[PATCH v5 2/6] winedbg: Buffer output of GDB qXfer commands for proper slicing.
Jinoh Kang
jinoh.kang.kr at gmail.com
Sat Nov 20 15:12:08 CST 2021
Today, gdbproxy reuses the same buffer for both the qXfer reply and the
actual GDB packet reply. This worked well, since each character in
the qXfer reply buffer matched 1:1 to the actual GDB reply packet.
Since we escape special characters now, this property no longer holds
and a single byte in qXfer reply will take up to two bytes in the GDB
reply packet. This causes offsets to shift, preventing the
offset/length response slicing from working correctly.
Fix this by buffering the qXfer reply data, and performing slicing from
there.
Signed-off-by: Jinoh Kang <jinoh.kang.kr at gmail.com>
---
Notes:
v3 -> v4:
- Fix pointer variable declaration style
- Fix indentation
- s/buffer_realloc/realloc/g
- s/vl_buffer/reply_buffer/g; s/vl_/reply_buffer_/g; s/vlbuf/reply/g
- Rewrite reply_buffer_add_uinthex(): convert for loop into while loop
- Rewrite reply_buffer_append_xmlstr(): convert for loop into while loop
- Split packet_reply_add() into packet_reply_add_data() here
v4 -> v5:
- Split out XML escaping in a separate patch
- Don't realloc/free when emptying
- Drop reply_buffer_resize(), merge into reply_buffer_grow()
- Remove "more" variables for now
- Don't empty buffer before and after
programs/winedbg/gdbproxy.c | 270 +++++++++++++++++++-----------------
1 file changed, 142 insertions(+), 128 deletions(-)
diff --git a/programs/winedbg/gdbproxy.c b/programs/winedbg/gdbproxy.c
index 2e7e04e6c93..a82588fd8b8 100644
--- a/programs/winedbg/gdbproxy.c
+++ b/programs/winedbg/gdbproxy.c
@@ -87,6 +87,7 @@ struct gdb_context
/* Unix environment */
ULONG_PTR wine_segs[3]; /* load addresses of the ELF wine exec segments (text, bss and data) */
BOOL no_ack_mode;
+ struct reply_buffer qxfer_buffer;
};
/* assume standard signal and errno values */
@@ -797,20 +798,20 @@ static inline BOOL is_gdb_special_char(unsigned char val)
return gdb_special_chars_lookup_table[val % length] == val;
}
-static void packet_reply_add(struct gdb_context* gdbctx, const char* str)
+static void packet_reply_add_data(struct gdb_context* gdbctx, const void* data, size_t len)
{
- const unsigned char *ptr = (unsigned char *)str, *curr;
+ const unsigned char *ptr = data, *end = ptr + len, *curr;
unsigned char esc_seq[2];
- while (*ptr)
+ while (ptr != end)
{
curr = ptr;
- while (*ptr && !is_gdb_special_char(*ptr))
+ while (ptr != end && !is_gdb_special_char(*ptr))
ptr++;
reply_buffer_append(&gdbctx->out_buf, curr, ptr - curr);
- if (!*ptr) break;
+ if (ptr == end) break;
esc_seq[0] = 0x7D;
esc_seq[1] = 0x20 ^ *ptr++;
@@ -818,6 +819,11 @@ static void packet_reply_add(struct gdb_context* gdbctx, const char* str)
}
}
+static inline void packet_reply_add(struct gdb_context* gdbctx, const char* str)
+{
+ packet_reply_add_data(gdbctx, str, strlen(str));
+}
+
static void packet_reply_open(struct gdb_context* gdbctx)
{
assert(gdbctx->out_curr_packet == -1);
@@ -837,36 +843,6 @@ static void packet_reply_close(struct gdb_context* gdbctx)
