diff options
Diffstat (limited to 'src/fs/io/FileOutputStream.cxx')
| -rw-r--r-- | src/fs/io/FileOutputStream.cxx | 66 |
1 files changed, 59 insertions, 7 deletions
diff --git a/src/fs/io/FileOutputStream.cxx b/src/fs/io/FileOutputStream.cxx index 2951149b9..7a6416557 100644 --- a/src/fs/io/FileOutputStream.cxx +++ b/src/fs/io/FileOutputStream.cxx @@ -79,14 +79,47 @@ FileOutputStream::Cancel() #include <unistd.h> #include <errno.h> +#ifdef HAVE_LINKAT +#ifndef O_TMPFILE +/* supported since Linux 3.11 */ +#define __O_TMPFILE 020000000 +#define O_TMPFILE (__O_TMPFILE | O_DIRECTORY) +#include <stdio.h> +#endif + +/** + * Open a file using Linux's O_TMPFILE for writing the given file. + */ +static int +OpenTempFile(Path path) +{ + const auto directory = path.GetDirectoryName(); + if (directory.IsNull()) + return -1; + + return OpenFile(directory, O_TMPFILE|O_WRONLY, 0666); +} + +#endif /* HAVE_LINKAT */ + FileOutputStream::FileOutputStream(Path _path, Error &error) - :path(_path), - fd(OpenFile(path, - O_WRONLY|O_CREAT|O_TRUNC, - 0666)) + :path(_path) { - if (fd < 0) - error.FormatErrno("Failed to create %s", path.c_str()); +#ifdef HAVE_LINKAT + /* try Linux's O_TMPFILE first */ + fd = OpenTempFile(path); + is_tmpfile = fd >= 0; + if (!is_tmpfile) { +#endif + /* fall back to plain POSIX */ + fd = OpenFile(path, + O_WRONLY|O_CREAT|O_TRUNC, + 0666); + if (fd < 0) + error.FormatErrno("Failed to create %s", path.c_str()); +#ifdef HAVE_LINKAT + } +#endif } bool @@ -112,6 +145,22 @@ FileOutputStream::Commit(Error &error) { assert(IsDefined()); +#if HAVE_LINKAT + if (is_tmpfile) { + RemoveFile(path); + + /* hard-link the temporary file to the final path */ + char fd_path[64]; + snprintf(fd_path, sizeof(fd_path), "/proc/self/fd/%d", fd); + if (linkat(AT_FDCWD, fd_path, AT_FDCWD, path.c_str(), + AT_SYMLINK_FOLLOW) < 0) { + error.FormatErrno("Failed to commit %s", path.c_str()); + close(fd); + return false; + } + } +#endif + bool success = close(fd) == 0; fd = -1; if (!success) @@ -128,7 +177,10 @@ FileOutputStream::Cancel() close(fd); fd = -1; - RemoveFile(path); +#ifdef HAVE_LINKAT + if (!is_tmpfile) +#endif + RemoveFile(path); } #endif |