coredump: split out metadata gathering to a separate function

In preparation for subsequenct changes...

Various stack allocations are changed to use the heap. This might be minimally
slower, but probably doesn't matter. The upside is that we will now properly
free all memory that is allocated.

1 files changed, 112 insertions, 158 deletions

diff --git a/src/coredump/coredump.c b/src/coredump/coredump.c
index 1f6fb5de1e..d5b638d7ec 100644
--- a/src/coredump/coredump.c
+++ b/src/coredump/coredump.c
@@ -1025,45 +1025,43 @@ static int process_special_crash(const char *context[], int input_fd) {
         return 0;
 }
 
-static int process_kernel(int argc, char* argv[]) {
+static char* set_iovec_field(struct iovec iovec[27], size_t *n_iovec, const char *field, const char *value) {
+        char *x;
 
-        /* The small core field we allocate on the stack, to keep things simple */
-        char
-                *core_pid = NULL, *core_uid = NULL, *core_gid = NULL, *core_signal = NULL,
-                *core_session = NULL, *core_exe = NULL, *core_comm = NULL, *core_cmdline = NULL,
-                *core_cgroup = NULL, *core_cwd = NULL, *core_root = NULL, *core_unit = NULL,
-                *core_user_unit = NULL, *core_slice = NULL, *core_timestamp = NULL, *core_rlimit = NULL;
+        x = strappend(field, value);
+        if (x)
+                IOVEC_SET_STRING(iovec[(*n_iovec)++], x);
+        return x;
+}
 
-        /* The larger ones we allocate on the heap */
-        _cleanup_free_ char
-                *core_owner_uid = NULL, *core_open_fds = NULL, *core_proc_status = NULL,
-                *core_proc_maps = NULL, *core_proc_limits = NULL, *core_proc_cgroup = NULL, *core_environ = NULL,
-                *core_proc_mountinfo = NULL, *core_container_cmdline = NULL;
+static char* set_iovec_field_free(struct iovec iovec[27], size_t *n_iovec, const char *field, char *value) {
+        char *x;
+
+        x = set_iovec_field(iovec, n_iovec, field, value);
+        free(value);
+        return x;
+}
+
+static int gather_pid_metadata(
+                const char *context[_CONTEXT_MAX],
+                char **comm_fallback,
+                struct iovec iovec[27], size_t *n_iovec) {
 
         _cleanup_free_ char *exe = NULL, *comm = NULL;
-        const char *context[_CONTEXT_MAX];
-        bool proc_self_root_is_slash;
-        struct iovec iovec[27];
-        size_t n_iovec = 0;
         uid_t owner_uid;
-        const char *p;
         pid_t pid;
         char *t;
+        const char *p;
         int r;
 
-        if (argc < CONTEXT_COMM + 1) {
-                log_error("Not enough arguments passed from kernel (%i, expected %i).", argc - 1, CONTEXT_COMM + 1 - 1);
-                return -EINVAL;
-        }
-
-        r = parse_pid(argv[CONTEXT_PID + 1], &pid);
+        r = parse_pid(context[CONTEXT_PID], &pid);
         if (r < 0)
                 return log_error_errno(r, "Failed to parse PID.");
 
         r = get_process_comm(pid, &comm);
         if (r < 0) {
                 log_warning_errno(r, "Failed to get COMM, falling back to the command line: %m");
-                comm = strv_join(argv + CONTEXT_COMM + 1, " ");
+                comm = strv_join(comm_fallback, " ");
                 if (!comm)
                         return log_oom();
         }
@@ -1072,15 +1070,6 @@ static int process_kernel(int argc, char* argv[]) {
         if (r < 0)
                 log_warning_errno(r, "Failed to get EXE, ignoring: %m");
 
-        context[CONTEXT_PID] = argv[CONTEXT_PID + 1];
-        context[CONTEXT_UID] = argv[CONTEXT_UID + 1];
-        context[CONTEXT_GID] = argv[CONTEXT_GID + 1];
-        context[CONTEXT_SIGNAL] = argv[CONTEXT_SIGNAL + 1];
-        context[CONTEXT_TIMESTAMP] = argv[CONTEXT_TIMESTAMP + 1];
-        context[CONTEXT_RLIMIT] = argv[CONTEXT_RLIMIT + 1];
-        context[CONTEXT_COMM] = comm;
-        context[CONTEXT_EXE] = exe;
-
         if (cg_pid_get_unit(pid, &t) >= 0) {
 
