env-file: port write_env_file() to label_ops_pre()

Let's make more use of label_ops_pre()/label_ops_post(), and replace
write_env_file_label() by a flag to write_env_file().

This simplifies and normalizes the code.

This also makes one relevant change: it sets the new
WRITE_ENV_FILE_LABEL flag in firstboot.c when we write locale.conf,
where we previously did not (but should have). This should address one
detail of #37857.

src/basic/env-file.c

@@ -5,10 +5,12 @@
 #include "alloc-util.h"
 #include "env-file.h"
 #include "env-util.h"
+#include "errno-util.h"
 #include "escape.h"
 #include "fd-util.h"
 #include "fileio.h"
 #include "fs-util.h"
+#include "label.h"
 #include "log.h"
 #include "string-util.h"
 #include "strv.h"
@@ -629,7 +631,7 @@ static void write_env_var(FILE *f, const char *v) {
         fputc_unlocked('\n', f);
 }
 
-int write_env_file(int dir_fd, const char *fname, char **headers, char **l) {
+int write_env_file(int dir_fd, const char *fname, char **headers, char **l, WriteEnvFileFlags flags) {
         _cleanup_fclose_ FILE *f = NULL;
         _cleanup_free_ char *p = NULL;
         int r;
@@ -637,7 +639,18 @@ int write_env_file(int dir_fd, const char *fname, char **headers, char **l) {
         assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
         assert(fname);
 
+        bool call_label_ops_post = false;
+        if (FLAGS_SET(flags, WRITE_ENV_FILE_LABEL)) {
+                r = label_ops_pre(dir_fd, fname, S_IFREG);
+                if (r < 0)
+                        return r;
+
+                call_label_ops_post = true;
+        }
+
         r = fopen_tmpfile_linkable_at(dir_fd, fname, O_WRONLY|O_CLOEXEC, &p, &f);
+        if (call_label_ops_post)
+                RET_GATHER(r, label_ops_post(f ? fileno(f) : dir_fd, f ? NULL : fname, /* created= */ !!f));
         if (r < 0)
                 return r;
 
@@ -672,5 +685,5 @@ int write_vconsole_conf(int dir_fd, const char *fname, char **l) {
                 "# Written by systemd-localed(8) or systemd-firstboot(1), read by systemd-localed",
                 "# and systemd-vconsole-setup(8). Use localectl(1) to update this file.");
 
-        return write_env_file(dir_fd, fname, headers, l);
+        return write_env_file(dir_fd, fname, headers, l, WRITE_ENV_FILE_LABEL);
 }

src/basic/env-file.h

@@ -15,7 +15,11 @@ int load_env_file_pairs_fd(int fd, const char *fname, char ***ret);
 
 int merge_env_file(char ***env, FILE *f, const char *fname);
 
-int write_env_file(int dir_fd, const char *fname, char **headers, char **l);
+typedef enum WriteEnvFileFlags {
+        WRITE_ENV_FILE_LABEL = 1 << 0,
+} WriteEnvFileFlags;
+
+int write_env_file(int dir_fd, const char *fname, char **headers, char **l, WriteEnvFileFlags flags);
 
 int write_vconsole_conf(int dir_fd, const char *fname, char **l);
 

src/firstboot/firstboot.c

@@ -448,7 +448,12 @@ static int process_locale(int rfd) {
 
         locales[i] = NULL;
 
-        r = write_env_file(pfd, f, NULL, locales);
+        r = write_env_file(
+                        pfd,
+                        f,
+                        /* headers= */ NULL,
+                        locales,
+                        WRITE_ENV_FILE_LABEL);
         if (r < 0)
                 return log_error_errno(r, "Failed to write /etc/locale.conf: %m");
 

src/hostname/hostnamed.c

@@ -21,7 +21,6 @@
 #include "daemon-util.h"
 #include "device-private.h"
 #include "env-file.h"
-#include "env-file-label.h"
 #include "env-util.h"
 #include "extract-word.h"
 #include "fileio.h"
@@ -860,7 +859,12 @@ static int context_write_data_machine_info(Context *c) {
                 return 0;
         }
 
-        r = write_env_file_label(AT_FDCWD, "/etc/machine-info", NULL, l);
+        r = write_env_file(
+                        AT_FDCWD,
+                        "/etc/machine-info",
+                        /* headers= */ NULL,
+                        l,
+                        WRITE_ENV_FILE_LABEL);
         if (r < 0)
                 return r;
 

src/locale/localed-util.c

@@ -8,7 +8,6 @@
 #include "alloc-util.h"
 #include "copy.h"
 #include "env-file.h"
-#include "env-file-label.h"
 #include "errno-util.h"
 #include "extract-word.h"
 #include "fd-util.h"
@@ -315,7 +314,7 @@ int vconsole_write_data(Context *c) {
                 return 0;
         }
 
