From 9b1fc991e07698d637f3dacb608be7ceb9ca853d Mon Sep 17 00:00:00 2001 From: Herbert Xu Date: Sat, 1 Oct 2005 18:38:09 +1000 Subject: [INPUT] Fix NUL skipping in preadbuffer On Sun, Sep 25, 2005 at 07:50:54PM +0000, Gerrit Pape wrote: > On Sat, Sep 03, 2005 at 02:56:00PM +0200, Martin Dickopp wrote: > > When analysing the bug I came to the following conclusion: The loop > > beginning at input.c:302 overwrites a single input line with itself, > > skipping NUL characters. Therefore, after the loop the line buffer > > has less characters than originally read if and only if the input line > > contains NUL characters. > > yes. Thanks a lot for the details and patch. > > > The pointer that is used to read from the buffer, 'parsenextc' (cf. > > input.h:66), is also used as the beginning of the next line in > > input.c:296. This fails if the buffer contains less characters > > than originally read into it due to NUL characters. > > > > The proposed patch (attached) keeps track of the number of skipped > > characters and advances 'parsenextc' accordingly before processing > > the next input line. > > Hi Herbert, please see > http://bugs.debian.org/317516 Instead of moving the characters in the loop, we will do memmove every time we see a NUL character. This hurts if there are a lot of NUL characters, but should be a win in normal situations. --- src/input.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'src') diff --git a/src/input.c b/src/input.c index 8c874c6..8a43824 100644 --- a/src/input.c +++ b/src/input.c @@ -300,9 +300,9 @@ again: something = 0; #endif for (more = 1; more;) { - switch (*p) { + switch (*p++) { case '\0': - p++; /* Skip nul */ + p = memmove(q, p, parselleft); goto check; #ifndef SMALL @@ -323,7 +323,7 @@ again: #endif } - *q++ = *p++; + q++; check: if (--parselleft <= 0 && more) { parsenleft = q - parsenextc - 1; -- cgit 1.4.1