[PATCH v2 2/4] strbuf: refactor strbuf_trim_trailing_ch()

[Christian Couder <christian.couder@gmail.com>]

We often have to split strings at some specified terminator character.
The strbuf_split*() functions, that we can use for this purpose,
return substrings that include the terminator character, so we often
need to remove that character.

When it is a whitespace, newline or directory separator, the
terminator character can easily be removed using an existing triming
function like strbuf_rtrim(), strbuf_trim_trailing_newline() or
strbuf_trim_trailing_dir_sep(). There is no function to remove that
character when it's not one of those characters though.

Let's introduce a new strbuf_trim_trailing_ch() function that can be
used to remove any trailing character, and let's refactor existing code
that manually removed trailing characters using this new function.

We are also going to use this new function in a following commit.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 strbuf.c         |  7 +++++++
 strbuf.h         |  3 +++
 trace2/tr2_cfg.c | 10 ++--------
 3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/strbuf.c b/strbuf.c
index cccfdec0e3..c986ec28f4 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -134,6 +134,13 @@ void strbuf_trim_trailing_dir_sep(struct strbuf *sb)
 	sb->buf[sb->len] = '\0';
 }
 
+void strbuf_trim_trailing_ch(struct strbuf *sb, int c)
+{
+	while (sb->len > 0 && sb->buf[sb->len - 1] == c)
+		sb->len--;
+	sb->buf[sb->len] = '\0';
+}
+
 void strbuf_trim_trailing_newline(struct strbuf *sb)
 {
 	if (sb->len > 0 && sb->buf[sb->len - 1] == '\n') {
diff --git a/strbuf.h b/strbuf.h
index 884157873e..5e389ab065 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -197,6 +197,9 @@ void strbuf_trim_trailing_dir_sep(struct strbuf *sb);
 /* Strip trailing LF or CR/LF */
 void strbuf_trim_trailing_newline(struct strbuf *sb);
 
+/* Strip trailing character c */
+void strbuf_trim_trailing_ch(struct strbuf *sb, int c);
+
 /**
  * Replace the contents of the strbuf with a reencoded form.  Returns -1
  * on error, 0 on success.
diff --git a/trace2/tr2_cfg.c b/trace2/tr2_cfg.c
index d96d908bb9..356fcd38f4 100644
--- a/trace2/tr2_cfg.c
+++ b/trace2/tr2_cfg.c
@@ -33,10 +33,7 @@ static int tr2_cfg_load_patterns(void)
 
 	tr2_cfg_patterns = strbuf_split_buf(envvar, strlen(envvar), ',', -1);
 	for (s = tr2_cfg_patterns; *s; s++) {
-		struct strbuf *buf = *s;
-
-		if (buf->len && buf->buf[buf->len - 1] == ',')
-			strbuf_setlen(buf, buf->len - 1);
+		strbuf_trim_trailing_ch(*s, ',');
 		strbuf_trim_trailing_newline(*s);
 		strbuf_trim(*s);
 	}
@@ -72,10 +69,7 @@ static int tr2_load_env_vars(void)
 
 	tr2_cfg_env_vars = strbuf_split_buf(varlist, strlen(varlist), ',', -1);
 	for (s = tr2_cfg_env_vars; *s; s++) {
-		struct strbuf *buf = *s;
-
-		if (buf->len && buf->buf[buf->len - 1] == ',')
-			strbuf_setlen(buf, buf->len - 1);
+		strbuf_trim_trailing_ch(*s, ',');
 		strbuf_trim_trailing_newline(*s);
 		strbuf_trim(*s);
 	}
-- 
2.46.0.4.g7a37e584ed