[PATCHv2,04/13] gdbserver: allows agent_mem_read to return an error code
Commit Message
Currently the gdbserver function agent_mem_read ignores any errors
from calling read_inferior_memory. This means that if there is an
attempt to access invalid memory then this will appear to succeed.
In this I update agent_mem_read so that if read_inferior_memory fails,
agent_mem_read will return an error code.
However, non of the callers of agent_mem_read actually check the
return value, so this commit will have no effect on anything. In the
next commit I will update the users of agent_mem_read to check for the
error code.
I've also updated the header comments on agent_mem_read to better
reflect what the function does, and its possible return values.
---
gdbserver/tracepoint.cc | 11 ++++-------
gdbserver/tracepoint.h | 9 +++++++--
2 files changed, 11 insertions(+), 9 deletions(-)
Comments
On Wednesday, January 18, 2023 5:18 PM, Andrew Burgess wrote:
> Currently the gdbserver function agent_mem_read ignores any errors
> from calling read_inferior_memory. This means that if there is an
> attempt to access invalid memory then this will appear to succeed.
>
> In this I update agent_mem_read so that if read_inferior_memory fails,
Did you mean "In this *patch* I update"?
> agent_mem_read will return an error code.
>
> However, non of the callers of agent_mem_read actually check the
non -> none
Regards
-Baris
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@@ -4914,8 +4914,7 @@ condition_true_at_tracepoint (struct tracepoint_hit_ctx *ctx,
return (value ? 1 : 0);
}
-/* Do memory copies for bytecodes. */
-/* Do the recording of memory blocks for actions and bytecodes. */
+/* See tracepoint.h. */
int
agent_mem_read (struct eval_agent_expr_context *ctx,
@@ -4927,10 +4926,7 @@ agent_mem_read (struct eval_agent_expr_context *ctx,
/* If a 'to' buffer is specified, use it. */
if (to != NULL)
- {
- read_inferior_memory (from, to, len);
- return 0;
- }
+ return read_inferior_memory (from, to, len);
/* Otherwise, create a new memory block in the trace buffer. */
while (remaining > 0)
@@ -4951,7 +4947,8 @@ agent_mem_read (struct eval_agent_expr_context *ctx,
memcpy (mspace, &blocklen, sizeof (blocklen));
mspace += sizeof (blocklen);
/* Record the memory block proper. */
- read_inferior_memory (from, mspace, blocklen);
+ if (read_inferior_memory (from, mspace, blocklen) != 0)
+ return 1;
trace_debug ("%d bytes recorded", blocklen);
remaining -= blocklen;
from += blocklen;
@@ -161,8 +161,13 @@ void gdb_agent_about_to_close (int pid);
struct traceframe;
struct eval_agent_expr_context;
-/* Do memory copies for bytecodes. */
-/* Do the recording of memory blocks for actions and bytecodes. */
+/* When TO is not NULL, do memory copies for bytecodes, read LEN bytes
+ starting at address FROM, and place the result in the buffer TO.
+ Return 0 on success, otherwise a non-zero error code.
+
+ When TO is NULL, do the recording of memory blocks for actions and
+ bytecodes into a new traceframe block. Return 0 on success, otherwise,
+ return 1 if there is an error. */
int agent_mem_read (struct eval_agent_expr_context *ctx,
unsigned char *to, CORE_ADDR from,