gdbctx->out_curr_packet = -1;
}
-static void packet_reply_open_xfer(struct gdb_context* gdbctx)
-{
- packet_reply_open(gdbctx);
- packet_reply_add(gdbctx, "m");
-}
-
-static void packet_reply_close_xfer(struct gdb_context* gdbctx, unsigned int off, unsigned int len)
-{
- int begin = gdbctx->out_curr_packet + 1;
- int plen;
-
- if (begin + off < gdbctx->out_buf.len)
- {
- gdbctx->out_buf.len -= off;
- memmove((unsigned char *)gdbctx->out_buf.base + begin,
- (unsigned char *)gdbctx->out_buf.base + begin + off,
- gdbctx->out_buf.len);
- }
- else
- {
- *((unsigned char *)gdbctx->out_buf.base + gdbctx->out_curr_packet) = 'l';
- gdbctx->out_buf.len = gdbctx->out_curr_packet + 1;
- }
-
- plen = gdbctx->out_buf.len - begin;
- if (plen > len) gdbctx->out_buf.len -= (plen - len);
- else *((unsigned char *)gdbctx->out_buf.base + gdbctx->out_curr_packet) = 'l';
-
- packet_reply_close(gdbctx);
-}
static enum packet_return packet_reply(struct gdb_context* gdbctx, const char* packet)
{
@@ -897,6 +873,29 @@ static inline void packet_reply_register_hex_to(struct gdb_context* gdbctx, dbg_
packet_reply_hex_to(gdbctx, cpu_register_ptr(gdbctx, ctx, idx), cpu_register_map[idx].length);
}
+static void packet_reply_xfer(struct gdb_context* gdbctx, const void *data, size_t datalen,
+ unsigned int off, unsigned int len)
+{
+ BOOL nonempty;
+ size_t trunc_len;
+
+ packet_reply_open(gdbctx);
+
+ nonempty = (size_t)off < datalen;
+ if (nonempty && (size_t)off + len < datalen)
+ packet_reply_add(gdbctx, "m");
+ else
+ packet_reply_add(gdbctx, "l");
+
+ if (nonempty)
+ {
+ trunc_len = min((size_t)len, datalen - off);
+ packet_reply_add_data(gdbctx, (const unsigned char *)data + off, trunc_len);
+ }
+
+ packet_reply_close(gdbctx);
+}
+
/* =============================================== *
* P A C K E T H A N D L E R S *
* =============================================== *
@@ -1604,6 +1603,7 @@ static enum packet_return packet_query_remote_command(struct gdb_context* gdbctx
static BOOL CALLBACK packet_query_libraries_cb(PCSTR mod_name, DWORD64 base, PVOID ctx)
{
struct gdb_context* gdbctx = ctx;
+ struct reply_buffer* reply = &gdbctx->qxfer_buffer;
MEMORY_BASIC_INFORMATION mbi;
IMAGE_SECTION_HEADER *sec;
IMAGE_DOS_HEADER *dos = NULL;
@@ -1616,11 +1616,11 @@ static BOOL CALLBACK packet_query_libraries_cb(PCSTR mod_name, DWORD64 base, PVO
mod.SizeOfStruct = sizeof(mod);
SymGetModuleInfo64(gdbctx->process->handle, base, &mod);
- packet_reply_add(gdbctx, "<library name=\"");
+ reply_buffer_append_str(reply, "<library name=\"");
if (strcmp(mod.LoadedImageName, "[vdso].so") == 0)
- packet_reply_add(gdbctx, "linux-vdso.so.1");
+ reply_buffer_append_str(reply, "linux-vdso.so.1");
else if (mod.LoadedImageName[0] == '/')
- packet_reply_add(gdbctx, mod.LoadedImageName);
+ reply_buffer_append_str(reply, mod.LoadedImageName);
else
{
UNICODE_STRING nt_name;
@@ -1635,15 +1635,15 @@ static BOOL CALLBACK packet_query_libraries_cb(PCSTR mod_name, DWORD64 base, PVO
if (IsWow64Process(gdbctx->process->handle, &is_wow64) &&
