lib: add `%pSQ` and `%pSE` string escape formats

These are for string quoting (`%pSQ`) and string escaping (`%pSE`); the
sets / escape methods are currently rather "basic" and might be extended
in the future.

Signed-off-by: David Lamparter <equinox@diac24.net>

1 files changed, 197 insertions, 0 deletions

diff --git a/lib/strformat.c b/lib/strformat.c
index 8e49a666fa..431e573a0c 100644
--- a/lib/strformat.c
+++ b/lib/strformat.c
@@ -18,7 +18,10 @@
 #include "config.h"
 #endif
 
+#include "compiler.h"
+
 #include <string.h>
+#include <ctype.h>
 
 #include "printfrr.h"
 
@@ -73,3 +76,197 @@ static ssize_t printfrr_hexdstr(struct fbuf *buf, struct printfrr_eargs *ea,
 
 	return ret;
 }
+
+enum escape_flags {
+	ESC_N_R_T	= (1 << 0),	/* use \n \r \t instead of \x0a ...*/
+	ESC_SPACE	= (1 << 1),	/* \  */
+	ESC_BACKSLASH	= (1 << 2),	/* \\ */
+	ESC_DBLQUOTE	= (1 << 3),	/* \" */
+	ESC_SGLQUOTE	= (1 << 4),	/* \' */
+	ESC_BACKTICK	= (1 << 5),	/* \` */
+	ESC_DOLLAR	= (1 << 6),	/* \$ */
+	ESC_CLBRACKET	= (1 << 7),	/* \] for RFC5424 syslog */
+	ESC_OTHER	= (1 << 8),	/* remaining non-alpha */
+
+	ESC_ALL = ESC_N_R_T | ESC_SPACE | ESC_BACKSLASH | ESC_DBLQUOTE
+		| ESC_SGLQUOTE | ESC_DOLLAR | ESC_OTHER,
+	ESC_QUOTSTRING = ESC_N_R_T | ESC_BACKSLASH | ESC_DBLQUOTE,
+	/* if needed: ESC_SHELL = ... */
+};
+
+static ssize_t bquote(struct fbuf *buf, const uint8_t *pos, size_t len,
+		      unsigned int flags)
+{
+	ssize_t ret = 0;
+	const uint8_t *end = pos + len;
+
+	for (; pos < end; pos++) {
+		/* here's to hoping this might be a bit faster... */
+		if (__builtin_expect(!!isalnum(*pos), 1)) {
+			ret += bputch(buf, *pos);
+			continue;
+		}
+
+		switch (*pos) {
+		case '%':
+		case '+':
+		case ',':
+		case '-':
+		case '.':
+		case '/':
+		case ':':
+		case '@':
+		case '_':
+			ret += bputch(buf, *pos);
+			continue;
+
+		case '\r':
+			if (!(flags & ESC_N_R_T))
+				break;
+			ret += bputch(buf, '\\');
+			ret += bputch(buf, 'r');
+			continue;
+		case '\n':
+			if (!(flags & ESC_N_R_T))
+				break;
+			ret += bputch(buf, '\\');
+			ret += bputch(buf, 'n');
+			continue;
+		case '\t':
+			if (!(flags & ESC_N_R_T))
+				break;
+			ret += bputch(buf, '\\');
+			ret += bputch(buf, 't');
+			continue;
+
+		case ' ':
+			if (flags & ESC_SPACE)
+				ret += bputch(buf, '\\');
+			ret += bputch(buf, *pos);
+			continue;
+
+		case '\\':
+			if (flags & ESC_BACKSLASH)
+				ret += bputch(buf, '\\');
+			ret += bputch(buf, *pos);
+			continue;
+
+		case '"':
+			if (flags & ESC_DBLQUOTE)
+				ret += bputch(buf, '\\');
+			ret += bputch(buf, *pos);
+			continue;
+
+		case '\'':
+			if (flags & ESC_SGLQUOTE)
+				ret += bputch(buf, '\\');
+			ret += bputch(buf, *pos);
+			continue;
+
+		case '`':
+			if (flags & ESC_BACKTICK)
+				ret += bputch(buf, '\\');
+			ret += bputch(buf, *pos);
+			continue;
+
+		case '$':
+			if (flags & ESC_DOLLAR)
+				ret += bputch(buf, '\\');
+			ret += bputch(buf, *pos);
+			continue;
+
+		case ']':
+			if (flags & ESC_CLBRACKET)
+				ret += bputch(buf, '\\');
+			ret += bputch(buf, *pos);
+			continue;
+
+		/* remaining: !#&'()*;<=>?[^{|}~ */
+
+		default:
+			if (*pos >= 0x20 && *pos < 0x7f) {
+				if (flags & ESC_OTHER)
+					ret += bputch(buf, '\\');
+				ret += bputch(buf, *pos);
+				continue;
+			}
+		}
+		ret += bputch(buf, '\\');
+		ret += bputch(buf, 'x');
+		ret += bputhex(buf, *pos);
+	}
+
+	return ret;
+}
+
+printfrr_ext_autoreg_p("SE", printfrr_escape)
+static ssize_t printfrr_escape(struct fbuf *buf, struct printfrr_eargs *ea,
+			       const void *vptr)
+{
+	ssize_t len = printfrr_ext_len(ea);
+	const uint8_t *ptr = vptr;
+	bool null_is_empty = false;
+
+	if (ea->fmt[0] == 'n') {
+		null_is_empty = true;
+		ea->fmt++;
+	}
+
+	if (!ptr) {
+		if (null_is_empty)
+			return 0;
+		return bputs(buf, "(null)");
+	}
+
+	if (len < 0)
+		len = strlen((const char *)ptr);
+
+	return bquote(buf, ptr, len, ESC_ALL);
+}
+
+printfrr_ext_autoreg_p("SQ", printfrr_quote)
+static ssize_t printfrr_quote(struct fbuf *buf, struct printfrr_eargs *ea,
+			      const void *vptr)
+{
+	ssize_t len = printfrr_ext_len(ea);
+	const uint8_t *ptr = vptr;
+	ssize_t ret = 0;
+	bool null_is_empty = false;
+	bool do_quotes = false;
+	unsigned int flags = ESC_QUOTSTRING;
+
+	while (ea->fmt[0]) {
+		switch (ea->fmt[0]) {
+		case 'n':
+			null_is_empty = true;
+			ea->fmt++;
+			continue;
+		case 'q':
+			do_quotes = true;
+			ea->fmt++;
+			continue;
+		case 's':
+			flags |= ESC_CLBRACKET;
+			flags &= ~ESC_N_R_T;
+			ea->fmt++;
+			continue;
+		}
+		break;
+	}
+
+	if (!ptr) {
+		if (null_is_empty)
+			return bputs(buf, do_quotes ? "\"\"" : "");
+		return bputs(buf, "(null)");
+	}
+
+	if (len < 0)
+		len = strlen((const char *)ptr);
+
+	if (do_quotes)
+		ret += bputch(buf, '"');
+	ret += bquote(buf, ptr, len, flags);
+	if (do_quotes)
+		ret += bputch(buf, '"');
+	return ret;
+}