util-lib: save/restore errno in cleanup calls

We should be careful with errno in cleanup functions, and not alter it
under any circumstances. In the safe_close cleanup handlers we are
already safe in that regard, but let's add similar protections on other
cleanup handlers that invoke system calls.

Why bother? Cleanup handlers insert code at function return in
non-obvious ways. Hence, code that sets errno and returns should not be
confused by us overrding the errno from a cleanup handler.

This is a paranoia fix only, I am not aware where this actually mattered
in real-life situations.

diff --git a/src/basic/fs-util.h b/src/basic/fs-util.h
index a7ba61625d89b56ae96bacbc14ef4eb9978bcc2b..82a5b2028db32a3542760ea6b778dd53faf52129 100644 (file)
--- a/src/basic/fs-util.h
+++ b/src/basic/fs-util.h
@@ -29,6 +29,7 @@
 #include <unistd.h>
 
 #include "time-util.h"
+#include "util.h"
 
 int unlink_noerrno(const char *path);
 
@@ -89,13 +90,14 @@ int chase_symlinks(const char *path_with_prefix, const char *root, unsigned flag
 
 /* Useful for usage with _cleanup_(), removes a directory and frees the pointer */
 static inline void rmdir_and_free(char *p) {
+        PROTECT_ERRNO;
         (void) rmdir(p);
         free(p);
 }
 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, rmdir_and_free);
 
 static inline void unlink_and_free(char *p) {
-        (void) unlink(p);
+        (void) unlink_noerrno(p);
         free(p);
 }
 DEFINE_TRIVIAL_CLEANUP_FUNC(char*, unlink_and_free);

diff --git a/src/basic/process-util.c b/src/basic/process-util.c
index ce6c0645bb20da202ff02a3560bf4d67cb2482c5..9fc546466558c2930edd4a92da3d76892348cd7f 100644 (file)
--- a/src/basic/process-util.c
+++ b/src/basic/process-util.c
@@ -796,6 +796,8 @@ void sigkill_wait(pid_t pid) {
 }
 
 void sigkill_waitp(pid_t *pid) {
+        PROTECT_ERRNO;
+
         if (!pid)
                 return;
         if (*pid <= 1)

diff --git a/src/basic/rm-rf.h b/src/basic/rm-rf.h
index 1127e326b2ba810c88836e62f8418d930a30b0a6..ad63e9be4070615a99efdf89657229497a11df16 100644 (file)
--- a/src/basic/rm-rf.h
+++ b/src/basic/rm-rf.h
@@ -22,6 +22,8 @@
 
 #include <sys/stat.h>
 
+#include "util.h"
+
 typedef enum RemoveFlags {
         REMOVE_ONLY_DIRECTORIES = 1,
         REMOVE_ROOT = 2,
@@ -34,6 +36,7 @@ int rm_rf(const char *path, RemoveFlags flags);
 
 /* Useful for usage with _cleanup_(), destroys a directory and frees the pointer */
 static inline void rm_rf_physical_and_free(char *p) {
+        PROTECT_ERRNO;
         (void) rm_rf(p, REMOVE_ROOT|REMOVE_PHYSICAL);
         free(p);
 }