From: Daan De Meyer <daan.j.demeyer@gmail.com>
Date: Tue, 25 Nov 2025 15:46:04 +0000 (+0100)
Subject: tree-wide: Fix constness issues with newer glibc
X-Git-Tag: v259-rc2~15^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0bac1ed2422f15308414dd1e9d09812a966b0348;p=thirdparty%2Fsystemd.git

tree-wide: Fix constness issues with newer glibc

Latest glibc uses _Generic to have strstr() and other functions return
const char* or char* based on whether the input is a const char* or a
char*. This causes build failures as we previously always expected a char*.

Let's fix the compilation failures and add our own macros similar to glibc's
to have string functions that return a mutable or const pointer depending on
the input.
---

diff --git a/src/analyze/analyze-chid.c b/src/analyze/analyze-chid.c
index cf9f0daae52..612465095f8 100644
--- a/src/analyze/analyze-chid.c
+++ b/src/analyze/analyze-chid.c
@@ -23,7 +23,7 @@
 #include "virt.h"
 
 static int parse_chid_type(const char *s, size_t *ret) {
-        char *e;
+        const char *e;
         unsigned u;
         int r;
 
diff --git a/src/basic/proc-cmdline.c b/src/basic/proc-cmdline.c
index fd9cfbae283..e5a8928cc90 100644
--- a/src/basic/proc-cmdline.c
+++ b/src/basic/proc-cmdline.c
@@ -163,9 +163,7 @@ int proc_cmdline_strv(char ***ret) {
 }
 
 static char *mangle_word(const char *word, ProcCmdlineFlags flags) {
-        char *c;
-
-        c = startswith(word, "rd.");
+        char *c = (char*) startswith(word, "rd.");
         if (c) {
                 /* Filter out arguments that are intended only for the initrd */
 
@@ -182,6 +180,8 @@ static char *mangle_word(const char *word, ProcCmdlineFlags flags) {
         return (char*) word;
 }
 
+#define mangle_word(word, flags) const_generic(word, mangle_word(word, flags))
+
 static int proc_cmdline_parse_strv(char **args, proc_cmdline_parse_t parse_item, void *data, ProcCmdlineFlags flags) {
         int r;
 
diff --git a/src/basic/socket-util.c b/src/basic/socket-util.c
index c98cd35d542..cd0bc4fd13f 100644
--- a/src/basic/socket-util.c
+++ b/src/basic/socket-util.c
@@ -1849,7 +1849,7 @@ int vsock_parse_cid(const char *s, unsigned *ret) {
 int socket_address_parse_vsock(SocketAddress *ret_address, const char *s) {
         /* AF_VSOCK socket in vsock:cid:port notation */
         _cleanup_free_ char *n = NULL;
-        char *e, *cid_start;
+        const char *e, *cid_start;
         unsigned port, cid;
         int type, r;
 
diff --git a/src/basic/sort-util.c b/src/basic/sort-util.c
index 1adbba8fcf4..d848745677d 100644
--- a/src/basic/sort-util.c
+++ b/src/basic/sort-util.c
@@ -30,7 +30,7 @@ void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
         return NULL;
 }
 
-void* bsearch_safe(const void *key, const void *base, size_t nmemb, size_t size, comparison_fn_t compar) {
+void* bsearch_safe_internal(const void *key, const void *base, size_t nmemb, size_t size, comparison_fn_t compar) {
         /**
         * Normal bsearch requires base to be nonnull. Here were require
         * that only if nmemb > 0.
@@ -40,7 +40,7 @@ void* bsearch_safe(const void *key, const void *base, size_t nmemb, size_t size,
                 return NULL;
 
         assert(base);
-        return bsearch(key, base, nmemb, size, compar);
+        return (void*) bsearch(key, base, nmemb, size, compar);
 }
 
 void qsort_safe(void *base, size_t nmemb, size_t size, comparison_fn_t compar) {
diff --git a/src/basic/sort-util.h b/src/basic/sort-util.h
index 2b558d6fd84..8e7a1991bb6 100644
--- a/src/basic/sort-util.h
+++ b/src/basic/sort-util.h
@@ -13,7 +13,9 @@ void *xbsearch_r(const void *key, const void *base, size_t nmemb, size_t size,
                 (typeof((b)[0])*) xbsearch_r((const void*) _k, (b), (n), sizeof((b)[0]), (comparison_userdata_fn_t) _func_, userdata); \
         })
 