                 /* If this is PID 1 disable coredump collection, we'll unlikely be able to process it later on. */
@@ -1096,170 +1085,129 @@ static int process_kernel(int argc, char* argv[]) {
                         return process_special_crash(context, STDIN_FILENO);
                 }
 
-                core_unit = strjoina("COREDUMP_UNIT=", t);
-                free(t);
-
-                IOVEC_SET_STRING(iovec[n_iovec++], core_unit);
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_UNIT=", t);
         }
 
         /* OK, now we know it's not the journal, hence we can make use of it now. */
         log_set_target(LOG_TARGET_JOURNAL_OR_KMSG);
         log_open();
 
-        if (cg_pid_get_user_unit(pid, &t) >= 0) {
-                core_user_unit = strjoina("COREDUMP_USER_UNIT=", t);
-                free(t);
+        if (cg_pid_get_user_unit(pid, &t) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_USER_UNIT=", t);
 
-                IOVEC_SET_STRING(iovec[n_iovec++], core_user_unit);
-        }
+        /* The next few are mandatory */
+        if (!set_iovec_field(iovec, n_iovec, "COREDUMP_PID=", context[CONTEXT_PID]))
+                return log_oom();
 
-        core_pid = strjoina("COREDUMP_PID=", context[CONTEXT_PID]);
-        IOVEC_SET_STRING(iovec[n_iovec++], core_pid);
+        if (!set_iovec_field(iovec, n_iovec, "COREDUMP_UID=", context[CONTEXT_UID]))
+                return log_oom();
 
-        core_uid = strjoina("COREDUMP_UID=", context[CONTEXT_UID]);
-        IOVEC_SET_STRING(iovec[n_iovec++], core_uid);
+        if (!set_iovec_field(iovec, n_iovec, "COREDUMP_GID=", context[CONTEXT_GID]))
+                return log_oom();
 
-        core_gid = strjoina("COREDUMP_GID=", context[CONTEXT_GID]);
-        IOVEC_SET_STRING(iovec[n_iovec++], core_gid);
+        if (!set_iovec_field(iovec, n_iovec, "COREDUMP_SIGNAL=", context[CONTEXT_SIGNAL]))
+                return log_oom();
 
-        core_signal = strjoina("COREDUMP_SIGNAL=", context[CONTEXT_SIGNAL]);
-        IOVEC_SET_STRING(iovec[n_iovec++], core_signal);
+        if (!set_iovec_field(iovec, n_iovec, "COREDUMP_RLIMIT=", context[CONTEXT_RLIMIT]))
+                return log_oom();
 
-        core_rlimit = strjoina("COREDUMP_RLIMIT=", context[CONTEXT_RLIMIT]);
-        IOVEC_SET_STRING(iovec[n_iovec++], core_rlimit);
+        if (!set_iovec_field(iovec, n_iovec, "COREDUMP_COMM=", comm))
+                return log_oom();
 
-        if (sd_pid_get_session(pid, &t) >= 0) {
-                core_session = strjoina("COREDUMP_SESSION=", t);
-                free(t);
+        if (exe &&
+            !set_iovec_field(iovec, n_iovec, "COREDUMP_EXE=", exe))
+                return log_oom();
 
-                IOVEC_SET_STRING(iovec[n_iovec++], core_session);
-        }
+        if (sd_pid_get_session(pid, &t) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_SESSION=", t);
 
         if (sd_pid_get_owner_uid(pid, &owner_uid) >= 0) {
-                r = asprintf(&core_owner_uid, "COREDUMP_OWNER_UID=" UID_FMT, owner_uid);
+                r = asprintf(&t, "COREDUMP_OWNER_UID=" UID_FMT, owner_uid);
                 if (r > 0)
-                        IOVEC_SET_STRING(iovec[n_iovec++], core_owner_uid);
-        }
-
-        if (sd_pid_get_slice(pid, &t) >= 0) {
-                core_slice = strjoina("COREDUMP_SLICE=", t);
-                free(t);
-
-                IOVEC_SET_STRING(iovec[n_iovec++], core_slice);
-        }
-
-        if (comm) {
-                core_comm = strjoina("COREDUMP_COMM=", comm);
-                IOVEC_SET_STRING(iovec[n_iovec++], core_comm);
-        }
-
-        if (exe) {
-                core_exe = strjoina("COREDUMP_EXE=", exe);
-                IOVEC_SET_STRING(iovec[n_iovec++], core_exe);
+                        IOVEC_SET_STRING(iovec[(*n_iovec)++], t);
         }
 