is_wow64 && (tmp = strstr(unix_path, "system32")))
memcpy(tmp, "syswow64", 8);
- packet_reply_add(gdbctx, unix_path);
+ reply_buffer_append_str(reply, unix_path);
}
else
- packet_reply_add(gdbctx, mod.LoadedImageName);
+ reply_buffer_append_str(reply, mod.LoadedImageName);
HeapFree(GetProcessHeap(), 0, unix_path);
RtlFreeUnicodeString(&nt_name);
}
- packet_reply_add(gdbctx, "\">");
+ reply_buffer_append_str(reply, "\">");
size = sizeof(buffer);
if (VirtualQueryEx(gdbctx->process->handle, (void *)(UINT_PTR)mod.BaseOfImage, &mbi, sizeof(mbi)) >= sizeof(mbi) &&
@@ -1674,72 +1674,75 @@ static BOOL CALLBACK packet_query_libraries_cb(PCSTR mod_name, DWORD64 base, PVO
for (i = 0; i < max(nth->FileHeader.NumberOfSections, 1); ++i)
{
if ((char *)(sec + i) >= buffer + size) break;
- packet_reply_add(gdbctx, "<segment address=\"0x");
- packet_reply_val(gdbctx, mod.BaseOfImage + sec[i].VirtualAddress, sizeof(ULONG_PTR));
- packet_reply_add(gdbctx, "\"/>");
+ reply_buffer_append_str(reply, "<segment address=\"0x");
+ reply_buffer_append_uinthex(reply, mod.BaseOfImage + sec[i].VirtualAddress, sizeof(ULONG_PTR));
+ reply_buffer_append_str(reply, "\"/>");
}
- packet_reply_add(gdbctx, "</library>");
+ reply_buffer_append_str(reply, "</library>");
return TRUE;
}
static void packet_query_libraries(struct gdb_context* gdbctx)
{
+ struct reply_buffer* reply = &gdbctx->qxfer_buffer;
BOOL opt;
/* this will resynchronize builtin dbghelp's internal ELF module list */
SymLoadModule(gdbctx->process->handle, 0, 0, 0, 0, 0);
- packet_reply_add(gdbctx, "<library-list>");
+ reply_buffer_append_str(reply, "<library-list>");
opt = SymSetExtendedOption(SYMOPT_EX_WINE_NATIVE_MODULES, TRUE);
SymEnumerateModules64(gdbctx->process->handle, packet_query_libraries_cb, gdbctx);
SymSetExtendedOption(SYMOPT_EX_WINE_NATIVE_MODULES, opt);
- packet_reply_add(gdbctx, "</library-list>");
+ reply_buffer_append_str(reply, "</library-list>");
}
static void packet_query_threads(struct gdb_context* gdbctx)
{
+ struct reply_buffer* reply = &gdbctx->qxfer_buffer;
struct dbg_process* process = gdbctx->process;
struct dbg_thread* thread;
- packet_reply_add(gdbctx, "<threads>");
+ reply_buffer_append_str(reply, "<threads>");
LIST_FOR_EACH_ENTRY(thread, &process->threads, struct dbg_thread, entry)
{
- packet_reply_add(gdbctx, "<thread ");
- packet_reply_add(gdbctx, "id=\"");
- packet_reply_val(gdbctx, thread->tid, 4);
- packet_reply_add(gdbctx, "\" name=\"");
- packet_reply_add(gdbctx, thread->name);
- packet_reply_add(gdbctx, "\"/>");
+ reply_buffer_append_str(reply, "<thread ");
+ reply_buffer_append_str(reply, "id=\"");
+ reply_buffer_append_uinthex(reply, thread->tid, 4);
+ reply_buffer_append_str(reply, "\" name=\"");
+ reply_buffer_append_str(reply, thread->name);
+ reply_buffer_append_str(reply, "\"/>");
}
- packet_reply_add(gdbctx, "</threads>");
+ reply_buffer_append_str(reply, "</threads>");
}
static void packet_query_target_xml(struct gdb_context* gdbctx, struct backend_cpu* cpu)
{
+ struct reply_buffer* reply = &gdbctx->qxfer_buffer;
const char* feature_prefix = NULL;