-void* bsearch_safe(const void *key, const void *base, size_t nmemb, size_t size, comparison_fn_t compar);
+void* bsearch_safe_internal(const void *key, const void *base, size_t nmemb, size_t size, comparison_fn_t compar);
+#define bsearch_safe(key, base, nmemb, size, compar) \
+        const_generic((base), bsearch_safe_internal(key, base, nmemb, size, compar))
 
 #define typesafe_bsearch(k, b, n, func)                                 \
         ({                                                              \
diff --git a/src/basic/string-util.c b/src/basic/string-util.c
index 0fe72342c7f..6e7da6f0bd6 100644
--- a/src/basic/string-util.c
+++ b/src/basic/string-util.c
@@ -1348,16 +1348,14 @@ char* strdupcspn(const char *a, const char *reject) {
         return strndup(a, strcspn(a, reject));
 }
 
-char* find_line_startswith(const char *haystack, const char *needle) {
-        char *p;
-
+char* find_line_startswith_internal(const char *haystack, const char *needle) {
         assert(haystack);
         assert(needle);
 
         /* Finds the first line in 'haystack' that starts with the specified string. Returns a pointer to the
          * first character after it */
 
-        p = strstr(haystack, needle);
+        char *p = (char*) strstr(haystack, needle);
         if (!p)
                 return NULL;
 
@@ -1371,16 +1369,14 @@ char* find_line_startswith(const char *haystack, const char *needle) {
         return p + strlen(needle);
 }
 
-char* find_line(const char *haystack, const char *needle) {
-        char *p;
-
+char* find_line_internal(const char *haystack, const char *needle) {
         assert(haystack);
         assert(needle);
 
         /* Finds the first line in 'haystack' that match the specified string. Returns a pointer to the
          * beginning of the line */
 
-        p = find_line_startswith(haystack, needle);
+        char *p = (char*) find_line_startswith(haystack, needle);
         if (!p)
                 return NULL;
 
@@ -1390,16 +1386,14 @@ char* find_line(const char *haystack, const char *needle) {
         return NULL;
 }
 
-char* find_line_after(const char *haystack, const char *needle) {
-        char *p;
-
+char* find_line_after_internal(const char *haystack, const char *needle) {
         assert(haystack);
         assert(needle);
 
         /* Finds the first line in 'haystack' that match the specified string. Returns a pointer to the
          * next line after it */
 
-        p = find_line_startswith(haystack, needle);
+        char *p = (char*) find_line_startswith(haystack, needle);
         if (!p)
                 return NULL;
 
@@ -1499,7 +1493,7 @@ ssize_t strlevenshtein(const char *x, const char *y) {
         return t1[yl];
 }
 
-char* strrstr(const char *haystack, const char *needle) {
+char* strrstr_internal(const char *haystack, const char *needle) {
         /* Like strstr() but returns the last rather than the first occurrence of "needle" in "haystack". */
 
         if (!haystack || !needle)
@@ -1508,7 +1502,7 @@ char* strrstr(const char *haystack, const char *needle) {
         /* Special case: for the empty string we return the very last possible occurrence, i.e. *after* the
          * last char, not before. */
         if (*needle == 0)
-                return strchr(haystack, 0);
+                return (char*) strchr(haystack, 0);
 
         for (const char *p = strstr(haystack, needle), *q; p; p = q) {
                 q = strstr(p + 1, needle);
diff --git a/src/basic/string-util.h b/src/basic/string-util.h
index c90134e5cd7..0143c37a656 100644
--- a/src/basic/string-util.h
+++ b/src/basic/string-util.h
@@ -7,24 +7,28 @@
 #include "basic-forward.h"
 #include "string-util-fundamental.h" /* IWYU pragma: export */
 
