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https://github.com/torvalds/linux
synced 2024-09-06 18:01:05 +00:00
lib/string_helpers.c: refactor string_escape_mem
When printf is given the format specifier %pE, it needs a way of obtaining the total output size that would be generated if the buffer was large enough, and string_escape_mem doesn't easily provide that. This is a refactorization of string_escape_mem in preparation of changing its external API to provide that information. The somewhat ugly early returns and subsequent seemingly redundant conditionals are to make the following patch touch as little as possible in string_helpers.c while still preserving the current behaviour of never outputting partial escape sequences. That behaviour must also change for %pE to work as one expects from every other printf specifier. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -239,29 +239,21 @@ int string_unescape(char *src, char *dst, size_t size, unsigned int flags)
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}
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}
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EXPORT_SYMBOL(string_unescape);
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EXPORT_SYMBOL(string_unescape);
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static int escape_passthrough(unsigned char c, char **dst, size_t *osz)
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static bool escape_passthrough(unsigned char c, char **dst, char *end)
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{
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{
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char *out = *dst;
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char *out = *dst;
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if (*osz < 1)
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if (out < end)
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return -ENOMEM;
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*out = c;
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*dst = out + 1;
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*out++ = c;
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return true;
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*dst = out;
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*osz -= 1;
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return 1;
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}
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}
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static int escape_space(unsigned char c, char **dst, size_t *osz)
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static bool escape_space(unsigned char c, char **dst, char *end)
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{
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{
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char *out = *dst;
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char *out = *dst;
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unsigned char to;
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unsigned char to;
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if (*osz < 2)
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return -ENOMEM;
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switch (c) {
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switch (c) {
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case '\n':
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case '\n':
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to = 'n';
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to = 'n';
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@ -279,26 +271,30 @@ static int escape_space(unsigned char c, char **dst, size_t *osz)
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to = 'f';
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to = 'f';
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break;
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break;
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default:
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default:
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return 0;
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return false;
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}
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}
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*out++ = '\\';
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if (out + 2 > end) {
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*out++ = to;
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*dst = out + 2;
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return true;
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}
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if (out < end)
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*out = '\\';
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++out;
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if (out < end)
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*out = to;
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++out;
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*dst = out;
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*dst = out;
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*osz -= 2;
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return true;
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return 1;
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}
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}
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static int escape_special(unsigned char c, char **dst, size_t *osz)
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static bool escape_special(unsigned char c, char **dst, char *end)
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{
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{
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char *out = *dst;
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char *out = *dst;
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unsigned char to;
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unsigned char to;
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if (*osz < 2)
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return -ENOMEM;
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switch (c) {
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switch (c) {
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case '\\':
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case '\\':
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to = '\\';
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to = '\\';
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@ -310,71 +306,98 @@ static int escape_special(unsigned char c, char **dst, size_t *osz)
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to = 'e';
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to = 'e';
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break;
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break;
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default:
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default:
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return 0;
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return false;
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}
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}
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*out++ = '\\';
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if (out + 2 > end) {
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*out++ = to;
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*dst = out + 2;
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return true;
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}
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if (out < end)
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*out = '\\';
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++out;
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if (out < end)
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*out = to;
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++out;
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*dst = out;
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*dst = out;
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*osz -= 2;
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return true;
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return 1;
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}
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}
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static int escape_null(unsigned char c, char **dst, size_t *osz)
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static bool escape_null(unsigned char c, char **dst, char *end)
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{
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{
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char *out = *dst;
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char *out = *dst;
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if (*osz < 2)
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return -ENOMEM;
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if (c)
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if (c)
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return 0;
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return false;
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*out++ = '\\';
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if (out + 2 > end) {
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*out++ = '0';
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*dst = out + 2;
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return true;
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}
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if (out < end)
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*out = '\\';
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++out;
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if (out < end)
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*out = '0';
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++out;
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*dst = out;
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*dst = out;
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*osz -= 2;
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return true;
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return 1;
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}
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}
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static int escape_octal(unsigned char c, char **dst, size_t *osz)
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static bool escape_octal(unsigned char c, char **dst, char *end)
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{
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{
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char *out = *dst;
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char *out = *dst;
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if (*osz < 4)
