libbb: make trim() return pointer to terminating NUL

function                                             old     new   delta
trim                                                  80      90     +10
angle_address                                         56      50      -6
sysctl_main                                          282     273      -9
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/3 up/down: +10/-15)           Total:  -5 bytes

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

5 files changed, 22 insertions, 12 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 6a2a2d640..6077f64c9 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -347,7 +347,7 @@ unsigned long long monotonic_ms(void) FAST_FUNC;
 unsigned monotonic_sec(void) FAST_FUNC;
 
 extern void chomp(char *s) FAST_FUNC;
-extern void trim(char *s) FAST_FUNC;
+extern char *trim(char *s) FAST_FUNC;
 extern char *skip_whitespace(const char *) FAST_FUNC;
 extern char *skip_non_whitespace(const char *) FAST_FUNC;
 extern char *skip_dev_pfx(const char *tty_name) FAST_FUNC;
diff --git a/libbb/trim.c b/libbb/trim.c
index 16cb4fbb0..e47fec74e 100644
--- a/libbb/trim.c
+++ b/libbb/trim.c
@@ -10,9 +10,10 @@
 
 #include "libbb.h"
 
-void FAST_FUNC trim(char *s)
+char* FAST_FUNC trim(char *s)
 {
         size_t len = strlen(s);
+        size_t old = len;
 
         /* trim trailing whitespace */
         while (len && isspace(s[len-1]))
@@ -26,5 +27,12 @@ void FAST_FUNC trim(char *s)
                         memmove(s, nws, len);
                 }
         }
-        s[len] = '\0';
+
+        s += len;
+        /* If it was a "const char*" which does not need trimming,
+         * avoid superfluous store */
+        if (old != len)
+                *s = '\0';
+
+        return s;
 }
diff --git a/mailutils/sendmail.c b/mailutils/sendmail.c
index 346de2712..65895f0ec 100644
--- a/mailutils/sendmail.c
+++ b/mailutils/sendmail.c
@@ -166,9 +166,8 @@ static char *angle_address(char *str)
 {
         char *s, *e;
 
-        trim(str);
-        e = last_char_is(str, '>');
-        if (e) {
+        e = trim(str);
+        if (e != str && e[-1] == '>') {
                 s = strrchr(str, '<');
                 if (s) {
                         *e = '\0';
diff --git a/miscutils/lsscsi.c b/miscutils/lsscsi.c
index b69ff1eef..c86630e31 100644
--- a/miscutils/lsscsi.c
+++ b/miscutils/lsscsi.c
@@ -37,9 +37,8 @@ static char *get_line(const char *filename, char *buf, unsigned *bufsize_p)
         if (sz < 0)
                 sz = 0;
         buf[sz] = '\0';
-        trim(buf);
 
-        sz = strlen(buf) + 1;
+        sz = (trim(buf) - buf) + 1;
         bufsize -= sz;
         buf += sz;
         buf[0] = '\0';
diff --git a/procps/sysctl.c b/procps/sysctl.c
index 619f4f1e4..ef1a1b99f 100644
--- a/procps/sysctl.c
+++ b/procps/sysctl.c
@@ -257,12 +257,16 @@ static int sysctl_handle_preload_file(const char *filename)
         parse_flags &= ~PARSE_EOL_COMMENTS; // NO (only first char) - comments are recognized even if not first char
         while (config_read(parser, token, 2, 2, "#=", parse_flags)) {
                 char *tp;
-                trim(token[0]);
+
                 trim(token[1]);
+                tp = trim(token[0]);
                 sysctl_dots_to_slashes(token[0]);
-                tp = xasprintf("%s=%s", token[0], token[1]);
-                sysctl_act_on_setting(tp);
-                free(tp);
+                /* ^^^converted in-place. tp still points to NUL */
+                /* now, add "=TOKEN1" */
+                *tp++ = '=';
+                overlapping_strcpy(tp, token[1]);
+
+                sysctl_act_on_setting(token[0]);
         }
         if (ENABLE_FEATURE_CLEAN_UP)
                 config_close(parser);