const char* feature = NULL;
char buffer[256];
int i;
- packet_reply_add(gdbctx, "<target>");
+ reply_buffer_append_str(reply, "<target>");
switch (cpu->machine)
{
case IMAGE_FILE_MACHINE_AMD64:
- packet_reply_add(gdbctx, "<architecture>i386:x86-64</architecture>");
+ reply_buffer_append_str(reply, "<architecture>i386:x86-64</architecture>");
feature_prefix = "org.gnu.gdb.i386.";
break;
case IMAGE_FILE_MACHINE_I386:
- packet_reply_add(gdbctx, "<architecture>i386</architecture>");
+ reply_buffer_append_str(reply, "<architecture>i386</architecture>");
feature_prefix = "org.gnu.gdb.i386.";
break;
case IMAGE_FILE_MACHINE_ARMNT:
- packet_reply_add(gdbctx, "<architecture>arm</architecture>");
+ reply_buffer_append_str(reply, "<architecture>arm</architecture>");
feature_prefix = "org.gnu.gdb.arm.";
break;
case IMAGE_FILE_MACHINE_ARM64:
- packet_reply_add(gdbctx, "<architecture>aarch64</architecture>");
+ reply_buffer_append_str(reply, "<architecture>aarch64</architecture>");
feature_prefix = "org.gnu.gdb.aarch64.";
break;
}
@@ -1748,87 +1751,87 @@ static void packet_query_target_xml(struct gdb_context* gdbctx, struct backend_c
{
if (cpu->gdb_register_map[i].feature)
{
- if (feature) packet_reply_add(gdbctx, "</feature>");
+ if (feature) reply_buffer_append_str(reply, "</feature>");
feature = cpu->gdb_register_map[i].feature;
- packet_reply_add(gdbctx, "<feature name=\"");
- if (feature_prefix) packet_reply_add(gdbctx, feature_prefix);
- packet_reply_add(gdbctx, feature);
- packet_reply_add(gdbctx, "\">");
+ reply_buffer_append_str(reply, "<feature name=\"");
+ if (feature_prefix) reply_buffer_append_str(reply, feature_prefix);
+ reply_buffer_append_str(reply, feature);
+ reply_buffer_append_str(reply, "\">");
if (strcmp(feature_prefix, "org.gnu.gdb.i386.") == 0 &&
strcmp(feature, "core") == 0)
- packet_reply_add(gdbctx, "<flags id=\"i386_eflags\" size=\"4\">"
- "<field name=\"CF\" start=\"0\" end=\"0\"/>"
- "<field name=\"\" start=\"1\" end=\"1\"/>"
- "<field name=\"PF\" start=\"2\" end=\"2\"/>"
- "<field name=\"AF\" start=\"4\" end=\"4\"/>"
- "<field name=\"ZF\" start=\"6\" end=\"6\"/>"
- "<field name=\"SF\" start=\"7\" end=\"7\"/>"
- "<field name=\"TF\" start=\"8\" end=\"8\"/>"
- "<field name=\"IF\" start=\"9\" end=\"9\"/>"
- "<field name=\"DF\" start=\"10\" end=\"10\"/>"
- "<field name=\"OF\" start=\"11\" end=\"11\"/>"
- "<field name=\"NT\" start=\"14\" end=\"14\"/>"
- "<field name=\"RF\" start=\"16\" end=\"16\"/>"
- "<field name=\"VM\" start=\"17\" end=\"17\"/>"
- "<field name=\"AC\" start=\"18\" end=\"18\"/>"
- "<field name=\"VIF\" start=\"19\" end=\"19\"/>"
- "<field name=\"VIP\" start=\"20\" end=\"20\"/>"
- "<field name=\"ID\" start=\"21\" end=\"21\"/>"
- "</flags>");
+ reply_buffer_append_str(reply, "<flags id=\"i386_eflags\" size=\"4\">"
+ "<field name=\"CF\" start=\"0\" end=\"0\"/>"
+ "<field name=\"\" start=\"1\" end=\"1\"/>"
+ "<field name=\"PF\" start=\"2\" end=\"2\"/>"
+ "<field name=\"AF\" start=\"4\" end=\"4\"/>"
+ "<field name=\"ZF\" start=\"6\" end=\"6\"/>"
+ "<field name=\"SF\" start=\"7\" end=\"7\"/>"
