From 6e317e4b96cf708eee0841e7c8a599efdecb2af1 Mon Sep 17 00:00:00 2001 From: Wayne Davison Date: Fri, 18 Dec 2009 19:50:45 +0000 Subject: Add symlink-based hist-file locking. --- Src/hist.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) (limited to 'Src/hist.c') diff --git a/Src/hist.c b/Src/hist.c index 86b08bd45..b1e4e82c4 100644 --- a/Src/hist.c +++ b/Src/hist.c @@ -2600,11 +2600,38 @@ lockhistfile(char *fn, int keep_trying) int fd; char *lockfile; #ifdef HAVE_LINK +# ifdef HAVE_SYMLINK + char pidbuf[32], *lnk; +# else char *tmpfile; +# endif #endif lockfile = bicat(unmeta(fn), ".LOCK"); + /* NOTE: only use symlink locking on a link()-having host in order to + * avoid a change from open()-based locking to symlink()-based. */ #ifdef HAVE_LINK +# ifdef HAVE_SYMLINK + sprintf(pidbuf, "/pid-%ld/host-", (long)mypid); + lnk = bicat(pidbuf, getsparam("HOST")); + /* We'll abuse fd as our success flag. */ + while ((fd = symlink(lnk, lockfile)) < 0) { + if (errno != EEXIST || !keep_trying) + break; + if (lstat(lockfile, &sb) < 0) { + if (errno == ENOENT) + continue; + break; + } + if (time(NULL) - sb.st_mtime < 10) + sleep(1); + else + unlink(lockfile); + } + if (fd < 0) + lockhistct--; + free(lnk); +# else /* not HAVE_SYMLINK */ if ((fd = gettempfile(fn, 0, &tmpfile)) >= 0) { FILE *out = fdopen(fd, "w"); if (out) { @@ -2618,7 +2645,7 @@ lockhistfile(char *fn, int keep_trying) lockfile, errno); else if (!keep_trying) ; - else if (stat(lockfile, &sb) < 0) { + else if (lstat(lockfile, &sb) < 0) { if (errno == ENOENT) continue; zerr("failed to stat lock file %s: %e", lockfile, errno); @@ -2635,11 +2662,12 @@ lockhistfile(char *fn, int keep_trying) unlink(tmpfile); free(tmpfile); } +# endif /* not HAVE_SYMLINK */ #else /* not HAVE_LINK */ while ((fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, 0644)) < 0) { if (errno != EEXIST || !keep_trying) break; - if (stat(lockfile, &sb) < 0) { + if (lstat(lockfile, &sb) < 0) { if (errno == ENOENT) continue; break; -- cgit 1.4.1