-static inline char* strstr_ptr(const char *haystack, const char *needle) {
+static inline char* strstr_ptr_internal(const char *haystack, const char *needle) {
         if (!haystack || !needle)
                 return NULL;
-        return strstr(haystack, needle);
+        return (char*) strstr(haystack, needle);
 }
 
-static inline char* strstrafter(const char *haystack, const char *needle) {
-        char *p;
+#define strstr_ptr(haystack, needle) \
+        const_generic(haystack, strstr_ptr_internal(haystack, needle))
 
+static inline char* strstrafter_internal(const char *haystack, const char *needle) {
         /* Returns NULL if not found, or pointer to first character after needle if found */
 
-        p = strstr_ptr(haystack, needle);
+        char *p = (char*) strstr_ptr(haystack, needle);
         if (!p)
                 return NULL;
 
         return p + strlen(needle);
 }
 
+#define strstrafter(haystack, needle) \
+        const_generic(haystack, strstrafter_internal(haystack, needle))
+
 static inline const char* strnull(const char *s) {
         return s ?: "(null)";
 }
@@ -287,15 +291,25 @@ char* strdupcspn(const char *a, const char *reject);
                 (char*) memdupa_suffix0(_t, strnlen(_t, n));            \
         })
 
-char* find_line_startswith(const char *haystack, const char *needle);
-char* find_line(const char *haystack, const char *needle);
-char* find_line_after(const char *haystack, const char *needle);
+char* find_line_startswith_internal(const char *haystack, const char *needle);
+#define find_line_startswith(haystack, needle) \
+        const_generic(haystack, find_line_startswith_internal(haystack, needle))
+
+char* find_line_internal(const char *haystack, const char *needle);
+#define find_line(haystack, needle) \
+        const_generic(haystack, find_line_internal(haystack, needle))
+
+char* find_line_after_internal(const char *haystack, const char *needle);
+#define find_line_after(haystack, needle) \
+        const_generic(haystack, find_line_after_internal(haystack, needle))
 
 bool version_is_valid(const char *s) _pure_;
 bool version_is_valid_versionspec(const char *s) _pure_;
 
 ssize_t strlevenshtein(const char *x, const char *y);
 
-char* strrstr(const char *haystack, const char *needle) _pure_;
+char* strrstr_internal(const char *haystack, const char *needle) _pure_;
+#define strrstr(haystack, needle) \
+        const_generic(haystack, strrstr_internal(haystack, needle))
 
 size_t str_common_prefix(const char *a, const char *b) _pure_;
diff --git a/src/basic/strv.c b/src/basic/strv.c
index a19e05edc3d..5e0fabc3c5e 100644
--- a/src/basic/strv.c
+++ b/src/basic/strv.c
@@ -933,9 +933,9 @@ int strv_extend_joined_with_size_sentinel(char ***l, size_t *n, ...) {
         return strv_consume_with_size(l, n, x);
 }
 
-char* startswith_strv(const char *s, char * const *l) {
+char* startswith_strv_internal(const char *s, char * const *l) {
         STRV_FOREACH(i, l) {
-                char *found = startswith(s, *i);
+                char *found = (char*) startswith(s, *i);
                 if (found)
                         return found;
         }
@@ -943,9 +943,9 @@ char* startswith_strv(const char *s, char * const *l) {
         return NULL;
 }
 
-char* endswith_strv(const char *s, char * const *l) {
+char* endswith_strv_internal(const char *s, char * const *l) {
         STRV_FOREACH(i, l) {
-                char *found = endswith(s, *i);
+                char *found = (char*) endswith(s, *i);
                 if (found)
                         return found;
         }
diff --git a/src/basic/strv.h b/src/basic/strv.h
index 7b0923a6983..4f7d5a82a4d 100644
--- a/src/basic/strv.h
+++ b/src/basic/strv.h
@@ -155,12 +155,14 @@ static inline void strv_print(char * const *l) {
         strv_print_full(l, NULL);
 }
 