+ "<field name=\"TF\" start=\"8\" end=\"8\"/>"
+ "<field name=\"IF\" start=\"9\" end=\"9\"/>"
+ "<field name=\"DF\" start=\"10\" end=\"10\"/>"
+ "<field name=\"OF\" start=\"11\" end=\"11\"/>"
+ "<field name=\"NT\" start=\"14\" end=\"14\"/>"
+ "<field name=\"RF\" start=\"16\" end=\"16\"/>"
+ "<field name=\"VM\" start=\"17\" end=\"17\"/>"
+ "<field name=\"AC\" start=\"18\" end=\"18\"/>"
+ "<field name=\"VIF\" start=\"19\" end=\"19\"/>"
+ "<field name=\"VIP\" start=\"20\" end=\"20\"/>"
+ "<field name=\"ID\" start=\"21\" end=\"21\"/>"
+ "</flags>");
if (strcmp(feature_prefix, "org.gnu.gdb.i386.") == 0 &&
strcmp(feature, "sse") == 0)
- packet_reply_add(gdbctx, "<vector id=\"v4f\" type=\"ieee_single\" count=\"4\"/>"
- "<vector id=\"v2d\" type=\"ieee_double\" count=\"2\"/>"
- "<vector id=\"v16i8\" type=\"int8\" count=\"16\"/>"
- "<vector id=\"v8i16\" type=\"int16\" count=\"8\"/>"
- "<vector id=\"v4i32\" type=\"int32\" count=\"4\"/>"
- "<vector id=\"v2i64\" type=\"int64\" count=\"2\"/>"
- "<union id=\"vec128\">"
- "<field name=\"v4_float\" type=\"v4f\"/>"
- "<field name=\"v2_double\" type=\"v2d\"/>"
- "<field name=\"v16_int8\" type=\"v16i8\"/>"
- "<field name=\"v8_int16\" type=\"v8i16\"/>"
- "<field name=\"v4_int32\" type=\"v4i32\"/>"
- "<field name=\"v2_int64\" type=\"v2i64\"/>"
- "<field name=\"uint128\" type=\"uint128\"/>"
- "</union>"
- "<flags id=\"i386_mxcsr\" size=\"4\">"
- "<field name=\"IE\" start=\"0\" end=\"0\"/>"
- "<field name=\"DE\" start=\"1\" end=\"1\"/>"
- "<field name=\"ZE\" start=\"2\" end=\"2\"/>"
- "<field name=\"OE\" start=\"3\" end=\"3\"/>"
- "<field name=\"UE\" start=\"4\" end=\"4\"/>"
- "<field name=\"PE\" start=\"5\" end=\"5\"/>"
- "<field name=\"DAZ\" start=\"6\" end=\"6\"/>"
- "<field name=\"IM\" start=\"7\" end=\"7\"/>"
- "<field name=\"DM\" start=\"8\" end=\"8\"/>"
- "<field name=\"ZM\" start=\"9\" end=\"9\"/>"
- "<field name=\"OM\" start=\"10\" end=\"10\"/>"
- "<field name=\"UM\" start=\"11\" end=\"11\"/>"
- "<field name=\"PM\" start=\"12\" end=\"12\"/>"
- "<field name=\"FZ\" start=\"15\" end=\"15\"/>"
- "</flags>");
+ reply_buffer_append_str(reply, "<vector id=\"v4f\" type=\"ieee_single\" count=\"4\"/>"
+ "<vector id=\"v2d\" type=\"ieee_double\" count=\"2\"/>"
+ "<vector id=\"v16i8\" type=\"int8\" count=\"16\"/>"
+ "<vector id=\"v8i16\" type=\"int16\" count=\"8\"/>"
+ "<vector id=\"v4i32\" type=\"int32\" count=\"4\"/>"
+ "<vector id=\"v2i64\" type=\"int64\" count=\"2\"/>"
+ "<union id=\"vec128\">"
+ "<field name=\"v4_float\" type=\"v4f\"/>"
+ "<field name=\"v2_double\" type=\"v2d\"/>"
+ "<field name=\"v16_int8\" type=\"v16i8\"/>"
+ "<field name=\"v8_int16\" type=\"v8i16\"/>"
+ "<field name=\"v4_int32\" type=\"v4i32\"/>"
+ "<field name=\"v2_int64\" type=\"v2i64\"/>"
+ "<field name=\"uint128\" type=\"uint128\"/>"
+ "</union>"
+ "<flags id=\"i386_mxcsr\" size=\"4\">"
+ "<field name=\"IE\" start=\"0\" end=\"0\"/>"
+ "<field name=\"DE\" start=\"1\" end=\"1\"/>"
+ "<field name=\"ZE\" start=\"2\" end=\"2\"/>"
+ "<field name=\"OE\" start=\"3\" end=\"3\"/>"
