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Allowed lseekable device files with iso_tree_add_new_cut_out_node(). Proof-of-concept by Ivan Shmakov.

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This commit is contained in:
Thomas Schmitt 2022-04-26 12:12:15 +02:00
parent f457a4f8b9
commit 011e2e85e6
5 changed files with 113 additions and 26 deletions
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57
libisofs/fsource.c
View File

@ -1,5 +1,6 @@
/*
* Copyright (c) 2007 Vreixo Formoso
* Copyright (c) 2022 Thomas Schmitt
*
* This file is part of the libisofs project; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
@ -133,3 +134,59 @@ int iso_file_source_get_aa_string(IsoFileSource *src,
return src->class->get_aa_string(src, aa_string, flag);
}
/* Determine whether src is random-access readable and return its capacity.
@flag bit0= Open and close src
@return <0 iso_file_source_lseek failed , >= 0 readable capacity
*/
off_t iso_file_source_lseek_capacity(IsoFileSource *src, int flag)
{
int ret, opened = 0;
off_t end, old, reset;
struct stat info;
ret = iso_file_source_stat(src, &info);
if (ret < 0) {
end = -1;
goto ex;
}
if (S_ISDIR(info.st_mode) || S_ISLNK(info.st_mode) ||
S_ISFIFO(info.st_mode) || S_ISSOCK(info.st_mode)) {
/* open(2) on fifo can block and have side effects.
Active Unix sockets have not been tested but they make as few sense
as directories or symbolic links.
*/
end = -1;
goto ex;
}
if (flag & 1) {
ret = iso_file_source_open(src);
if (ret < 0) {
end = -1;
goto ex;
}
opened = 1;
}
old = iso_file_source_lseek(src, 0, 1);
if (old < 0) {
end = -1;
goto ex;
}
end = iso_file_source_lseek(src, 0, 2);
if (end < 0) {
end = -1;
goto ex;
}
reset = iso_file_source_lseek(src, old, 0);
if (reset != old) {
end = -1;
goto ex;
}
ex:;
if (opened) {
iso_file_source_close(src);
}
return end;
}

8
libisofs/fsource.h
View File

@ -1,6 +1,6 @@
/*
* Copyright (c) 2007 Vreixo Formoso
* Copyright (c) 2009 - 2016 Thomas Schmitt
* Copyright (c) 2009 - 2022 Thomas Schmitt
*
* This file is part of the libisofs project; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
@ -49,4 +49,10 @@ int iso_ifs_source_clone(IsoFileSource *old_source, IsoFileSource **new_source,
int flag);
/* Determine whether src is random-access readable and return its capacity.
@return -1 iso_file_source_lseek failed , >= 0 readable capacity
*/
off_t iso_file_source_lseek_capacity(IsoFileSource *src, int flag);
#endif /*LIBISO_FSOURCE_H_*/

10
libisofs/libisofs.h
View File

@ -4,7 +4,7 @@
/*
* Copyright (c) 2007-2008 Vreixo Formoso, Mario Danic
* Copyright (c) 2009-2021 Thomas Schmitt
* Copyright (c) 2009-2022 Thomas Schmitt
*
* This file is part of the libisofs project; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
@ -6349,8 +6349,9 @@ int iso_tree_add_new_node(IsoImage *image, IsoDir *parent, const char *name,
* according to iso_image_set_truncate_mode().
* Its directory path depends on the parent node.
* @param path
* The absolute path of the file in the local filesystem. For now
* only regular files and symlinks to regular files are supported.
* The absolute path of the random-access capable file in the local
* filesystem. Only regular files and device files are supported.
* On Linux, only regular files and block device offer random-access.
* @param offset
* Byte number in the given file from where to start reading data.
* @param size
@ -6368,8 +6369,11 @@ int iso_tree_add_new_node(IsoImage *image, IsoDir *parent, const char *name,
* ISO_NODE_NAME_NOT_UNIQUE, a node with same name already exists
* ISO_OUT_OF_MEM
* ISO_RR_NAME_TOO_LONG
* ISO_WRONG_ARG_VALUE, if path is not suitable for random access
*
* @since 0.6.4
*
* Device files as path: @since 1.5.6
*/
int iso_tree_add_new_cut_out_node(IsoImage *image, IsoDir *parent,
const char *name, const char *path,

