shared: extract edit-util from systemctl-edit

1 files changed, 261 insertions, 0 deletions

diff --git a/src/shared/edit-util.c b/src/shared/edit-util.c
new file mode 100644
index 0000000000..6ef6fa984f
--- /dev/null
+++ b/src/shared/edit-util.c
@@ -0,0 +1,261 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <stdio.h>
+
+#include "alloc-util.h"
+#include "copy.h"
+#include "edit-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "mkdir-label.h"
+#include "path-util.h"
+#include "process-util.h"
+#include "selinux-util.h"
+#include "stat-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "tmpfile-util.h"
+
+void edit_file_free_all(EditFile **f) {
+        if (!f || !*f)
+                return;
+
+        for (EditFile *i = *f; i->path; i++) {
+                free(i->path);
+                free(i->tmp);
+        }
+
+        free(*f);
+}
+
+int create_edit_temp_file(
+                const char *new_path,
+                const char *original_path,
+                char ** const original_unit_paths,
+                const char *marker_start,
+                const char *marker_end,
+                char **ret_tmp_fn,
+                unsigned *ret_edit_line) {
+
+        _cleanup_free_ char *t = NULL;
+        unsigned ln = 1;
+        int r;
+
+        assert(new_path);
+        assert(ret_tmp_fn);
+        assert(ret_edit_line);
+
+        r = tempfn_random(new_path, NULL, &t);
+        if (r < 0)
+                return log_error_errno(r, "Failed to determine temporary filename for \"%s\": %m", new_path);
+
+        r = mkdir_parents_label(new_path, 0755);
+        if (r < 0)
+                return log_error_errno(r, "Failed to create directories for \"%s\": %m", new_path);
+
+        if (original_path) {
+                r = mac_selinux_create_file_prepare(new_path, S_IFREG);
+                if (r < 0)
+                        return r;
+
+                r = copy_file(original_path, t, 0, 0644, 0, 0, COPY_REFLINK);
+                if (r == -ENOENT) {
+                        r = touch(t);
+                        mac_selinux_create_file_clear();
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to create temporary file \"%s\": %m", t);
+                } else {
+                        mac_selinux_create_file_clear();
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to create temporary file for \"%s\": %m", new_path);
+                }
+        } else if (original_unit_paths) {
+                _cleanup_free_ char *new_contents = NULL;
+                _cleanup_fclose_ FILE *f = NULL;
+
+                r = mac_selinux_create_file_prepare(new_path, S_IFREG);
+                if (r < 0)
+                        return r;
+
+                f = fopen(t, "we");
+                mac_selinux_create_file_clear();
+                if (!f)
+                        return log_error_errno(errno, "Failed to open \"%s\": %m", t);
+
+                if (fchmod(fileno(f), 0644) < 0)
+                        return log_error_errno(errno, "Failed to change mode of \"%s\": %m", t);
+
+                r = read_full_file(new_path, &new_contents, NULL);
+                if (r < 0 && r != -ENOENT)
+                        return log_error_errno(r, "Failed to read \"%s\": %m", new_path);
+
+                fprintf(f,
+                        "### Editing %s\n"
+                        "%s\n"
+                        "\n"
+                        "%s%s"
+                        "\n"
+                        "%s\n",
+                        new_path,
+                        strempty(marker_start),
+                        strempty(new_contents),
+                        new_contents && endswith(new_contents, "\n") ? "" : "\n",
+                        strempty(marker_end));
+
+                ln = 4; /* start editing at the contents */
+
+                /* Add a comment with the contents of the original unit files */
+                STRV_FOREACH(path, original_unit_paths) {
+                        _cleanup_free_ char *contents = NULL;
+
+                        /* Skip the file that's being edited */
+                        if (path_equal(*path, new_path))
+                                continue;
+
+                        r = read_full_file(*path, &contents, NULL);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to read \"%s\": %m", *path);
+
+                        fprintf(f, "\n\n### %s", *path);
+                        if (!isempty(contents)) {
+                                _cleanup_free_ char *commented_contents = NULL;
+
+                                commented_contents = strreplace(strstrip(contents), "\n", "\n# ");
+                                if (!commented_contents)
+                                        return log_oom();
+                                fprintf(f, "\n# %s", commented_contents);
+                        }
+                }
+
+                r = fflush_and_check(f);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to create temporary file \"%s\": %m", t);
