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Introduced file content stability check with iso_write_opts_set_record_md5().

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This commit is contained in:
Thomas Schmitt 2009-08-19 22:26:18 +02:00
parent 363a39af3e
commit 62edebad06
6 changed files with 125 additions and 24 deletions
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5
doc/checksums.txt
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@ -19,10 +19,11 @@ is enabled by iso_read_opts_set_no_md5(). Loaded checksums can be inquired by
iso_image_get_session_md5() and iso_file_get_md5().
Stream recognizable checksum tags occupy exactly one block each. They can
be detected by submitting a read-in block to iso_util_decode_md5_tag().
be detected by submitting a block to iso_util_decode_md5_tag().
libisofs has own MD5 computation functions:
iso_md5_start(), iso_md5_compute(), iso_md5_clone(), iso_md5_end()
iso_md5_start(), iso_md5_compute(), iso_md5_clone(), iso_md5_end(),
iso_md5_match()
Representation in the Image

8
libisofs/ecma119.c
View File

@ -1135,7 +1135,7 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
#ifdef Libisofs_with_checksumS
if (target->md5_file_checksums || target->md5_session_checksum) {
if ((target->md5_file_checksums & 1) || target->md5_session_checksum) {
nwriters++;
ret = checksum_prepare_image(src, 0);
if (ret < 0)
@ -1213,7 +1213,7 @@ int ecma119_image_new(IsoImage *src, IsoWriteOpts *opts, Ecma119Image **img)
#ifdef Libisofs_with_checksumS
if (target->md5_file_checksums || target->md5_session_checksum) {
if ((target->md5_file_checksums & 1) || target->md5_session_checksum) {
ret = checksum_writer_create(target);
if (ret < 0)
goto target_cleanup;
@ -1805,8 +1805,8 @@ int iso_write_opts_set_record_md5(IsoWriteOpts *opts, int session, int files)
#ifdef Libisofs_with_checksumS
opts->md5_session_checksum = !!session;
opts->md5_file_checksums = !!files;
opts->md5_session_checksum = session & 1;
opts->md5_file_checksums = files & 3;
#endif /* Libisofs_with_checksumS */

7
libisofs/ecma119.h
View File

@ -163,8 +163,11 @@ struct iso_write_opts {
* blocks will be recorded in xattr "isofs.ca" of the root node.
* The indice of the MD5 sums will be recorded with the IsoFile directory
* entries as xattr "isofs.cx". See also API call iso_file_get_md5().
* bit0= compute individual checksums
* bit1= pre-compute checksum and compare it with actual one.
* Raise MISHAP if mismatch.
*/
unsigned int md5_file_checksums :1;
unsigned int md5_file_checksums :2;
#endif /* Libisofs_with_checksumS */
@ -336,7 +339,7 @@ struct ecma119_image
#ifdef Libisofs_with_checksumS
unsigned int md5_session_checksum :1;
unsigned int md5_file_checksums :1;
unsigned int md5_file_checksums :2;
#endif /* Libisofs_with_checksumS */

