diff options
Diffstat (limited to 'lib')
-rw-r--r-- | lib/fsusage.c | 31 |
1 files changed, 27 insertions, 4 deletions
diff --git a/lib/fsusage.c b/lib/fsusage.c index 98993b17a..1853d67f3 100644 --- a/lib/fsusage.c +++ b/lib/fsusage.c @@ -26,6 +26,13 @@ #include <sys/stat.h> #include "fsusage.h" +#if HAVE_LIMITS_H +# include <limits.h> +#endif +#ifndef CHAR_BIT +# define CHAR_BIT 8 +#endif + int statfs (); #if HAVE_SYS_PARAM_H @@ -68,9 +75,22 @@ int statvfs (); /* Many space usage primitives use all 1 bits to denote a value that is not applicable or unknown. Propagate this information by returning a uintmax_t value that is all 1 bits if the argument is all 1 bits, - even if the argument is unsigned and smaller than unitmax_t. */ + even if the argument is unsigned and smaller than uintmax_t. */ #define PROPAGATE_ALL_ONES(x) ((x) == -1 ? (uintmax_t) -1 : (uintmax_t) (x)) +/* Extract the top bit of X as an uintmax_t value. */ +#define EXTRACT_TOP_BIT(x) ((x) \ + & ((uintmax_t) 1 << (sizeof (x) * CHAR_BIT - 1))) + +/* If a value is negative, many space usage primitives store it into an + integer variable by assignment, even if the variable's type is unsigned. + So, if a space usage variable X's top bit is set, convert X to the + uintmax_t value V such that (- (uintmax_t) V) is the negative of + the original value. If X's top bit is clear, just yield X. + Use PROPAGATE_TOP_BIT if the original value might be negative; + otherwise, use PROPAGATE_ALL_ONES. */ +#define PROPAGATE_TOP_BIT(x) ((x) | ~ (EXTRACT_TOP_BIT (x) - 1)) + int safe_read (); /* Fill in the fields of FSP with information about space usage for @@ -107,7 +127,8 @@ get_fs_usage (path, disk, fsp) fsp->fsu_blocksize = 1024; fsp->fsu_blocks = PROPAGATE_ALL_ONES (fsd.fd_req.btot); fsp->fsu_bfree = PROPAGATE_ALL_ONES (fsd.fd_req.bfree); - fsp->fsu_bavail = PROPAGATE_ALL_ONES (fsd.fd_req.bfreen); + fsp->fsu_bavail = PROPAGATE_TOP_BIT (fsd.fd_req.bfreen); + fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (fsd.fd_req.bfreen) != 0; fsp->fsu_files = PROPAGATE_ALL_ONES (fsd.fd_req.gtot); fsp->fsu_ffree = PROPAGATE_ALL_ONES (fsd.fd_req.gfree); @@ -141,7 +162,8 @@ get_fs_usage (path, disk, fsp) fsp->fsu_blocksize = (fsd.s_type == Fs2b ? 1024 : 512); fsp->fsu_blocks = PROPAGATE_ALL_ONES (fsd.s_fsize); fsp->fsu_bfree = PROPAGATE_ALL_ONES (fsd.s_tfree); - fsp->fsu_bavail = PROPAGATE_ALL_ONES (fsd.s_tfree); + fsp->fsu_bavail = PROPAGATE_TOP_BIT (fsd.s_tfree); + fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (fsd.s_tfree) != 0; fsp->fsu_files = (fsd.s_isize == -1 ? (uintmax_t) -1 : (fsd.s_isize - 2) * INOPB * (fsd.s_type == Fs2b ? 2 : 1)); @@ -226,7 +248,8 @@ get_fs_usage (path, disk, fsp) fsp->fsu_blocks = PROPAGATE_ALL_ONES (fsd.f_blocks); fsp->fsu_bfree = PROPAGATE_ALL_ONES (fsd.f_bfree); - fsp->fsu_bavail = PROPAGATE_ALL_ONES (fsd.f_bavail); + fsp->fsu_bavail = PROPAGATE_TOP_BIT (fsd.f_bavail); + fsp->fsu_bavail_top_bit_set = EXTRACT_TOP_BIT (fsd.f_bavail) != 0; fsp->fsu_files = PROPAGATE_ALL_ONES (fsd.f_files); fsp->fsu_ffree = PROPAGATE_ALL_ONES (fsd.f_ffree); |