tree-wide: use startswith return value to avoid hardcoded offset

I think it's an antipattern to have to count the number of bytes in
the prefix by hand. We should do this automatically to avoid wasting
programmer time, and possible errors. I didn't any offsets that were
wrong, so this change is mostly to make future development easier.

3 files changed, 112 insertions, 114 deletions

diff --git a/src/core/cgroup.c b/src/core/cgroup.c
index 23a92f9651..09bbe038e9 100644
--- a/src/core/cgroup.c
+++ b/src/core/cgroup.c
@@ -928,7 +928,7 @@ static void cgroup_context_apply(Unit *u, CGroupMask mask, ManagerState state) {
                 }
 
                 LIST_FOREACH(device_allow, a, c->device_allow) {
-                        char acc[4];
+                        char acc[4], *val;
                         unsigned k = 0;
 
                         if (a->r)
@@ -945,10 +945,10 @@ static void cgroup_context_apply(Unit *u, CGroupMask mask, ManagerState state) {
 
                         if (startswith(a->path, "/dev/"))
                                 whitelist_device(path, a->path, acc);
-                        else if (startswith(a->path, "block-"))
-                                whitelist_major(path, a->path + 6, 'b', acc);
-                        else if (startswith(a->path, "char-"))
-                                whitelist_major(path, a->path + 5, 'c', acc);
+                        else if ((val = startswith(a->path, "block-")))
+                                whitelist_major(path, val, 'b', acc);
+                        else if ((val = startswith(a->path, "char-")))
+                                whitelist_major(path, val, 'c', acc);
                         else
                                 log_unit_debug(u, "Ignoring device %s while writing cgroup attribute.", a->path);
                 }
diff --git a/src/core/manager.c b/src/core/manager.c
index 65f163de31..0549f5ef1b 100644
--- a/src/core/manager.c
+++ b/src/core/manager.c
@@ -2582,6 +2582,7 @@ int manager_deserialize(Manager *m, FILE *f, FDSet *fds) {
 
         for (;;) {
                 char line[LINE_MAX], *l;
+                const char *val;
 
                 if (!fgets(line, sizeof(line), f)) {
                         if (feof(f))
@@ -2598,63 +2599,63 @@ int manager_deserialize(Manager *m, FILE *f, FDSet *fds) {
                 if (l[0] == 0)
                         break;
 
-                if (startswith(l, "current-job-id=")) {
+                if ((val = startswith(l, "current-job-id="))) {
                         uint32_t id;
 
-                        if (safe_atou32(l+15, &id) < 0)
-                                log_debug("Failed to parse current job id value %s", l+15);
+                        if (safe_atou32(val, &id) < 0)
+                                log_debug("Failed to parse current job id value %s", val);
                         else
                                 m->current_job_id = MAX(m->current_job_id, id);
 
-                } else if (startswith(l, "n-installed-jobs=")) {
+                } else if ((val = startswith(l, "n-installed-jobs="))) {
                         uint32_t n;
 
-                        if (safe_atou32(l+17, &n) < 0)
-                                log_debug("Failed to parse installed jobs counter %s", l+17);
+                        if (safe_atou32(val, &n) < 0)
+                                log_debug("Failed to parse installed jobs counter %s", val);
                         else
                                 m->n_installed_jobs += n;
 
-                } else if (startswith(l, "n-failed-jobs=")) {
+                } else if ((val = startswith(l, "n-failed-jobs="))) {
                         uint32_t n;
 
-                        if (safe_atou32(l+14, &n) < 0)
-                                log_debug("Failed to parse failed jobs counter %s", l+14);
+                        if (safe_atou32(val, &n) < 0)
+                                log_debug("Failed to parse failed jobs counter %s", val);
                         else
                                 m->n_failed_jobs += n;
 
-                } else if (startswith(l, "taint-usr=")) {
+                } else if ((val = startswith(l, "taint-usr="))) {
                         int b;
 
-                        b = parse_boolean(l+10);
+                        b = parse_boolean(val);
                         if (b < 0)
-                                log_debug("Failed to parse taint /usr flag %s", l+10);
+                                log_debug("Failed to parse taint /usr flag %s", val);
                         else
                                 m->taint_usr = m->taint_usr || b;
 
