bootctl: clean up handling of files with no version information

get_file_version() would return:
- various negative errors if the file could not be accessed or if it was not a
  regular file
- 0/NULL if the file was too small
- -ESRCH or -EINVAL if the file did not contain the marker
- -ENOMEM or permissions errors
-  1 if the marker was found

bootctl status iterates over /EFI/{systemd,BOOT}/*.efi and checks if the files
contain a systemd-boot version tag. Resource or permission errors should be
fatal, but lack of version information should be silently ignored.

OTOH, when updating or installing bootloader files, the version is expected
to be present.

get_file_version() is changed to return -ESRCH if the version is unavailable,
and other errnos for permission or resource errors.

The logging is reworked to always display an error if encountered, but also
to log the status at debug level what the result of the version inquiry is.
This makes it figure out what is going on:
  /efi/EFI/systemd/systemd-bootx64.efi: EFI binary LoaderInfo marker: "systemd-boot 253-6.fc38"
  /efi/EFI/BOOT/BOOTfbx64.efi: EFI binary has no LoaderInfo marker.
  /efi/EFI/BOOT/BOOTIA32.EFI: EFI binary has no LoaderInfo marker.
  /efi/EFI/BOOT/BOOTX64.EFI: EFI binary LoaderInfo marker: "systemd-boot 253-6.fc38"

Replaces #27034.
Fixes https://github.com/NixOS/nixpkgs/issues/223579.

3 files changed, 42 insertions, 31 deletions

diff --git a/src/boot/bootctl-install.c b/src/boot/bootctl-install.c
index a50f984a23..dc8596fa05 100644
--- a/src/boot/bootctl-install.c
+++ b/src/boot/bootctl-install.c
@@ -189,29 +189,29 @@ static int version_check(int fd_from, const char *from, int fd_to, const char *t
         assert(to);
 
         r = get_file_version(fd_from, &a);
+        if (r == -ESRCH)
+                return log_notice_errno(r, "Source file \"%s\" does not carry version information!", from);
         if (r < 0)
                 return r;
-        if (r == 0)
-                return log_notice_errno(SYNTHETIC_ERRNO(EREMOTE),
-                                       "Source file \"%s\" does not carry version information!",
-                                       from);
 
         r = get_file_version(fd_to, &b);
+        if (r == -ESRCH)
+                return log_notice_errno(r, "Skipping \"%s\", it's owned by another boot loader (no version info found).",
+                                        to);
         if (r < 0)
                 return r;
-        if (r == 0 || compare_product(a, b) != 0)
-                return log_notice_errno(SYNTHETIC_ERRNO(EREMOTE),
-                                        "Skipping \"%s\", since it's owned by another boot loader.",
-                                        to);
+        if (compare_product(a, b) != 0)
+                return log_notice_errno(SYNTHETIC_ERRNO(ESRCH),
+                                        "Skipping \"%s\", it's owned by another boot loader.", to);
 
         r = compare_version(a, b);
         log_debug("Comparing versions: \"%s\" %s \"%s", a, comparison_operator(r), b);
         if (r < 0)
                 return log_warning_errno(SYNTHETIC_ERRNO(ESTALE),
-                                         "Skipping \"%s\", since newer boot loader version in place already.", to);
+                                         "Skipping \"%s\", newer boot loader version in place already.", to);
         if (r == 0)
                 return log_info_errno(SYNTHETIC_ERRNO(ESTALE),
-                                      "Skipping \"%s\", since same boot loader version in place already.", to);
+                                      "Skipping \"%s\", same boot loader version in place already.", to);
 
         return 0;
 }
@@ -415,7 +415,7 @@ static int install_binaries(const char *esp_path, const char *arch, bool force)
                 k = copy_one_file(esp_path, de->d_name, force);
                 /* Don't propagate an error code if no update necessary, installed version already equal or
                  * newer version, or other boot loader in place. */
-                if (arg_graceful && IN_SET(k, -ESTALE, -EREMOTE))
+                if (arg_graceful && IN_SET(k, -ESTALE, -ESRCH))
                         continue;
                 if (k < 0 && r == 0)
                         r = k;
@@ -852,9 +852,11 @@ static int remove_boot_efi(const char *esp_path) {
                         return log_error_errno(errno, "Failed to open \"%s/%s\" for reading: %m", p, de->d_name);
 
                 r = get_file_version(fd, &v);
+                if (r == -ESRCH)
+                        continue;  /* No version information */
                 if (r < 0)
                         return r;
-                if (r > 0 && startswith(v, "systemd-boot ")) {
+                if (startswith(v, "systemd-boot ")) {
                         r = unlinkat(dirfd(d), de->d_name, 0);
                         if (r < 0)
                                 return log_error_errno(errno, "Failed to remove \"%s/%s\": %m", p, de->d_name);
diff --git a/src/boot/bootctl-status.c b/src/boot/bootctl-status.c
index cc0c3ad34a..3da6478259 100644
--- a/src/boot/bootctl-status.c
+++ b/src/boot/bootctl-status.c
@@ -207,7 +207,7 @@ static int enumerate_binaries(
                 return log_error_errno(r, "Failed to read \"%s/%s\": %m", esp_path, path);
 
