various: use strdup_to() in various obvious cases

strdup_to() returns 0 on success and here we convert obvious blocks
which either return -ENOMEM or 0.

src/basic/chase.c

@@ -741,12 +741,7 @@ int chase_extract_filename(const char *path, const char *root, char **ret) {
                         return r;
         }
 
-        char *fname = strdup(".");
-        if (!fname)
-                return -ENOMEM;
-
-        *ret = fname;
-        return 0;
+        return strdup_to(ret, ".");
 }
 
 int chase_and_open(const char *path, const char *root, ChaseFlags chase_flags, int open_flags, char **ret_path) {

src/basic/devnum-util.c

@@ -58,21 +58,18 @@ int device_path_make_major_minor(mode_t mode, dev_t devnum, char **ret) {
 }
 
 int device_path_make_inaccessible(mode_t mode, char **ret) {
-        char *s;
+        const char *s;
 
         assert(ret);
 
         if (S_ISCHR(mode))
-                s = strdup("/run/systemd/inaccessible/chr");
+                s = "/run/systemd/inaccessible/chr";
         else if (S_ISBLK(mode))
-                s = strdup("/run/systemd/inaccessible/blk");
+                s = "/run/systemd/inaccessible/blk";
         else
                 return -ENODEV;
-        if (!s)
-                return -ENOMEM;
 
-        *ret = s;
-        return 0;
+        return strdup_to(ret, s);
 }
 
 int device_path_make_canonical(mode_t mode, dev_t devnum, char **ret) {

src/basic/format-util.c

@@ -25,7 +25,7 @@ int format_ifname_full(int ifindex, FormatIfnameFlag flag, char buf[static IF_NA
 }
 
 int format_ifname_full_alloc(int ifindex, FormatIfnameFlag flag, char **ret) {
-        char buf[IF_NAMESIZE], *copy;
+        char buf[IF_NAMESIZE];
         int r;
 
         assert(ret);
@@ -34,12 +34,7 @@ int format_ifname_full_alloc(int ifindex, FormatIfnameFlag flag, char **ret) {
         if (r < 0)
                 return r;
 
-        copy = strdup(buf);
-        if (!copy)
-                return -ENOMEM;
-
-        *ret = copy;
-        return 0;
+        return strdup_to(ret, buf);
 }
 
 char *format_bytes_full(char *buf, size_t l, uint64_t t, FormatBytesFlag flag) {

src/basic/path-util.c

@@ -1094,7 +1094,6 @@ int path_extract_filename(const char *path, char **ret) {
 }
 
 int path_extract_directory(const char *path, char **ret) {
-        _cleanup_free_ char *a = NULL;
         const char *c, *next = NULL;
         int r;
 
@@ -1118,14 +1117,10 @@ int path_extract_directory(const char *path, char **ret) {
                 if (*path != '/') /* filename only */
                         return -EDESTADDRREQ;
 
-                a = strdup("/");
-                if (!a)
-                        return -ENOMEM;
-                *ret = TAKE_PTR(a);
-                return 0;
+                return strdup_to(ret, "/");
         }
 
-        a = strndup(path, next - path);
+        _cleanup_free_ char *a = strndup(path, next - path);
         if (!a)
                 return -ENOMEM;
 

src/basic/terminal-util.c

@@ -697,18 +697,10 @@ int vtnr_from_tty(const char *tty) {
                 tty = active;
         }
 
-        if (tty == active)
-                *ret = TAKE_PTR(active);
-        else {
-                char *tmp;
-
-                tmp = strdup(tty);
-                if (!tmp)
-                        return -ENOMEM;
-
-                *ret = tmp;
-        }
+        if (tty != active)
+                return strdup_to(ret, tty);
 
+        *ret = TAKE_PTR(active);
         return 0;
 }
 
@@ -988,7 +980,7 @@ bool on_tty(void) {
 }
 
 int getttyname_malloc(int fd, char **ret) {
-        char path[PATH_MAX], *c; /* PATH_MAX is counted *with* the trailing NUL byte */
+        char path[PATH_MAX]; /* PATH_MAX is counted *with* the trailing NUL byte */
         int r;
 
         assert(fd >= 0);
@@ -1001,12 +993,7 @@ int getttyname_malloc(int fd, char **ret) {
         if (r > 0)
                 return -r;
 
-        c = strdup(skip_dev_prefix(path));
-        if (!c)
-                return -ENOMEM;
-
-        *ret = c;
-        return 0;
+        return strdup_to(ret, skip_dev_prefix(path));
 }
 
 int getttyname_harder(int fd, char **ret) {

src/basic/unit-name.c

@@ -793,12 +793,7 @@ int unit_name_mangle_with_suffix(
         return 1;
 
 good:
-        s = strdup(name);
-        if (!s)
-                return -ENOMEM;
-
-        *ret = TAKE_PTR(s);
-        return 0;
+        return strdup_to(ret, name);
 }
 
 int slice_build_parent_slice(const char *slice, char **ret) {