From 0576dff20f052ab6d1ddba861235c7dc2584a145 Mon Sep 17 00:00:00 2001 From: Andrew Burgess Date: Thu, 20 Oct 2022 10:58:02 +0100 Subject: [PATCH] gdbserver: allows agent_mem_read to return an error code 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. --- gdbserver/tracepoint.cc | 11 ++++------- gdbserver/tracepoint.h | 9 +++++++-- 2 files changed, 11 insertions(+), 9 deletions(-) diff --git a/gdbserver/tracepoint.cc b/gdbserver/tracepoint.cc index 3f60989e4c7..125a384ffb3 100644 --- a/gdbserver/tracepoint.cc +++ b/gdbserver/tracepoint.cc @@ -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; diff --git a/gdbserver/tracepoint.h b/gdbserver/tracepoint.h index 060d44d0033..1f40d7b5177 100644 --- a/gdbserver/tracepoint.h +++ b/gdbserver/tracepoint.h @@ -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, -- 2.30.2