From: Ævar Arnfjörð Bjarmason Date: Thu, 10 Jun 2010 18:09:26 GMT Subject: Re: [PATCH next v2] log_ref_setup: don't return stack-allocated array Message-ID: In-Reply-To: On Thu, Jun 10, 2010 at 16:46, Erick Mattos wrote: > Hi there, > > 2010/6/10 Thomas Rast >> >> 859c301 (refs: split log_ref_write logic into log_ref_setup, >> 2010-05-21) refactors the stack allocation of the log_file array into >> the new log_ref_setup() function, but passes it back to the caller. >> >> Since the original intent seems to have been to split the work between >> log_ref_setup and log_ref_write, make it the caller's responsibility >> to allocate the buffer. >> >> Signed-off-by: Thomas Rast >> Reported-by: Ævar Arnfjörð Bjarmason >> --- >> >> Sorry for the first one, that was completely botched and didn't even >> compile. >> >> This one does, and as an added bonus also passes some tests. >> >>  builtin/checkout.c |    4 ++-- >>  refs.c             |   26 ++++++++++++-------------- >>  refs.h             |    2 +- >>  3 files changed, 15 insertions(+), 17 deletions(-) >> >> diff --git a/builtin/checkout.c b/builtin/checkout.c >> index 5107eda..1994be9 100644 >> --- a/builtin/checkout.c >> +++ b/builtin/checkout.c >> @@ -496,12 +496,12 @@ static void update_refs_for_switch(struct >> checkout_opts *opts, >>                if (opts->new_orphan_branch) { >>                        if (opts->new_branch_log && !log_all_ref_updates) { >>                                int temp; >> -                               char *log_file; >> +                               char log_file[PATH_MAX]; >>                                char *ref_name = mkpath("refs/heads/%s", >> opts->new_orphan_branch); >> >>                                temp = log_all_ref_updates; >>                                log_all_ref_updates = 1; >> -                               if (log_ref_setup(ref_name, &log_file)) { >> +                               if (log_ref_setup(ref_name, log_file, >> sizeof(log_file))) { >>                                        fprintf(stderr, "Can not do reflog >> for '%s'\n", >>                                            opts->new_orphan_branch); >>                                        log_all_ref_updates = temp; >> diff --git a/refs.c b/refs.c >> index 3436649..6f486ae 100644 >> --- a/refs.c >> +++ b/refs.c >> @@ -1262,43 +1262,41 @@ static int copy_msg(char *buf, const char *msg) >>        return cp - buf; >>  } >> >> -int log_ref_setup(const char *ref_name, char **log_file) >> +int log_ref_setup(const char *ref_name, char *logfile, int bufsize) >>  { >>        int logfd, oflags = O_APPEND | O_WRONLY; >> -       char logfile[PATH_MAX]; >> >> -       git_snpath(logfile, sizeof(logfile), "logs/%s", ref_name); >> -       *log_file = logfile; >> +       git_snpath(logfile, bufsize, "logs/%s", ref_name); >>        if (log_all_ref_updates && >>            (!prefixcmp(ref_name, "refs/heads/") || >>             !prefixcmp(ref_name, "refs/remotes/") || >>             !prefixcmp(ref_name, "refs/notes/") || >>             !strcmp(ref_name, "HEAD"))) { >> -               if (safe_create_leading_directories(*log_file) < 0) >> +               if (safe_create_leading_directories(logfile) < 0) >>                        return error("unable to create directory for %s", >> -                                    *log_file); >> +                                    logfile); >>                oflags |= O_CREAT; >>        } >> >> -       logfd = open(*log_file, oflags, 0666); >> +       logfd = open(logfile, oflags, 0666); >>        if (logfd < 0) { >>                if (!(oflags & O_CREAT) && errno == ENOENT) >>                        return 0; >> >>                if ((oflags & O_CREAT) && errno == EISDIR) { >> -                       if (remove_empty_directories(*log_file)) { >> +                       if (remove_empty_directories(logfile)) { >>                                return error("There are still logs under >> '%s'", >> -                                            *log_file); >> +                                            logfile); >>                        } >> -                       logfd = open(*log_file, oflags, 0666); >> +                       logfd = open(logfile, oflags, 0666); >>                } >> >>                if (logfd < 0) >>                        return error("Unable to append to %s: %s", >> -                                    *log_file, strerror(errno)); >> +                                    logfile, strerror(errno)); >>        } >> >> -       adjust_shared_perm(*log_file); >> +       adjust_shared_perm(logfile); >>        close(logfd); >>        return 0; >>  } >> @@ -1309,14 +1307,14 @@ static int log_ref_write(const char *ref_name, >> const unsigned char *old_sha1, >>        int logfd, result, written, oflags = O_APPEND | O_WRONLY; >>        unsigned maxlen, len; >>        int msglen; >> -       char *log_file; >> +       char log_file[PATH_MAX]; >>        char *logrec; >>        const char *committer; >> >>        if (log_all_ref_updates < 0) >>                log_all_ref_updates = !is_bare_repository(); >> >> -       result = log_ref_setup(ref_name, &log_file); >> +       result = log_ref_setup(ref_name, log_file, sizeof(log_file)); >>        if (result) >>                return result; >> >> diff --git a/refs.h b/refs.h >> index 594c9d9..762ce50 100644 >> --- a/refs.h >> +++ b/refs.h >> @@ -69,7 +69,7 @@ extern void unlock_ref(struct ref_lock *lock); >>  extern int write_ref_sha1(struct ref_lock *lock, const unsigned char >> *sha1, const char *msg); >> >>  /** Setup reflog before using. **/ >> -int log_ref_setup(const char *ref_name, char **log_file); >> +int log_ref_setup(const char *ref_name, char *logfile, int bufsize); >> >>  /** Reads log for the value of ref during at_time. **/ >>  extern int read_ref_at(const char *ref, unsigned long at_time, int cnt, >> unsigned char *sha1, char **msg, unsigned long *cutoff_time, int *cutoff_tz, >> int *cutoff_cnt); >> -- >> 1.7.1.553.ga798e >> > > I can't get your point. > > I don't see any improvement here.  Unless you want to get rid of using > references on calling functions which is only going to add another buffer to > the stack, sized PATH_MAX, once that log_file is going to be really > allocated in the heap after git_snpath().  As folks use to say here: > "changing six by half a dozen". > > Even though I think you will need to turn static log_file or to call > git_snpath again in the calling functions for this proposed change, don't > you? > >> Causes t5516 to fail, but only if I run it under valgrind.  (Ævar >> managed to trigger it in other ways apparently.) > > I haven't ever seen this happening so I think you have found some > particularity of valgrind which could route a patch to it. Actually I think my test failure is related to da3efdb17b, see the "[PATCH v2 2/2] receive-pack: detect aliased updates which can occur with symrefs" thread. The patch under discussion here might be good, I don't have the knowledge to review it. But it's probably not what's causing the issue i had with t5516.