From 288a81d8470b1fd2e8a8f0814abe4cbfed71497c Mon Sep 17 00:00:00 2001 From: Dan McGee Date: Mon, 19 Sep 2011 14:08:14 -0500 Subject: Use more efficient way of restoring working directory Rather than using a string-based path, we can restore the working directory via a file descriptor and use of fchdir(). From the getcwd manpage: Opening the current directory (".") and calling fchdir(2) to return is usually a faster and more reliable alternative when sufficiently many file descriptors are available. Signed-off-by: Dan McGee --- lib/libalpm/add.c | 19 ++++++++++++------- lib/libalpm/handle.c | 2 +- lib/libalpm/util.c | 40 ++++++++++++++++++++++++---------------- 3 files changed, 37 insertions(+), 24 deletions(-) diff --git a/lib/libalpm/add.c b/lib/libalpm/add.c index b526145a..eb05f841 100644 --- a/lib/libalpm/add.c +++ b/lib/libalpm/add.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include @@ -528,8 +529,7 @@ static int commit_single_pkg(alpm_handle_t *handle, alpm_pkg_t *newpkg, if(!(trans->flags & ALPM_TRANS_FLAG_DBONLY)) { struct archive *archive; struct archive_entry *entry; - char cwd[PATH_MAX] = ""; - int restore_cwd = 0; + int cwdfd; _alpm_log(handle, ALPM_LOG_DEBUG, "extracting files\n"); @@ -551,10 +551,11 @@ static int commit_single_pkg(alpm_handle_t *handle, alpm_pkg_t *newpkg, } /* save the cwd so we can restore it later */ - if(getcwd(cwd, PATH_MAX) == NULL) { + do { + cwdfd = open(".", O_RDONLY); + } while(cwdfd == -1 && errno == EINTR); + if(cwdfd < 0) { _alpm_log(handle, ALPM_LOG_ERROR, _("could not get current working directory\n")); - } else { - restore_cwd = 1; } /* libarchive requires this for extracting hard links */ @@ -607,8 +608,12 @@ static int commit_single_pkg(alpm_handle_t *handle, alpm_pkg_t *newpkg, archive_read_finish(archive); /* restore the old cwd if we have it */ - if(restore_cwd && chdir(cwd) != 0) { - _alpm_log(handle, ALPM_LOG_ERROR, _("could not change directory to %s (%s)\n"), cwd, strerror(errno)); + if(cwdfd >= 0) { + if(fchdir(cwdfd) != 0) { + _alpm_log(handle, ALPM_LOG_ERROR, + _("could not restore working directory (%s)\n"), strerror(errno)); + } + close(cwdfd); } if(errors) { diff --git a/lib/libalpm/handle.c b/lib/libalpm/handle.c index 5fb4f2bb..dcd81cea 100644 --- a/lib/libalpm/handle.c +++ b/lib/libalpm/handle.c @@ -115,7 +115,7 @@ int _alpm_handle_lock(alpm_handle_t *handle) do { fd = open(handle->lockfile, O_WRONLY | O_CREAT | O_EXCL, 0000); } while(fd == -1 && errno == EINTR); - if(fd > 0) { + if(fd >= 0) { FILE *f = fdopen(fd, "w"); fprintf(f, "%ld\n", (long)getpid()); fflush(f); diff --git a/lib/libalpm/util.c b/lib/libalpm/util.c index f4fecabb..e2f2f441 100644 --- a/lib/libalpm/util.c +++ b/lib/libalpm/util.c @@ -31,6 +31,7 @@ #include #include #include +#include #include #include #include @@ -277,8 +278,7 @@ int _alpm_unpack(alpm_handle_t *handle, const char *archive, const char *prefix, mode_t oldmask; struct archive *_archive; struct archive_entry *entry; - char cwd[PATH_MAX]; - int restore_cwd = 0; + int cwdfd; if((_archive = archive_read_new()) == NULL) { RET_ERR(handle, ALPM_ERR_LIBARCHIVE, 1); @@ -297,10 +297,11 @@ int _alpm_unpack(alpm_handle_t *handle, const char *archive, const char *prefix, oldmask = umask(0022); /* save the cwd so we can restore it later */ - if(getcwd(cwd, PATH_MAX) == NULL) { + do { + cwdfd = open(".", O_RDONLY); + } while(cwdfd == -1 && errno == EINTR); + if(cwdfd < 0) { _alpm_log(handle, ALPM_LOG_ERROR, _("could not get current working directory\n")); - } else { - restore_cwd = 1; } /* just in case our cwd was removed in the upgrade operation */ @@ -365,10 +366,14 @@ int _alpm_unpack(alpm_handle_t *handle, const char *archive, const char *prefix, cleanup: umask(oldmask); archive_read_finish(_archive); - if(restore_cwd && chdir(cwd) != 0) { - _alpm_log(handle, ALPM_LOG_ERROR, _("could not change directory to %s (%s)\n"), - cwd, strerror(errno)); + if(cwdfd >= 0) { + if(fchdir(cwdfd) != 0) { + _alpm_log(handle, ALPM_LOG_ERROR, + _("could not restore working directory (%s)\n"), strerror(errno)); + } + close(cwdfd); } + return ret; } @@ -490,17 +495,16 @@ int _alpm_logaction(alpm_handle_t *handle, const char *fmt, va_list args) int _alpm_run_chroot(alpm_handle_t *handle, const char *path, char *const argv[]) { - char cwd[PATH_MAX]; pid_t pid; - int pipefd[2]; - int restore_cwd = 0; + int pipefd[2], cwdfd; int retval = 0; /* save the cwd so we can restore it later */ - if(getcwd(cwd, PATH_MAX) == NULL) { + do { + cwdfd = open(".", O_RDONLY); + } while(cwdfd == -1 && errno == EINTR); + if(cwdfd < 0) { _alpm_log(handle, ALPM_LOG_ERROR, _("could not get current working directory\n")); - } else { - restore_cwd = 1; } /* just in case our cwd was removed in the upgrade operation */ @@ -598,8 +602,12 @@ int _alpm_run_chroot(alpm_handle_t *handle, const char *path, char *const argv[] } cleanup: - if(restore_cwd && chdir(cwd) != 0) { - _alpm_log(handle, ALPM_LOG_ERROR, _("could not change directory to %s (%s)\n"), cwd, strerror(errno)); + if(cwdfd >= 0) { + if(fchdir(cwdfd) != 0) { + _alpm_log(handle, ALPM_LOG_ERROR, + _("could not restore working directory (%s)\n"), strerror(errno)); + } + close(cwdfd); } return retval; -- cgit v1.2.3-24-g4f1b