-char* startswith_strv(const char *s, char * const *l);
+char* startswith_strv_internal(const char *s, char * const *l);
+#define startswith_strv(s, l) const_generic(s, startswith_strv_internal(s, l))
 
 #define STARTSWITH_SET(p, ...)                                  \
         startswith_strv(p, STRV_MAKE(__VA_ARGS__))
 
-char* endswith_strv(const char *s, char * const *l);
+char* endswith_strv_internal(const char *s, char * const *l);
+#define endswith_strv(s, l) const_generic(s, endswith_strv_internal(s, l))
 
 #define ENDSWITH_SET(p, ...)                                    \
         endswith_strv(p, STRV_MAKE(__VA_ARGS__))
diff --git a/src/basic/time-util.c b/src/basic/time-util.c
index 62f1fcaed83..a596afa84d1 100644
--- a/src/basic/time-util.c
+++ b/src/basic/time-util.c
@@ -1156,9 +1156,7 @@ static const char* extract_multiplier(const char *p, usec_t *ret) {
         assert(ret);
 
         FOREACH_ELEMENT(i, table) {
-                char *e;
-
-                e = startswith(p, i->suffix);
+                const char *e = startswith(p, i->suffix);
                 if (e) {
                         *ret = i->usec;
                         return e;
@@ -1334,9 +1332,7 @@ static const char* extract_nsec_multiplier(const char *p, nsec_t *ret) {
         assert(ret);
 
         FOREACH_ELEMENT(i, table) {
-                char *e;
-
-                e = startswith(p, i->suffix);
+                const char *e = startswith(p, i->suffix);
                 if (e) {
                         *ret = i->nsec;
                         return e;
diff --git a/src/basic/unit-name.c b/src/basic/unit-name.c
index 6a42ece0b3e..43b3f683122 100644
--- a/src/basic/unit-name.c
+++ b/src/basic/unit-name.c
@@ -213,7 +213,7 @@ UnitType unit_name_to_type(const char *n) {
 int unit_name_change_suffix(const char *n, const char *suffix, char **ret) {
         _cleanup_free_ char *s = NULL;
         size_t a, b;
-        char *e;
+        const char *e;
 
         assert(n);
         assert(suffix);
@@ -521,7 +521,7 @@ int unit_name_template(const char *f, char **ret) {
 }
 
 bool unit_name_is_hashed(const char *name) {
-        char *s;
+        const char *s;
 
         if (!unit_name_is_valid(name, UNIT_NAME_PLAIN))
                 return false;
@@ -544,7 +544,7 @@ bool unit_name_is_hashed(const char *name) {
 
 int unit_name_hash_long(const char *name, char **ret) {
         _cleanup_free_ char *n = NULL, *hash = NULL;
-        char *suffix;
+        const char *suffix;
         le64_t h;
         size_t len;
 
@@ -834,7 +834,7 @@ int slice_build_subslice(const char *slice, const char *name, char **ret) {
         if (streq(slice, SPECIAL_ROOT_SLICE))
                 subslice = strjoin(name, ".slice");
         else {
-                char *e;
+                const char *e;
 
                 assert_se(e = endswith(slice, ".slice"));
 
diff --git a/src/cryptsetup/cryptsetup-generator.c b/src/cryptsetup/cryptsetup-generator.c
index d4b72dcf31e..e7d71779226 100644
--- a/src/cryptsetup/cryptsetup-generator.c
+++ b/src/cryptsetup/cryptsetup-generator.c
@@ -798,10 +798,9 @@ static int parse_proc_cmdline_item(const char *key, const char *value, void *dat
 static int add_crypttab_device(const char *name, const char *device, const char *keyspec, const char *options) {
         _cleanup_free_ char *keyfile = NULL, *keydev = NULL, *headerdev = NULL, *filtered_header = NULL;
         crypto_device *d = NULL;
-        char *uuid;
         int r;
 
