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authorRasmus Villemoes2018-09-12 16:06:36 +0200
committerDenys Vlasenko2018-10-31 11:13:55 +0100
commit571e525a141a2de87b9c2ced485745e96418d921 (patch)
tree0841c003d074777df7cb3a0fd7ece733b7bf9988 /libbb/u_signal_names.c
parent93ef5dd640ef41edc72c80fa59c7cc9427b5945b (diff)
downloadbusybox-571e525a141a2de87b9c2ced485745e96418d921.zip
busybox-571e525a141a2de87b9c2ced485745e96418d921.tar.gz
libbb: optionally honour libc provided SIGRTMIN/SIGRTMAX in get_signum()
When an application documents that it responds such and such to SIGRTMIN+n, that almost always means with respect to the libc-provided SIGRTMIN. Hence I disagree with the "more correct" in commit 7b276fc17594. In any case, this is rather unfortunate: 36 34 (the first shell is bash). We probably can't change default behaviour after 7 years, but at least we can provide a config option. We avoid a little code generation (repeated calls to __libc_current_sigrtmin) by stashing SIGRTMIN/SIGRTMAX in local variables, but it does cost ~50 bytes. The next patch serves as penance for that. Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'libbb/u_signal_names.c')
-rw-r--r--libbb/u_signal_names.c76
1 files changed, 53 insertions, 23 deletions
diff --git a/libbb/u_signal_names.c b/libbb/u_signal_names.c
index b3038e3..866ca85 100644
--- a/libbb/u_signal_names.c
+++ b/libbb/u_signal_names.c
@@ -12,6 +12,18 @@
//config: help
//config: Support RTMIN[+n] and RTMAX[-n] signal names
//config: in kill, killall etc. This costs ~250 bytes.
+//config:
+//config:config FEATURE_RTMINMAX_USE_LIBC_DEFINITIONS
+//config: bool "Use the definitions of SIGRTMIN/SIGRTMAX provided by libc"
+//config: default y
+//config: depends on FEATURE_RTMINMAX
+//config: help
+//config: Some C libraries reserve a few real-time signals for internal
+//config: use, and adjust the values of SIGRTMIN/SIGRTMAX seen by
+//config: applications accordingly. Saying yes here means that a signal
+//config: name RTMIN+n will be interpreted according to the libc definition
+//config: of SIGRTMIN, and not the raw definition provided by the kernel.
+//config: This behavior matches "kill -l RTMIN+n" from bash.
#include "libbb.h"
@@ -123,7 +135,7 @@ static const char signals[][7] ALIGN1 = {
#ifdef SIGSYS
[SIGSYS ] = "SYS",
#endif
-#if ENABLE_FEATURE_RTMINMAX
+#if ENABLE_FEATURE_RTMINMAX && !ENABLE_FEATURE_RTMINMAX_USE_LIBC_DEFINITIONS
# ifdef __SIGRTMIN
[__SIGRTMIN] = "RTMIN",
# endif
@@ -168,36 +180,46 @@ int FAST_FUNC get_signum(const char *name)
# endif
#endif
-#if ENABLE_FEATURE_RTMINMAX
-# if defined(SIGRTMIN) && defined(SIGRTMAX)
-/* libc may use some rt sigs for pthreads and therefore "remap" SIGRTMIN/MAX,
- * but we want to use "raw" SIGRTMIN/MAX. Underscored names, if exist, provide
- * them. If they don't exist, fall back to non-underscored ones: */
+#if ENABLE_FEATURE_RTMINMAX && defined(SIGRTMIN) && defined(SIGRTMAX)
+ {
+# if ENABLE_FEATURE_RTMINMAX_USE_LIBC_DEFINITIONS
+ /* Use the libc provided values. */
+ unsigned sigrtmin = SIGRTMIN;
+ unsigned sigrtmax = SIGRTMAX;
+# else
+ /* Use the "raw" SIGRTMIN/MAX. Underscored names, if exist, provide
+ * them. If they don't exist, fall back to non-underscored ones: */
# if !defined(__SIGRTMIN)
# define __SIGRTMIN SIGRTMIN
# endif
# if !defined(__SIGRTMAX)
# define __SIGRTMAX SIGRTMAX
# endif
- if (strncasecmp(name, "RTMIN", 5) == 0) {
- if (!name[5])
- return __SIGRTMIN;
- if (name[5] == '+') {
- i = bb_strtou(name + 6, NULL, 10);
- if (!errno && i <= __SIGRTMAX - __SIGRTMIN)
- return __SIGRTMIN + i;
+
+# define sigrtmin __SIGRTMIN
+# define sigrtmax __SIGRTMAX
+# endif
+ if (strncasecmp(name, "RTMIN", 5) == 0) {
+ if (!name[5])
+ return sigrtmin;
+ if (name[5] == '+') {
+ i = bb_strtou(name + 6, NULL, 10);
+ if (!errno && i <= sigrtmax - sigrtmin)
+ return sigrtmin + i;
+ }
}
- }
- else if (strncasecmp(name, "RTMAX", 5) == 0) {
- if (!name[5])
- return __SIGRTMAX;
- if (name[5] == '-') {
- i = bb_strtou(name + 6, NULL, 10);
- if (!errno && i <= __SIGRTMAX - __SIGRTMIN)
- return __SIGRTMAX - i;
+ else if (strncasecmp(name, "RTMAX", 5) == 0) {
+ if (!name[5])
+ return sigrtmax;
+ if (name[5] == '-') {
+ i = bb_strtou(name + 6, NULL, 10);
+ if (!errno && i <= sigrtmax - sigrtmin)
+ return sigrtmax - i;
+ }
}
+# undef sigrtmin
+# undef sigrtmax
}
-# endif
#endif
return -1;
@@ -228,8 +250,16 @@ void FAST_FUNC print_signames(void)
printf("%2u) %s\n", signo, name);
}
#if ENABLE_FEATURE_RTMINMAX
-# ifdef __SIGRTMAX
+# if ENABLE_FEATURE_RTMINMAX_USE_LIBC_DEFINITIONS
+# if defined(SIGRTMIN) && defined(SIGRTMAX)
+ printf("%2u) %s\n", SIGRTMIN, "RTMIN");
+ printf("%2u) %s\n", SIGRTMAX, "RTMAX");
+# endif
+# else
+// __SIGRTMIN is included in signals[] array.
+# ifdef __SIGRTMAX
printf("%2u) %s\n", __SIGRTMAX, "RTMAX");
+# endif
# endif
#endif
}