[PATCH 21/21] dm: rewrite structure decoding
Eugene Syromyatnikov
evgsyr at gmail.com
Sun Oct 9 13:31:42 UTC 2016
Rewrite structure decoding in attempt to make it more in line with how
structures and arrays are decoded in strace.
* Replace single structure retrieval with on-demand retrieval. It
allows limiting amount of memory being allocated (suppose ioctl with
data_size = -1)
* Check for abbrev in structure decoders itself. It allows
distinguishing cases when we want to decode some additional data from
cases when we are not.
---
dm.c | 363 +++++++++++++++++++++++++++++++++++++++---------------------------
1 file changed, 217 insertions(+), 146 deletions(-)
diff --git a/dm.c b/dm.c
index ff9e8ad..d846233 100644
--- a/dm.c
+++ b/dm.c
@@ -101,165 +101,254 @@ dm_decode_flags(const struct dm_ioctl *ioc)
}
static void
-dm_decode_dm_target_spec(struct tcb *tcp, const struct dm_ioctl *ioc,
- const char *extra, uint32_t extra_size)
+dm_decode_dm_target_spec(struct tcb *tcp, unsigned long addr,
+ const struct dm_ioctl *ioc)
{
static const uint32_t target_spec_size =
sizeof(struct dm_target_spec);
uint32_t i;
uint32_t offset = ioc->data_start;
+ if (abbrev(tcp)) {
+ if (ioc->target_count)
+ tprints(", ...");
+
+ return;
+ }
+
for (i = 0; i < ioc->target_count; i++) {
- if (offset + target_spec_size >= offset &&
- offset + target_spec_size < extra_size) {
- uint32_t new_offset;
- const struct dm_target_spec *s =
- (const struct dm_target_spec *) (extra + offset);
- tprintf(", {sector_start=%" PRIu64 ", length=%" PRIu64,
- (uint64_t) s->sector_start,
- (uint64_t) s->length);
- if (!entering(tcp))
- tprintf(", status=%" PRId32, s->status);
- tprints(", target_type=");
- print_quoted_string(s->target_type, DM_MAX_TYPE_NAME,
- QUOTE_0_TERMINATED);
- tprints(", string=");
- print_quoted_string((const char *) (s + 1), extra_size -
- (offset + target_spec_size),
- QUOTE_0_TERMINATED);
- tprintf("}");
- if (entering(tcp))
- new_offset = offset + s->next;
- else
- new_offset = ioc->data_start + s->next;
- if (new_offset <= offset + target_spec_size)
- goto misplaced;
- offset = new_offset;
- } else {
-misplaced:
- tprints(", /* misplaced struct dm_target_spec */ ...");
+ struct dm_target_spec s;
+ uint32_t new_offset;
+
+ if ((offset + target_spec_size) <= offset ||
+ (offset + target_spec_size) > ioc->data_size)
+ goto misplaced;
+
+ tprints(", ");
+
+ if (i >= max_strlen) {
+ tprints("...");
break;
}
+
+ if (umove_or_printaddr(tcp, addr + offset, &s))
+ break;
+
+ tprintf("{sector_start=%" PRI__u64 ", length=%" PRI__u64,
+ s.sector_start, s.length);
+
+ if (!entering(tcp))
+ tprintf(", status=%" PRId32, s.status);
+
+ tprints(", target_type=");
+ print_quoted_string(s.target_type, DM_MAX_TYPE_NAME,
+ QUOTE_0_TERMINATED);
+
+ tprints(", string=");
+ printstr_ex(tcp, addr + offset + target_spec_size,
+ ioc->data_size - (offset + target_spec_size),
+ QUOTE_0_TERMINATED);
+ tprintf("}");
+
+ if (entering(tcp))
+ new_offset = offset + s.next;
+ else
+ new_offset = ioc->data_start + s.next;
+
+ if (new_offset <= offset + target_spec_size)
+ goto misplaced;
+
+ offset = new_offset;
}
+
+ return;
+
+misplaced:
+ tprints(", /* misplaced struct dm_target_spec */ ...");
+}
+
+bool
