REF: Replace kill_subtree code so it uses only pgrep (procps)

Avoids dependencies: bash, awk, coreutils, findutils.
Other approaches (e.g. libprocps or parsing /proc) aren't portable.

src/exec.c

@@ -9,14 +9,16 @@
static inline
int
execute (char **argv,
         char **envp)
         char **envp,
         char **stdout)
{
    g_autoptr (GError) err = NULL;
    gint exit_status = -1;
    GSpawnFlags flags = G_SPAWN_STDOUT_TO_DEV_NULL | G_SPAWN_STDERR_TO_DEV_NULL;
    GSpawnFlags flags = G_SPAWN_STDERR_TO_DEV_NULL |
                        (stdout ? G_SPAWN_DEFAULT : G_SPAWN_STDOUT_TO_DEV_NULL);

    g_spawn_sync (NULL, argv, envp, flags | G_SPAWN_SEARCH_PATH,
                  NULL, NULL, NULL, NULL, &exit_status, &err);
                  NULL, NULL, stdout, NULL, &exit_status, &err);
    if (err)
        g_warning ("Unexpected subprocess execution error: %s", err->message);

@@ -43,7 +45,7 @@ xsus_exec_subprocess (char **argv,

    // Execute and return result
    g_debug ("Exec %#lx (%d): %s", entry->xid, entry->pid, argv[2]);
    int exit_status = execute (argv, envp);
    int exit_status = execute (argv, envp, NULL);
    g_debug ("Exit status: %d", exit_status);

    // Free envp
@@ -53,44 +55,41 @@ xsus_exec_subprocess (char **argv,
}


int
static
void
kill_recursive (char* pid_str, int signal, char* cmd_pattern)
{
    // Kill the process
    g_debug ("    -  %s", pid_str);
    kill ((pid_t) g_ascii_strtoll (pid_str, NULL, 10), signal);

    // Pgrep its children
    char *argv[] = {"pgrep", "-fP", pid_str, cmd_pattern, NULL};
    g_autofree char *standard_output = NULL;
    execute (argv, NULL, &standard_output);
    if (! standard_output)
        return;  // No children

    // Recurse
    g_auto (GStrv) child_pids = g_strsplit (g_strstrip (standard_output), "\n", 0);
    for (int i = 0; child_pids[i]; ++i)
        kill_recursive (child_pids[i], signal, cmd_pattern);
}


void
xsus_kill_subtree (pid_t pid,
                   int signal,
                   char *cmd_pattern)
{
    if (! cmd_pattern)
        return 0;
        return;

    g_assert (signal == SIGSTOP || signal == SIGCONT);
    char *sig = signal == SIGSTOP ? "STOP" : "CONT";

    // Prefer this short script to using pstree (induces extra dependency)
    // or involved parsing of /proc
    g_autofree char *script = g_strdup_printf (
        "pid=%d\n"
            "ps_output=\"$(ps -e -o ppid,pid,cmd | awk \"/%s/\"'{ print $1, $2 }')\"\n"
            "while [ \"$pid\" ]; do\n"
            "    pid=\"$(echo \"$ps_output\" | awk \"/^($pid) /{ print \\$2 }\")\"\n"
            "    echo -n $pid\" \"\n"
            "    pid=\"$(echo \"$pid\" | paste -sd '|' -)\"\n"
            "done%s | xargs kill -%s 2>/dev/null",
        pid, cmd_pattern, (IS_DEBUG ? " | tee /dev/fd/2" : ""), sig);

    char *argv[] = {
        "sh", "-c", script, NULL};
    char *envp[] = {
        g_strdup_printf ("PATH=%s", g_getenv ("PATH")),
        g_strdup_printf ("LC_ALL=C"),  // Speeds up locale-aware awk
        NULL
    };

    // Execute and return result
    g_debug ("Exec: pstree %d | kill -%s", pid, sig);
    int exit_status = execute (argv, envp);
    g_debug ("Exit status: %d", exit_status);

    // Free envp
    char **e = envp; while (*e) g_free(*e++);

    return exit_status;
    g_debug ("Exec: pstree %d (%s) | kill -%s",
             pid, cmd_pattern, signal == SIGSTOP ? "STOP" : "CONT");
    char pid_str[11];
    g_snprintf ((char*) &pid_str, sizeof (pid_str), "%d", pid);
    kill_recursive (pid_str, signal, cmd_pattern);
}

src/exec.h

@@ -7,6 +7,6 @@


int xsus_exec_subprocess (char **argv, WindowEntry *entry);
int xsus_kill_subtree (pid_t pid, int signal, char *cmd_pattern);
void xsus_kill_subtree (pid_t pid, int signal, char *cmd_pattern);

#endif  // XSUSPENDER_SUBPROCESS_H