strv: declare iterator of FOREACH_STRING() in the loop

Same idea as 03677889f0.

No functional change intended. The type of the iterator is generally changed to
be 'const char*' instead of 'char*'. Despite the type commonly used, modifying
the string was not allowed.

I adjusted the naming of some short variables for clarity and reduced the scope
of some variable declarations in code that was being touched anyway.

src/shared/chown-recursive.c

@@ -21,7 +21,6 @@ static int chown_one(
                 gid_t gid,
                 mode_t mask) {
 
-        const char *n;
         int r;
 
         assert(fd >= 0);

src/shared/discover-image.c

@@ -85,7 +85,7 @@ DEFINE_HASH_OPS_WITH_VALUE_DESTRUCTOR(image_hash_ops, char, string_hash_func, st
 
 static char **image_settings_path(Image *image) {
         _cleanup_strv_free_ char **l = NULL;
-        const char *fn, *s;
+        const char *fn;
         unsigned i = 0;
 
         assert(image);

src/shared/dissect-image.c

@@ -3041,7 +3041,6 @@ int dissected_image_acquire_metadata(DissectedImage *m, DissectImageFlags extra_
 
                         case META_HAS_INIT_SYSTEM: {
                                 bool found = false;
-                                const char *init;
 
                                 FOREACH_STRING(init,
                                                "/usr/lib/systemd/systemd",  /* systemd on /usr merged system */

src/shared/find-esp.c

@@ -435,7 +435,8 @@ int find_esp_and_warn(
                 goto found;
         }
 
-        FOREACH_STRING(path, "/efi", "/boot", "/boot/efi") {
+        FOREACH_STRING(_path, "/efi", "/boot", "/boot/efi") {
+                path = _path;
 
                 r = verify_esp(path, /* searching= */ true, unprivileged_mode, ret_part, ret_pstart, ret_psize, ret_uuid, ret_devid);
                 if (r >= 0)

src/shared/machine-id-setup.c

@@ -197,7 +197,7 @@ finish:
 
 int machine_id_commit(const char *root) {
         _cleanup_close_ int fd = -1, initial_mntns_fd = -1;
-        const char *etc_machine_id, *sync_path;
+        const char *etc_machine_id;
         sd_id128_t id;
         int r;
 

src/shared/mount-setup.c

@@ -126,9 +126,6 @@ bool mount_point_is_api(const char *path) {
 }
 
 bool mount_point_ignore(const char *path) {
-
-        const char *i;
-
         /* These are API file systems that might be mounted by other software, we just list them here so that
          * we know that we should ignore them. */
         FOREACH_STRING(i,
@@ -515,7 +512,6 @@ int mount_setup(bool loaded_policy, bool leave_propagation) {
          * use the same label for all their files. */
         if (loaded_policy) {
                 usec_t before_relabel, after_relabel;
-                const char *i;
                 int n_extra;
 
                 before_relabel = now(CLOCK_MONOTONIC);

src/shared/netif-util.c

@@ -54,14 +54,15 @@ int net_get_type_string(sd_device *device, uint16_t iftype, char **ret) {
 }
 
 const char *net_get_persistent_name(sd_device *device) {
-        const char *name, *field;
-
         assert(device);
 
         /* fetch some persistent data unique (on this machine) to this device */
-        FOREACH_STRING(field, "ID_NET_NAME_ONBOARD", "ID_NET_NAME_SLOT", "ID_NET_NAME_PATH", "ID_NET_NAME_MAC")
+        FOREACH_STRING(field, "ID_NET_NAME_ONBOARD", "ID_NET_NAME_SLOT", "ID_NET_NAME_PATH", "ID_NET_NAME_MAC") {
+                const char *name;
+
                 if (sd_device_get_property_value(device, field, &name) >= 0)
                         return name;
+        }
 
         return NULL;
 }

src/shared/pager.c

@@ -144,7 +144,7 @@ void pager_open(PagerFlags flags) {
         if (r < 0)
                 return;
         if (r == 0) {
-                const char *less_charset, *exe;
+                const char *less_charset;
 
