[CRIU] [PATCH 1/5] crtools: preload libraries

[Pavel Emelyanov]

>>> @@ -0,0 +1,22 @@
>>> +#ifndef __CR_PLUGIN_H__
>>> +#define __CR_PLUGIN_H__
>>> +
>>> +#include "criu-plugin.h"
>>> +
>>> +struct cr_plugin_entry {
>>> +	union {
>>> +		cr_plugin_fini_t *cr_fini;
>>> +	};
>>> +
>>> +	struct cr_plugin_entry *next;
>>> +};
>>> +
>>> +struct cr_plugins {
>>> +	struct cr_plugin_entry *cr_fini;
>>> +};
>>> +
>>> +extern struct cr_plugins cr_plugins;
>>
>> Why should this info be public?
> 
> criu-plugin.h is public, this one isn't.

OK, s/public/criu-sources-visible/
Why?

>>
>>> +
>>> +void cr_lib_fini(void);
>>> +int cr_lib_init(void);
>>> +#endif
>>> diff --git a/lib.c b/lib.c
>>> new file mode 100644
>>> index 0000000..387bb84
>>> --- /dev/null
>>> +++ b/lib.c
>>> @@ -0,0 +1,123 @@
>>> +#include <stdlib.h>
>>> +#include <string.h>
>>> +#include <dirent.h>
>>> +#include <errno.h>
>>> +#include <stdio.h>
>>> +#include <dlfcn.h>
>>> +
>>> +#include "cr_options.h"
>>> +#include "plugin.h"
>>> +#include "log.h"
>>> +#include "xmalloc.h"
>>> +
>>> +struct cr_plugins cr_plugins;
>>> +
>>> +static int cr_lib_load(char *path)
>>> +{
>>> +	struct cr_plugin_entry *ce;
>>> +	cr_plugin_init_t *f_init;
>>> +	cr_plugin_fini_t *f_fini;
>>> +	void *h;
>>> +
>>> +	h = dlopen(path, RTLD_LAZY);
>>> +	if (h == NULL) {
>>> +		pr_err("Unable to load %s: %s", path, dlerror());
>>> +		return -1;
>>> +	}
>>> +
>>> +	ce = NULL;
>>> +	f_fini = dlsym(h, "cr_plugin_fini");
>>> +	if (f_fini) {
>>> +		ce = xmalloc(sizeof(struct cr_plugin_entry));
>>> +		if (ce == NULL)
>>> +			return -1;
>>> +		ce->cr_fini = f_fini;
>>
>> In patch #3 you use some fancy macro for this.
> 
> f_fini is a special case.
>>
>>> +	}
>>> +
>>> +	f_init = dlsym(h, "cr_plugin_init");
>>> +	if (f_init && f_init()) {
>>> +		xfree(ce);
>>> +		return -1;
>>> +	}
>>> +
>>> +	if (ce) {
>>> +		ce->next = cr_plugins.cr_fini;
>>> +		cr_plugins.cr_fini = ce;
>>> +	}
> 
> because it's added in the list here

Why?

>>> +
>>> +	return 0;
>>> +}
>>> +
>>> +void cr_lib_fini(void)
>>> +{
>>> +	struct cr_plugin_entry *ce;
>>> +
>>> +	while (cr_plugins.cr_fini) {
>>> +		ce = cr_plugins.cr_fini;
>>> +		cr_plugins.cr_fini = cr_plugins.cr_fini->next;
>>> +
>>> +		ce->cr_fini();
>>> +		xfree(ce);
>>> +	}
>>> +}
>>> +
>>> +int cr_lib_init(void)
>>> +{
>>> +	int exit_code = -1;
>>> +	DIR *d;
>>> +
>>> +	memset(&cr_plugins, 0, sizeof(cr_plugins));
>>> +
>>> +	if (opts.libdir == NULL) {
>>> +		char *path;
>>> +
>>> +		path = getenv("CRIU_LIBS_DIR");
>>> +		if (path == NULL)
>>
>> I think we should declare some default library for it.
> 
> I thought about this. I don't know which path can be default and we can
> add the default path in any moment.

Plz, declare the /var/lib/criu/ and use it.

> 
>>
>>> +			return 0;
>>> +
>>> +		opts.libdir = strdup(path);
>>
>> Why strdup?
> 
> becuase we need to copy the string, when we are parsing options,
> so we are going to call free(opts.libdir)
> 
>>
>>> +		if (opts.libdir == NULL) {
>>> +			pr_perror("Can't allocate memory");
>>> +			return -1;
>>> +		}
>>> +	}
>>> +
>>> +	d = opendir(opts.libdir);
>>> +	if (d == 0) {
>>> +		pr_perror("Unable to open directory %s", opts.libdir);
>>> +		return -1;
>>> +	}
>>> +
>>> +	while (1) {
>>> +		char path[PATH_MAX];
>>> +		struct dirent *de;
>>> +		int len;
>>> +
>>> +		errno = 0;
>>> +		de = readdir(d);
>>> +		if (de == NULL) {
>>> +			if (errno == 0)
>>> +				break;
>>> +			pr_perror("Unable to read the libraries directory");
>>> +			goto err;
>>> +		}
>>> +
>>> +		len = strlen(de->d_name);
>>> +
>>> +		if (len < 3 || strncmp(de->d_name + len - 3, ".so", 3))
>>> +			continue;
>>> +
>>> +		snprintf(path, sizeof(path), "%s/%s", opts.libdir, de->d_name);
>>> +
>>> +		if (cr_lib_load(path))
>>> +			goto err;
>>> +	}
>>> +
>>> +	exit_code = 0;
>>> +err:
>>> +	closedir(d);
>>> +
>>> +	cr_lib_fini();
>>> +
>>> +	return exit_code;
>>> +}
>>>
>>
>>
> .
>