discover/boot: Allow boot hooks to alter boot data

By exiting with status == 2, boot hooks can update boot data by
printing name=value to stdout.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

diff --git a/discover/boot.c b/discover/boot.c
index 8c2e8e19607d1ff056479e084f58c6d958a5be9c..ed30ef9fe085104d1e94f957d426e1c7555089e0 100644 (file)
--- a/discover/boot.c
+++ b/discover/boot.c
@@ -21,12 +21,17 @@
 #include "resource.h"
 
 static const char *boot_hook_dir = PKG_SYSCONF_DIR "/boot.d";
+enum {
+       BOOT_HOOK_EXIT_OK       = 0,
+       BOOT_HOOK_EXIT_UPDATE   = 2,
+};
+
 
 struct boot_task {
        char *local_image;
        char *local_initrd;
        char *local_dtb;
-       const char *args;
+       char *args;
 
        bool dry_run;
 };
@@ -148,6 +153,72 @@ static void update_status(boot_status_fn fn, void *arg, int type,
        fn(arg, &status);
 }
 
+static void boot_hook_update_param(void *ctx, struct boot_task *task,
+               const char *name, const char *value)
+{
+       struct p {
+               const char *name;
+               char **p;
+       } *param, params[] = {
+               { "boot_image",         &task->local_image },
+               { "boot_initrd",        &task->local_initrd },
+               { "boot_dtb",           &task->local_dtb },
+               { "boot_args",          &task->args },
+               { NULL, NULL },
+       };
+
+       for (param = params; param->name; param++) {
+               if (strcmp(param->name, name))
+                       continue;
+
+               *param->p = talloc_strdup(ctx, value);
+               return;
+       }
+}
+
+static void boot_hook_update(void *ctx, const char *hookname,
+               struct boot_task *task, char *buf)
+{
+       char *line, *name, *val, *sep;
+       char *saveptr;
+
+       for (;; buf = NULL) {
+
+               line = strtok_r(buf, "\n", &saveptr);
+               if (!line)
+                       break;
+
+               sep = strchr(line, '=');
+               if (!sep)
+                       continue;
+
+               *sep = '\0';
+               name = line;
+               val = sep + 1;
+
+               boot_hook_update_param(ctx, task, name, val);
+
+               pb_log("boot hook %s specified %s=%s\n",
+                               hookname, name, val);
+       }
+}
+
+static void boot_hook_setenv(struct boot_task *task)
+{
+       unsetenv("boot_image");
+       unsetenv("boot_initrd");
+       unsetenv("boot_dtb");
+       unsetenv("boot_args");
+
+       setenv("boot_image", task->local_image, 1);
+       if (task->local_initrd)
+               setenv("boot_initrd", task->local_initrd, 1);
+       if (task->local_dtb)
+               setenv("boot_dtb", task->local_dtb, 1);
+       if (task->args)
+               setenv("boot_args", task->args, 1);
+}
+
 static int hook_filter(const struct dirent *dirent)
 {
        return dirent->d_type == DT_REG || dirent->d_type == DT_LNK;
@@ -171,18 +242,12 @@ static void run_boot_hooks(void *ctx, struct boot_task *task,
        update_status(status_fn, status_arg, BOOT_STATUS_INFO,
                        "running boot hooks");
 
-       /* pass boot data to hooks */
-       setenv("boot_image", task->local_image, 1);
-       if (task->local_initrd)
-               setenv("boot_initrd", task->local_initrd, 1);
-       if (task->local_dtb)
-               setenv("boot_dtb", task->local_dtb, 1);
-       if (task->args)
-               setenv("boot_args", task->args, 1);
+       boot_hook_setenv(task);
 
        for (i = 0; i < n; i++) {
-               char *path;
                const char *argv[2] = { NULL, NULL };
+               char *path, *buf;
+               int buf_len, rc;
 
                path = join_paths(ctx, boot_hook_dir, hooks[i]->d_name);
 
@@ -192,8 +257,18 @@ static void run_boot_hooks(void *ctx, struct boot_task *task,
                pb_log("running boot hook %s\n", hooks[i]->d_name);
 
                argv[0] = path;
-               pb_run_cmd(argv, 1, task->dry_run);
+               rc = pb_run_cmd_pipe(argv, 1, task->dry_run, ctx,
+                               &buf, &buf_len);
+
+               /* if the hook returned with BOOT_HOOK_EXIT_UPDATE,
+                * then we process stdout to look for updated params
+                */
+               if (rc == BOOT_HOOK_EXIT_UPDATE) {
+                       boot_hook_update(ctx, hooks[i]->d_name, task, buf);
+                       boot_hook_setenv(task);
+               }
 
+               talloc_free(buf);
                talloc_free(path);
        }
 

diff --git a/lib/system/system.c b/lib/system/system.c
index 7bb49973333f3ebebcd4eec0a87fe37994acc67c..528e134127f307f17d9dcfaa70b2b1ef60eb7a52 100644 (file)
--- a/lib/system/system.c
+++ b/lib/system/system.c
@@ -159,9 +159,9 @@ int pb_run_cmd_pipe(const char *const *cmd_argv, int wait, int dry_run,
        int status, pipefd[2];
        pid_t pid;
 
-       assert(!wait && stdout_buf);
-       assert(!!ctx != !!stdout_buf);
-       assert(!!stdout_buf != !!stdout_buf_len);
+       assert(!stdout_buf || wait);
+       assert(!stdout_buf || ctx);
+       assert(!stdout_buf || stdout_buf_len);
 
        if (do_debug) {
                const char *const *p = cmd_argv;