+        }
+
+        *ret_tmp_fn = TAKE_PTR(t);
+        *ret_edit_line = ln;
+
+        return 0;
+}
+
+int run_editor(const EditFile *files) {
+        int r;
+
+        assert(files);
+
+        r = safe_fork("(editor)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG|FORK_WAIT, NULL);
+        if (r < 0)
+                return r;
+        if (r == 0) {
+                size_t n_editor_args = 0, i = 1, argc;
+                char **editor_args = NULL, **args;
+                const char *editor;
+
+                /* SYSTEMD_EDITOR takes precedence over EDITOR which takes precedence over VISUAL.  If
+                 * neither SYSTEMD_EDITOR nor EDITOR nor VISUAL are present, we try to execute well known
+                 * editors. */
+                editor = getenv("SYSTEMD_EDITOR");
+                if (!editor)
+                        editor = getenv("EDITOR");
+                if (!editor)
+                        editor = getenv("VISUAL");
+
+                if (isempty(editor))
+                        argc = 1;
+                else {
+                        editor_args = strv_split(editor, WHITESPACE);
+                        if (!editor_args) {
+                                (void) log_oom();
+                                _exit(EXIT_FAILURE);
+                        }
+                        n_editor_args = strv_length(editor_args);
+                        argc = n_editor_args;
+                }
+
+                for (const EditFile *f = files; f->path; f++)
+                        argc += 2;
+
+                args = newa(char*, argc + 1);
+
+                if (n_editor_args > 0) {
+                        args[0] = editor_args[0];
+                        for (; i < n_editor_args; i++)
+                                args[i] = editor_args[i];
+                }
+
+                if (files[0].path && files[0].line > 1 && !files[1].path) {
+                        /* If editing a single file only, use the +LINE syntax to put cursor on the right line */
+                        if (asprintf(args + i, "+%u", files[0].line) < 0) {
+                                (void) log_oom();
+                                _exit(EXIT_FAILURE);
+                        }
+
+                        i++;
+                        args[i++] = files[0].tmp;
+                } else
+                        for (const EditFile *f = files; f->path; f++)
+                                args[i++] = f->tmp;
+
+                args[i] = NULL;
+
+                if (n_editor_args > 0)
+                        execvp(args[0], (char* const*) args);
+
+                FOREACH_STRING(name, "editor", "nano", "vim", "vi") {
+                        args[0] = (char*) name;
+                        execvp(name, (char* const*) args);
+                        /* We do not fail if the editor doesn't exist because we want to try each one of them
+                         * before failing. */
+                        if (errno != ENOENT) {
+                                log_error_errno(errno, "Failed to execute %s: %m", name);
+                                _exit(EXIT_FAILURE);
+                        }
+                }
+
+                log_error("Cannot edit units, no editor available. Please set either $SYSTEMD_EDITOR, $EDITOR or $VISUAL.");
+                _exit(EXIT_FAILURE);
+        }
+
+        return 0;
+}
+
+int trim_edit_markers(const char *path, const char *marker_start, const char *marker_end) {
+        _cleanup_free_ char *old_contents = NULL, *new_contents = NULL;
+        char *contents_start, *contents_end;
+        const char *c = NULL;
+        int r;
+
+        /* Trim out the lines between the two markers */
+        r = read_full_file(path, &old_contents, NULL);
+        if (r < 0)
+                return log_error_errno(r, "Failed to read temporary file \"%s\": %m", path);
+
+        contents_start = strstr(old_contents, marker_start);
+        if (contents_start)
+                contents_start += strlen(marker_start);
+        else
+                contents_start = old_contents;
+
+        contents_end = strstr(contents_start, marker_end);
+        if (contents_end)
+                contents_end[0] = 0;
+
+        c = strstrip(contents_start);
+        if (isempty(c))
+                return 0; /* All gone now */
+
+        new_contents = strjoin(c, "\n"); /* Trim prefix and suffix, but ensure suffixed by single newline */
+        if (!new_contents)
+                return log_oom();
+
+        if (streq(old_contents, new_contents)) /* Don't touch the file if the above didn't change a thing */
+                return 1; /* Unchanged, but good */
+
+        r = write_string_file(path, new_contents, WRITE_STRING_FILE_CREATE | WRITE_STRING_FILE_TRUNCATE | WRITE_STRING_FILE_AVOID_NEWLINE);
+        if (r < 0)
+                return log_error_errno(r, "Failed to modify temporary file \"%s\": %m", path);
+
+        return 1; /* Changed, but good */
+}