-                } else if (startswith(l, "firmware-timestamp="))
-                        dual_timestamp_deserialize(l+19, &m->firmware_timestamp);
-                else if (startswith(l, "loader-timestamp="))
-                        dual_timestamp_deserialize(l+17, &m->loader_timestamp);
-                else if (startswith(l, "kernel-timestamp="))
-                        dual_timestamp_deserialize(l+17, &m->kernel_timestamp);
-                else if (startswith(l, "initrd-timestamp="))
-                        dual_timestamp_deserialize(l+17, &m->initrd_timestamp);
-                else if (startswith(l, "userspace-timestamp="))
-                        dual_timestamp_deserialize(l+20, &m->userspace_timestamp);
-                else if (startswith(l, "finish-timestamp="))
-                        dual_timestamp_deserialize(l+17, &m->finish_timestamp);
-                else if (startswith(l, "security-start-timestamp="))
-                        dual_timestamp_deserialize(l+25, &m->security_start_timestamp);
-                else if (startswith(l, "security-finish-timestamp="))
-                        dual_timestamp_deserialize(l+26, &m->security_finish_timestamp);
-                else if (startswith(l, "generators-start-timestamp="))
-                        dual_timestamp_deserialize(l+27, &m->generators_start_timestamp);
-                else if (startswith(l, "generators-finish-timestamp="))
-                        dual_timestamp_deserialize(l+28, &m->generators_finish_timestamp);
-                else if (startswith(l, "units-load-start-timestamp="))
-                        dual_timestamp_deserialize(l+27, &m->units_load_start_timestamp);
-                else if (startswith(l, "units-load-finish-timestamp="))
-                        dual_timestamp_deserialize(l+28, &m->units_load_finish_timestamp);
+                } else if ((val = startswith(l, "firmware-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->firmware_timestamp);
+                else if ((val = startswith(l, "loader-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->loader_timestamp);
+                else if ((val = startswith(l, "kernel-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->kernel_timestamp);
+                else if ((val = startswith(l, "initrd-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->initrd_timestamp);
+                else if ((val = startswith(l, "userspace-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->userspace_timestamp);
+                else if ((val = startswith(l, "finish-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->finish_timestamp);
+                else if ((val = startswith(l, "security-start-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->security_start_timestamp);
+                else if ((val = startswith(l, "security-finish-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->security_finish_timestamp);
+                else if ((val = startswith(l, "generators-start-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->generators_start_timestamp);
+                else if ((val = startswith(l, "generators-finish-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->generators_finish_timestamp);
+                else if ((val = startswith(l, "units-load-start-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->units_load_start_timestamp);
+                else if ((val = startswith(l, "units-load-finish-timestamp=")))
+                        dual_timestamp_deserialize(val, &m->units_load_finish_timestamp);
                 else if (startswith(l, "env=")) {
                         _cleanup_free_ char *uce = NULL;
                         char **e;
@@ -2672,21 +2673,21 @@ int manager_deserialize(Manager *m, FILE *f, FDSet *fds) {
                         strv_free(m->environment);
                         m->environment = e;
 
-                } else if (startswith(l, "notify-fd=")) {
+                } else if ((val = startswith(l, "notify-fd="))) {
                         int fd;
 
-                        if (safe_atoi(l + 10, &fd) < 0 || fd < 0 || !fdset_contains(fds, fd))
-                                log_debug("Failed to parse notify fd: %s", l + 10);
+                        if (safe_atoi(val, &fd) < 0 || fd < 0 || !fdset_contains(fds, fd))
+                                log_debug("Failed to parse notify fd: %s", val);
                         else {
                                 m->notify_event_source = sd_event_source_unref(m->notify_event_source);
                                 safe_close(m->notify_fd);
                                 m->notify_fd = fdset_remove(fds, fd);
                         }
 
-                } else if (startswith(l, "notify-socket=")) {
+                } else if ((val = startswith(l, "notify-socket="))) {
                         char *n;
 
-                        n = strdup(l+14);
+                        n = strdup(val);
                         if (!n) {
                                 r = -ENOMEM;
                                 goto finish;
@@ -2695,22 +2696,22 @@ int manager_deserialize(Manager *m, FILE *f, FDSet *fds) {
                         free(m->notify_socket);
                         m->notify_socket = n;
 
-                } else if (startswith(l, "cgroups-agent-fd=")) {
+                } else if ((val = startswith(l, "cgroups-agent-fd="))) {
                         int fd;
 
-                        if (safe_atoi(l + 17, &fd) < 0 || fd < 0 || !fdset_contains(fds, fd))
-                                log_debug("Failed to parse cgroups agent fd: %s", l + 10);
+                        if (safe_atoi(val, &fd) < 0 || fd < 0 || !fdset_contains(fds, fd))
+                                log_debug("Failed to parse cgroups agent fd: %s", val);
                         else {
                                 m->cgroups_agent_event_source = sd_event_source_unref(m->cgroups_agent_event_source);
                                 safe_close(m->cgroups_agent_fd);
                                 m->cgroups_agent_fd = fdset_remove(fds, fd);
                         }
 
