[OpenWrt-Devel] [PATCH] fstools: add a hook before mounting the overlay

[John Crispin]

On 09/10/2019 14:41, Alin Nastac wrote:
> Scripts located in the directory /lib/mount_root will be executed
> before mounting the overlay.
>
> Signed-off-by: Alin Nastac <alin.nastac at gmail.com>

Hi,

should it not be /etc/mount_root.d/ ? what do you need this for if I may 
ask ?

further comments inline ...

     John


> ---
>   libfstools/hook.h    | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
>   libfstools/overlay.c |  3 ++-
>   2 files changed, 53 insertions(+), 1 deletion(-)
>   create mode 100644 libfstools/hook.h
>
> diff --git a/libfstools/hook.h b/libfstools/hook.h
> new file mode 100644
> index 0000000..76ee9d0
> --- /dev/null
> +++ b/libfstools/hook.h
> @@ -0,0 +1,51 @@
> +#ifndef _HOOK_H
> +#define _HOOK_H
> +
> +#include <sys/types.h>
> +#include <sys/wait.h>
> +
> +static inline int hook_execute(const char *path)
this should not be in a header file nor should it be inline
> +{
> +	DIR *dir;
> +	struct dirent *dent;
> +	char script[256];
> +	pid_t pid;
> +
> +	ULOG_INFO("executing script in %s\n", path);
> +
> +	if ((dir = opendir(path)) == NULL) {
> +		ULOG_INFO("cannot open %s (%s)\n", path, strerror(errno));
> +		return 0;
> +	}
> +
> +	while ((dent = readdir(dir)) != NULL) {
> +		struct stat st;
> +		int wstatus;
> +
> +		snprintf(script, sizeof(script), "%s/%s", path, dent->d_name);
> +		if (stat(script, &st))
> +			continue;
> +		if (!S_ISREG(st.st_mode))
> +			continue;
> +		ULOG_INFO("%s\n", script);
     you should consider using runqueue API here
> +		pid = fork();
> +		if (!pid) {
> +			char *cmd[] = {script, NULL};
> +
> +			execvp(cmd[0], cmd);
> +			ULOG_ERR("Failed to execute %s\n", script);
> +			exit(-1);
> +		}
> +		if (pid <= 0) {
> +			ULOG_INFO("Failed to fork() for %s\n", script);
> +			continue;
> +		}
> +		waitpid(pid, &wstatus, 0);
> +	}
> +
> +	closedir(dir);
> +
> +	return 0;
> +}
> +
> +#endif
> diff --git a/libfstools/overlay.c b/libfstools/overlay.c
> index 14214a3..10a16b5 100644
> --- a/libfstools/overlay.c
> +++ b/libfstools/overlay.c
> @@ -29,6 +29,7 @@
>   
>   #include "libfstools.h"
>   #include "volume.h"
> +#include "hook.h"
>   
>   #define SWITCH_JFFS2 "/tmp/.switch_jffs2"
>   
> @@ -439,7 +440,7 @@ int mount_overlay(struct volume *v)
>   
>   	fs_name = overlay_fs_name(volume_identify(v));
>   	ULOG_INFO("switching to %s overlay\n", fs_name);
> -	if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
> +	if (mount_move("/tmp", "", "/overlay") || hook_execute("/lib/mount_root") || fopivot("/overlay", "/rom")) {
>   		ULOG_ERR("switching to %s failed - fallback to ramoverlay\n", fs_name);
>   		return ramoverlay();
>   	}

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