[PATCH] Append to input history file instead of overwriting it

[Sergio Durigan Junior]

On Friday, November 28 2014, Patrick Palka wrote:

> This patch makes readline append new history lines to the GDB history
> file on exit instead of overwriting the entire history file on exit.
> This change allows us to run multiple simultaneous GDB sessions without
> having each session overwrite the added history of each other session on
> exit.  It is particularly helpful when debugging GDB with GDB.
>
> Does this look OK to commit?  Tested on x86_64-unknown-linux-gnu.

Thanks, Patrick.

The patch makes sense to me, and it is a good thing to have, I agree.

> gdb/ChangeLog:
>
> 	* top.h (gdb_add_history): Declare.
> 	* top.c (command_count): New variable.
> 	(gdb_add_history): New function.
> 	(quit_force): Append to history file instead of overwriting it.
> 	(command_line_input): Use gdb_add_history instead of
> 	add_history.
> 	* event-top.c (command_line_handler): Likewise.
> ---
>  gdb/event-top.c |  2 +-
>  gdb/top.c       | 19 ++++++++++++++++---
>  gdb/top.h       |  2 ++
>  3 files changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/gdb/event-top.c b/gdb/event-top.c
> index cb438ac..490bca6 100644
> --- a/gdb/event-top.c
> +++ b/gdb/event-top.c
> @@ -667,7 +667,7 @@ command_line_handler (char *rl)
>  
>    /* Add line to history if appropriate.  */
>    if (*linebuffer && input_from_terminal_p ())
> -    add_history (linebuffer);
> +    gdb_add_history (linebuffer);
>  
>    /* Note: lines consisting solely of comments are added to the command
>       history.  This is useful when you type a command, and then
> diff --git a/gdb/top.c b/gdb/top.c
> index c4b5c2c..6ec3acc 100644
> --- a/gdb/top.c
> +++ b/gdb/top.c
> @@ -895,7 +895,20 @@ gdb_rl_operate_and_get_next (int count, int key)
>  
>    return rl_newline (1, key);
>  }
> -
> +
> +/* Number of user commands executed during this session.  */
> +
> +static int command_count;

You should initialize this variable.

Other than that, looks good.  Let's wait for a maintainer to take a
look.

> +
> +/* Add the user command COMMAND to the input history list.  */
> +
> +void
> +gdb_add_history (const char *command)
> +{
> +  add_history (command);
> +  command_count++;
> +}
> +
>  /* Read one line from the command input stream `instream'
>     into the local static buffer `linebuffer' (whose current length
>     is `linelength').
> @@ -1090,7 +1103,7 @@ command_line_input (char *prompt_arg, int repeat, char *annotation_suffix)
>  
>    /* Add line to history if appropriate.  */
>    if (*linebuffer && input_from_terminal_p ())
> -    add_history (linebuffer);
> +    gdb_add_history (linebuffer);
>  
>    /* Save into global buffer if appropriate.  */
>    if (repeat)
> @@ -1441,7 +1454,7 @@ quit_force (char *args, int from_tty)
>      {
>        if (write_history_p && history_filename
>  	  && input_from_terminal_p ())
> -	write_history (history_filename);
> +	append_history (command_count, history_filename);
>      }
>    DO_PRINT_EX;
>  
> diff --git a/gdb/top.h b/gdb/top.h
> index 94f6c48..d8baea8 100644
> --- a/gdb/top.h
> +++ b/gdb/top.h
> @@ -79,6 +79,8 @@ extern int history_expansion_p;
>  extern int server_command;
>  extern char *lim_at_start;
>  
> +extern void gdb_add_history (const char *);
> +
>  extern void show_commands (char *args, int from_tty);
>  
>  extern void set_history (char *, int);
> -- 
> 2.2.0.rc1.23.gf570943

-- 
Sergio
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