104
libisofs/filesrc.c
View File

@ -118,14 +118,15 @@ int iso_file_src_create(Ecma119Image *img, IsoFile *file, IsoFileSrc **src)
#ifdef Libisofs_with_checksumS
if (img->md5_file_checksums && file->from_old_session && img->appendable) {
if ((img->md5_file_checksums & 1) &&
file->from_old_session && img->appendable) {
/* Omit MD5 indexing with old image nodes which have no MD5 */
ret = iso_node_get_xinfo((IsoNode *) file, checksum_xinfo_func, &xipt);
if (ret <= 0)
no_md5 = 1;
}
if (img->md5_file_checksums && !no_md5) {
if ((img->md5_file_checksums & 1) && !no_md5) {
img->checksum_idx_counter++;
if (img->checksum_idx_counter < 0x80000000) {
fsrc->checksum_index= img->checksum_idx_counter;
@ -313,10 +314,59 @@ int filesrc_read(IsoFileSrc *file, char *buf, size_t count)
}
}
#ifdef Libisofs_with_checksumS
/* @return 1=ok, md5 is valid,
0= not ok, go on,
<0 fatal error, abort
*/
static
int filesrc_make_md5(Ecma119Image *t, IsoFileSrc *file, char md5[16], int flag)
{
int res, is_open = 0;
char buffer[BLOCK_SIZE];
void *ctx= NULL;
off_t file_size;
uint32_t b, nblocks;
if (! iso_stream_is_repeatable(file->stream))
return 0;
res = iso_md5_start(&ctx);
if (res < 0)
return res;
res = filesrc_open(file);
if (res < 0)
return 0;
is_open = 1;
file_size = iso_file_src_get_size(file);
nblocks = DIV_UP(file_size, BLOCK_SIZE);
for (b = 0; b < nblocks; ++b) {
res = filesrc_read(file, buffer, BLOCK_SIZE);
if (res < 0) {
res = 0;
goto ex;
}
if (file_size - b * BLOCK_SIZE > BLOCK_SIZE)
res = BLOCK_SIZE;
else
res = file_size - b * BLOCK_SIZE;
iso_md5_compute(ctx, buffer, res);
}
res = 1;
ex:;
if (is_open)
filesrc_close(file);
if (ctx != NULL)
iso_md5_end(&ctx, md5);
return res;
}
#endif /* Libisofs_with_checksumS */
static
int filesrc_writer_write_data(IsoImageWriter *writer)
{
int res, ret;
int res, ret, was_error;
size_t i, b;
Ecma119Image *t;
IsoFileSrc *file;
@ -328,7 +378,8 @@ int filesrc_writer_write_data(IsoImageWriter *writer)
#ifdef Libisofs_with_checksumS
void *ctx= NULL;
char md5[16];
char md5[16], pre_md5[16];
int pre_md5_valid = 0;
#endif
@ -343,10 +394,19 @@ int filesrc_writer_write_data(IsoImageWriter *writer)
i = 0;
while ((file = filelist[i++]) != NULL) {
was_error = 0;
file_size = iso_file_src_get_size(file);
nblocks = DIV_UP(file_size, BLOCK_SIZE);
#ifdef Libisofs_with_checksumS
/* >>> Eventually obtain an MD5 of content by a first read pass */;
pre_md5_valid = 0;
if (file->checksum_index > 0 && (t->md5_file_checksums & 2)) {
/* Obtain an MD5 of content by a first read pass */
pre_md5_valid = filesrc_make_md5(t, file, pre_md5, 0);
}
#endif /* Libisofs_with_checksumS */
res = filesrc_open(file);
iso_stream_get_file_name(file->stream, name);
@ -356,6 +416,7 @@ int filesrc_writer_write_data(IsoImageWriter *writer)
* 0's to image
*/
iso_report_errfile(name, ISO_FILE_CANT_WRITE, 0, 0);
was_error = 1;
res = iso_msg_submit(t->image->id, ISO_FILE_CANT_WRITE, res,
"File \"%s\" can't be opened. Filling with 0s.", name);
if (res < 0) {
@ -374,6 +435,7 @@ int filesrc_writer_write_data(IsoImageWriter *writer)
continue;
} else if (res > 1) {
iso_report_errfile(name, ISO_FILE_CANT_WRITE, 0, 0);
was_error = 1;
res = iso_msg_submit(t->image->id, ISO_FILE_CANT_WRITE, 0,
"Size of file \"%s\" has changed. It will be %s", name,
(res == 2 ? "truncated" : "padded with 0's"));
@ -400,7 +462,7 @@ int filesrc_writer_write_data(IsoImageWriter *writer)
}
#endif /* Libisofs_with_checksumS */
/* write file contents to image */
for (b = 0; b < nblocks; ++b) {
int wres;
@ -421,9 +483,10 @@ int filesrc_writer_write_data(IsoImageWriter *writer)
if (file->checksum_index > 0) {
/* Add to file checksum */
res = file_size - b * BLOCK_SIZE;
if (res > BLOCK_SIZE)
if (file_size - b * BLOCK_SIZE > BLOCK_SIZE)
res = BLOCK_SIZE;
else
res = file_size - b * BLOCK_SIZE;
res = iso_md5_compute(ctx, buffer, res);
if (res <= 0)
file->checksum_index = 0;
@ -438,6 +501,7 @@ int filesrc_writer_write_data(IsoImageWriter *writer)
if (b < nblocks) {
/* premature end of file, due to error or eof */
iso_report_errfile(name, ISO_FILE_CANT_WRITE, 0, 0);
was_error = 1;
if (res < 0) {
/* error */
res = iso_msg_submit(t->image->id, ISO_FILE_CANT_WRITE, res,
@ -469,9 +533,10 @@ int filesrc_writer_write_data(IsoImageWriter *writer)
if (file->checksum_index > 0) {
/* Add to file checksum */
res = file_size - b * BLOCK_SIZE;
if (res > BLOCK_SIZE)
if (file_size - b * BLOCK_SIZE > BLOCK_SIZE)
res = BLOCK_SIZE;
else
res = file_size - b * BLOCK_SIZE;
res = iso_md5_compute(ctx, buffer, res);
if (res <= 0)
file->checksum_index = 0;
@ -489,10 +554,21 @@ int filesrc_writer_write_data(IsoImageWriter *writer)
res = iso_md5_end(&ctx, md5);
if (res <= 0)
file->checksum_index = 0;
/* >>> Eventually compare with MD5 of first read pass
and issue error if mismatch */;
if ((t->md5_file_checksums & 2) && pre_md5_valid > 0 &&
!was_error) {
if (! iso_md5_match(md5, pre_md5)) {
/* Issue MISHAP event */
iso_report_errfile(name, ISO_MD5_STREAM_CHANGE, 0, 0);
was_error = 1;
res = iso_msg_submit(t->image->id, ISO_MD5_STREAM_CHANGE,0,
"Content of file '%s' changed while it was written into the image.",
name);
if (res < 0) {
ret = res; /* aborted due to error severity */
goto ex;
}
}
}
/* Write md5 into checksum buffer at file->checksum_index */
memcpy(t->checksum_buffer + 16 * file->checksum_index, md5, 16);
}

