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);