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Systemd/src/basic/escape.c
Zbigniew Jędrzejewski-Szmek 11a1589223 tree-wide: drop license boilerplate 
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.

I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
2018-04-06 18:58:55 +02:00

511 lines
14 KiB
C
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/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
***/
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include "alloc-util.h"
#include "escape.h"
#include "hexdecoct.h"
#include "macro.h"
#include "utf8.h"
size_t cescape_char(char c, char *buf) {
char * buf_old = buf;
switch (c) {
case '\a':
*(buf++) = '\\';
*(buf++) = 'a';
break;
case '\b':
*(buf++) = '\\';
*(buf++) = 'b';
break;
case '\f':
*(buf++) = '\\';
*(buf++) = 'f';
break;
case '\n':
*(buf++) = '\\';
*(buf++) = 'n';
break;
case '\r':
*(buf++) = '\\';
*(buf++) = 'r';
break;
case '\t':
*(buf++) = '\\';
*(buf++) = 't';
break;
case '\v':
*(buf++) = '\\';
*(buf++) = 'v';
break;
case '\\':
*(buf++) = '\\';
*(buf++) = '\\';
break;
case '"':
*(buf++) = '\\';
*(buf++) = '"';
break;
case '\'':
*(buf++) = '\\';
*(buf++) = '\'';
break;
default:
/* For special chars we prefer octal over
* hexadecimal encoding, simply because glib's
* g_strescape() does the same */
if ((c < ' ') || (c >= 127)) {
*(buf++) = '\\';
*(buf++) = octchar((unsigned char) c >> 6);
*(buf++) = octchar((unsigned char) c >> 3);
*(buf++) = octchar((unsigned char) c);
} else
*(buf++) = c;
break;
}
return buf - buf_old;
}
char *cescape_length(const char *s, size_t n) {
const char *f;
char *r, *t;
assert(s || n == 0);
/* Does C style string escaping. May be reversed with
* cunescape(). */
r = new(char, n*4 + 1);
if (!r)
return NULL;
for (f = s, t = r; f < s + n; f++)
t += cescape_char(*f, t);
*t = 0;
return r;
}
char *cescape(const char *s) {
assert(s);
return cescape_length(s, strlen(s));
}
int cunescape_one(const char *p, size_t length, char32_t *ret, bool *eight_bit) {
int r = 1;
assert(p);
assert(*p);
assert(ret);
/* Unescapes C style. Returns the unescaped character in ret.
* Sets *eight_bit to true if the escaped sequence either fits in
* one byte in UTF-8 or is a non-unicode literal byte and should
* instead be copied directly.
*/
if (length != (size_t) -1 && length < 1)
return -EINVAL;
switch (p[0]) {
case 'a':
*ret = '\a';
break;
case 'b':
*ret = '\b';
break;
case 'f':
*ret = '\f';
break;
case 'n':
*ret = '\n';
break;
case 'r':
*ret = '\r';
break;
case 't':
*ret = '\t';
break;
case 'v':
*ret = '\v';
break;
case '\\':
*ret = '\\';
break;
case '"':
*ret = '"';
break;
case '\'':
*ret = '\'';
break;
case 's':
/* This is an extension of the XDG syntax files */
*ret = ' ';
break;
case 'x': {
/* hexadecimal encoding */
int a, b;
if (length != (size_t) -1 && length < 3)
return -EINVAL;
a = unhexchar(p[1]);
if (a < 0)
return -EINVAL;
b = unhexchar(p[2]);
if (b < 0)
return -EINVAL;
/* Don't allow NUL bytes */
if (a == 0 && b == 0)
return -EINVAL;
*ret = (a << 4U) | b;
*eight_bit = true;
r = 3;
break;
}
case 'u': {
/* C++11 style 16bit unicode */
int a[4];
unsigned i;
uint32_t c;
if (length != (size_t) -1 && length < 5)
return -EINVAL;
for (i = 0; i < 4; i++) {
a[i] = unhexchar(p[1 + i]);
if (a[i] < 0)
return a[i];
}
c = ((uint32_t) a[0] << 12U) | ((uint32_t) a[1] << 8U) | ((uint32_t) a[2] << 4U) | (uint32_t) a[3];
/* Don't allow 0 chars */
if (c == 0)
return -EINVAL;
*ret = c;
r = 5;
break;
}
case 'U': {
/* C++11 style 32bit unicode */
int a[8];
unsigned i;
char32_t c;
if (length != (size_t) -1 && length < 9)
return -EINVAL;
for (i = 0; i < 8; i++) {
a[i] = unhexchar(p[1 + i]);
if (a[i] < 0)
return a[i];
}
c = ((uint32_t) a[0] << 28U) | ((uint32_t) a[1] << 24U) | ((uint32_t) a[2] << 20U) | ((uint32_t) a[3] << 16U) |
((uint32_t) a[4] << 12U) | ((uint32_t) a[5] << 8U) | ((uint32_t) a[6] << 4U) | (uint32_t) a[7];
/* Don't allow 0 chars */
if (c == 0)
return -EINVAL;
/* Don't allow invalid code points */
if (!unichar_is_valid(c))
return -EINVAL;
*ret = c;
r = 9;
break;
}
case '0':
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7': {
/* octal encoding */
int a, b, c;
char32_t m;
if (length != (size_t) -1 && length < 3)
return -EINVAL;
a = unoctchar(p[0]);
