Add 3 methods that help when dealing with escaping output strings.
util_isesc() checks whether a character should be escaped.
util_c2str() converts a character to a possibly escaped sequence
util_quoted_strlen() calculates the length of a quoted string.
Signed-off-by: Pantelis Antoniou <pantelis.antoniou@xxxxxxxxxxxx>
---
util.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
util.h | 35 +++++++++++++++++++++++++++++++++
2 files changed, 104 insertions(+), 1 deletion(-)
diff --git a/util.c b/util.c
index 9953c32..6895515 100644
--- a/util.c
+++ b/util.c
@@ -100,10 +100,17 @@ char *join_path(const char *path, const char *name)
return str;
}
+bool util_isesc(char c)
+{
+ return c == '\a' || c == '\b' || c == '\t' || c == '\n' || c == '\v' ||
+ c == '\f' || c == '\r' || c == '\\' || c == '\"';
+}
+
bool util_is_printable_string(const void *data, int len)
{
const char *s = data;
const char *ss, *se;
+ char c;
/* zero length is not */
if (len == 0)
@@ -117,8 +124,13 @@ bool util_is_printable_string(const void *data, int len)
while (s < se) {
ss = s;
- while (s < se && *s && isprint((unsigned char)*s))
+ while (s < se && *s) {
+ c = *s;
+ if (!(isprint(c) || util_isesc(c)))
+ break;
s++;
+ }
+
/* not zero, or not done yet */
if (*s != '\0' || s == ss)
@@ -130,6 +142,62 @@ bool util_is_printable_string(const void *data, int len)
return 1;
}
+char *util_c2str(char c, char *buf, int bufsz)
+{
+ char *s = buf;
+
+ if (util_isesc(c)) {
+
+ if (bufsz < 3)
+ return NULL;
+
+ /* escape case */
+ *s++ = '\\';
+ switch (c) {
+ case '\a': *s++ = 'a'; break;
+ case '\b': *s++ = 'b'; break;
+ case '\t': *s++ = 't'; break;
+ case '\n': *s++ = 'n'; break;
+ case '\v': *s++ = 'v'; break;
+ case '\f': *s++ = 'f'; break;
+ case '\r': *s++ = 'r'; break;
+ case '\\': *s++ = '\\'; break;
+ case '\"': *s++ = '\"'; break;
+ }
+ } else if (!isprint(c)) {
+ static const char *hexb = "0123456789abcdef";
+
+ if (bufsz < 5)
+ return NULL;
+
+ /* hexadecimal escape case */
+ *s++ = '\\';
+ *s++ = 'x';
+ *s++ = hexb[(((unsigned int)c >> 4) & 0xf)];
+ *s++ = hexb[ (unsigned int)c & 0xf ];
+ } else {
+ if (bufsz < 2)
+ return NULL;
+
+ *s++ = c; /* normal printable */
+ }
+
+ *s = '\0';
+
+ return buf;
+}
+
+int util_quoted_strlen(const char *str)
+{
+ int len;
+ char c, buf[C2STR_BUF_MAX];
+
+ len = 1;
+ while ((c = *str++) != '\0' && util_c2str(c, buf, sizeof(buf)))
+ len += strlen(buf);
+ return len + 1;
+}
+
/*
* Parse a octal encoded character starting at index i in string s. The
* resulting character will be returned and the index i will be updated to
diff --git a/util.h b/util.h
index ad5f411..3ed617c 100644
--- a/util.h
+++ b/util.h
@@ -82,6 +82,41 @@ extern char *join_path(const char *path, const char *name);
*/
bool util_is_printable_string(const void *data, int len);
+/**
+ * Check if this is is a character we should escape.
+ * The list of valid escaped chars is: \a\b\t\n\b\f\r\\\"
+ *
+ * @param c The character to check
+ * @return 1 if the character is one that should be escaped
+ */
+bool util_isesc(char c);
+
+/**
+ * Convert a given character to it's escaped form
+ * If it's a normal printable character the buffer is filled with "c\0"
+ * If it's an escaped character the corresponding escape * is terminated
+ * with \<esc>\0
+ * For any other a hex form is used (\xYY) where YY is the ascii in hex of c.
+ *
+ * @param c The character to convert
+ * @param buf The corresponding buffer to fill
+ * @param bufsz The maximum buffer size (including NULL).
+ * Note that the absolute maximum buffer fill is 5 for \xYY\0
+ * @return buf if the result fits or NULL on error
+ */
+char *util_c2str(char c, char *buf, int bufsz);
+
+/* maximum buffer for c2str */
+#define C2STR_BUF_MAX 5
+
+/**
+ * Return the length in characters when quoting the given string
+ *
+ * @param str The string to query it's quoted length
+ * @return Length in characters of the quoted string generated from str.
+ */
+int util_quoted_strlen(const char *str);
+
/*
* Parse an escaped character starting at index i in string s. The resulting
* character will be returned and the index i will be updated to point at the
--
2.1.4
--
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