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From: Alexey Gladkov <gladkov.alexey@gmail.com>
To: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: linux-modules@vger.kernel.org
Subject: Re: [PATCH v1 1/4] libkmod: Add parser for modules.builtin.modinfo
Date: Fri, 8 Nov 2019 18:31:12 +0100
Message-ID: <20191108173112.7aknksgqtb4akdus@Legion-PC.fortress> (raw)
In-Reply-To: <20191107082310.as5zrubafgaaeb4e@ldmartin-desk1>

On Thu, Nov 07, 2019 at 12:23:10AM -0800, Lucas De Marchi wrote:
> On Fri, Oct 11, 2019 at 10:19:53AM +0200, Alexey Gladkov wrote:
> > The kernel since version v5.2-rc1 exports information about built-in
> > modules in the modules.builtin.modinfo. Information is stored in
> > the same format as in the separate modules (null-terminated string
> > array). The module name is a prefix for each line.
> > 
> > $ tr '\0' '\n' < modules.builtin.modinfo
> > ext4.softdep=pre: crc32c
> > ext4.license=GPL
> > ext4.description=Fourth Extended Filesystem
> > ext4.author=Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others
> > ext4.alias=fs-ext4
> > ext4.alias=ext3
> > ext4.alias=fs-ext3
> > ext4.alias=ext2
> > ext4.alias=fs-ext2
> > md_mod.alias=block-major-9-*
> > md_mod.alias=md
> > md_mod.description=MD RAID framework
> > md_mod.license=GPL
> > md_mod.parmtype=create_on_open:bool
> > md_mod.parmtype=start_dirty_degraded:int
> 
> 
> Apologies, I thought I had replied to this already. Having this
> functionality is very welcome, thanks. I have some comments about the
> implementation. See below.
> 
> 
> > ...
> > 
> > Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com>
> > ---
> > Makefile.am                |   1 +
> > libkmod/libkmod-builtin.c  | 231 +++++++++++++++++++++++++++++++++++++
> > libkmod/libkmod-internal.h |   8 ++
> > 3 files changed, 240 insertions(+)
> > create mode 100644 libkmod/libkmod-builtin.c
> > 
> > diff --git a/Makefile.am b/Makefile.am
> > index c5c2f06..176dcfc 100644
> > --- a/Makefile.am
> > +++ b/Makefile.am
> > @@ -68,6 +68,7 @@ libkmod_libkmod_la_SOURCES = \
> > 	libkmod/libkmod.h \
> > 	libkmod/libkmod-internal.h \
> > 	libkmod/libkmod.c \
> > +	libkmod/libkmod-builtin.c \
> > 	libkmod/libkmod-list.c \
> > 	libkmod/libkmod-config.c \
> > 	libkmod/libkmod-index.c \
> > diff --git a/libkmod/libkmod-builtin.c b/libkmod/libkmod-builtin.c
> > new file mode 100644
> > index 0000000..9da0010
> > --- /dev/null
> > +++ b/libkmod/libkmod-builtin.c
> > @@ -0,0 +1,231 @@
> > +/*
> > + * libkmod - interface to kernel built-in modules
> > + *
> > + * Copyright (C) 2019  Alexey Gladkov <gladkov.alexey@gmail.com>
> > + *
> > + * This library is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU Lesser General Public
> > + * License as published by the Free Software Foundation; either
> > + * version 2.1 of the License, or (at your option) any later version.
> > + *
> > + * This library is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> > + * Lesser General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU Lesser General Public
> > + * License along with this library; if not, see <http://www.gnu.org/licenses/>.
> > + */
> 
> this remembers me we should convert these headers to spdx
> 
> > +
> > +#include <stdio.h>
> > +#include <stdlib.h>
> > +#include <string.h>
> > +#include <errno.h>
> > +
> > +#include "libkmod.h"
> > +#include "libkmod-internal.h"
> > +
> > +#define MODULES_BUILTIN_MODINFO "modules.builtin.modinfo"
> > +
> > +struct kmod_builtin_iter {
> > +	struct kmod_ctx *ctx;
> > +	struct kmod_file *file;
> > +	off_t pos;
> > +	off_t next;
> > +};
> > +
> > +struct kmod_builtin_iter *kmod_builtin_iter_new(struct kmod_ctx *ctx)
> > +{
> > +	char path[PATH_MAX];
> > +	struct kmod_file *file;
> > +	struct kmod_builtin_iter *iter;
> > +	const char *dirname = kmod_get_dirname(ctx);
> > +	size_t len = strlen(dirname);
> > +
> > +	if ((len + 1 + strlen(MODULES_BUILTIN_MODINFO) + 1) >= PATH_MAX) {
> > +		errno = ENAMETOOLONG;
> > +		return NULL;
> > +	}
> > +
> > +	snprintf(path, PATH_MAX, "%s/%s", dirname, MODULES_BUILTIN_MODINFO);
> > +
> > +	file = kmod_file_open(ctx, path);
> > +	if (!file)
> > +		return NULL;
> > +
> > +	iter = malloc(sizeof(*iter));
> > +	if (!iter) {
> > +		kmod_file_unref(file);
> > +		errno = ENOMEM;
> > +		return NULL;
> > +	}
> > +
> > +	iter->ctx = ctx;
> > +	iter->file = file;
> > +	iter->pos = 0;
> > +	iter->next = 0;
> > +
> > +	return iter;
> > +}
> > +
> > +bool kmod_builtin_iter_next(struct kmod_builtin_iter *iter)
> > +{
> > +	char *mm, *s, *dot;
> > +	off_t offset, mmsize;
> > +	size_t len, modlen;
> > +	char *modname = NULL;
> > +
> > +	mm = kmod_file_get_contents(iter->file);
> > +	mmsize = kmod_file_get_size(iter->file);
> 
> humn... kmod_file is more target for handling modules. This is only
> < 100k  and we would access it sequentially. I think we are fine just
> using stdio.

