diff options
Diffstat (limited to 'cmds/idmap/scan.cpp')
| -rw-r--r-- | cmds/idmap/scan.cpp | 21 |
1 files changed, 17 insertions, 4 deletions
diff --git a/cmds/idmap/scan.cpp b/cmds/idmap/scan.cpp index 6d30f0d0ce34..ab6adfb9475f 100644 --- a/cmds/idmap/scan.cpp +++ b/cmds/idmap/scan.cpp @@ -1,5 +1,6 @@ #include <dirent.h> #include <inttypes.h> +#include <sys/file.h> #include <sys/stat.h> #include "idmap.h" @@ -35,16 +36,31 @@ namespace { bool writePackagesList(const char *filename, const SortedVector<Overlay>& overlayVector) { - FILE* fout = fopen(filename, "w"); + // the file is opened for appending so that it doesn't get truncated + // before we can guarantee mutual exclusion via the flock + FILE* fout = fopen(filename, "a"); if (fout == NULL) { return false; } + if (TEMP_FAILURE_RETRY(flock(fileno(fout), LOCK_EX)) != 0) { + fclose(fout); + return false; + } + + if (TEMP_FAILURE_RETRY(ftruncate(fileno(fout), 0)) != 0) { + TEMP_FAILURE_RETRY(flock(fileno(fout), LOCK_UN)); + fclose(fout); + return false; + } + for (size_t i = 0; i < overlayVector.size(); ++i) { const Overlay& overlay = overlayVector[i]; fprintf(fout, "%s %s\n", overlay.apk_path.string(), overlay.idmap_path.string()); } + TEMP_FAILURE_RETRY(fflush(fout)); + TEMP_FAILURE_RETRY(flock(fileno(fout), LOCK_UN)); fclose(fout); // Make file world readable since Zygote (running as root) will read @@ -171,9 +187,6 @@ int idmap_scan(const char *target_package_name, const char *target_apk_path, { String8 filename = String8(idmap_dir); filename.appendPath("overlays.list"); - if (unlink(filename.string()) != 0 && errno != ENOENT) { - return EXIT_FAILURE; - } SortedVector<Overlay> overlayVector; const size_t N = overlay_dirs->size(); |