if (a < 0)
return -EINVAL;
b = unoctchar(p[1]);
if (b < 0)
return -EINVAL;
c = unoctchar(p[2]);
if (c < 0)
return -EINVAL;
/* don't allow NUL bytes */
if (a == 0 && b == 0 && c == 0)
return -EINVAL;
/* Don't allow bytes above 255 */
m = ((uint32_t) a << 6U) | ((uint32_t) b << 3U) | (uint32_t) c;
if (m > 255)
return -EINVAL;
*ret = m;
*eight_bit = true;
r = 3;
break;
}
default:
return -EINVAL;
}
return r;
}
int cunescape_length_with_prefix(const char *s, size_t length, const char *prefix, UnescapeFlags flags, char **ret) {
char *r, *t;
const char *f;
size_t pl;
assert(s);
assert(ret);
/* Undoes C style string escaping, and optionally prefixes it. */
pl = strlen_ptr(prefix);
r = new(char, pl+length+1);
if (!r)
return -ENOMEM;
if (prefix)
memcpy(r, prefix, pl);
for (f = s, t = r + pl; f < s + length; f++) {
size_t remaining;
bool eight_bit = false;
char32_t u;
int k;
remaining = s + length - f;
assert(remaining > 0);
if (*f != '\\') {
/* A literal, copy verbatim */
*(t++) = *f;
continue;
}
if (remaining == 1) {
if (flags & UNESCAPE_RELAX) {
/* A trailing backslash, copy verbatim */
*(t++) = *f;
continue;
}
free(r);
return -EINVAL;
}
k = cunescape_one(f + 1, remaining - 1, &u, &eight_bit);
if (k < 0) {
if (flags & UNESCAPE_RELAX) {
/* Invalid escape code, let's take it literal then */
*(t++) = '\\';
continue;
}
free(r);
return k;
}
f += k;
if (eight_bit)
/* One byte? Set directly as specified */
*(t++) = u;
else
/* Otherwise encode as multi-byte UTF-8 */
t += utf8_encode_unichar(t, u);
}
*t = 0;
*ret = r;
return t - r;
}
int cunescape_length(const char *s, size_t length, UnescapeFlags flags, char **ret) {
return cunescape_length_with_prefix(s, length, NULL, flags, ret);
}
int cunescape(const char *s, UnescapeFlags flags, char **ret) {
return cunescape_length(s, strlen(s), flags, ret);
}
char *xescape(const char *s, const char *bad) {
char *r, *t;
const char *f;
/* Escapes all chars in bad, in addition to \ and all special
* chars, in \xFF style escaping. May be reversed with
* cunescape(). */
r = new(char, strlen(s) * 4 + 1);
if (!r)
return NULL;
for (f = s, t = r; *f; f++) {
if ((*f < ' ') || (*f >= 127) ||
(*f == '\\') || strchr(bad, *f)) {
*(t++) = '\\';
*(t++) = 'x';
*(t++) = hexchar(*f >> 4);
*(t++) = hexchar(*f);
} else
*(t++) = *f;
}
*t = 0;
return r;
}
char *octescape(const char *s, size_t len) {
char *r, *t;
const char *f;
/* Escapes all chars in bad, in addition to \ and " chars,
* in \nnn style escaping. */
r = new(char, len * 4 + 1);
if (!r)
return NULL;
for (f = s, t = r; f < s + len; f++) {
if (*f < ' ' || *f >= 127 || IN_SET(*f, '\\', '"')) {
*(t++) = '\\';
*(t++) = '0' + (*f >> 6);
*(t++) = '0' + ((*f >> 3) & 8);
*(t++) = '0' + (*f & 8);
} else
*(t++) = *f;
}
*t = 0;
return r;
}
static char *strcpy_backslash_escaped(char *t, const char *s, const char *bad, bool escape_tab_nl) {
assert(bad);
for (; *s; s++) {
if (escape_tab_nl && IN_SET(*s, '\n', '\t')) {
*(t++) = '\\';
*(t++) = *s == '\n' ? 'n' : 't';
continue;
}
if (*s == '\\' || strchr(bad, *s))
*(t++) = '\\';
*(t++) = *s;
}
return t;
}
char *shell_escape(const char *s, const char *bad) {
char *r, *t;
r = new(char, strlen(s)*2+1);
if (!r)
return NULL;
t = strcpy_backslash_escaped(r, s, bad, false);
*t = 0;
return r;
}
char* shell_maybe_quote(const char *s, EscapeStyle style) {
const char *p;
char *r, *t;
assert(s);
/* Encloses a string in quotes if necessary to make it OK as a shell
* string. Note that we treat benign UTF-8 characters as needing
* escaping too, but that should be OK. */
for (p = s; *p; p++)
if (*p <= ' ' ||
*p >= 127 ||
strchr(SHELL_NEED_QUOTES, *p))
break;
if (!*p)
return strdup(s);
r = new(char, (style == ESCAPE_POSIX) + 1 + strlen(s)*2 + 1 + 1);
if (!r)
return NULL;
t = r;
if (style == ESCAPE_BACKSLASH)
*(t++) = '"';
else if (style == ESCAPE_POSIX) {
*(t++) = '$';
*(t++) = '\'';
} else
assert_not_reached("Bad EscapeStyle");
t = mempcpy(t, s, p - s);
if (style == ESCAPE_BACKSLASH)
t = strcpy_backslash_escaped(t, p, SHELL_NEED_ESCAPE, false);
else
t = strcpy_backslash_escaped(t, p, SHELL_NEED_ESCAPE_POSIX, true);
if (style == ESCAPE_BACKSLASH)
*(t++) = '"';
else
*(t++) = '\'';
*t = 0;
return r;
}
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