Make sense.

> > +
> > +	offset = iter->next;
> > +
> > +	while (offset < mmsize) {
> > +		s = mm + offset;
> > +
> > +		dot = strchr(s, '.');
> > +		if (!dot)
> > +			return false;
> 
> wouldn't this fail if in the description of a module/param we have a dot?

No. All fields have a module name as a prefix.

> I think a more correct approach is to search for \0 and then try to
> match the prefix.
> 
> Actually, maybe even better to memmem() "\0<module-name>.", first being
> an exception.
> 
> 
> > +
> > +		len = dot - s;
> > +
> > +		if (!modname) {
> > +			modname = s;
> > +			modlen = len;
> > +		} else if (modlen != len || strncmp(modname, s, len)) {
> > +			break;
> > +		}
> > +
> > +		offset += strlen(s) + 1;
> > +	}
> > +
> > +	if (!modname)
> > +		return false;
> > +
> > +	iter->next = offset;
> > +
> > +	return true;
> > +}
> > +
> > +void kmod_builtin_iter_free(struct kmod_builtin_iter *iter)
> > +{
> > +	kmod_file_unref(iter->file);
> > +	free(iter);
> > +}
> > +
> > +int kmod_builtin_iter_get_strings(struct kmod_builtin_iter *iter,
> > +					const char **strings)
> > +{
> > +	char *mm = kmod_file_get_contents(iter->file);
> > +	off_t pos = iter->pos;
> > +
> > +	char *start = NULL;
> > +	size_t count = 0;
> > +	size_t modlen = 0;
> > +
> > +	while (pos < iter->next) {
> > +		char *dot = strchr(mm + pos, '.');
> > +		size_t len;
> > +
> > +		if (!dot)
> > +			return -1;
> > +
> > +		len = dot - (mm + pos);
> > +
> > +		if (!start) {
> > +			start = mm + pos;
> > +			modlen = len;
> > +		} else if (modlen != len || strncmp(start, mm + pos, len)) {
> > +			break;
> > +		}
> > +
> > +		pos += strlen(mm + pos) + 1;
> > +		count++;
> > +	}
> > +
> > +	*strings = start;
> > +	iter->pos = iter->next;
> > +
> > +	return count;
> > +}
> > +
> > +/* array will be allocated with strings in a single malloc, just free *array */
> > +int kmod_builtin_get_modinfo(struct kmod_ctx *ctx, const char *modname,
> > +				char ***modinfo)
> > +{
> > +	char *mm, *s, *section, *dot;
> > +	off_t n, size, offset, mmoffset, mmsize;
> > +	size_t modlen, len;
> > +	struct kmod_builtin_iter *iter;
> > +	int count = 0;
> > +
> > +	iter = kmod_builtin_iter_new(ctx);
> > +
> > +	if (!iter)
> > +		return -1;
> > +
> > +	modlen = strlen(modname);
> > +
> > +	mmsize = kmod_file_get_size(iter->file);
> > +	mm = kmod_file_get_contents(iter->file);
> > +
> > +	section = NULL;
> > +	size = 0;
> > +
> > +	for (mmoffset = 0; mmoffset < mmsize;) {
> > +		s = mm + mmoffset;
> > +		dot = strchr(s, '.');
> > +
> > +		if (!dot) {
> > +			count = -ENODATA;
> > +			goto fail;
> > +		}
> > +
> > +		len = dot - s;
> > +
> > +		if (modlen != len || strncmp(modname, s, len)) {
> > +			if (count)
> > +				break;
> > +			mmoffset += strlen(s) + 1;
> > +			continue;
