Zbigniew Jędrzejewski-Szmek
8a07b4033e
It's hard to even say what exactly this combination means. Escaping is necessary when quoting to have quotes within the string. So the escaping of quote characters is inherently tied to quoting. When unquoting, it seems natural to remove escaping which was done for the quoting purposes. But with both flags we would be expected to re-add this escaping after unqouting? Or maybe keep the escaping which is not necessary for quoting but otherwise present? This all seems too complicated, let's just forbid such usage and always fully unescape when unquoting.
288 lines
11 KiB
C
288 lines
11 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <errno.h>
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#include <stdarg.h>
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#include <stdbool.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <syslog.h>
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#include "alloc-util.h"
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#include "escape.h"
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#include "extract-word.h"
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#include "log.h"
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#include "macro.h"
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#include "string-util.h"
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#include "utf8.h"
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int extract_first_word(const char **p, char **ret, const char *separators, ExtractFlags flags) {
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_cleanup_free_ char *s = NULL;
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size_t allocated = 0, sz = 0;
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char c;
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int r;
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char quote = 0; /* 0 or ' or " */
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bool backslash = false; /* whether we've just seen a backslash */
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assert(p);
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assert(ret);
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/* Those two don't make sense together. */
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assert(!FLAGS_SET(flags, EXTRACT_UNQUOTE|EXTRACT_RETAIN_ESCAPE));
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/* Bail early if called after last value or with no input */
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if (!*p)
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goto finish;
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c = **p;
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if (!separators)
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separators = WHITESPACE;
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/* Parses the first word of a string, and returns it in
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* *ret. Removes all quotes in the process. When parsing fails
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* (because of an uneven number of quotes or similar), leaves
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* the pointer *p at the first invalid character. */
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if (flags & EXTRACT_DONT_COALESCE_SEPARATORS)
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if (!GREEDY_REALLOC(s, allocated, sz+1))
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return -ENOMEM;
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for (;; (*p)++, c = **p) {
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if (c == 0)
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goto finish_force_terminate;
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else if (strchr(separators, c)) {
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if (flags & EXTRACT_DONT_COALESCE_SEPARATORS) {
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(*p)++;
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goto finish_force_next;
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}
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} else {
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/* We found a non-blank character, so we will always
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* want to return a string (even if it is empty),
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* allocate it here. */
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if (!GREEDY_REALLOC(s, allocated, sz+1))
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return -ENOMEM;
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break;
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}
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}
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for (;; (*p)++, c = **p) {
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if (backslash) {
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if (!GREEDY_REALLOC(s, allocated, sz+7))
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return -ENOMEM;
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if (c == 0) {
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if ((flags & EXTRACT_CUNESCAPE_RELAX) &&
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(!quote || flags & EXTRACT_RELAX)) {
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/* If we find an unquoted trailing backslash and we're in
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* EXTRACT_CUNESCAPE_RELAX mode, keep it verbatim in the
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* output.
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*
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* Unbalanced quotes will only be allowed in EXTRACT_RELAX
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* mode, EXTRACT_CUNESCAPE_RELAX mode does not allow them.