-        uuid = startswith(device, "UUID=");
+        const char *uuid = startswith(device, "UUID=");
         if (!uuid)
                 uuid = path_startswith(device, "/dev/disk/by-uuid/");
         if (!uuid)
diff --git a/src/fundamental/macro-fundamental.h b/src/fundamental/macro-fundamental.h
index 8fc23c5e6a1..92b6de6cdce 100644
--- a/src/fundamental/macro-fundamental.h
+++ b/src/fundamental/macro-fundamental.h
@@ -483,3 +483,10 @@ assert_cc(STRLEN(__FILE__) > STRLEN(RELATIVE_SOURCE_PATH) + 1);
 #else
 #  define ENUM_TYPE_S64(id) id
 #endif
+
+/* This macro is used to have a const-returning and non-const returning version of a function based on
+ * whether its first argument is const or not (e.g. strstr()). */
+#define const_generic(ptr, call)                              \
+        _Generic(0 ? (ptr) : (void*) 1,                       \
+                 const void*: (const typeof(*call)*) (call),  \
+                 void*: (call))
diff --git a/src/fundamental/string-util-fundamental.c b/src/fundamental/string-util-fundamental.c
index 0141b42e397..6877dd439a4 100644
--- a/src/fundamental/string-util-fundamental.c
+++ b/src/fundamental/string-util-fundamental.c
@@ -3,7 +3,7 @@
 #include "macro-fundamental.h"
 #include "string-util-fundamental.h"
 
-sd_char *startswith(const sd_char *s, const sd_char *prefix) {
+sd_char *startswith_internal(const sd_char *s, const sd_char *prefix) {
         size_t l;
 
         assert(s);
@@ -16,7 +16,7 @@ sd_char *startswith(const sd_char *s, const sd_char *prefix) {
         return (sd_char*) s + l;
 }
 
-sd_char *startswith_no_case(const sd_char *s, const sd_char *prefix) {
+sd_char *startswith_no_case_internal(const sd_char *s, const sd_char *prefix) {
         size_t l;
 
         assert(s);
@@ -29,7 +29,7 @@ sd_char *startswith_no_case(const sd_char *s, const sd_char *prefix) {
         return (sd_char*) s + l;
 }
 
-sd_char* endswith(const sd_char *s, const sd_char *suffix) {
+sd_char* endswith_internal(const sd_char *s, const sd_char *suffix) {
         size_t sl, pl;
 
         assert(s);
@@ -50,7 +50,7 @@ sd_char* endswith(const sd_char *s, const sd_char *suffix) {
         return (sd_char*) s + sl - pl;
 }
 
-sd_char* endswith_no_case(const sd_char *s, const sd_char *suffix) {
+sd_char* endswith_no_case_internal(const sd_char *s, const sd_char *suffix) {
         size_t sl, pl;
 
         assert(s);
diff --git a/src/fundamental/string-util-fundamental.h b/src/fundamental/string-util-fundamental.h
index 2aa8d43bf93..e2eb73a4a9d 100644
--- a/src/fundamental/string-util-fundamental.h
+++ b/src/fundamental/string-util-fundamental.h
@@ -88,10 +88,17 @@ static inline size_t strlen_ptr(const sd_char *s) {
         return strlen(s);
 }
 
-sd_char *startswith(const sd_char *s, const sd_char *prefix) _pure_;
-sd_char *startswith_no_case(const sd_char *s, const sd_char *prefix) _pure_;
-sd_char *endswith(const sd_char *s, const sd_char *suffix) _pure_;
-sd_char *endswith_no_case(const sd_char *s, const sd_char *suffix) _pure_;
+sd_char *startswith_internal(const sd_char *s, const sd_char *prefix) _pure_;
+#define startswith(s, prefix) const_generic(s, startswith_internal(s, prefix))
+
+sd_char *startswith_no_case_internal(const sd_char *s, const sd_char *prefix) _pure_;
+#define startswith_no_case(s, prefix) const_generic(s, startswith_no_case_internal(s, prefix))
+
+sd_char *endswith_internal(const sd_char *s, const sd_char *suffix) _pure_;
+#define endswith(s, suffix) const_generic(s, endswith_internal(s, suffix))
+
+sd_char *endswith_no_case_internal(const sd_char *s, const sd_char *suffix) _pure_;
+#define endswith_no_case(s, suffix) const_generic(s, endswith_no_case_internal(s, suffix))
 
