#include <linux/math64.h>
#include <linux/export.h>
#include <linux/ctype.h>
+#include <linux/errno.h>
+#include <linux/string.h>
#include <linux/string_helpers.h>
/**
return true;
}
+/**
+ * string_unescape - unquote characters in the given string
+ * @src: source buffer (escaped)
+ * @dst: destination buffer (unescaped)
+ * @size: size of the destination buffer (0 to unlimit)
+ * @flags: combination of the flags (bitwise OR):
+ * %UNESCAPE_SPACE:
+ * '\f' - form feed
+ * '\n' - new line
+ * '\r' - carriage return
+ * '\t' - horizontal tab
+ * '\v' - vertical tab
+ * %UNESCAPE_OCTAL:
+ * '\NNN' - byte with octal value NNN (1 to 3 digits)
+ * %UNESCAPE_HEX:
+ * '\xHH' - byte with hexadecimal value HH (1 to 2 digits)
+ * %UNESCAPE_SPECIAL:
+ * '\"' - double quote
+ * '\\' - backslash
+ * '\a' - alert (BEL)
+ * '\e' - escape
+ * %UNESCAPE_ANY:
+ * all previous together
+ *
+ * Description:
+ * The function unquotes characters in the given string.
+ *
+ * Because the size of the output will be the same as or less than the size of
+ * the input, the transformation may be performed in place.
+ *
+ * Caller must provide valid source and destination pointers. Be aware that
+ * destination buffer will always be NULL-terminated. Source string must be
+ * NULL-terminated as well.
+ *
+ * Return:
+ * The amount of the characters processed to the destination buffer excluding
+ * trailing '\0' is returned.
+ */
int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
{
char *out = dst;
return out - dst;
}
EXPORT_SYMBOL(string_unescape);
+
+static int escape_passthrough(unsigned char c, char **dst, size_t *osz)
+{
+ char *out = *dst;
+
+ if (*osz < 1)
+ return -ENOMEM;
+
+ *out++ = c;
+
+ *dst = out;
+ *osz -= 1;
+
+ return 1;
+}
+
+static int escape_space(unsigned char c, char **dst, size_t *osz)
+{
+ char *out = *dst;
+ unsigned char to;
+
+ if (*osz < 2)
+ return -ENOMEM;
+
+ switch (c) {
+ case '\n':
+ to = 'n';
+ break;
+ case '\r':
+ to = 'r';
+ break;
+ case '\t':
+ to = 't';
+ break;
+ case '\v':
+ to = 'v';
+ break;
+ case '\f':
+ to = 'f';
+ break;
+ default:
+ return 0;
+ }
+
+ *out++ = '\\';
+ *out++ = to;
+
+ *dst = out;
+ *osz -= 2;
+
+ return 1;
+}
+
+static int escape_special(unsigned char c, char **dst, size_t *osz)
+{
+ char *out = *dst;
+ unsigned char to;
+
+ if (*osz < 2)
+ return -ENOMEM;
+
+ switch (c) {
+ case '\\':
+ to = '\\';
+ break;
+ case '\a':
+ to = 'a';
+ break;
+ case '\e':
+ to = 'e';
+ break;
+ default:
+ return 0;
+ }
+
+ *out++ = '\\';
+ *out++ = to;
+
+ *dst = out;
+ *osz -= 2;
+
+ return 1;
+}
+
+static int escape_null(unsigned char c, char **dst, size_t *osz)
+{
+ char *out = *dst;
+
+ if (*osz < 2)
+ return -ENOMEM;
+
+ if (c)
+ return 0;
+
+ *out++ = '\\';
+ *out++ = '0';
+
+ *dst = out;
+ *osz -= 2;
+
+ return 1;
+}
+
+static int escape_octal(unsigned char c, char **dst, size_t *osz)
+{
+ char *out = *dst;
+
+ if (*osz < 4)
+ return -ENOMEM;
+
+ *out++ = '\\';
+ *out++ = ((c >> 6) & 0x07) + '0';
+ *out++ = ((c >> 3) & 0x07) + '0';
+ *out++ = ((c >> 0) & 0x07) + '0';
+
+ *dst = out;
+ *osz -= 4;
+
+ return 1;
+}
+
+static int escape_hex(unsigned char c, char **dst, size_t *osz)
+{
+ char *out = *dst;
+
+ if (*osz < 4)
+ return -ENOMEM;
+
+ *out++ = '\\';
+ *out++ = 'x';
+ *out++ = hex_asc_hi(c);
+ *out++ = hex_asc_lo(c);
+
+ *dst = out;
+ *osz -= 4;
+
+ return 1;
+}
+
+/**
+ * string_escape_mem - quote characters in the given memory buffer
+ * @src: source buffer (unescaped)