                 /* In the child start the pager */
 

src/shared/psi-util.c

@@ -106,8 +106,6 @@ int read_resource_pressure(const char *path, PressureType type, ResourcePressure
 }
 
 int is_pressure_supported(void) {
-        const char *p;
-
         /* The pressure files, both under /proc and in cgroups, will exist
          * even if the kernel has PSI support disabled; we have to read
          * the file to make sure it doesn't return -EOPNOTSUPP */

src/shared/switch-root.c

@@ -33,7 +33,6 @@ int switch_root(const char *new_root,
         _cleanup_free_ char *resolved_old_root_after = NULL;
         _cleanup_close_ int old_root_fd = -1;
         bool old_root_remove;
-        const char *i;
         int r;
 
         assert(new_root);
@@ -64,12 +63,12 @@ int switch_root(const char *new_root,
         if (mount(NULL, "/", NULL, MS_REC|MS_PRIVATE, NULL) < 0)
                 return log_error_errno(errno, "Failed to set \"/\" mount propagation to private: %m");
 
-        FOREACH_STRING(i, "/sys", "/dev", "/run", "/proc") {
+        FOREACH_STRING(path, "/sys", "/dev", "/run", "/proc") {
                 _cleanup_free_ char *chased = NULL;
 
-                r = chase_symlinks(i, new_root, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &chased, NULL);
+                r = chase_symlinks(path, new_root, CHASE_PREFIX_ROOT|CHASE_NONEXISTENT, &chased, NULL);
                 if (r < 0)
-                        return log_error_errno(r, "Failed to resolve %s/%s: %m", new_root, i);
+                        return log_error_errno(r, "Failed to resolve %s/%s: %m", new_root, path);
                 if (r > 0) {
                         /* Already exists. Let's see if it is a mount point already. */
                         r = path_is_mount_point(chased, NULL, 0);
@@ -81,8 +80,8 @@ int switch_root(const char *new_root,
                          /* Doesn't exist yet? */
                         (void) mkdir_p_label(chased, 0755);
 
-                if (mount(i, chased, NULL, mount_flags, NULL) < 0)
-                        return log_error_errno(errno, "Failed to mount %s to %s: %m", i, chased);
+                if (mount(path, chased, NULL, mount_flags, NULL) < 0)
+                        return log_error_errno(errno, "Failed to mount %s to %s: %m", path, chased);
         }
 
         /* Do not fail if base_filesystem_create() fails. Not all switch roots are like base_filesystem_create() wants

src/shared/tests.c

@@ -306,16 +306,15 @@ const char *ci_environment(void) {
          * just the general CI environment type, but also whether we're sanitizing or not, etc. The caller is
          * expected to use strstr on the returned value. */
         static const char *ans = POINTER_MAX;
-        const char *p;
         int r;
 
         if (ans != POINTER_MAX)
                 return ans;
 
         /* We allow specifying the environment with $CITYPE. Nobody uses this so far, but we are ready. */
-        p = getenv("CITYPE");
-        if (!isempty(p))
-                return (ans = p);
+        const char *citype = getenv("CITYPE");
+        if (!isempty(citype))
+                return (ans = citype);
 
         if (getenv_bool("TRAVIS") > 0)
                 return (ans = "travis");
@@ -326,12 +325,12 @@ const char *ci_environment(void) {
         if (getenv("AUTOPKGTEST_ARTIFACTS") || getenv("AUTOPKGTEST_TMP"))
                 return (ans = "autopkgtest");
 
-        FOREACH_STRING(p, "CI", "CONTINOUS_INTEGRATION") {
+        FOREACH_STRING(var, "CI", "CONTINOUS_INTEGRATION") {
                 /* Those vars are booleans according to Semaphore and Travis docs:
                  * https://docs.travis-ci.com/user/environment-variables/#default-environment-variables
                  * https://docs.semaphoreci.com/ci-cd-environment/environment-variables/#ci
                  */
-                r = getenv_bool(p);
+                r = getenv_bool(var);
                 if (r > 0)
                         return (ans = "unknown"); /* Some other unknown thing */
                 if (r == 0)