libbb: optionally support RTMIN[+n] and RTMAX[-n] signal names

function                                             old     new   delta
get_signum                                           140     336    +196
__libc_allocate_rtsig                                  -      56     +56
__libc_current_sigrtmin                                -       6      +6
__libc_current_sigrtmax                                -       6      +6
current_rtmin                                          -       4      +4
current_rtmax                                          -       4      +4
bbconfig_config_bz2                                 4961    4962      +1
------------------------------------------------------------------------------
(add/remove: 6/0 grow/shrink: 2/0 up/down: 273/0)             Total: 273 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 38 insertions, 6 deletions

diff --git a/libbb/Config.src b/libbb/Config.src
index f6c7a11ea..85892d3fe 100644
--- a/libbb/Config.src
+++ b/libbb/Config.src
@@ -135,7 +135,7 @@ config FEATURE_NON_POSIX_CP
           and create a regular file. This does not conform to POSIX,
           but prevents a symlink attack.
           Similarly, "cp file device" will not send file's data
-          to the device.
+          to the device. (To do that, use "cat file >device")
 
 config FEATURE_VERBOSE_CP_MESSAGE
         bool "Give more precise messages when copy fails (cp, mv etc)"
diff --git a/libbb/u_signal_names.c b/libbb/u_signal_names.c
index 9263859f5..53ccdd1a7 100644
--- a/libbb/u_signal_names.c
+++ b/libbb/u_signal_names.c
@@ -7,6 +7,13 @@
  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 
+//config:config FEATURE_RTMINMAX
+//config:       bool "Support RTMIN[+n] and RTMAX[-n] signal names"
+//config:       default y
+//config:       help
+//config:         Support RTMIN[+n] and RTMAX[-n] signal names
+//config:         in kill, killall etc. This costs ~250 bytes.
+
 #include "libbb.h"
 
 /* Believe it or not, but some arches have more than 32 SIGs!
@@ -134,20 +141,45 @@ int FAST_FUNC get_signum(const char *name)
                 if (strcasecmp(name, signals[i]) == 0)
                         return i;
 
-#if ENABLE_DESKTOP && (defined(SIGIOT) || defined(SIGIO))
+#if ENABLE_DESKTOP
+# if defined(SIGIOT) || defined(SIGIO)
         /* SIGIO[T] are aliased to other names,
          * thus cannot be stored in the signals[] array.
          * Need special code to recognize them */
         if ((name[0] | 0x20) == 'i' && (name[1] | 0x20) == 'o') {
-#ifdef SIGIO
+#  ifdef SIGIO
                 if (!name[2])
                         return SIGIO;
-#endif
-#ifdef SIGIOT
+#  endif
+#  ifdef SIGIOT
                 if ((name[2] | 0x20) == 't' && !name[3])
                         return SIGIOT;
-#endif
+#  endif
+        }
+# endif
+#endif
+
+#if ENABLE_FEATURE_RTMINMAX
+# if defined(SIGRTMIN) && defined(SIGRTMAX)
+        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;
+                }
+        }
+        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;
+                }
         }
+# endif
 #endif
 
         return -1;