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rework sysconf table to treat zero entries as invalid

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based on patch by Timo Teräs. previously, the value zero was used as a
literal zero, meaning that all invalid sysconf "names", which should
result in sysconf returning -1, had to be explicitly listed. (in
addition, it was not possible for sysconf to set errno to EINVAL, as
there was no distinction between -1 as an error and -1 as a valid
result.)

now, the value 0 is used for invalid/undefined slots in the table and
a new switch table entry is used for returning literal zeros.

in addition, an off-by-one error in checking against the table size is
fixed.
This commit is contained in:
Rich Felker 2014-05-19 11:19:49 -04:00
commit ff78355bc1
1 changed files with 13 additions and 10 deletions
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23
src/conf/sysconf.c
View file

@ -17,6 +17,7 @@
#define JT_NPROCESSORS_ONLN JT(7)
#define JT_PHYS_PAGES JT(8)
#define JT_AVPHYS_PAGES JT(9)
#define JT_ZERO JT(10)
#define RLIM(x) (-32768|(RLIMIT_ ## x))
@ -48,7 +49,7 @@ long sysconf(int name)
[_SC_SHARED_MEMORY_OBJECTS] = VER,
[_SC_AIO_LISTIO_MAX] = -1,
[_SC_AIO_MAX] = -1,
[_SC_AIO_PRIO_DELTA_MAX] = 0, /* ?? */
[_SC_AIO_PRIO_DELTA_MAX] = JT_ZERO, /* ?? */
[_SC_DELAYTIMER_MAX] = _POSIX_DELAYTIMER_MAX,
[_SC_MQ_OPEN_MAX] = -1,
[_SC_MQ_PRIO_MAX] = JT_MQ_PRIO_MAX,
@ -149,8 +150,8 @@ long sysconf(int name)
[_SC_NL_SETMAX] = -1,
[_SC_NL_TEXTMAX] = -1,
[_SC_XBS5_ILP32_OFF32] = -1,
[_SC_XBS5_ILP32_OFFBIG] = 2*(sizeof(long)==4)-1,
[_SC_XBS5_LP64_OFF64] = 2*(sizeof(long)==8)-1,
[_SC_XBS5_ILP32_OFFBIG] = sizeof(long)==4 ? 1 : JT_ZERO,
[_SC_XBS5_LP64_OFF64] = sizeof(long)==8 ? 1 : JT_ZERO,
[_SC_XBS5_LPBIG_OFFBIG] = -1,
[_SC_XOPEN_LEGACY] = -1,
[_SC_XOPEN_REALTIME] = -1,
@ -197,11 +198,11 @@ long sysconf(int name)
[_SC_2_PBS_MESSAGE] = -1,
[_SC_2_PBS_TRACK] = -1,
[_SC_SYMLOOP_MAX] = SYMLOOP_MAX,
[_SC_STREAMS] = 0,
[_SC_STREAMS] = JT_ZERO,
[_SC_2_PBS_CHECKPOINT] = -1,
[_SC_V6_ILP32_OFF32] = -1,
[_SC_V6_ILP32_OFFBIG] = 2*(sizeof(long)==4)-1,
[_SC_V6_LP64_OFF64] = 2*(sizeof(long)==8)-1,
[_SC_V6_ILP32_OFFBIG] = sizeof(long)==4 ? 1 : JT_ZERO,
[_SC_V6_LP64_OFF64] = sizeof(long)==8 ? 1 : JT_ZERO,
[_SC_V6_LPBIG_OFFBIG] = -1,
[_SC_HOST_NAME_MAX] = HOST_NAME_MAX,
[_SC_TRACE] = -1,
@ -212,20 +213,20 @@ long sysconf(int name)
[_SC_IPV6] = VER,
[_SC_RAW_SOCKETS] = VER,
[_SC_V7_ILP32_OFF32] = -1,
[_SC_V7_ILP32_OFFBIG] = 2*(sizeof(long)==4)-1,
[_SC_V7_LP64_OFF64] = 2*(sizeof(long)==8)-1,
[_SC_V7_ILP32_OFFBIG] = sizeof(long)==4 ? 1 : JT_ZERO,
[_SC_V7_LP64_OFF64] = sizeof(long)==8 ? 1 : JT_ZERO,
[_SC_V7_LPBIG_OFFBIG] = -1,
[_SC_SS_REPL_MAX] = -1,
[_SC_TRACE_EVENT_NAME_MAX] = -1,
[_SC_TRACE_NAME_MAX] = -1,
[_SC_TRACE_SYS_MAX] = -1,
[_SC_TRACE_USER_EVENT_MAX] = -1,
[_SC_XOPEN_STREAMS] = 0,
[_SC_XOPEN_STREAMS] = JT_ZERO,
[_SC_THREAD_ROBUST_PRIO_INHERIT] = -1,
[_SC_THREAD_ROBUST_PRIO_PROTECT] = -1,
};
if (name > sizeof(values)/sizeof(values[0])) {
if (name >= sizeof(values)/sizeof(values[0]) || !values[name]) {
errno = EINVAL;
return -1;
} else if (values[name] >= -1) {
@ -267,6 +268,8 @@ long sysconf(int name)
mem *= si.mem_unit;
mem /= PAGE_SIZE;
return (mem > LONG_MAX) ? LONG_MAX : mem;
case JT_ZERO & 255:
return 0;
}
return values[name];
}