-        if (get_process_cmdline(pid, 0, false, &t) >= 0) {
-                core_cmdline = strjoina("COREDUMP_CMDLINE=", t);
-                free(t);
+        if (sd_pid_get_slice(pid, &t) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_SLICE=", t);
 
-                IOVEC_SET_STRING(iovec[n_iovec++], core_cmdline);
-        }
-
-        if (cg_pid_get_path_shifted(pid, NULL, &t) >= 0) {
-                core_cgroup = strjoina("COREDUMP_CGROUP=", t);
-                free(t);
+        if (get_process_cmdline(pid, 0, false, &t) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_CMDLINE=", t);
 
-                IOVEC_SET_STRING(iovec[n_iovec++], core_cgroup);
-        }
+        if (cg_pid_get_path_shifted(pid, NULL, &t) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_CGROUP=", t);
 
-        if (compose_open_fds(pid, &t) >= 0) {
-                core_open_fds = strappend("COREDUMP_OPEN_FDS=", t);
-                free(t);
-
-                if (core_open_fds)
-                        IOVEC_SET_STRING(iovec[n_iovec++], core_open_fds);
-        }
+        if (compose_open_fds(pid, &t) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_OPEN_FDS=", t);
 
         p = procfs_file_alloca(pid, "status");
-        if (read_full_file(p, &t, NULL) >= 0) {
-                core_proc_status = strappend("COREDUMP_PROC_STATUS=", t);
-                free(t);
-
-                if (core_proc_status)
-                        IOVEC_SET_STRING(iovec[n_iovec++], core_proc_status);
-        }
+        if (read_full_file(p, &t, NULL) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_PROC_STATUS=", t);
 
         p = procfs_file_alloca(pid, "maps");
-        if (read_full_file(p, &t, NULL) >= 0) {
-                core_proc_maps = strappend("COREDUMP_PROC_MAPS=", t);
-                free(t);
-
-                if (core_proc_maps)
-                        IOVEC_SET_STRING(iovec[n_iovec++], core_proc_maps);
-        }
+        if (read_full_file(p, &t, NULL) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_PROC_MAPS=", t);
 
         p = procfs_file_alloca(pid, "limits");
-        if (read_full_file(p, &t, NULL) >= 0) {
-                core_proc_limits = strappend("COREDUMP_PROC_LIMITS=", t);
-                free(t);
-
-                if (core_proc_limits)
-                        IOVEC_SET_STRING(iovec[n_iovec++], core_proc_limits);
-        }
+        if (read_full_file(p, &t, NULL) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_PROC_LIMITS=", t);
 
         p = procfs_file_alloca(pid, "cgroup");
-        if (read_full_file(p, &t, NULL) >=0) {
-                core_proc_cgroup = strappend("COREDUMP_PROC_CGROUP=", t);
-                free(t);
-
-                if (core_proc_cgroup)
-                        IOVEC_SET_STRING(iovec[n_iovec++], core_proc_cgroup);
-        }
+        if (read_full_file(p, &t, NULL) >=0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_PROC_CGROUP=", t);
 
         p = procfs_file_alloca(pid, "mountinfo");
-        if (read_full_file(p, &t, NULL) >=0) {
-                core_proc_mountinfo = strappend("COREDUMP_PROC_MOUNTINFO=", t);
-                free(t);
+        if (read_full_file(p, &t, NULL) >=0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_PROC_MOUNTINFO=", t);
 
-                if (core_proc_mountinfo)
-                        IOVEC_SET_STRING(iovec[n_iovec++], core_proc_mountinfo);
-        }
-
-        if (get_process_cwd(pid, &t) >= 0) {
-                core_cwd = strjoina("COREDUMP_CWD=", t);
-                free(t);
-
-                IOVEC_SET_STRING(iovec[n_iovec++], core_cwd);
-        }
+        if (get_process_cwd(pid, &t) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_CWD=", t);
 
         if (get_process_root(pid, &t) >= 0) {
-                core_root = strjoina("COREDUMP_ROOT=", t);
+                bool proc_self_root_is_slash;
+
+                proc_self_root_is_slash = strcmp(t, "/") == 0;
 
-                IOVEC_SET_STRING(iovec[n_iovec++], core_root);
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_ROOT=", t);
 