-        r = write_vconsole_conf_label(l);
+        r = write_vconsole_conf(AT_FDCWD, "/etc/vconsole.conf", l);
         if (r < 0)
                 return r;
 

src/shared/env-file-label.c

@@ -1,35 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1-or-later */
-
-#include <sys/stat.h>
-
-#include "env-file.h"
-#include "env-file-label.h"
-#include "selinux-util.h"
-
-int write_env_file_label(int dir_fd, const char *fname, char **headers, char **l) {
-        int r;
-
-        r = mac_selinux_create_file_prepare(fname, S_IFREG);
-        if (r < 0)
-                return r;
-
-        r = write_env_file(dir_fd, fname, headers, l);
-
-        mac_selinux_create_file_clear();
-
-        return r;
-}
-
-int write_vconsole_conf_label(char **l) {
-        int r;
-
-        r = mac_selinux_create_file_prepare("/etc/vconsole.conf", S_IFREG);
-        if (r < 0)
-                return r;
-
-        r = write_vconsole_conf(AT_FDCWD, "/etc/vconsole.conf", l);
-
-        mac_selinux_create_file_clear();
-
-        return r;
-}

src/shared/env-file-label.h

@@ -1,12 +0,0 @@
-/* SPDX-License-Identifier: LGPL-2.1-or-later */
-#pragma once
-
-#include "forward.h"
-
-/* These functions are split out of fileio.h (and not for example just flags to the functions they wrap) in order to
- * optimize linking: This way, -lselinux is needed only for the callers of these functions that need selinux, but not
- * for all */
-
-int write_env_file_label(int dir_fd, const char *fname, char **headers, char **l);
-
-int write_vconsole_conf_label(char **l);

src/shared/locale-setup.c

@@ -6,7 +6,6 @@
 
 #include "alloc-util.h"
 #include "env-file.h"
-#include "env-file-label.h"
 #include "env-util.h"
 #include "errno-util.h"
 #include "fd-util.h"
@@ -212,7 +211,12 @@ int locale_context_save(LocaleContext *c, char ***ret_set, char ***ret_unset) {
                 return 0;
         }
 
-        r = write_env_file_label(AT_FDCWD, "/etc/locale.conf", NULL, set);
+        r = write_env_file(
+                        AT_FDCWD,
+                        "/etc/locale.conf",
+                        /* headers= */ NULL,
+                        set,
+                        WRITE_ENV_FILE_LABEL);
         if (r < 0)
                 return r;
 

src/shared/meson.build

@@ -68,7 +68,6 @@ shared_sources = files(
         'efi-loader.c',
         'elf-util.c',
         'enable-mempool.c',
-        'env-file-label.c',
         'ethtool-util.c',
         'exec-util.c',
         'exit-status.c',

src/test/test-env-file.c

@@ -171,7 +171,7 @@ TEST(write_and_load_env_file) {
                 assert_se(tempfn_random_child(NULL, NULL, &p) >= 0);
 
                 assert_se(j = strjoin("TEST=", v));
-                assert_se(write_env_file(AT_FDCWD, p, STRV_MAKE("# header 1", "", "# header 2"), STRV_MAKE(j)) >= 0);
+                assert_se(write_env_file(AT_FDCWD, p, STRV_MAKE("# header 1", "", "# header 2"), STRV_MAKE(j), /* flags= */ 0) >= 0);
 
                 assert_se(cmd = strjoin(". ", p, " && /bin/echo -n \"$TEST\""));
                 assert_se(f = popen(cmd, "re"));

src/test/test-fileio.c

@@ -143,7 +143,7 @@ TEST(parse_env_file) {
                 assert_se(fd >= 0);
         }
 
-        r = write_env_file(AT_FDCWD, p, NULL, a);
+        r = write_env_file(AT_FDCWD, p, /* headers= */ NULL, a, /* flags= */ 0);
         assert_se(r >= 0);
 
         r = load_env_file(NULL, p, &b);
@@ -206,7 +206,7 @@ TEST(parse_multiline_env_file) {
                 assert_se(fd >= 0);
         }
 
-        r = write_env_file(AT_FDCWD, p, NULL, a);
+        r = write_env_file(AT_FDCWD, p, /* headers= */ NULL, a, /* flags= */ 0);
         assert_se(r >= 0);
 
         r = load_env_file(NULL, p, &b);