libbb/u_signal_names.c: don't check errno after bb_strtou

Since we're comparing the return value to a smallish integer anyway, we
might as well use that bb_strtou() returns UINT_MAX for malformed
input. Referencing errno is kinda bloaty on glibc.

While NSIG is not in POSIX, we do already rely on it being defined,
compile-time const and smallish, since arrays in struct globals_misc are
defined in terms of it.

function                                             old     new   delta
get_signum                                           312     286     -26

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/libbb/u_signal_names.c b/libbb/u_signal_names.c
index 866ca85fd..f7d598c7a 100644
--- a/libbb/u_signal_names.c
+++ b/libbb/u_signal_names.c
@@ -153,8 +153,12 @@ int FAST_FUNC get_signum(const char *name)
 {
         unsigned i;
 
+        /* bb_strtou returns UINT_MAX on error. NSIG is smaller
+         * than UINT_MAX on any sane Unix. Hence no need
+         * to check errno after bb_strtou().
+         */
         i = bb_strtou(name, NULL, 10);
-        if (!errno && i < NSIG) /* for shells, we allow 0 too */
+        if (i < NSIG) /* for shells, we allow 0 too */
                 return i;
         if (strncasecmp(name, "SIG", 3) == 0)
                 name += 3;
@@ -204,7 +208,7 @@ int FAST_FUNC get_signum(const char *name)
                                 return sigrtmin;
                         if (name[5] == '+') {
                                 i = bb_strtou(name + 6, NULL, 10);
-                                if (!errno && i <= sigrtmax - sigrtmin)
+                                if (i <= sigrtmax - sigrtmin)
                                         return sigrtmin + i;
                         }
                 }
@@ -213,7 +217,7 @@ int FAST_FUNC get_signum(const char *name)
                                 return sigrtmax;
                         if (name[5] == '-') {
                                 i = bb_strtou(name + 6, NULL, 10);
-                                if (!errno && i <= sigrtmax - sigrtmin)
+                                if (i <= sigrtmax - sigrtmin)
                                         return sigrtmax - i;
                         }
                 }