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if (out + 4 > end) {
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return -ENOMEM;
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*dst = out + 4;
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return true;
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}
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*out++ = '\\';
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if (out < end)
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*out++ = ((c >> 6) & 0x07) + '0';
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*out = '\\';
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*out++ = ((c >> 3) & 0x07) + '0';
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++out;
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*out++ = ((c >> 0) & 0x07) + '0';
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if (out < end)
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*out = ((c >> 6) & 0x07) + '0';
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++out;
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if (out < end)
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*out = ((c >> 3) & 0x07) + '0';
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++out;
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if (out < end)
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*out = ((c >> 0) & 0x07) + '0';
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++out;
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*dst = out;
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*dst = out;
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*osz -= 4;
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return true;
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return 1;
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}
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}
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static int escape_hex(unsigned char c, char **dst, size_t *osz)
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static bool escape_hex(unsigned char c, char **dst, char *end)
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{
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{
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char *out = *dst;
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char *out = *dst;
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if (*osz < 4)
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if (out + 4 > end) {
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return -ENOMEM;
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*dst = out + 4;
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return true;
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}
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*out++ = '\\';
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if (out < end)
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*out++ = 'x';
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*out = '\\';
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*out++ = hex_asc_hi(c);
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++out;
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*out++ = hex_asc_lo(c);
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if (out < end)
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*out = 'x';
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++out;
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if (out < end)
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*out = hex_asc_hi(c);
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++out;
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if (out < end)
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*out = hex_asc_lo(c);
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++out;
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*dst = out;
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*dst = out;
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*osz -= 4;
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return true;
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return 1;
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}
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}
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/**
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/**
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@ -436,9 +459,10 @@ static int escape_hex(unsigned char c, char **dst, size_t *osz)
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int string_escape_mem(const char *src, size_t isz, char **dst, size_t osz,
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int string_escape_mem(const char *src, size_t isz, char **dst, size_t osz,
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unsigned int flags, const char *esc)
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unsigned int flags, const char *esc)
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{
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{
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char *out = *dst, *p = out;
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char *p = *dst;
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char *end = p + osz;
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bool is_dict = esc && *esc;
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bool is_dict = esc && *esc;
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int ret = 0;
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int ret;
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while (isz--) {
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while (isz--) {
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unsigned char c = *src++;
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unsigned char c = *src++;
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@ -458,55 +482,33 @@ int string_escape_mem(const char *src, size_t isz, char **dst, size_t osz,
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(is_dict && !strchr(esc, c))) {
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(is_dict && !strchr(esc, c))) {
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/* do nothing */
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/* do nothing */
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} else {
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} else {
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if (flags & ESCAPE_SPACE) {
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if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
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ret = escape_space(c, &p, &osz);
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continue;
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if (ret < 0)
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break;
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if (ret > 0)
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continue;
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}
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if (flags & ESCAPE_SPECIAL) {
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if (flags & ESCAPE_SPECIAL && escape_special(c, &p, end))
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ret = escape_special(c, &p, &osz);
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continue;
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if (ret < 0)
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break;
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if (ret > 0)
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continue;
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}
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if (flags & ESCAPE_NULL) {
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if (flags & ESCAPE_NULL && escape_null(c, &p, end))
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ret = escape_null(c, &p, &osz);
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continue;
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if (ret < 0)
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break;
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if (ret > 0)
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continue;
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}
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/* ESCAPE_OCTAL and ESCAPE_HEX always go last */
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/* ESCAPE_OCTAL and ESCAPE_HEX always go last */
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if (flags & ESCAPE_OCTAL) {
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if (flags & ESCAPE_OCTAL && escape_octal(c, &p, end))
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ret = escape_octal(c, &p, &osz);
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if (ret < 0)
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break;
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continue;
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continue;
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}
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if (flags & ESCAPE_HEX) {
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if (flags & ESCAPE_HEX && escape_hex(c, &p, end))
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ret = escape_hex(c, &p, &osz);
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if (ret < 0)
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break;
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continue;
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continue;
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}
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}
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}
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ret = escape_passthrough(c, &p, &osz);
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escape_passthrough(c, &p, end);
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if (ret < 0)
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break;
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}
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}
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if (p > end) {
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*dst = end;
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return -ENOMEM;
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}
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ret = p - *dst;
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*dst = p;
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*dst = p;
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return ret;
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if (ret < 0)
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return ret;
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return p - out;
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}
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}
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EXPORT_SYMBOL(string_escape_mem);
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EXPORT_SYMBOL(string_escape_mem);
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