MINOR: tools: add append_prefixed_str()
This is somewhat related to indent_msg() except that this one places a
known prefix at the beginning of each line, allows to replace the EOL
character, and not to insert a prefix on the first line if not desired.
It works with a normal output buffer/chunk so it doesn't need to allocate
anything nor to modify the input string. It is suitable for use in multi-
line backtraces.
diff --git a/src/standard.c b/src/standard.c
index 2f205f7..717c14a 100644
--- a/src/standard.c
+++ b/src/standard.c
@@ -3709,6 +3709,41 @@
return ret;
}
+/* makes a copy of message <in> into <out>, with each line prefixed with <pfx>
+ * and end of lines replaced with <eol> if not 0. The first line to indent has
+ * to be indicated in <first> (starts at zero), so that it is possible to skip
+ * indenting the first line if it has to be appended after an existing message.
+ * Empty strings are never indented, and NULL strings are considered empty both
+ * for <in> and <pfx>. It returns non-zero if an EOL was appended as the last
+ * character, non-zero otherwise.
+ */
+int append_prefixed_str(struct buffer *out, const char *in, const char *pfx, char eol, int first)
+{
+ int bol, lf;
+ int pfxlen = pfx ? strlen(pfx) : 0;
+
+ if (!in)
+ return 0;
+
+ bol = 1;
+ lf = 0;
+ while (*in) {
+ if (bol && pfxlen) {
+ if (first > 0)
+ first--;
+ else
+ b_putblk(out, pfx, pfxlen);
+ bol = 0;
+ }
+
+ lf = (*in == '\n');
+ bol |= lf;
+ b_putchr(out, (lf && eol) ? eol : *in);
+ in++;
+ }
+ return lf;
+}
+
/* removes environment variable <name> from the environment as found in
* environ. This is only provided as an alternative for systems without
* unsetenv() (old Solaris and AIX versions). THIS IS NOT THREAD SAFE.