+ * @isz: source buffer size
+ * @dst: destination buffer (escaped)
+ * @osz: destination buffer size
+ * @flags: combination of the flags (bitwise OR):
+ * %ESCAPE_SPACE:
+ * '\f' - form feed
+ * '\n' - new line
+ * '\r' - carriage return
+ * '\t' - horizontal tab
+ * '\v' - vertical tab
+ * %ESCAPE_SPECIAL:
+ * '\\' - backslash
+ * '\a' - alert (BEL)
+ * '\e' - escape
+ * %ESCAPE_NULL:
+ * '\0' - null
+ * %ESCAPE_OCTAL:
+ * '\NNN' - byte with octal value NNN (3 digits)
+ * %ESCAPE_ANY:
+ * all previous together
+ * %ESCAPE_NP:
+ * escape only non-printable characters (checked by isprint)
+ * %ESCAPE_ANY_NP:
+ * all previous together
+ * %ESCAPE_HEX:
+ * '\xHH' - byte with hexadecimal value HH (2 digits)
+ * @esc: NULL-terminated string of characters any of which, if found in
+ * the source, has to be escaped
+ *
+ * Description:
+ * The process of escaping byte buffer includes several parts. They are applied
+ * in the following sequence.
+ * 1. The character is matched to the printable class, if asked, and in
+ * case of match it passes through to the output.
+ * 2. The character is not matched to the one from @esc string and thus
+ * must go as is to the output.
+ * 3. The character is checked if it falls into the class given by @flags.
+ * %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any
+ * character. Note that they actually can't go together, otherwise
+ * %ESCAPE_HEX will be ignored.
+ *
+ * Caller must provide valid source and destination pointers. Be aware that
+ * destination buffer will not be NULL-terminated, thus caller have to append
+ * it if needs.
+ *
+ * Return:
+ * The amount of the characters processed to the destination buffer, or
+ * %-ENOMEM if the size of buffer is not enough to put an escaped character is
+ * returned.
+ *
+ * Even in the case of error @dst pointer will be updated to point to the byte
+ * after the last processed character.
+ */
+int string_escape_mem(const char *src, size_t isz, char **dst, size_t osz,
+ unsigned int flags, const char *esc)
+{
+ char *out = *dst, *p = out;
+ bool is_dict = esc && *esc;
+ int ret = 0;
+
+ while (isz--) {
+ unsigned char c = *src++;
+
+ /*
+ * Apply rules in the following sequence:
+ * - the character is printable, when @flags has
+ * %ESCAPE_NP bit set
+ * - the @esc string is supplied and does not contain a
+ * character under question
+ * - the character doesn't fall into a class of symbols
+ * defined by given @flags
+ * In these cases we just pass through a character to the
+ * output buffer.
+ */
+ if ((flags & ESCAPE_NP && isprint(c)) ||
+ (is_dict && !strchr(esc, c))) {
+ /* do nothing */
+ } else {
+ if (flags & ESCAPE_SPACE) {
+ ret = escape_space(c, &p, &osz);
+ if (ret < 0)
+ break;
+ if (ret > 0)
+ continue;
+ }
+
+ if (flags & ESCAPE_SPECIAL) {
+ ret = escape_special(c, &p, &osz);
+ if (ret < 0)
+ break;
+ if (ret > 0)
+ continue;
+ }
+
+ if (flags & ESCAPE_NULL) {
+ ret = escape_null(c, &p, &osz);
+ if (ret < 0)
+ break;
+ if (ret > 0)
+ continue;
+ }
+
+ /* ESCAPE_OCTAL and ESCAPE_HEX always go last */
+ if (flags & ESCAPE_OCTAL) {
+ ret = escape_octal(c, &p, &osz);
+ if (ret < 0)
+ break;
+ continue;
+ }
+ if (flags & ESCAPE_HEX) {
+ ret = escape_hex(c, &p, &osz);
+ if (ret < 0)
+ break;
+ continue;
+ }
+ }
+
+ ret = escape_passthrough(c, &p, &osz);
+ if (ret < 0)
+ break;
+ }
+
+ *dst = p;
+
+ if (ret < 0)
+ return ret;
+
+ return p - out;
+}
+EXPORT_SYMBOL(string_escape_mem);
projects / cascardo / linux.git / blobdiff