-                } else if (startswith(l, "user-lookup=")) {
+                } else if ((val = startswith(l, "user-lookup="))) {
                         int fd0, fd1;
 
-                        if (sscanf(l + 12, "%i %i", &fd0, &fd1) != 2 || fd0 < 0 || fd1 < 0 || fd0 == fd1 || !fdset_contains(fds, fd0) || !fdset_contains(fds, fd1))
-                                log_debug("Failed to parse user lookup fd: %s", l + 12);
+                        if (sscanf(val, "%i %i", &fd0, &fd1) != 2 || fd0 < 0 || fd1 < 0 || fd0 == fd1 || !fdset_contains(fds, fd0) || !fdset_contains(fds, fd1))
+                                log_debug("Failed to parse user lookup fd: %s", val);
                         else {
                                 m->user_lookup_event_source = sd_event_source_unref(m->user_lookup_event_source);
                                 safe_close_pair(m->user_lookup_fds);
@@ -2718,15 +2719,15 @@ int manager_deserialize(Manager *m, FILE *f, FDSet *fds) {
                                 m->user_lookup_fds[1] = fdset_remove(fds, fd1);
                         }
 
-                } else if (startswith(l, "dynamic-user="))
-                        dynamic_user_deserialize_one(m, l + 13, fds);
-                else if (startswith(l, "destroy-ipc-uid="))
-                        manager_deserialize_uid_refs_one(m, l + 16);
-                else if (startswith(l, "destroy-ipc-gid="))
-                        manager_deserialize_gid_refs_one(m, l + 16);
-                else if (startswith(l, "subscribed=")) {
+                } else if ((val = startswith(l, "dynamic-user=")))
+                        dynamic_user_deserialize_one(m, val, fds);
+                else if ((val = startswith(l, "destroy-ipc-uid=")))
+                        manager_deserialize_uid_refs_one(m, val);
+                else if ((val = startswith(l, "destroy-ipc-gid=")))
+                        manager_deserialize_gid_refs_one(m, val);
+                else if ((val = startswith(l, "subscribed="))) {
 
-                        if (strv_extend(&m->deserialized_subscribed, l+11) < 0)
+                        if (strv_extend(&m->deserialized_subscribed, val) < 0)
                                 log_oom();
 
                 } else if (!startswith(l, "kdbus-fd=")) /* ignore this one */
diff --git a/src/cryptsetup/cryptsetup.c b/src/cryptsetup/cryptsetup.c
index 9927621ea0..1e17fbbb03 100644
--- a/src/cryptsetup/cryptsetup.c
+++ b/src/cryptsetup/cryptsetup.c
@@ -68,26 +68,25 @@ static usec_t arg_timeout = 0;
 */
 
 static int parse_one_option(const char *option) {
+        const char *val;
+        int r;
+
         assert(option);
 
         /* Handled outside of this tool */
         if (STR_IN_SET(option, "noauto", "auto", "nofail", "fail"))
                 return 0;
 
-        if (startswith(option, "cipher=")) {
-                char *t;
-
-                t = strdup(option+7);
-                if (!t)
+        if ((val = startswith(option, "cipher="))) {
+                r = free_and_strdup(&arg_cipher, val);
+                if (r < 0)
                         return log_oom();
 
-                free(arg_cipher);
-                arg_cipher = t;
-
-        } else if (startswith(option, "size=")) {
+        } else if ((val = startswith(option, "size="))) {
 
-                if (safe_atou(option+5, &arg_key_size) < 0) {
-                        log_error("size= parse failure, ignoring.");
+                r = safe_atou(val, &arg_key_size);
+                if (r < 0) {
+                        log_error_errno(r, "Failed to parse %s, ignoring: %m", option);
                         return 0;
                 }
 
@@ -98,68 +97,67 @@ static int parse_one_option(const char *option) {
 
                 arg_key_size /= 8;
 
-        } else if (startswith(option, "key-slot=")) {
+        } else if ((val = startswith(option, "key-slot="))) {
 
                 arg_type = CRYPT_LUKS1;
-                if (safe_atoi(option+9, &arg_key_slot) < 0) {
-                        log_error("key-slot= parse failure, ignoring.");
+                r = safe_atoi(val, &arg_key_slot);
+                if (r < 0) {
+                        log_error_errno(r, "Failed to parse %s, ignoring: %m", option);
                         return 0;
                 }
 
