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gdbserver: allows agent_mem_read to return an error code

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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 patch I update agent_mem_read so that if read_inferior_memory
fails, agent_mem_read will return an error code.

However, none 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.
This commit is contained in:
Andrew Burgess 2022-10-20 10:58:02 +01:00
parent 2dc3457a45
commit 0576dff20f
2 changed files with 11 additions and 9 deletions
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11
gdbserver/tracepoint.cc
View File

@ -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;

9
gdbserver/tracepoint.h
View File

@ -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,