From: Paul Eggert Date: Mon, 12 Jul 1999 13:03:58 +0000 (+0000) Subject: (append_file): Open the file before statting it, to avoid a race. X-Git-Url: https://git.dogcows.com/gitweb?a=commitdiff_plain;h=4dd9bd50bdcf78b6fbe86cb1153579d3fe57334b;p=chaz%2Ftar (append_file): Open the file before statting it, to avoid a race. Complain about file shrinkage only when we reach EOF. --- diff --git a/src/update.c b/src/update.c index ea4dccf..5982b9f 100644 --- a/src/update.c +++ b/src/update.c @@ -45,52 +45,51 @@ char *output_start; static void append_file (char *path) { - int handle; + int handle = open (path, O_RDONLY | O_BINARY); struct stat stat_data; - off_t bytes_left; - if (stat (path, &stat_data) != 0 - || (handle = open (path, O_RDONLY | O_BINARY), handle < 0)) + if (handle < 0) { ERROR ((0, errno, _("Cannot open file %s"), path)); return; } - bytes_left = stat_data.st_size; - - while (bytes_left > 0) + if (fstat (handle, &stat_data) != 0) + ERROR ((0, errno, "%s", path)); + else { - union block *start = find_next_block (); - size_t buffer_size = available_space_after (start); - ssize_t status; - - if (bytes_left < buffer_size) - { - buffer_size = bytes_left; - status = buffer_size % BLOCKSIZE; - if (status) - memset (start->buffer + bytes_left, 0, - (size_t) (BLOCKSIZE - status)); - } + off_t bytes_left = stat_data.st_size; - status = safe_read (handle, start->buffer, buffer_size); - if (status < 0) + while (bytes_left > 0) { + union block *start = find_next_block (); + size_t buffer_size = available_space_after (start); + ssize_t status; char buf[UINTMAX_STRSIZE_BOUND]; - FATAL_ERROR ((0, errno, - _("Read error at byte %s reading %lu bytes in file %s"), - STRINGIFY_BIGINT (stat_data.st_size - bytes_left, buf), - (unsigned long) buffer_size, path)); - } - bytes_left -= status; - set_next_block_after (start + (status - 1) / BLOCKSIZE); + if (bytes_left < buffer_size) + { + buffer_size = bytes_left; + status = buffer_size % BLOCKSIZE; + if (status) + memset (start->buffer + bytes_left, 0, + (size_t) (BLOCKSIZE - status)); + } - if (status != buffer_size) - { - char buf[UINTMAX_STRSIZE_BOUND]; - FATAL_ERROR ((0, 0, _("%s: File shrunk by %s bytes, (yark!)"), - path, STRINGIFY_BIGINT (bytes_left, buf))); + status = safe_read (handle, start->buffer, buffer_size); + if (status < 0) + FATAL_ERROR ((0, errno, + _("Read error at byte %s reading %lu bytes in file %s"), + STRINGIFY_BIGINT (stat_data.st_size - bytes_left, + buf), + (unsigned long) buffer_size, path)); + if (status == 0) + FATAL_ERROR ((0, 0, _("%s: File shrunk by %s bytes, (yark!)"), + path, STRINGIFY_BIGINT (bytes_left, buf))); + + bytes_left -= status; + + set_next_block_after (start + (status - 1) / BLOCKSIZE); } }