bootctl: split-out entry token related definitions into boot-entry.[ch]

No functional change, just preparation for later commits.
These can be used in kernel-install later.

Note, unlike the our usual coding style, the arguments for
boot_entry_token_ensure() and parse_boot_entry_token_type() are
referenced, updated, and may freed, hence, always pass initialized
values. That's why they are not named as 'ret_xyz'.

3 files changed, 250 insertions, 0 deletions

diff --git a/src/shared/boot-entry.c b/src/shared/boot-entry.c
new file mode 100644
index 0000000000..90e72bd754
--- /dev/null
+++ b/src/shared/boot-entry.c
@@ -0,0 +1,224 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "boot-entry.h"
+#include "fileio.h"
+#include "id128-util.h"
+#include "os-util.h"
+#include "path-util.h"
+#include "string-util.h"
+#include "utf8.h"
+
+bool boot_entry_token_valid(const char *p) {
+        return utf8_is_valid(p) && string_is_safe(p) && filename_is_valid(p);
+}
+
+static int entry_token_load(const char *root, const char *etc_kernel, BootEntryTokenType *type, char **token) {
+        _cleanup_free_ char *buf = NULL, *p = NULL;
+        int r;
+
+        assert(type);
+        assert(*type == BOOT_ENTRY_TOKEN_AUTO);
+        assert(token);
+
+        if (!etc_kernel)
+                return 0;
+
+        p = path_join(root, etc_kernel, "entry-token");
+        if (!p)
+                return log_oom();
+
+        r = read_one_line_file(p, &buf);
+        if (r == -ENOENT)
+                return 0;
+        if (r < 0)
+                return log_error_errno(r, "Failed to read %s: %m", p);
+
+        if (isempty(buf))
+                return 0;
+
+        if (!boot_entry_token_valid(buf)) {
+                log_debug("Invalid entry token specified in %s, ignoring.", p);
+                return 0;
+        }
+
+        *token = TAKE_PTR(buf);
+        *type = BOOT_ENTRY_TOKEN_LITERAL;
+        return 1;
+}
+
+static int entry_token_from_machine_id(sd_id128_t machine_id, BootEntryTokenType *type, char **token) {
+        char *p;
+
+        assert(type);
+        assert(IN_SET(*type, BOOT_ENTRY_TOKEN_AUTO, BOOT_ENTRY_TOKEN_MACHINE_ID));
+        assert(token);
+
+        if (sd_id128_is_null(machine_id))
+                return 0;
+
+        p = strdup(SD_ID128_TO_STRING(machine_id));
+        if (!p)
+                return log_oom();
+
+        *token = p;
+        *type = BOOT_ENTRY_TOKEN_MACHINE_ID;
+        return 1;
+}
+
+static int entry_token_from_os_release(const char *root, BootEntryTokenType *type, char **token) {
+        _cleanup_free_ char *id = NULL, *image_id = NULL;
+        int r;
+
+        assert(type);
+        assert(IN_SET(*type, BOOT_ENTRY_TOKEN_AUTO, BOOT_ENTRY_TOKEN_OS_IMAGE_ID, BOOT_ENTRY_TOKEN_OS_ID));
+        assert(token);
+
+        switch (*type) {
+        case BOOT_ENTRY_TOKEN_AUTO:
+                r = parse_os_release(root,
+                                     "IMAGE_ID", &image_id,
+                                     "ID",       &id);
+                break;
+
+        case BOOT_ENTRY_TOKEN_OS_IMAGE_ID:
+                r = parse_os_release(root, "IMAGE_ID", &image_id);
+                break;
+
+        case BOOT_ENTRY_TOKEN_OS_ID:
+                r = parse_os_release(root, "ID", &id);
+                break;
+
+        default:
+                assert_not_reached();
+        }
+        if (r == -ENOENT)
+                return 0;
+        if (r < 0)
+                return log_error_errno(r, "Failed to load %s/etc/os-release: %m", strempty(root));
+
+        if (!isempty(image_id) && boot_entry_token_valid(image_id)) {
+                *token = TAKE_PTR(image_id);
+                *type = BOOT_ENTRY_TOKEN_OS_IMAGE_ID;
+                return 1;
+        }
+
+        if (!isempty(id) && boot_entry_token_valid(id)) {
+                *token = TAKE_PTR(id);
+                *type = BOOT_ENTRY_TOKEN_OS_ID;
+                return 1;
+        }
+
+        return 0;
+}
+
+int boot_entry_token_ensure(
+                const char *root,
+                const char *etc_kernel,
+                sd_id128_t machine_id,
+                BootEntryTokenType *type,
+                char **token) {
+
+        int r;
+
+        assert(type);
+        assert(token);
+
+        if (*token)
+                return 0; /* Already set. */
+
+        switch (*type) {
+
+        case BOOT_ENTRY_TOKEN_AUTO:
+                r = entry_token_load(root, etc_kernel, type, token);
+                if (r != 0)
+                        return r;
+