-        } else if (startswith(option, "tcrypt-keyfile=")) {
+        } else if ((val = startswith(option, "tcrypt-keyfile="))) {
 
                 arg_type = CRYPT_TCRYPT;
-                if (path_is_absolute(option+15)) {
-                        if (strv_extend(&arg_tcrypt_keyfiles, option + 15) < 0)
+                if (path_is_absolute(val)) {
+                        if (strv_extend(&arg_tcrypt_keyfiles, val) < 0)
                                 return log_oom();
                 } else
-                        log_error("Key file path '%s' is not absolute. Ignoring.", option+15);
+                        log_error("Key file path \"%s\" is not absolute. Ignoring.", val);
 
-        } else if (startswith(option, "keyfile-size=")) {
+        } else if ((val = startswith(option, "keyfile-size="))) {
 
-                if (safe_atou(option+13, &arg_keyfile_size) < 0) {
-                        log_error("keyfile-size= parse failure, ignoring.");
+                r = safe_atou(val, &arg_keyfile_size);
+                if (r < 0) {
+                        log_error_errno(r, "Failed to parse %s, ignoring: %m", option);
                         return 0;
                 }
 
-        } else if (startswith(option, "keyfile-offset=")) {
+        } else if ((val = startswith(option, "keyfile-offset="))) {
 
-                if (safe_atou(option+15, &arg_keyfile_offset) < 0) {
-                        log_error("keyfile-offset= parse failure, ignoring.");
+                r = safe_atou(val, &arg_keyfile_offset);
+                if (r < 0) {
+                        log_error_errno(r, "Failed to parse %s, ignoring: %m", option);
                         return 0;
                 }
 
-        } else if (startswith(option, "hash=")) {
-                char *t;
-
-                t = strdup(option+5);
-                if (!t)
+        } else if ((val = startswith(option, "hash="))) {
+                r = free_and_strdup(&arg_hash, val);
+                if (r < 0)
                         return log_oom();
 
-                free(arg_hash);
-                arg_hash = t;
-
-        } else if (startswith(option, "header=")) {
+        } else if ((val = startswith(option, "header="))) {
                 arg_type = CRYPT_LUKS1;
 
-                if (!path_is_absolute(option+7)) {
-                        log_error("Header path '%s' is not absolute, refusing.", option+7);
+                if (!path_is_absolute(val)) {
+                        log_error("Header path \"%s\" is not absolute, refusing.", val);
                         return -EINVAL;
                 }
 
                 if (arg_header) {
-                        log_error("Duplicate header= options, refusing.");
+                        log_error("Duplicate header= option, refusing.");
                         return -EINVAL;
                 }
 
-                arg_header = strdup(option+7);
+                arg_header = strdup(val);
                 if (!arg_header)
                         return log_oom();
 
-        } else if (startswith(option, "tries=")) {
+        } else if ((val = startswith(option, "tries="))) {
 
-                if (safe_atou(option+6, &arg_tries) < 0) {
-                        log_error("tries= parse failure, ignoring.");
+                r = safe_atou(val, &arg_tries);
+                if (r < 0) {
+                        log_error_errno(r, "Failed to parse %s, ignoring: %m", option);
                         return 0;
                 }
 
@@ -181,29 +179,28 @@ static int parse_one_option(const char *option) {
                 arg_tcrypt_system = true;
         } else if (STR_IN_SET(option, "plain", "swap", "tmp"))
                 arg_type = CRYPT_PLAIN;
-        else if (startswith(option, "timeout=")) {
+        else if ((val = startswith(option, "timeout="))) {
 
-                if (parse_sec(option+8, &arg_timeout) < 0) {
-                        log_error("timeout= parse failure, ignoring.");
+                r = parse_sec(val, &arg_timeout);
+                if (r < 0) {
+                        log_error_errno(r, "Failed to parse %s, ignoring: %m", option);
                         return 0;
                 }
 
-        } else if (startswith(option, "offset=")) {
+        } else if ((val = startswith(option, "offset="))) {
 
-                if (safe_atou64(option+7, &arg_offset) < 0) {
-                        log_error("offset= parse failure, refusing.");
-                        return -EINVAL;
-                }
+                r = safe_atou64(val, &arg_offset);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to parse %s: %m", option);
 
-        } else if (startswith(option, "skip=")) {
+        } else if ((val = startswith(option, "skip="))) {
 
-                if (safe_atou64(option+5, &arg_skip) < 0) {
-                        log_error("skip= parse failure, refusing.");
-                        return -EINVAL;
-                }
+                r = safe_atou64(val, &arg_skip);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to parse %s: %m", option);
 
         } else if (!streq(option, "none"))
-                log_error("Encountered unknown /etc/crypttab option '%s', ignoring.", option);
+                log_warning("Encountered unknown /etc/crypttab option '%s', ignoring.", option);
 
         return 0;
 }