CVS commit: src/lib/libedit

["Christos Zoulas" <christos%netbsd.org@localhost>]

Module Name:    src
Committed By:   christos
Date:           Mon May  9 21:25:11 UTC 2016

Modified Files:
        src/lib/libedit: readline.c

Log Message:
The libedit implementation of history_get() also differs from the GNU
implementation:  libedit goes to the entry with the given number
stored in the HistEvent structure, while GNU subtracts history_base,
then advances that many entries from the oldest one.  If entries were
removed in between, GNU advances further than libedit.

The call sequence H_CURR, H_DELDATA, H_CURR, H_NEXT_EVDATA looks
weird, as if part of that must somehow be redundant.  But actually,
the user interface is so counter-intuitive that every single step
is really required.

 - The first H_CURR is needed to be able to go back after an error.
 - The H_DELDATA is needed to move the cursor.  Even though it takes
   a pointer to ev, that structure is not filled in when the call
   succeeds.  H_DELDATA only moves the cursor, it doesn't tell us
   the new event number.
 - Consequently, the second H_CURR is required to get ev.num filled
   in.  But it doesn't return the data because ev has no field for
   that.
 - So even though the cursor is already positioned correctly,
   H_NEXT_EVDATA is needed as the final step merely to get the data.

(Ingo Schwarze)


To generate a diff of this commit:
cvs rdiff -u -r1.130 -r1.131 src/lib/libedit/readline.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.