> > +		} else if (!count) {
> > +			section = s;
> > +		}
> > +
> > +		len = strlen(dot + 1) + 1;
> > +		mmoffset += modlen + 1 + len;
> > +		size += len;
> > +
> > +		count++;
> > +	}
> > +
> > +	if (!count) {
> > +		count = -ENOSYS;
> > +		goto fail;
> > +	}
> > +
> > +	*modinfo = malloc(size + sizeof(char *) * (count + 1));
> > +	if (!*modinfo) {
> > +		count = -errno;
> > +		goto fail;
> > +	}
> > +
> > +	s = (char *)(*modinfo + count + 1);
> > +
> > +	n = 0;
> > +	mmoffset = 0;
> > +
> > +	for (offset = 0; offset < size;) {
> > +		len = strlen(section + mmoffset + modlen + 1) + 1;
> > +
> > +		strncpy(s + offset, section + mmoffset + modlen + 1, len);
> > +		(*modinfo)[n++] = s + offset;
> > +
> > +		mmoffset += modlen + 1 + len;
> > +		offset += len;
> > +	}
> > +
> > +fail:
> > +	kmod_builtin_iter_free(iter);
> > +	return count;
> > +}
> > diff --git a/libkmod/libkmod-internal.h b/libkmod/libkmod-internal.h
> > index a65ddd1..17ae541 100644
> > --- a/libkmod/libkmod-internal.h
> > +++ b/libkmod/libkmod-internal.h
> > @@ -193,3 +193,11 @@ struct kmod_signature_info {
> > };
> > bool kmod_module_signature_info(const struct kmod_file *file, struct kmod_signature_info *sig_info) _must_check_ __attribute__((nonnull(1, 2)));
> > void kmod_module_signature_info_free(struct kmod_signature_info *sig_info) __attribute__((nonnull));
> > +
> > +/* libkmod-builtin.c */
> > +struct kmod_builtin_iter;
> > +struct kmod_builtin_iter *kmod_builtin_iter_new(struct kmod_ctx *ctx) __attribute__((nonnull(1)));
> > +void kmod_builtin_iter_free(struct kmod_builtin_iter *iter) __attribute__((nonnull(1)));
> > +bool kmod_builtin_iter_next(struct kmod_builtin_iter *iter) __attribute__((nonnull(1)));
> > +int kmod_builtin_iter_get_strings(struct kmod_builtin_iter *iter, const char **modinfo) __attribute__((nonnull(1, 2)));
> > +int kmod_builtin_get_modinfo(struct kmod_ctx *ctx, const char *modname, char ***modinfo) __attribute__((nonnull(1, 2, 3)));
> > -- 
> > 2.21.0
> > 
> 

-- 
Rgrds, legion


  reply index

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-11  8:19 [PATCH v1 0/4] Add modules.builtin.modinfo support Alexey Gladkov
2019-10-11  8:19 ` [PATCH v1 1/4] libkmod: Add parser for modules.builtin.modinfo Alexey Gladkov
2019-11-07  8:23   ` Lucas De Marchi
2019-11-08 17:31     ` Alexey Gladkov [this message]
2019-10-11  8:19 ` [PATCH v1 2/4] libkmod: Add function to get list of built-in modules Alexey Gladkov
2019-10-11  8:19 ` [PATCH v1 3/4] Lookup aliases in the modules.builtin.modinfo Alexey Gladkov
2019-10-11  8:19 ` [PATCH v1 4/4] modinfo: Show information about built-in modules Alexey Gladkov
2019-11-07 10:30 ` [PATCH v1 0/4] Add modules.builtin.modinfo support Alexey Gladkov

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