47
libisofs/stream.c
View File

@ -1,6 +1,6 @@
/*
* Copyright (c) 2007 Vreixo Formoso
* Copyright (c) 2009 - 2015 Thomas Schmitt
* Copyright (c) 2009 - 2022 Thomas Schmitt
*
* This file is part of the libisofs project; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
@ -330,6 +330,7 @@ int cut_out_open(IsoStream *stream)
{
int ret;
struct stat info;
off_t src_size, pos;
IsoFileSource *src;
struct cut_out_stream *data;
@ -348,20 +349,25 @@ int cut_out_open(IsoStream *stream)
return ret;
}
{
off_t ret;
if (data->offset > info.st_size) {
/* file is smaller than expected */
ret = iso_file_source_lseek(src, info.st_size, 0);
} else {
ret = iso_file_source_lseek(src, data->offset, 0);
}
if (ret < 0) {
return (int) ret;
}
if (S_ISREG(info.st_mode)) {
src_size= info.st_size;
} else {
/* Determine src_size and lseekability of device */
src_size = iso_file_source_lseek_capacity(src, 0);
if (src_size <= 0)
return ISO_WRONG_ARG_VALUE;
}
if (data->offset > src_size) {
/* file is smaller than expected */
pos = iso_file_source_lseek(src, src_size, 0);
} else {
pos = iso_file_source_lseek(src, data->offset, 0);
}
if (pos < 0) {
return (int) pos;
}
data->pos = 0;
if (data->offset + data->size > info.st_size) {
if (data->offset + data->size > src_size) {
return 3; /* file smaller than expected */
} else {
return ISO_SUCCESS;
@ -508,6 +514,7 @@ int iso_cut_out_stream_new(IsoFileSource *src, off_t offset, off_t size,
IsoStream **stream)
{
int r;
off_t src_size;
struct stat info;
IsoStream *str;
struct cut_out_stream *data;
@ -523,10 +530,16 @@ int iso_cut_out_stream_new(IsoFileSource *src, off_t offset, off_t size,
if (r < 0) {
return r;
}
if (!S_ISREG(info.st_mode)) {
return ISO_WRONG_ARG_VALUE;
if (S_ISREG(info.st_mode)) {
src_size = info.st_size;
} else {
/* Open src, do iso_source_lseek(SEEK_END), close src */
src_size = iso_file_source_lseek_capacity(src, 1);
if (src_size <= 0)
return ISO_WRONG_ARG_VALUE;
}
if (offset > info.st_size) {
if (offset > src_size) {
return ISO_FILE_OFFSET_TOO_BIG;
}
@ -551,7 +564,7 @@ int iso_cut_out_stream_new(IsoFileSource *src, off_t offset, off_t size,
iso_file_source_ref(src);
data->offset = offset;
data->size = MIN(info.st_size - offset, size);
data->size = MIN(src_size - offset, size);
/* get the id numbers */
data->dev_id = (dev_t) 0;

17
libisofs/tree.c
View File

@ -1,6 +1,6 @@
/*
* Copyright (c) 2007 Vreixo Formoso
* Copyright (c) 2011 - 2015 Thomas Schmitt
* Copyright (c) 2011 - 2022 Thomas Schmitt
*
* This file is part of the libisofs project; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
@ -677,6 +677,7 @@ int iso_tree_add_new_cut_out_node(IsoImage *image, IsoDir *parent,
IsoNode **node)
{
int result;
off_t src_size;
struct stat info;
IsoFilesystem *fs;
IsoFileSource *src;
@ -715,17 +716,23 @@ int iso_tree_add_new_cut_out_node(IsoImage *image, IsoDir *parent,
iso_file_source_unref(src);
return result;
}
if (!S_ISREG(info.st_mode)) {
return ISO_WRONG_ARG_VALUE;
if (S_ISREG(info.st_mode)) {
src_size = info.st_size;
} else {
/* Open src, do iso_source_lseek(SEEK_END), close src */
src_size = iso_file_source_lseek_capacity(src, 1);
if (src_size <= 0)
return ISO_WRONG_ARG_VALUE;
}
if (offset >= info.st_size) {
if (offset >= src_size) {
return ISO_WRONG_ARG_VALUE;
}
/* force regular file */
result = image->builder->create_file(image->builder, image, src, &new);
/* free the file */
/* Give up the newly acquired surplus reference to src */
iso_file_source_unref(src);
if (result < 0) {