+dm_print_dev(struct tcb *tcp, void *dev_ptr, size_t dev_size, void *dummy)
+{
+ uint64_t *dev = (uint64_t *) dev_ptr;
+
+ tprintf("makedev(%u, %u)", major(*dev), minor(*dev));
+
+ return 1;
}
static void
-dm_decode_dm_target_deps(const struct dm_ioctl *ioc, const char *extra,
- uint32_t extra_size)
+dm_decode_dm_target_deps(struct tcb *tcp, unsigned long addr,
+ const struct dm_ioctl *ioc)
{
static const uint32_t target_deps_dev_offs =
offsetof(struct dm_target_deps, dev);
+ uint64_t dev_buf;
+ struct dm_target_deps s;
uint32_t offset = ioc->data_start;
+ uint32_t space;
- if (offset + target_deps_dev_offs >= offset &&
- offset + target_deps_dev_offs <= extra_size) {
- uint32_t i;
- uint32_t space = (extra_size - offset - target_deps_dev_offs) /
- sizeof(__u64);
- const struct dm_target_deps *s =
- (const struct dm_target_deps *) (extra + offset);
-
- if (s->count > space)
- goto misplaced;
- tprints(", deps={");
- for (i = 0; i < s->count; i++) {
- tprintf("%smakedev(%u, %u)", i ? ", " : "",
- major(s->dev[i]), minor(s->dev[i]));
- }
- tprints("}");
- } else {
- misplaced:
- tprints(", /* misplaced struct dm_target_deps */ ...");
+ if (abbrev(tcp)) {
+ tprints(", ...");
+ return;
}
+
+ tprints(", ");
+
+ if (offset + target_deps_dev_offs <= offset ||
+ offset + target_deps_dev_offs > ioc->data_size)
+ goto misplaced;
+
+ if (umove_or_printaddr(tcp, addr + offset, &s))
+ return;
+
+ space = (ioc->data_size - offset - target_deps_dev_offs) / sizeof(__u64);
+
+ if (s.count > space)
+ goto misplaced;
+
+ tprintf("{count=%u, deps=", s.count);
+
+ print_array(tcp, addr + offset + target_deps_dev_offs, s.count,
+ &dev_buf, sizeof(dev_buf), umoven_or_printaddr,
+ dm_print_dev, NULL);
+
+ tprints("}");
+
+ return;
+
+misplaced:
+ tprints("/* misplaced struct dm_target_deps */ ...");
}
static void
-dm_decode_dm_name_list(const struct dm_ioctl *ioc, const char *extra,
- uint32_t extra_size)
+dm_decode_dm_name_list(struct tcb *tcp, unsigned long addr,
+ const struct dm_ioctl *ioc)
{
static const uint32_t name_list_name_offs =
offsetof(struct dm_name_list, name);
+ struct dm_name_list s;
uint32_t offset = ioc->data_start;
+ uint32_t count;
- while (1) {
- if (offset + name_list_name_offs >= offset &&
- offset + name_list_name_offs < extra_size) {
- const struct dm_name_list *s =
- (const struct dm_name_list *) (extra + offset);
+ if (abbrev(tcp)) {
+ tprints(", ...");
+ return;
+ }
- if (!s->dev)
- break;
- tprintf(", {dev=makedev(%u, %u), name=", major(s->dev),
- minor(s->dev));
- print_quoted_string(s->name, extra_size - (offset +
- name_list_name_offs),
- QUOTE_0_TERMINATED);
- tprints("}");
- if (!s->next)
- break;
- if (offset + s->next <= offset + name_list_name_offs)
- goto misplaced;
- offset = offset + s->next;
- } else {
- misplaced:
- tprints(", /* misplaced struct dm_name_list */ ...");
+ for (count = 0;; count++) {
+ if (offset + name_list_name_offs <= offset ||
+ offset + name_list_name_offs > ioc->data_size)
+ goto misplaced;
+
+ tprints(", ");
+
+ if (count >= max_strlen) {
+ tprints("...");
+ break;
+ }
+
+ if (umove_or_printaddr(tcp, addr + offset, &s))
+ break;
+ if (!count && !s.dev) {
+ tprints("/* no devices present */");
break;
}
+
+ tprintf("{dev=makedev(%u, %u), name=", major(s.dev),