 static inline bool isempty(const sd_char *a) {
         return !a || a[0] == '\0';
diff --git a/src/home/homed-manager.c b/src/home/homed-manager.c
index a2ac04f2774..3185cd6feca 100644
--- a/src/home/homed-manager.c
+++ b/src/home/homed-manager.c
@@ -861,7 +861,7 @@ static int manager_assess_image(
                 const char *dir_path,
                 const char *dentry_name) {
 
-        char *luks_suffix, *directory_suffix;
+        const char *luks_suffix, *directory_suffix;
         _cleanup_free_ char *path = NULL;
         struct stat st;
         int r;
diff --git a/src/journal/journalctl-util.c b/src/journal/journalctl-util.c
index 586f702bb4d..aedb2da20dc 100644
--- a/src/journal/journalctl-util.c
+++ b/src/journal/journalctl-util.c
@@ -151,9 +151,8 @@ int get_possible_units(
 
                 SD_JOURNAL_FOREACH_UNIQUE(j, data, size) {
                         _cleanup_free_ char *u = NULL;
-                        char *eq;
 
-                        eq = memchr(data, '=', size);
+                        const char *eq = memchr(data, '=', size);
                         if (eq) {
                                 size -= eq - (char*) data + 1;
                                 data = ++eq;
diff --git a/src/libsystemd/sd-bus/sd-bus.c b/src/libsystemd/sd-bus/sd-bus.c
index 5644263fb55..050cfac55ea 100644
--- a/src/libsystemd/sd-bus/sd-bus.c
+++ b/src/libsystemd/sd-bus/sd-bus.c
@@ -1438,7 +1438,7 @@ _public_ int sd_bus_open_user(sd_bus **ret) {
 
 int bus_set_address_system_remote(sd_bus *b, const char *host) {
         _cleanup_free_ char *e = NULL;
-        char *m = NULL, *c = NULL, *a, *rbracket = NULL, *p = NULL;
+        const char *m = NULL, *c = NULL, *a, *rbracket = NULL, *p = NULL;
 
         assert(b);
         assert(host);
@@ -1476,7 +1476,7 @@ int bus_set_address_system_remote(sd_bus *b, const char *host) {
         /* Let's see if a port was given */
         m = strchr(rbracket ? rbracket + 1 : host, ':');
         if (m) {
-                char *t;
+                const char *t;
                 bool got_forward_slash = false;
 
                 p = m + 1;
@@ -1522,14 +1522,15 @@ interpret_port_as_machine_old_syntax:
         if (!ssh_escaped)
                 return -ENOMEM;
 
-        a = strjoin("unixexec:path=", ssh_escaped, ",argv1=-xT",
-                    p ? ",argv2=-p,argv3=" : "", strempty(p),
-                    ",argv", p ? "4" : "2", "=--,argv", p ? "5" : "3", "=", e,
-                    ",argv", p ? "6" : "4", "=systemd-stdio-bridge", c);
-        if (!a)
+        char *address = strjoin(
+                        "unixexec:path=", ssh_escaped, ",argv1=-xT",
+                        p ? ",argv2=-p,argv3=" : "", strempty(p),
+                        ",argv", p ? "4" : "2", "=--,argv", p ? "5" : "3", "=", e,
+                        ",argv", p ? "6" : "4", "=systemd-stdio-bridge", c);
+        if (!address)
                 return -ENOMEM;
 
-        return free_and_replace(b->address, a);
+        return free_and_replace(b->address, address);
 }
 
