Re: [PATCH 3/5] gdbstub: Use fixed-size array in GdbCmdParseEntry instead of pointer

[Alex Bennée]

Philippe Mathieu-Daudé <philmd@redhat.com> writes:

> GdbCmdParseEntry should have enough room with 20 chars for the command
> string, and 8 for the schema. Add the GDB_CMD_PARSE_ENTRY_CMD_SIZE and
> GDB_CMD_PARSE_ENTRY_SCHEMA_SIZE definitions.
>
> Do not use pointer to string of unknown length, but array of fixed
> size. Having constant size will help use to remove the alloca() call
> in process_string_cmd() in the next commit.

I don't understand how this helps. The alloca is being used for an array
of GdbCmdVariant so why do we want to enlarge the size of the parse
table entries?

>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  gdbstub.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/gdbstub.c b/gdbstub.c
> index 6f663cbd8dd..0d5569ee539 100644
> --- a/gdbstub.c
> +++ b/gdbstub.c
> @@ -1457,11 +1457,13 @@ typedef void (*GdbCmdHandler)(GdbCmdContext *gdb_ctx, 
> void *user_ctx);
>   * '.' -> Skip 1 char unless reached "\0"
>   * Any other value is treated as the delimiter value itself
>   */
> +#define GDB_CMD_PARSE_ENTRY_CMD_SIZE    20
> +#define GDB_CMD_PARSE_ENTRY_SCHEMA_SIZE 8
>  typedef struct GdbCmdParseEntry {
>      GdbCmdHandler handler;
> -    const char *cmd;
> +    const char cmd[GDB_CMD_PARSE_ENTRY_CMD_SIZE];
>      bool cmd_startswith;
> -    const char *schema;
> +    const char schema[GDB_CMD_PARSE_ENTRY_SCHEMA_SIZE];
>  } GdbCmdParseEntry;
>  
>  static inline int startswith(const char *string, const char *pattern)
> @@ -1481,14 +1483,14 @@ static int process_string_cmd(void *user_ctx, const 
> char *data,
>  
>      for (i = 0; i < num_cmds; i++) {
>          const GdbCmdParseEntry *cmd = &cmds[i];
> -        g_assert(cmd->handler && cmd->cmd);
> +        g_assert(cmd->handler && *cmd->cmd);
>  
>          if ((cmd->cmd_startswith && !startswith(data, cmd->cmd)) ||
>              (!cmd->cmd_startswith && strcmp(cmd->cmd, data))) {
>              continue;
>          }
>  
> -        if (cmd->schema) {
> +        if (*cmd->schema) {
>              schema_len = strlen(cmd->schema);
>              if (schema_len % 2) {
>                  return -2;


-- 
Alex Bennée