Re: [PATCH next v2] log_ref_setup: don't return stack-allocated array
From: Ævar Arnfjörð Bjarmason <hidden>
Date: 2016-06-15 22:48:57
On Thu, Jun 10, 2010 at 16:46, Erick Mattos [off-list ref] wrote:
Hi there, 2010/6/10 Thomas Rast [off-list ref]quoted
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 <redacted> Reported-by: Ævar Arnfjörð Bjarmason <redacted> --- 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(structcheckout_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.ga798eI 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?quoted
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.