From 3bd23802ad65a4379e0c97d736dc6c2ab2d37f1d Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Tue, 2 Nov 2004 20:17:37 +0000 Subject: [PATCH] (MAXSIZE): New macro. (xreadlink): Use it instead of SSIZE_MAX. Ensure initial buffer size does not exceed MAXSIZE. Avoid cast. As suggested by Mark D. Baushke in , if readlink fails with buffer size just under MAXSIZE, try again with MAXSIZE. --- lib/xreadlink.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) diff --git a/lib/xreadlink.c b/lib/xreadlink.c index 2e66c07f24..c38e2d3aad 100644 --- a/lib/xreadlink.c +++ b/lib/xreadlink.c @@ -41,6 +41,8 @@ # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2)) #endif +#define MAXSIZE (SIZE_MAX < SSIZE_MAX ? SIZE_MAX : SSIZE_MAX) + #include "xalloc.h" /* Call readlink to get the symbolic link value of FILENAME. @@ -56,14 +58,15 @@ xreadlink (char const *filename, size_t size) { /* The initial buffer size for the link value. A power of 2 detects arithmetic overflow earlier, but is not required. */ - size_t buf_size = size + 1; + size_t buf_size = size < MAXSIZE ? size + 1 : MAXSIZE; while (1) { char *buffer = xmalloc (buf_size); - ssize_t link_length = readlink (filename, buffer, buf_size); + ssize_t r = readlink (filename, buffer, buf_size); + size_t link_length = r; - if (link_length < 0) + if (r < 0) { int saved_errno = errno; free (buffer); @@ -71,15 +74,18 @@ xreadlink (char const *filename, size_t size) return NULL; } - if ((size_t) link_length < buf_size) + if (link_length < buf_size) { buffer[link_length] = 0; return buffer; } free (buffer); - buf_size *= 2; - if (! (0 < buf_size && buf_size <= SSIZE_MAX)) + if (buf_size <= MAXSIZE / 2) + buf_size *= 2; + else if (buf_size < MAXSIZE) + buf_size = MAXSIZE; + else xalloc_die (); } } -- 2.30.2