         FOREACH_DIRENT(de, d, break) {
-                _cleanup_free_ char *v = NULL;
+                _cleanup_free_ char *v = NULL, *filename = NULL;
                 _cleanup_close_ int fd = -EBADF;
 
                 if (!endswith_no_case(de->d_name, ".efi"))
@@ -216,15 +216,23 @@ static int enumerate_binaries(
                 if (prefix && !startswith_no_case(de->d_name, prefix))
                         continue;
 
+                filename = path_join(p, de->d_name);
+                if (!filename)
+                        return log_oom();
+                LOG_SET_PREFIX(filename);
+
                 fd = openat(dirfd(d), de->d_name, O_RDONLY|O_CLOEXEC);
                 if (fd < 0)
-                        return log_error_errno(errno, "Failed to open \"%s/%s\" for reading: %m", p, de->d_name);
+                        return log_error_errno(errno, "Failed to open file for reading: %m");
 
                 r = get_file_version(fd, &v);
+                if (r == -ESRCH) /* Not the file we are looking for. */
+                        continue;
                 if (r < 0)
                         return r;
 
-                if (*previous) { /* let's output the previous entry now, since now we know that there will be one more, and can draw the tree glyph properly */
+                if (*previous) { /* Let's output the previous entry now, since now we know that there will be
+                                  * one more, and can draw the tree glyph properly. */
                         printf("         %s %s%s\n",
                                *is_first ? "File:" : "     ",
                                special_glyph(SPECIAL_GLYPH_TREE_BRANCH), *previous);
diff --git a/src/boot/bootctl-util.c b/src/boot/bootctl-util.c
index 6cae9b4deb..d93cc20318 100644
--- a/src/boot/bootctl-util.c
+++ b/src/boot/bootctl-util.c
@@ -63,7 +63,7 @@ int get_file_version(int fd, char **ret) {
         struct stat st;
         char *buf;
         const char *s, *e;
-        char *x = NULL;
+        char *marker = NULL;
         int r;
 
         assert(fd >= 0);
@@ -73,42 +73,43 @@ int get_file_version(int fd, char **ret) {
                 return log_error_errno(errno, "Failed to stat EFI binary: %m");
 
         r = stat_verify_regular(&st);
-        if (r < 0)
-                return log_error_errno(r, "EFI binary is not a regular file: %m");
-
-        if (st.st_size < 27 || file_offset_beyond_memory_size(st.st_size)) {
-                *ret = NULL;
-                return 0;
+        if (r < 0) {
+                log_debug_errno(r, "EFI binary is not a regular file, assuming no version information: %m");
+                return -ESRCH;
         }
 
+        if (st.st_size < 27 || file_offset_beyond_memory_size(st.st_size))
+                return log_debug_errno(SYNTHETIC_ERRNO(ESRCH),
+                                       "EFI binary size too %s: %"PRIi64,
+                                       st.st_size < 27 ? "small" : "large", st.st_size);
+
         buf = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
         if (buf == MAP_FAILED)
-                return log_error_errno(errno, "Failed to memory map EFI binary: %m");
+                return log_error_errno(errno, "Failed to mmap EFI binary: %m");
 
         s = mempmem_safe(buf, st.st_size - 8, "#### LoaderInfo: ", 17);
         if (!s) {
-                r = -ESRCH;
+                r = log_debug_errno(SYNTHETIC_ERRNO(ESRCH), "EFI binary has no LoaderInfo marker.");
                 goto finish;
         }
 
         e = memmem_safe(s, st.st_size - (s - buf), " ####", 5);
         if (!e || e - s < 3) {
-                r = log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Malformed version string.");
+                r = log_error_errno(SYNTHETIC_ERRNO(EINVAL), "EFI binary has malformed LoaderInfo marker.");
                 goto finish;
         }
 
-        x = strndup(s, e - s);
-        if (!x) {
+        marker = strndup(s, e - s);
+        if (!marker) {
                 r = log_oom();
                 goto finish;
         }
-        r = 1;
 
+        log_debug("EFI binary LoaderInfo marker: \"%s\"", marker);
+        r = 0;
+        *ret = marker;
 finish:
         (void) munmap(buf, st.st_size);
-        if (r >= 0)
-                *ret = x;
-
         return r;
 }