+                r = entry_token_from_machine_id(machine_id, type, token);
+                if (r != 0)
+                        return r;
+
+                r = entry_token_from_os_release(root, type, token);
+                if (r != 0)
+                        return r;
+
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "No machine ID set, and %s/etc/os-release carries no ID=/IMAGE_ID= fields.",
+                                       strempty(root));
+
+        case BOOT_ENTRY_TOKEN_MACHINE_ID:
+                r = entry_token_from_machine_id(machine_id, type, token);
+                if (r != 0)
+                        return r;
+
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "No machine ID set.");
+
+        case BOOT_ENTRY_TOKEN_OS_IMAGE_ID:
+                r = entry_token_from_os_release(root, type, token);
+                if (r != 0)
+                        return r;
+
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "IMAGE_ID= field not set in %s/etc/os-release.",
+                                       strempty(root));
+
+        case BOOT_ENTRY_TOKEN_OS_ID:
+                r = entry_token_from_os_release(root, type, token);
+                if (r != 0)
+                        return r;
+
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                       "ID= field not set in %s/etc/os-release.",
+                                       strempty(root));
+
+        case BOOT_ENTRY_TOKEN_LITERAL:
+                /* In this case, the token should be already set by the user input. */
+                return -EINVAL;
+
+        default:
+                assert_not_reached();
+        }
+}
+
+int parse_boot_entry_token_type(const char *s, BootEntryTokenType *type, char **token) {
+        assert(s);
+        assert(type);
+        assert(token);
+
+        /*
+         * This function is intended to be used in command line parsers, to handle token that are passed in.
+         *
+         * NOTE THAT THIS WILL FREE THE PREVIOUS ARGUMENT POINTER ON SUCCESS!
+         * Hence, do not pass in uninitialized pointers.
+         */
+
+        if (streq(s, "machine-id")) {
+                *type = BOOT_ENTRY_TOKEN_MACHINE_ID;
+                *token = mfree(*token);
+                return 0;
+        }
+
+        if (streq(s, "os-image-id")) {
+                *type = BOOT_ENTRY_TOKEN_OS_IMAGE_ID;
+                *token = mfree(*token);
+                return 0;
+        }
+
+        if (streq(s, "os-id")) {
+                *type = BOOT_ENTRY_TOKEN_OS_ID;
+                *token = mfree(*token);
+                return 0;
+        }
+
+        const char *e = startswith(s, "literal:");
+        if (e) {
+                if (!boot_entry_token_valid(e))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                                               "Invalid entry token literal is specified for --entry-token=.");
+
+                *type = BOOT_ENTRY_TOKEN_LITERAL;
+                return free_and_strdup_warn(token, e);
+        }
+
+        return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
+                               "Unexpected parameter for --entry-token=: %s", s);
+}
diff --git a/src/shared/boot-entry.h b/src/shared/boot-entry.h
new file mode 100644
index 0000000000..97b30702bc
--- /dev/null
+++ b/src/shared/boot-entry.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include <stdbool.h>
+
+#include "sd-id128.h"
+
+typedef enum BootEntryTokenType {
+        BOOT_ENTRY_TOKEN_MACHINE_ID,
+        BOOT_ENTRY_TOKEN_OS_IMAGE_ID,
+        BOOT_ENTRY_TOKEN_OS_ID,
+        BOOT_ENTRY_TOKEN_LITERAL,
+        BOOT_ENTRY_TOKEN_AUTO,
+} BootEntryTokenType;
+
+bool boot_entry_token_valid(const char *p);
+
+int boot_entry_token_ensure(
+                const char *root,
+                const char *etc_kernel,   /* will be prefixed with root, typically /etc/kernel. */
+                sd_id128_t machine_id,
+                BootEntryTokenType *type, /* input and output */
+                char **token);            /* output, but do not pass uninitialized value. */
+
+int parse_boot_entry_token_type(const char *s, BootEntryTokenType *type, char **token);
diff --git a/src/shared/meson.build b/src/shared/meson.build
index 9342d25273..cb0697d1b9 100644
--- a/src/shared/meson.build
+++ b/src/shared/meson.build
@@ -10,6 +10,7 @@ shared_sources = files(
         'bitmap.c',
         'blockdev-util.c',
         'bond-util.c',
+        'boot-entry.c',
         'boot-timestamps.c',
         'bootspec.c',
         'bpf-dlopen.c',