+ "<field name=\"UE\" start=\"4\" end=\"4\"/>"
+ "<field name=\"PE\" start=\"5\" end=\"5\"/>"
+ "<field name=\"DAZ\" start=\"6\" end=\"6\"/>"
+ "<field name=\"IM\" start=\"7\" end=\"7\"/>"
+ "<field name=\"DM\" start=\"8\" end=\"8\"/>"
+ "<field name=\"ZM\" start=\"9\" end=\"9\"/>"
+ "<field name=\"OM\" start=\"10\" end=\"10\"/>"
+ "<field name=\"UM\" start=\"11\" end=\"11\"/>"
+ "<field name=\"PM\" start=\"12\" end=\"12\"/>"
+ "<field name=\"FZ\" start=\"15\" end=\"15\"/>"
+ "</flags>");
}
snprintf(buffer, ARRAY_SIZE(buffer), "<reg name=\"%s\" bitsize=\"%Iu\"",
cpu->gdb_register_map[i].name, 8 * cpu->gdb_register_map[i].length);
- packet_reply_add(gdbctx, buffer);
+ reply_buffer_append_str(reply, buffer);
if (cpu->gdb_register_map[i].type)
{
- packet_reply_add(gdbctx, " type=\"");
- packet_reply_add(gdbctx, cpu->gdb_register_map[i].type);
- packet_reply_add(gdbctx, "\"");
+ reply_buffer_append_str(reply, " type=\"");
+ reply_buffer_append_str(reply, cpu->gdb_register_map[i].type);
+ reply_buffer_append_str(reply, "\"");
}
- packet_reply_add(gdbctx, "/>");
+ reply_buffer_append_str(reply, "/>");
}
- if (feature) packet_reply_add(gdbctx, "</feature>");
- packet_reply_add(gdbctx, "</target>");
+ if (feature) reply_buffer_append_str(reply, "</feature>");
+ reply_buffer_append_str(reply, "</target>");
}
static enum packet_return packet_query(struct gdb_context* gdbctx)
@@ -1960,9 +1963,12 @@ static enum packet_return packet_query(struct gdb_context* gdbctx)
{
if (!gdbctx->process) return packet_error;
- packet_reply_open_xfer(gdbctx);
packet_query_libraries(gdbctx);
- packet_reply_close_xfer(gdbctx, off, len);
+ packet_reply_xfer(gdbctx,
+ gdbctx->qxfer_buffer.base,
+ gdbctx->qxfer_buffer.len,
+ off, len);
+ reply_buffer_empty(&gdbctx->qxfer_buffer);
return packet_done;
}
@@ -1970,9 +1976,12 @@ static enum packet_return packet_query(struct gdb_context* gdbctx)
{
if (!gdbctx->process) return packet_error;
- packet_reply_open_xfer(gdbctx);
packet_query_threads(gdbctx);
- packet_reply_close_xfer(gdbctx, off, len);
+ packet_reply_xfer(gdbctx,
+ gdbctx->qxfer_buffer.base,
+ gdbctx->qxfer_buffer.len,
+ off, len);
+ reply_buffer_empty(&gdbctx->qxfer_buffer);
return packet_done;
}
@@ -1981,9 +1990,12 @@ static enum packet_return packet_query(struct gdb_context* gdbctx)
if (!gdbctx->process) return packet_error;
if (!(cpu = gdbctx->process->be_cpu)) return packet_error;
- packet_reply_open_xfer(gdbctx);
packet_query_target_xml(gdbctx, cpu);
- packet_reply_close_xfer(gdbctx, off, len);
+ packet_reply_xfer(gdbctx,
+ gdbctx->qxfer_buffer.base,
+ gdbctx->qxfer_buffer.len,
+ off, len);
+ reply_buffer_empty(&gdbctx->qxfer_buffer);
return packet_done;
}
break;
@@ -2301,6 +2313,8 @@ static BOOL gdb_init_context(struct gdb_context* gdbctx, unsigned flags, unsigne
for (i = 0; i < ARRAY_SIZE(gdbctx->wine_segs); i++)
gdbctx->wine_segs[i] = 0;
+ memset(&gdbctx->qxfer_buffer, 0, sizeof(gdbctx->qxfer_buffer));
+
/* wait for first trap */
while (WaitForDebugEvent(&gdbctx->de, INFINITE))
{
--
2.31.1
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