diff options
Diffstat (limited to 'src/xz/file_io.c')
| -rw-r--r-- | src/xz/file_io.c | 156 |
1 files changed, 111 insertions, 45 deletions
diff --git a/src/xz/file_io.c b/src/xz/file_io.c index 6598ef6e..fd22dc4f 100644 --- a/src/xz/file_io.c +++ b/src/xz/file_io.c @@ -17,6 +17,7 @@ #ifdef TUKLIB_DOSLIKE # include <io.h> #else +# include <poll.h> static bool warn_fchown; #endif @@ -41,6 +42,11 @@ static bool warn_fchown; static bool try_sparse = true; #ifndef TUKLIB_DOSLIKE +/// File status flags of standard input. This is used by io_open_src() +/// and io_close_src(). +static int stdin_flags; +static bool restore_stdin_flags = false; + /// Original file status flags of standard output. This is used by /// io_open_dest() and io_close_dest() to save and restore the flags. static int stdout_flags; @@ -84,6 +90,47 @@ io_no_sparse(void) } +#ifndef TUKLIB_DOSLIKE +/// \brief Waits for input or output to become available +static bool +io_wait(file_pair *pair, bool is_reading) +{ + struct pollfd pfd[1]; + + if (is_reading) { + pfd[0].fd = pair->src_fd; + pfd[0].events = POLLIN; + } else { + pfd[0].fd = pair->dest_fd; + pfd[0].events = POLLOUT; + } + + while (true) { + const int ret = poll(pfd, 1, -1); + + if (ret == -1) { + if (errno == EINTR) { + if (user_abort) + return true; + + continue; + } + + if (errno == EAGAIN) + continue; + + message_error(_("%s: poll() failed: %s"), + is_reading ? pair->src_name + : pair->dest_name, + strerror(errno)); + } + + return false; + } +} +#endif + + /// \brief Unlink a file /// /// This tries to verify that the file being unlinked really is the file that @@ -293,6 +340,27 @@ io_open_src_real(file_pair *pair) pair->src_fd = STDIN_FILENO; #ifdef TUKLIB_DOSLIKE setmode(STDIN_FILENO, O_BINARY); +#else + // Enable O_NONBLOCK for stdin. + stdin_flags = fcntl(STDIN_FILENO, F_GETFL); + if (stdin_flags == -1) { + message_error(_("Error getting the file status flags " + "from standard input: %s"), + strerror(errno)); + return true; + } + + if ((stdin_flags & O_NONBLOCK) == 0) { + if (fcntl(STDIN_FILENO, F_SETFL, + stdin_flags | O_NONBLOCK) == -1) { + message_error(_("Error setting O_NONBLOCK " + "on standard input: %s"), + strerror(errno)); + return true; + } + + restore_stdin_flags = true; + } #endif #ifdef HAVE_POSIX_FADVISE // It will fail if stdin is a pipe and that's fine. @@ -314,13 +382,12 @@ io_open_src_real(file_pair *pair) int flags = O_RDONLY | O_BINARY | O_NOCTTY; #ifndef TUKLIB_DOSLIKE - // If we accept only regular files, we need to be careful to avoid - // problems with special files like devices and FIFOs. O_NONBLOCK - // prevents blocking when opening such files. When we want to accept - // special files, we must not use O_NONBLOCK, or otherwise we won't - // block waiting e.g. FIFOs to become readable. - if (reg_files_only) - flags |= O_NONBLOCK; + // Use non-blocking I/O: + // - It prevents blocking when opening FIFOs and some other + // special files, which is good if we want to accept only + // regular files. + // - It can help avoiding some race conditions with signal handling. + flags |= O_NONBLOCK; #endif #if defined(O_NOFOLLOW) @@ -348,30 +415,13 @@ io_open_src_real(file_pair *pair) (void)follow_symlinks; #endif - // Try to open the file. If we are accepting non-regular files, - // unblock the caught signals so that open() can be interrupted - // if it blocks e.g. due to a FIFO file. - if (!reg_files_only) - signals_unblock(); - - // Maybe this wouldn't need a loop, since all the signal handlers for - // which we don't use SA_RESTART set user_abort to true. But it - // doesn't hurt to have it just in case. - do { - pair->src_fd = open(pair->src_name, flags); - } while (pair->src_fd == -1 && errno == EINTR && !user_abort); - - if (!reg_files_only) - signals_block(); + // Try to open the file. Signals have been blocked so EINTR shouldn't + // be possible. + pair->src_fd = open(pair->src_name, flags); if (pair->src_fd == -1) { - // If we were interrupted, don't display any error message. - if (errno == EINTR) { - // All the signals that don't have SA_RESTART - // set user_abort. - assert(user_abort); - return true; - } + // Signals (that have a signal handler) have been blocked. + assert(errno != EINTR); #ifdef O_NOFOLLOW // Give an understandable error message if the reason @@ -430,22 +480,6 @@ io_open_src_real(file_pair *pair) return true; } -#ifndef TUKLIB_DOSLIKE - // Drop O_NONBLOCK, which is used only when we are accepting only - // regular files. After the open() call, we want things to block - // instead of giving EAGAIN. - if (reg_files_only) { - flags = fcntl(pair->src_fd, F_GETFL); - if (flags == -1) - goto error_msg; - - flags &= ~O_NONBLOCK; - - if (fcntl(pair->src_fd, F_SETFL, flags) == -1) - goto error_msg; - } -#endif - // Stat the source file. We need the result also when we copy // the permissions, and when unlinking. // @@ -505,6 +539,18 @@ io_open_src_real(file_pair *pair) goto error; } } + + // If it is something else than a regular file, wait until + // there is input available. This way reading from FIFOs + // will work when open() is used with O_NONBLOCK. + if (!S_ISREG(pair->src_st.st_mode)) { + signals_unblock(); + const bool ret = io_wait(pair, true); + signals_block(); + + if (ret) + goto error; + } #endif #ifdef HAVE_POSIX_FADVISE @@ -560,6 +606,17 @@ io_open_src(const char *src_name) static void io_close_src(file_pair *pair, bool success) { + if (restore_stdin_flags) { + assert(pair->src_fd == STDIN_FILENO); + + restore_stdin_flags = false; + + if (fcntl(STDIN_FILENO, F_SETFL, stdin_flags) == -1) + message_error(_("Error restoring the status flags " + "to standard input: %s"), + strerror(errno)); + } + if (pair->src_fd != STDIN_FILENO && pair->src_fd != -1) { #ifdef TUKLIB_DOSLIKE (void)close(pair->src_fd); @@ -872,6 +929,15 @@ io_read(file_pair *pair, io_buf *buf_union, size_t size) continue; } +#ifndef TUKLIB_DOSLIKE + if (errno == EAGAIN || errno == EWOULDBLOCK) { + if (!io_wait(pair, true)) + continue; + + return SIZE_MAX; + } +#endif + message_error(_("%s: Read error: %s"), pair->src_name, strerror(errno)); |