+ minor(s.dev));
+ printstr_ex(tcp, addr + offset + name_list_name_offs,
+ ioc->data_size - (offset + name_list_name_offs),
+ QUOTE_0_TERMINATED);
+ tprints("}");
+
+ if (!s.next)
+ break;
+ if (offset + s.next <= offset + name_list_name_offs)
+ goto misplaced;
+ offset = offset + s.next;
}
+
+ return;
+
+misplaced:
+ tprints(", /* misplaced struct dm_name_list */ ...");
}
static void
-dm_decode_dm_target_versions(const struct dm_ioctl *ioc, const char *extra,
- uint32_t extra_size)
+dm_decode_dm_target_versions(struct tcb *tcp, unsigned long addr,
+ const struct dm_ioctl *ioc)
{
static const uint32_t target_vers_name_offs =
offsetof(struct dm_target_versions, name);
+ struct dm_target_versions s;
uint32_t offset = ioc->data_start;
+ uint32_t count;
- while (1) {
- if (offset + target_vers_name_offs >= offset &&
- offset + target_vers_name_offs < extra_size) {
- const struct dm_target_versions *s =
- (const struct dm_target_versions *)(extra + offset);
+ if (abbrev(tcp)) {
+ tprints(", ...");
+ return;
+ }
- tprints(", {name=");
- print_quoted_string(s->name, extra_size - (offset +
- target_vers_name_offs),
- QUOTE_0_TERMINATED);
- tprintf(", version=%" PRIu32 ".%" PRIu32 ".%" PRIu32 "}",
- s->version[0], s->version[1], s->version[2]);
- if (!s->next)
- break;
- if (offset + s->next <= offset + target_vers_name_offs)
- goto misplaced;
- offset = offset + s->next;
- } else {
- misplaced:
- tprints(", /* misplaced struct dm_target_versions */ "
- "...");
+ for (count = 0;; count++) {
+ if (offset + target_vers_name_offs <= offset ||
+ offset + target_vers_name_offs > ioc->data_size)
+ goto misplaced;
+
+ tprints(", ");
+
+ if (count >= max_strlen) {
+ tprints("...");
break;
}
+
+ if (umove_or_printaddr(tcp, addr + offset, &s))
+ break;
+
+ tprints("{name=");
+ printstr_ex(tcp, addr + offset + target_vers_name_offs,
+ ioc->data_size - (offset + target_vers_name_offs),
+ QUOTE_0_TERMINATED);
+ tprintf(", version=%" PRIu32 ".%" PRIu32 ".%" PRIu32 "}",
+ s.version[0], s.version[1], s.version[2]);
+
+ if (!s.next)
+ break;
+ if (offset + s.next <= offset + target_vers_name_offs)
+ goto misplaced;
+ offset = offset + s.next;
}
+
+ return;
+
+misplaced:
+ tprints(", /* misplaced struct dm_target_versions */ ...");
}
static void
-dm_decode_dm_target_msg(const struct dm_ioctl *ioc, const char *extra,
- uint32_t extra_size)
+dm_decode_dm_target_msg(struct tcb *tcp, unsigned long addr,
+ const struct dm_ioctl *ioc)
{
static const uint32_t target_msg_message_offs =
offsetof(struct dm_target_msg, message);
uint32_t offset = ioc->data_start;
- if (offset + target_msg_message_offs >= offset &&
- offset + target_msg_message_offs < extra_size) {
- const struct dm_target_msg *s =
- (const struct dm_target_msg *) (extra + offset);
+ if (abbrev(tcp)) {
+ tprints(", ...");
+ return;
+ }
+
+ if (offset + target_msg_message_offs > offset &&
+ offset + target_msg_message_offs <= ioc->data_size) {
+ struct dm_target_msg s;
- tprintf(", {sector=%" PRIu64 ", message=",
- (uint64_t) s->sector);
- print_quoted_string(s->message, extra_size -
- target_msg_message_offs,
- QUOTE_0_TERMINATED);
+ if (umove_or_printaddr(tcp, addr + offset, &s))
+ return;
+
+ tprintf(", {sector=%" PRI__u64 ", message=", s.sector);
