systemd/SOURCES/0986-fstab-generator-allow-overriding-etc-fstab-with-SYST.patch

From d0f59d4190a9f1e0e6db4b22b5e87bec2db4f7fb Mon Sep 17 00:00:00 2001
From: Frantisek Sumsal <fsumsal@redhat.com>
Date: Mon, 27 Nov 2023 15:20:47 +0100
Subject: [PATCH] fstab-generator: allow overriding /etc/fstab with
 $SYSTEMD_FSTAB

Based on: ed4ad4889723a9acdf75ed86f10cee0024bbbcbc
Related: RHEL-1087

rhel-only
---
 src/cryptsetup/cryptsetup.c           |  3 ++-
 src/fstab-generator/fstab-generator.c | 28 ++++++++++++++-------------
 src/remount-fs/remount-fs.c           |  5 +++--
 src/shared/fstab-util.c               |  4 ++--
 src/shared/fstab-util.h               |  4 ++++
 5 files changed, 26 insertions(+), 18 deletions(-)

diff --git a/src/cryptsetup/cryptsetup.c b/src/cryptsetup/cryptsetup.c
index 11162eb722..de4bc9579c 100644
--- a/src/cryptsetup/cryptsetup.c
+++ b/src/cryptsetup/cryptsetup.c
@@ -13,6 +13,7 @@
 #include "device-util.h"
 #include "escape.h"
 #include "fileio.h"
+#include "fstab-util.h"
 #include "log.h"
 #include "mount-util.h"
 #include "parse-util.h"
@@ -318,7 +319,7 @@ static char *disk_mount_point(const char *label) {
         if (asprintf(&device, "/dev/mapper/%s", label) < 0)
                 return NULL;
 
-        f = setmntent("/etc/fstab", "re");
+        f = setmntent(fstab_path(), "re");
         if (!f)
                 return NULL;
 
diff --git a/src/fstab-generator/fstab-generator.c b/src/fstab-generator/fstab-generator.c
index f24c1d29da..105ddd2fd0 100644
--- a/src/fstab-generator/fstab-generator.c
+++ b/src/fstab-generator/fstab-generator.c
@@ -105,15 +105,17 @@ static int add_swap(
         if (r < 0)
                 return log_error_errno(r, "Failed to generate unit name: %m");
 
-        r = generator_open_unit_file(arg_dest, "/etc/fstab", name, &f);
+        r = generator_open_unit_file(arg_dest, fstab_path(), name, &f);
         if (r < 0)
                 return r;
 
-        fputs("# Automatically generated by systemd-fstab-generator\n\n"
-              "[Unit]\n"
-              "SourcePath=/etc/fstab\n"
-              "Documentation=man:fstab(5) man:systemd-fstab-generator(8)\n\n"
-              "[Swap]\n", f);
+        fprintf(f,
+                "# Automatically generated by systemd-fstab-generator\n\n"
+                "[Unit]\n"
+                "SourcePath=%s\n"
+                "Documentation=man:fstab(5) man:systemd-fstab-generator(8)\n\n"
+                "[Swap]\n",
+                fstab_path());
 
         r = write_what(f, what);
         if (r < 0)
@@ -334,7 +336,7 @@ static int add_mount(
         if (r < 0)
                 return log_error_errno(r, "Failed to generate unit name: %m");
 
-        r = generator_open_unit_file(dest, "/etc/fstab", name, &f);
+        r = generator_open_unit_file(dest, fstab_path(), name, &f);
         if (r < 0)
                 return r;
 
@@ -451,7 +453,7 @@ static int add_mount(
 
                 fclose(f);
 
-                r = generator_open_unit_file(dest, "/etc/fstab", automount_name, &f);
+                r = generator_open_unit_file(dest, fstab_path(), automount_name, &f);
                 if (r < 0)
                         return r;
 
@@ -503,17 +505,17 @@ static int add_mount(
 
 static int parse_fstab(bool initrd) {
         _cleanup_endmntent_ FILE *f = NULL;
-        const char *fstab_path;
+        const char *fstab;
         struct mntent *me;
         int r = 0;
 
-        fstab_path = initrd ? "/sysroot/etc/fstab" : "/etc/fstab";
-        f = setmntent(fstab_path, "re");
+        fstab = initrd ? "/sysroot/etc/fstab" : fstab_path();
+        f = setmntent(fstab, "re");
         if (!f) {
                 if (errno == ENOENT)
                         return 0;
 
-                return log_error_errno(errno, "Failed to open %s: %m", fstab_path);
+                return log_error_errno(errno, "Failed to open %s: %m", fstab);
         }
 
         while ((me = getmntent(f))) {
@@ -592,7 +594,7 @@ static int parse_fstab(bool initrd) {
                                       me->mnt_passno,
                                       makefs*MAKEFS | growfs*GROWFS | noauto*NOAUTO | nofail*NOFAIL | automount*AUTOMOUNT,
                                       post,
-                                      fstab_path);
+                                      fstab);
                 }
 
                 if (r >= 0 && k < 0)
diff --git a/src/remount-fs/remount-fs.c b/src/remount-fs/remount-fs.c
index 9220a00215..5bcee999cc 100644
--- a/src/remount-fs/remount-fs.c
+++ b/src/remount-fs/remount-fs.c
@@ -9,6 +9,7 @@
 #include <unistd.h>
 
 #include "exit-status.h"
+#include "fstab-util.h"
 #include "log.h"
 #include "mount-setup.h"
 #include "mount-util.h"
@@ -39,14 +40,14 @@ int main(int argc, char *argv[]) {
 
         umask(0022);
 
-        f = setmntent("/etc/fstab", "re");
+        f = setmntent(fstab_path(), "re");
         if (!f) {
                 if (errno == ENOENT) {
                         r = 0;
                         goto finish;
                 }
 
-                r = log_error_errno(errno, "Failed to open /etc/fstab: %m");
+                r = log_error_errno(errno, "Failed to open %s: %m", fstab_path());
                 goto finish;
         }
 
diff --git a/src/shared/fstab-util.c b/src/shared/fstab-util.c
index 6fd9866c00..bc0c047509 100644
--- a/src/shared/fstab-util.c
+++ b/src/shared/fstab-util.c
@@ -21,7 +21,7 @@ int fstab_has_fstype(const char *fstype) {
         _cleanup_endmntent_ FILE *f = NULL;
         struct mntent *m;
 
-        f = setmntent("/etc/fstab", "re");
+        f = setmntent(fstab_path(), "re");
         if (!f)
                 return errno == ENOENT ? false : -errno;
 
@@ -41,7 +41,7 @@ int fstab_is_mount_point(const char *mount) {
         _cleanup_endmntent_ FILE *f = NULL;
         struct mntent *m;
 
-        f = setmntent("/etc/fstab", "re");
+        f = setmntent(fstab_path(), "re");
         if (!f)
                 return errno == ENOENT ? false : -errno;
 
diff --git a/src/shared/fstab-util.h b/src/shared/fstab-util.h
index 9820f78ca8..9ec6db068c 100644
--- a/src/shared/fstab-util.h
+++ b/src/shared/fstab-util.h
@@ -33,3 +33,7 @@ static inline bool fstab_test_yes_no_option(const char *opts, const char *yes_no
 }
 
 char *fstab_node_to_udev_node(const char *p);
+
+static inline const char *fstab_path(void) {
+        return secure_getenv("SYSTEMD_FSTAB") ?: "/etc/fstab";
+}