1 files changed, 321 insertions, 6 deletions

diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index ed5c1454dd62..58b78ba57439 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -8,6 +8,8 @@
 #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>
 
 /**
@@ -25,12 +27,15 @@
 int string_get_size(u64 size, const enum string_size_units units,
                     char *buf, int len)
 {
-        static const char *units_10[] = { "B", "kB", "MB", "GB", "TB", "PB",
-                                   "EB", "ZB", "YB", NULL};
-        static const char *units_2[] = {"B", "KiB", "MiB", "GiB", "TiB", "PiB",
-                                 "EiB", "ZiB", "YiB", NULL };
-        static const char **units_str[] = {
-                [STRING_UNITS_10] =  units_10,
+        static const char *const units_10[] = {
+                "B", "kB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB", NULL
+        };
+        static const char *const units_2[] = {
+                "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB",
+                NULL
+        };
+        static const char *const *const units_str[] = {
+                [STRING_UNITS_10] = units_10,
                 [STRING_UNITS_2] = units_2,
         };
         static const unsigned int divisor[] = {
@@ -165,6 +170,44 @@ static bool unescape_special(char **src, char **dst)
         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;
@@ -199,3 +242,275 @@ int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
         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);