                 /* If the process' root is "/", then there is a chance it has
                  * mounted own root and hence being containerized. */
-                proc_self_root_is_slash = strcmp(t, "/") == 0;
-                free(t);
-                if (proc_self_root_is_slash && get_process_container_parent_cmdline(pid, &t) > 0) {
-                        core_container_cmdline = strappend("COREDUMP_CONTAINER_CMDLINE=", t);
-                        free(t);
-
-                        if (core_container_cmdline)
-                                IOVEC_SET_STRING(iovec[n_iovec++], core_container_cmdline);
-                }
+                if (proc_self_root_is_slash && get_process_container_parent_cmdline(pid, &t) > 0)
+                        set_iovec_field_free(iovec, n_iovec, "COREDUMP_CONTAINER_CMDLINE=", t);
         }
 
-        if (get_process_environ(pid, &t) >= 0) {
-                core_environ = strappend("COREDUMP_ENVIRON=", t);
-                free(t);
+        if (get_process_environ(pid, &t) >= 0)
+                set_iovec_field_free(iovec, n_iovec, "COREDUMP_ENVIRON=", t);
+
+        t = strjoin("COREDUMP_TIMESTAMP=", context[CONTEXT_TIMESTAMP], "000000", NULL);
+        if (t)
+                IOVEC_SET_STRING(iovec[(*n_iovec)++], t);
+
+        return 0;
+}
 
-                if (core_environ)
-                        IOVEC_SET_STRING(iovec[n_iovec++], core_environ);
+static int process_kernel(int argc, char* argv[]) {
+
+        const char *context[_CONTEXT_MAX];
+        struct iovec iovec[27];
+        size_t n_iovec = 0, i, n_to_free;
+        int r;
+
+        if (argc < CONTEXT_COMM + 1) {
+                log_error("Not enough arguments passed from kernel (%i, expected %i).", argc - 1, CONTEXT_COMM + 1 - 1);
+                return -EINVAL;
         }
 
-        core_timestamp = strjoina("COREDUMP_TIMESTAMP=", context[CONTEXT_TIMESTAMP], "000000");
-        IOVEC_SET_STRING(iovec[n_iovec++], core_timestamp);
+        context[CONTEXT_PID]       = argv[CONTEXT_PID + 1];
+        context[CONTEXT_UID]       = argv[CONTEXT_UID + 1];
+        context[CONTEXT_GID]       = argv[CONTEXT_GID + 1];
+        context[CONTEXT_SIGNAL]    = argv[CONTEXT_SIGNAL + 1];
+        context[CONTEXT_TIMESTAMP] = argv[CONTEXT_TIMESTAMP + 1];
+        context[CONTEXT_RLIMIT]    = argv[CONTEXT_RLIMIT + 1];
+
+        r = gather_pid_metadata(context, argv + CONTEXT_COMM + 1, iovec, &n_iovec);
+        if (r < 0)
+                goto finish;
+        n_to_free = n_iovec;
 
         IOVEC_SET_STRING(iovec[n_iovec++], "MESSAGE_ID=fc2e22bc6ee647b6b90729ab34a250b1");
 
@@ -1268,14 +1216,20 @@ static int process_kernel(int argc, char* argv[]) {
 
         assert(n_iovec <= ELEMENTSOF(iovec));
 
-        return send_iovec(iovec, n_iovec, STDIN_FILENO);
+        r = send_iovec(iovec, n_iovec, STDIN_FILENO);
+
+ finish:
+        for (i = 0; i < n_to_free; i++)
+                free(iovec[i].iov_base);
+
+        return r;
 }
 
 int main(int argc, char *argv[]) {
         int r;
 
-        /* First, log to a safe place, since we don't know what crashed and it might be journald which we'd rather not
-         * log to then. */
+        /* First, log to a safe place, since we don't know what crashed and it might
+         * be journald which we'd rather not log to then. */
 
         log_set_target(LOG_TARGET_KMSG);
         log_open();
@@ -1295,8 +1249,8 @@ int main(int argc, char *argv[]) {
                 goto finish;
         }
 
-        /* If we got an fd passed, we are running in coredumpd mode. Otherwise we are invoked from the kernel as
-         * coredump handler */
+        /* If we got an fd passed, we are running in coredumpd mode. Otherwise we
+         * are invoked from the kernel as coredump handler. */
         if (r == 0)
                 r = process_kernel(argc, argv);
         else if (r == 1)