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*/
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s[sz++] = '\\';
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goto finish_force_terminate;
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}
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if (flags & EXTRACT_RELAX)
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goto finish_force_terminate;
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return -EINVAL;
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}
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if (flags & EXTRACT_CUNESCAPE) {
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bool eight_bit = false;
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char32_t u;
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r = cunescape_one(*p, (size_t) -1, &u, &eight_bit);
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if (r < 0) {
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if (flags & EXTRACT_CUNESCAPE_RELAX) {
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s[sz++] = '\\';
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s[sz++] = c;
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} else
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return -EINVAL;
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} else {
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(*p) += r - 1;
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if (eight_bit)
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s[sz++] = u;
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else
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sz += utf8_encode_unichar(s + sz, u);
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}
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} else
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s[sz++] = c;
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backslash = false;
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} else if (quote) { /* inside either single or double quotes */
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for (;; (*p)++, c = **p) {
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if (c == 0) {
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if (flags & EXTRACT_RELAX)
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goto finish_force_terminate;
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return -EINVAL;
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} else if (c == quote) { /* found the end quote */
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quote = 0;
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break;
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} else if (c == '\\' && !(flags & EXTRACT_RETAIN_ESCAPE)) {
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backslash = true;
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break;
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} else {
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if (!GREEDY_REALLOC(s, allocated, sz+2))
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return -ENOMEM;
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s[sz++] = c;
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}
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}
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} else {
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for (;; (*p)++, c = **p) {
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if (c == 0)
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goto finish_force_terminate;
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else if (IN_SET(c, '\'', '"') && (flags & EXTRACT_UNQUOTE)) {
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quote = c;
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break;
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} else if (c == '\\' && !(flags & EXTRACT_RETAIN_ESCAPE)) {
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backslash = true;
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break;
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} else if (strchr(separators, c)) {
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if (flags & EXTRACT_DONT_COALESCE_SEPARATORS) {
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(*p)++;
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goto finish_force_next;
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}
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/* Skip additional coalesced separators. */
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for (;; (*p)++, c = **p) {
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if (c == 0)
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goto finish_force_terminate;
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if (!strchr(separators, c))
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break;
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}
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goto finish;
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} else {
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if (!GREEDY_REALLOC(s, allocated, sz+2))
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return -ENOMEM;
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s[sz++] = c;
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}
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}
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}
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}
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finish_force_terminate:
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*p = NULL;
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finish:
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if (!s) {
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*p = NULL;
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*ret = NULL;
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return 0;
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}
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finish_force_next:
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s[sz] = 0;
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*ret = TAKE_PTR(s);
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return 1;
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}
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int extract_first_word_and_warn(
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const char **p,
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char **ret,
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const char *separators,
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ExtractFlags flags,
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const char *unit,
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const char *filename,
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unsigned line,
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const char *rvalue) {
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/* Try to unquote it, if it fails, warn about it and try again
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* but this time using EXTRACT_CUNESCAPE_RELAX to keep the
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* backslashes verbatim in invalid escape sequences. */
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const char *save;
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int r;
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save = *p;
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r = extract_first_word(p, ret, separators, flags);
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if (r >= 0)
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return r;
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if (r == -EINVAL && !(flags & EXTRACT_CUNESCAPE_RELAX)) {
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/* Retry it with EXTRACT_CUNESCAPE_RELAX. */
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*p = save;
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r = extract_first_word(p, ret, separators, flags|EXTRACT_CUNESCAPE_RELAX);
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if (r >= 0) {
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/* It worked this time, hence it must have been an invalid escape sequence. */
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log_syntax(unit, LOG_WARNING, filename, line, EINVAL, "Ignoring unknown escape sequences: \"%s\"", *ret);
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return r;
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}
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/* If it's still EINVAL; then it must be unbalanced quoting, report this. */
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if (r == -EINVAL)
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return log_syntax(unit, LOG_ERR, filename, line, r, "Unbalanced quoting, ignoring: \"%s\"", rvalue);
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}
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/* Can be any error, report it */
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return log_syntax(unit, LOG_ERR, filename, line, r, "Unable to decode word \"%s\", ignoring: %m", rvalue);
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}
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/* We pass ExtractFlags as unsigned int (to avoid undefined behaviour when passing
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* an object that undergoes default argument promotion as an argument to va_start).
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* Let's make sure that ExtractFlags fits into an unsigned int. */
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assert_cc(sizeof(enum ExtractFlags) <= sizeof(unsigned));
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int extract_many_words(const char **p, const char *separators, unsigned flags, ...) {
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va_list ap;
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char **l;
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int n = 0, i, c, r;
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/* Parses a number of words from a string, stripping any
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* quotes if necessary. */
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assert(p);
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/* Count how many words are expected */
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va_start(ap, flags);
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for (;;) {
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if (!va_arg(ap, char **))
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break;
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n++;
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}
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va_end(ap);
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if (n <= 0)
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return 0;
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/* Read all words into a temporary array */
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l = newa0(char*, n);
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for (c = 0; c < n; c++) {
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r = extract_first_word(p, &l[c], separators, flags);
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if (r < 0) {
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int j;
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for (j = 0; j < c; j++)
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free(l[j]);
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return r;
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}
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if (r == 0)
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break;
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}
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/* If we managed to parse all words, return them in the passed
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* in parameters */
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va_start(ap, flags);
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for (i = 0; i < n; i++) {
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char **v;
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v = va_arg(ap, char **);
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assert(v);
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*v = l[i];
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}
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va_end(ap);
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return c;
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}
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