xzdec: Tweak coding style and comments.

diff --git a/src/xzdec/xzdec.c b/src/xzdec/xzdec.c
index ef8c80f31358ff0dc26ff33e008b86845911d30a..adfa17e84b1b6d612af89ab02fb839e9fc670191 100644 (file)
--- a/src/xzdec/xzdec.c
+++ b/src/xzdec/xzdec.c
@@ -313,10 +313,12 @@ sandbox_enter(int src_fd)
                        STDIN_FILENO, cap_rights_clear(&rights)))
                goto error;
 
-       if (cap_rights_limit(STDOUT_FILENO, cap_rights_init(&rights, CAP_WRITE)))
+       if (cap_rights_limit(STDOUT_FILENO, cap_rights_init(&rights,
+                       CAP_WRITE)))
                goto error;
 
-       if (cap_rights_limit(STDERR_FILENO, cap_rights_init(&rights, CAP_WRITE)))
+       if (cap_rights_limit(STDERR_FILENO, cap_rights_init(&rights,
+                       CAP_WRITE)))
                goto error;
 
 #elif defined(HAVE_PLEDGE)
@@ -325,6 +327,7 @@ sandbox_enter(int src_fd)
                goto error;
 
        (void)src_fd;
+
 #elif defined(HAVE_LINUX_LANDLOCK)
        int landlock_abi = syscall(SYS_landlock_create_ruleset,
                        (void *)NULL, 0, LANDLOCK_CREATE_RULESET_VERSION);
@@ -351,6 +354,7 @@ sandbox_enter(int src_fd)
        }
 
        (void)src_fd;
+
 #else
 #      error ENABLE_SANDBOX is defined but no sandboxing method was found.
 #endif
@@ -367,6 +371,7 @@ error:
        if (errno == ENOSYS)
                return;
 #endif
+
        my_errorf("Failed to enable the sandbox");
        exit(EXIT_FAILURE);
 }
@@ -390,8 +395,14 @@ main(int argc, char **argv)
 #endif
 
 #ifdef HAVE_LINUX_LANDLOCK
-       // Prevent the process from gaining new privileges. The return
-       // is ignored to keep compatibility with old kernels.
+       // Prevent the process from gaining new privileges. This must be done
+       // before landlock_restrict_self(2) but since we will never need new
+       // privileges, this call can be done here already.
+       //
+       // This is supported since Linux 3.5. Ignore the return value to
+       // keep compatibility with old kernels. landlock_restrict_self(2)
+       // will fail if the no_new_privs attribute isn't set, thus if prctl()
+       // fails here the error will still be detected when it matters.
        (void)prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
 #endif
 
@@ -438,19 +449,18 @@ main(int argc, char **argv)
                                }
                        }
 #ifdef ENABLE_SANDBOX
-                       // Enable the sandbox for the last file. When the
-                       // strict sandbox is enabled the process can no
-                       // longer open additional files. It is likely that
-                       // the most common way to use xzdec is to
-                       // decompress a single file, so this fully protects
-                       // most use cases.
+                       // Enable the strict sandbox for the last file.
+                       // Then the process can no longer open additional
+                       // files. The typical xzdec use case is to decompress
+                       // a single file so this way the strictest sandboxing
+                       // is used in most cases.
                        if (optind == argc - 1)
                                sandbox_enter(fileno(src_file));
 #endif
                        uncompress(&strm, src_file, src_name);
 
                        if (src_file != stdin)
-                               fclose(src_file);
+                               (void)fclose(src_file);
                } while (++optind < argc);
        }