Mercurial > hg > octave-nkf > gnulib-hg
changeset 3461:8ac2c1e256a9
(xreadlink): Omit size_t* arg. All uses changed.
Use ssize_t, not int, to store result of readlink.
Check for ssize_t overflow as well as size_t overflow,
as POSIX says the result of readlink is implementation-defined
when ssize_t overflows.
Remove unnecessary cast to char*.
Use free+malloc instead of realloc, as the storage doesn't need
to be preserved and it's clearer and can be more efficient that way.
(SIZE_MAX, SSIZE_MAX): New macros, if <limits.h> doesn't declare.
| author | Jim Meyering <jim@meyering.net> |
|---|---|
| date | Tue, 04 Sep 2001 20:20:16 +0000 |
| parents | 28c66612bada |
| children | dcd3e3763dee |
| files | lib/xreadlink.c |
| diffstat | 1 files changed, 18 insertions(+), 7 deletions(-) [+] |
line wrap: on
line diff
--- a/lib/xreadlink.c +++ b/lib/xreadlink.c @@ -29,6 +29,9 @@ extern int errno; #endif +#if HAVE_LIMITS_H +# include <limits.h> +#endif #if HAVE_SYS_TYPES_H # include <sys/types.h> #endif @@ -39,6 +42,13 @@ # include <unistd.h> #endif +#ifndef SIZE_MAX +# define SIZE_MAX ((size_t) -1) +#endif +#ifndef SSIZE_MAX +# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2)) +#endif + #include "xalloc.h" #include "xreadlink.h" @@ -49,18 +59,17 @@ give a diagnostic and exit. */ char * -xreadlink (char const *filename, size_t *link_length_arg) +xreadlink (char const *filename) { /* The initial buffer size for the link value. A power of 2 detects arithmetic overflow earlier, but is not required. */ size_t buf_size = 128; - char *buffer = NULL; while (1) { - int link_length; - buffer = (char *) xrealloc (buffer, buf_size); - link_length = readlink (filename, buffer, buf_size); + char *buffer = xmalloc (buf_size); + ssize_t link_length = readlink (filename, buffer, buf_size); + if (link_length < 0) { int saved_errno = errno; @@ -68,14 +77,16 @@ errno = saved_errno; return NULL; } + if (link_length < buf_size) { - *link_length_arg = link_length; buffer[link_length] = 0; return buffer; } + + free (buffer); buf_size *= 2; - if (buf_size == 0) + if (SSIZE_MAX < buf_size || (SIZE_MAX / 2 < SSIZE_MAX && buf_size == 0)) xalloc_die (); } }