23
libisofs/libisofs.h
View File

@ -1424,9 +1424,21 @@ int iso_write_opts_set_sort_files(IsoWriteOpts *opts, int sort);
* @param opts
* The option set to be manipulated.
* @param session
* If not 0: compute session checksum
* If bit0 set: compute session checksum
* @param files
* If not 0: compute a checksum for each single IsoFile object.
* If bit0 set: compute a checksum for each single IsoFile object.
* If bit1 set: check content stability (only with bit0). I.e. before
* writing the file content into to image stream, read it
* once and compute a MD5. Do a second reading for writing
* into the image stream. Afterwards compare both MD5 and
* issue a MISHAP event ISO_MD5_STREAM_CHANGE if they do not
* match.
* Such a mismatch indicates content changes between the
* time point when the first MD5 reading started and the
* time point when the last block was read for writing.
* So there is high risk that the image stream was fed from
* changing and possibly inconsistent file content.
*
* @since 0.6.22
*/
int iso_write_opts_set_record_md5(IsoWriteOpts *opts, int session, int files);
@ -5478,6 +5490,13 @@ int iso_md5_match(char first_md5[16], char second_md5[16]);
*/
#define ISO_MD5_TAG_OTHER_RANGE 0xD030FE9B
/**
* Detected file content changes while it was written into the image.
* (MISHAP, HIGH, -358)
* @since 0.6.22
*/
#define ISO_MD5_STREAM_CHANGE 0xE430FE9A
/* ! PLACE NEW ERROR CODES HERE ! */

2
libisofs/messages.c
View File

@ -272,6 +272,8 @@ const char *iso_error_to_msg(int errcode)
return "Misplaced checksum tag type encountered";
case ISO_MD5_TAG_OTHER_RANGE:
return "Checksum tag with unexpected address range encountered";
case ISO_MD5_STREAM_CHANGE:
return "Detected file content changes while it was written into the image";
default:
return "Unknown error";
}