 _public_ int sd_bus_open_system_remote(sd_bus **ret, const char *host) {
diff --git a/src/libsystemd/sd-hwdb/sd-hwdb.c b/src/libsystemd/sd-hwdb/sd-hwdb.c
index bc96e409074..1197c4f954c 100644
--- a/src/libsystemd/sd-hwdb/sd-hwdb.c
+++ b/src/libsystemd/sd-hwdb/sd-hwdb.c
@@ -95,7 +95,7 @@ static int trie_children_cmp_f(const void *v1, const void *v2) {
 }
 
 static const struct trie_node_f *node_lookup_f(sd_hwdb *hwdb, const struct trie_node_f *node, uint8_t c) {
-        struct trie_child_entry_f *child;
+        const struct trie_child_entry_f *child;
         struct trie_child_entry_f search;
 
         search.c = c;
diff --git a/src/libsystemd/sd-journal/catalog.c b/src/libsystemd/sd-journal/catalog.c
index ec0445f1227..0751480fe5b 100644
--- a/src/libsystemd/sd-journal/catalog.c
+++ b/src/libsystemd/sd-journal/catalog.c
@@ -210,23 +210,21 @@ static int finish_item(
 }
 
 int catalog_file_lang(const char *filename, char **ret) {
-        char *beg, *end, *lang;
-
         assert(filename);
         assert(ret);
 
-        end = endswith(filename, ".catalog");
+        const char *end = endswith(filename, ".catalog");
         if (!end)
                 return 0;
 
-        beg = end - 1;
+        const char *beg = end - 1;
         while (beg > filename && !IN_SET(*beg, '.', '/') && end - beg < 32)
                 beg--;
 
         if (*beg != '.' || end <= beg + 1)
                 return 0;
 
-        lang = strndup(beg + 1, end - beg - 1);
+        char *lang = strndup(beg + 1, end - beg - 1);
         if (!lang)
                 return -ENOMEM;
 
@@ -553,7 +551,8 @@ static int open_mmap(const char *database, int *ret_fd, struct stat *ret_st, voi
 }
 
 static const char* find_id(const void *p, sd_id128_t id) {
-        CatalogItem *f = NULL, key = { .id = id };
+        CatalogItem key = { .id = id };
+        const CatalogItem *f = NULL;
         const CatalogHeader *h = ASSERT_PTR(p);
         const char *loc;
 
diff --git a/src/network/networkd-dhcp-server.c b/src/network/networkd-dhcp-server.c
index 75ecfdca91a..7ab11332543 100644
--- a/src/network/networkd-dhcp-server.c
+++ b/src/network/networkd-dhcp-server.c
@@ -832,7 +832,6 @@ int config_parse_dhcp_server_relay_agent_suboption(
                 void *userdata) {
 
         char **suboption_value = data;
-        char* p;
 
         assert(filename);
         assert(lvalue);
@@ -843,7 +842,7 @@ int config_parse_dhcp_server_relay_agent_suboption(
                 return 0;
         }
 
-        p = startswith(rvalue, "string:");
+        const char *p = startswith(rvalue, "string:");
         if (!p) {
                 log_syntax(unit, LOG_WARNING, filename, line, 0,
                            "Failed to parse %s=%s'. Invalid format, ignoring.", lvalue, rvalue);
diff --git a/src/shared/bus-unit-util.c b/src/shared/bus-unit-util.c
index 3d49cf5415b..74f22297a23 100644
--- a/src/shared/bus-unit-util.c
+++ b/src/shared/bus-unit-util.c
@@ -1639,7 +1639,6 @@ static int bus_append_root_hash(sd_bus_message *m, const char *field, const char
 }
 
 static int bus_append_root_hash_signature(sd_bus_message *m, const char *field, const char *eq) {
-        char *value;
         _cleanup_free_ void *roothash_sig_decoded = NULL;
         size_t roothash_sig_decoded_size = 0;
         int r;
@@ -1648,7 +1647,8 @@ static int bus_append_root_hash_signature(sd_bus_message *m, const char *field,
         if (path_is_absolute(eq))
                 return bus_append_string(m, "RootHashSignaturePath", eq);
 