+ printstr_ex(tcp, addr + offset + target_msg_message_offs,
+ ioc->data_size - offset - target_msg_message_offs,
+ QUOTE_0_TERMINATED);
tprints("}");
} else {
tprints(", /* misplaced struct dm_target_msg */");
@@ -267,15 +356,20 @@ dm_decode_dm_target_msg(const struct dm_ioctl *ioc, const char *extra,
}
static void
-dm_decode_string(const struct dm_ioctl *ioc, const char *extra,
- uint32_t extra_size)
+dm_decode_string(struct tcb *tcp, unsigned long addr,
+ const struct dm_ioctl *ioc)
{
uint32_t offset = ioc->data_start;
- if (offset < extra_size) {
+ if (abbrev(tcp)) {
+ tprints(", ...");
+ return;
+ }
+
+ if (offset < ioc->data_size) {
tprints(", string=");
- print_quoted_string(extra + offset, extra_size - offset,
- QUOTE_0_TERMINATED);
+ printstr_ex(tcp, addr + offset, ioc->data_size - offset,
+ QUOTE_0_TERMINATED);
} else {
tprints(", /* misplaced string */");
}
@@ -301,11 +395,9 @@ dm_ioctl_has_params(const unsigned int code)
static int
dm_known_ioctl(struct tcb *tcp, const unsigned int code, long arg)
{
- struct dm_ioctl *ioc;
+ struct dm_ioctl *ioc = NULL;
struct dm_ioctl *entering_ioc = NULL;
bool ioc_changed = false;
- char *extra = NULL;
- uint32_t extra_size = 0;
ioc = malloc(sizeof(* ioc));
if (!ioc)
@@ -371,70 +463,49 @@ dm_known_ioctl(struct tcb *tcp, const unsigned int code, long arg)
dm_decode_values(tcp, code, ioc);
dm_decode_flags(ioc);
- if (dm_ioctl_has_params(code) && (ioc->data_size > sizeof(ioc))) {
- extra = malloc(ioc->data_size);
- if (extra) {
- extra_size = ioc->data_size;
- if (umoven(tcp, arg, extra_size, extra) < 0) {
- free(extra);
- extra = NULL;
- extra_size = 0;
- }
- }
- }
-
- if (abbrev(tcp)) {
- tprints(", ...");
- goto skip;
- }
-
switch (code) {
case DM_DEV_WAIT:
case DM_TABLE_STATUS:
if (entering(tcp) || syserror(tcp))
break;
- dm_decode_dm_target_spec(tcp, ioc, extra, extra_size);
+ dm_decode_dm_target_spec(tcp, arg, ioc);
break;
case DM_TABLE_LOAD:
if (!entering(tcp))
break;
- dm_decode_dm_target_spec(tcp, ioc, extra, extra_size);
+ dm_decode_dm_target_spec(tcp, arg, ioc);
break;
case DM_TABLE_DEPS:
if (entering(tcp) || syserror(tcp))
break;
- dm_decode_dm_target_deps(ioc, extra, extra_size);
+ dm_decode_dm_target_deps(tcp, arg, ioc);
break;
case DM_LIST_DEVICES:
if (entering(tcp) || syserror(tcp))
break;
- dm_decode_dm_name_list(ioc, extra, extra_size);
+ dm_decode_dm_name_list(tcp, arg, ioc);
break;
case DM_LIST_VERSIONS:
if (entering(tcp) || syserror(tcp))
break;
- dm_decode_dm_target_versions(ioc, extra, extra_size);
+ dm_decode_dm_target_versions(tcp, arg, ioc);
break;
case DM_TARGET_MSG:
- if (entering(tcp)) {
- dm_decode_dm_target_msg(ioc, extra,
- extra_size);
- } else if (!syserror(tcp) && ioc->flags & DM_DATA_OUT_FLAG) {
- dm_decode_string(ioc, extra, extra_size);
- }
+ if (entering(tcp))
+ dm_decode_dm_target_msg(tcp, arg, ioc);
+ else if (!syserror(tcp) && ioc->flags & DM_DATA_OUT_FLAG)
+ dm_decode_string(tcp, arg, ioc);
break;
case DM_DEV_RENAME:
case DM_DEV_SET_GEOMETRY:
if (!entering(tcp))
break;
- dm_decode_string(ioc, extra, extra_size);
+ dm_decode_string(tcp, arg, ioc);
break;
}
skip:
tprints("}");
- if (extra)
- free(extra);
if (exiting(tcp))
free(ioc);
return 1;
--
1.7.10.4
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