXPORTS_LOCK, ZFS_EXPORTS_FILE, NULL, impl_share));
 }
 
 /*

lib/libshare/os/linux/nfs.c

@@ -350,49 +350,6 @@ get_linux_shareopts(const char *shareopts, char **plinux_opts)
 	return (error);
 }
 
-static char *
-nfs_init_tmpfile(void)
-{
-	char *tmpfile = NULL;
-	struct stat sb;
-
-	if (stat(ZFS_EXPORTS_DIR, &sb) < 0 &&
-	    mkdir(ZFS_EXPORTS_DIR, 0755) < 0) {
-		fprintf(stderr, "failed to create %s: %s\n",
-		    ZFS_EXPORTS_DIR, strerror(errno));
-		return (NULL);
-	}
-
-	if (asprintf(&tmpfile, "%s%s", ZFS_EXPORTS_FILE, ".XXXXXXXX") == -1) {
-		fprintf(stderr, "Unable to allocate temporary file\n");
-		return (NULL);
-	}
-
-	int fd = mkstemp(tmpfile);
-	if (fd == -1) {
-		fprintf(stderr, "Unable to create temporary file: %s",
-		    strerror(errno));
-		free(tmpfile);
-		return (NULL);
-	}
-	close(fd);
-	return (tmpfile);
-}
-
-static int
-nfs_fini_tmpfile(char *tmpfile)
-{
-	if (rename(tmpfile, ZFS_EXPORTS_FILE) == -1) {
-		fprintf(stderr, "Unable to rename %s: %s\n", tmpfile,
-		    strerror(errno));
-		unlink(tmpfile);
-		free(tmpfile);
-		return (SA_SYSTEM_ERR);
-	}
-	free(tmpfile);
-	return (SA_OK);
-}
-
 /*
  * This function populates an entry into /etc/exports.d/zfs.exports.
  * This file is consumed by the linux nfs server so that zfs shares are
@@ -443,7 +400,7 @@ nfs_add_entry(const char *filename, const char *sharepath,
  * This function copies all entries from the exports file to "filename",
  * omitting any entries for the specified mountpoint.
  */
-static int
+__attribute__((visibility("hidden"))) int
 nfs_copy_entries(char *filename, const char *mountpoint)
 {
 	char *buf = NULL;
@@ -516,7 +473,8 @@ nfs_enable_share(sa_share_impl_t impl_share)
 	char *filename = NULL;
 	int error;
 
-	if ((filename = nfs_init_tmpfile()) == NULL)
+	if ((filename =
+	    nfs_init_tmpfile(ZFS_EXPORTS_FILE, ZFS_EXPORTS_DIR)) == NULL)
 		return (SA_SYSTEM_ERR);
 
 	error = nfs_exports_lock(ZFS_EXPORTS_LOCK);
@@ -547,7 +505,7 @@ nfs_enable_share(sa_share_impl_t impl_share)
 	    linux_opts);
 	free(linux_opts);
 	if (error == 0) {
-		error = nfs_fini_tmpfile(filename);
+		error = nfs_fini_tmpfile(ZFS_EXPORTS_FILE, filename);
 	} else {
 		unlink(filename);
 		free(filename);
@@ -562,29 +520,8 @@ nfs_enable_share(sa_share_impl_t impl_share)
 static int
 nfs_disable_share(sa_share_impl_t impl_share)
 {
-	int error;
-	char *filename = NULL;
-
-	if ((filename = nfs_init_tmpfile()) == NULL)
-		return (SA_SYSTEM_ERR);
-
-	error = nfs_exports_lock(ZFS_EXPORTS_LOCK);
-	if (error != 0) {
-		unlink(filename);
-		free(filename);
-		return (error);
-	}
-
-	error = nfs_copy_entries(filename, impl_share->sa_mountpoint);
-	if (error != SA_OK) {
-		unlink(filename);
-		free(filename);
-		nfs_exports_unlock(ZFS_EXPORTS_LOCK);
-		return (error);
-	}
-	error = nfs_fini_tmpfile(filename);
-	nfs_exports_unlock(ZFS_EXPORTS_LOCK);
-	return (error);
+	return (nfs_disable_share_impl(
+	    ZFS_EXPORTS_LOCK, ZFS_EXPORTS_FILE, ZFS_EXPORTS_DIR, impl_share));
 }
 
 static boolean_t