-        if (!(value = startswith(eq, "base64:")))
+        const char *value = startswith(eq, "base64:");
+        if (!value)
                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
                                        "Failed to decode %s value '%s': neither a path nor starts with 'base64:'.",
                                        field, eq);
diff --git a/src/shared/pager.c b/src/shared/pager.c
index 3797adbb7cc..2b66dc91d20 100644
--- a/src/shared/pager.c
+++ b/src/shared/pager.c
@@ -298,7 +298,7 @@ bool pager_have(void) {
 
 int show_man_page(const char *desc, bool null_stdio) {
         const char *args[4] = { "man", NULL, NULL, NULL };
-        char *e = NULL;
+        const char *e = NULL;
         pid_t pid;
         size_t k;
         int r;
diff --git a/src/shared/seccomp-util.c b/src/shared/seccomp-util.c
index 0f4c692613c..c3eb9049e8d 100644
--- a/src/shared/seccomp-util.c
+++ b/src/shared/seccomp-util.c
@@ -2505,7 +2505,7 @@ uint32_t scmp_act_kill_process(void) {
 
 int parse_syscall_and_errno(const char *in, char **name, int *error) {
         _cleanup_free_ char *n = NULL;
-        char *p;
+        const char *p;
         int e = -1;
 
         assert(in);
diff --git a/src/shared/vpick.c b/src/shared/vpick.c
index b1b2d930543..07d9d9ffd8c 100644
--- a/src/shared/vpick.c
+++ b/src/shared/vpick.c
@@ -343,7 +343,7 @@ static int make_choice(
                 unsigned found_tries_done = UINT_MAX, found_tries_left = UINT_MAX;
                 _cleanup_free_ char *dname = NULL;
                 size_t found_architecture_index = SIZE_MAX;
-                const char *e;
+                char *e;
 
                 dname = strdup((*entry)->d_name);
                 if (!dname)
diff --git a/src/udev/udev-builtin-net_id.c b/src/udev/udev-builtin-net_id.c
index 0724de8241a..339c73ed3a8 100644
--- a/src/udev/udev-builtin-net_id.c
+++ b/src/udev/udev-builtin-net_id.c
@@ -950,7 +950,7 @@ static int names_pci(UdevEvent *event, const char *prefix) {
 }
 
 static int get_usb_specifier(sd_device *dev, char **ret) {
-        char *ports, *config, *interf, *s, *buf;
+        char *ports, *config, *interf, *buf;
         const char *sysname;
         int r;
 
@@ -962,26 +962,26 @@ static int get_usb_specifier(sd_device *dev, char **ret) {
                 return log_device_debug_errno(dev, r, "Failed to get sysname: %m");
 
         /* get USB port number chain, configuration, interface */
-        s = strchr(sysname, '-');
+        const char *s = strchr(sysname, '-');
         if (!s)
                 return log_device_debug_errno(dev, SYNTHETIC_ERRNO(EINVAL),
                                               "sysname \"%s\" does not have '-' in the expected place.", sysname);
 
         ports = strdupa_safe(s + 1);
-        s = strchr(ports, ':');
+        char *t = strchr(ports, ':');
         if (!s)
                 return log_device_debug_errno(dev, SYNTHETIC_ERRNO(EINVAL),
                                               "sysname \"%s\" does not have ':' in the expected place.", sysname);
 
-        *s = '\0';
-        config = s + 1;
+        *t = '\0';
+        config = t + 1;
         s = strchr(config, '.');
         if (!s)
                 return log_device_debug_errno(dev, SYNTHETIC_ERRNO(EINVAL),
                                               "sysname \"%s\" does not have '.' in the expected place.", sysname);
 
-        *s = '\0';
-        interf = s + 1;
+        *t = '\0';
+        interf = t + 1;
 
         /* prefix every port number in the chain with "u" */
         string_replace_char(ports, '.', 'u');