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-rw-r--r--src/basic/extract-word.c285
1 files changed, 285 insertions, 0 deletions
diff --git a/src/basic/extract-word.c b/src/basic/extract-word.c
new file mode 100644
index 0000000..a861b56
--- /dev/null
+++ b/src/basic/extract-word.c
@@ -0,0 +1,285 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <syslog.h>
+
+#include "alloc-util.h"
+#include "escape.h"
+#include "extract-word.h"
+#include "log.h"
+#include "macro.h"
+#include "string-util.h"
+#include "utf8.h"
+
+int extract_first_word(const char **p, char **ret, const char *separators, ExtractFlags flags) {
+ _cleanup_free_ char *s = NULL;
+ size_t allocated = 0, sz = 0;
+ char c;
+ int r;
+
+ char quote = 0; /* 0 or ' or " */
+ bool backslash = false; /* whether we've just seen a backslash */
+
+ assert(p);
+ assert(ret);
+
+ /* Bail early if called after last value or with no input */
+ if (!*p)
+ goto finish;
+ c = **p;
+
+ if (!separators)
+ separators = WHITESPACE;
+
+ /* Parses the first word of a string, and returns it in
+ * *ret. Removes all quotes in the process. When parsing fails
+ * (because of an uneven number of quotes or similar), leaves
+ * the pointer *p at the first invalid character. */
+
+ if (flags & EXTRACT_DONT_COALESCE_SEPARATORS)
+ if (!GREEDY_REALLOC(s, allocated, sz+1))
+ return -ENOMEM;
+
+ for (;; (*p)++, c = **p) {
+ if (c == 0)
+ goto finish_force_terminate;
+ else if (strchr(separators, c)) {
+ if (flags & EXTRACT_DONT_COALESCE_SEPARATORS) {
+ (*p)++;
+ goto finish_force_next;
+ }
+ } else {
+ /* We found a non-blank character, so we will always
+ * want to return a string (even if it is empty),
+ * allocate it here. */
+ if (!GREEDY_REALLOC(s, allocated, sz+1))
+ return -ENOMEM;
+ break;
+ }
+ }
+
+ for (;; (*p)++, c = **p) {
+ if (backslash) {
+ if (!GREEDY_REALLOC(s, allocated, sz+7))
+ return -ENOMEM;
+
+ if (c == 0) {
+ if ((flags & EXTRACT_CUNESCAPE_RELAX) &&
+ (!quote || flags & EXTRACT_RELAX)) {
+ /* If we find an unquoted trailing backslash and we're in
+ * EXTRACT_CUNESCAPE_RELAX mode, keep it verbatim in the
+ * output.
+ *
+ * Unbalanced quotes will only be allowed in EXTRACT_RELAX
+ * mode, EXTRACT_CUNESCAPE_RELAX mode does not allow them.
+ */
+ s[sz++] = '\\';
+ goto finish_force_terminate;
+ }
+ if (flags & EXTRACT_RELAX)
+ goto finish_force_terminate;
+ return -EINVAL;
+ }
+
+ if (flags & EXTRACT_CUNESCAPE) {
+ bool eight_bit = false;
+ char32_t u;
+
+ r = cunescape_one(*p, (size_t) -1, &u, &eight_bit);
+ if (r < 0) {
+ if (flags & EXTRACT_CUNESCAPE_RELAX) {
+ s[sz++] = '\\';
+ s[sz++] = c;
+ } else
+ return -EINVAL;
+ } else {
+ (*p) += r - 1;
+
+ if (eight_bit)
+ s[sz++] = u;
+ else
+ sz += utf8_encode_unichar(s + sz, u);
+ }
+ } else
+ s[sz++] = c;
+
+ backslash = false;
+
+ } else if (quote) { /* inside either single or double quotes */
+ for (;; (*p)++, c = **p) {
+ if (c == 0) {
+ if (flags & EXTRACT_RELAX)
+ goto finish_force_terminate;
+ return -EINVAL;
+ } else if (c == quote) { /* found the end quote */
+ quote = 0;
+ break;
+ } else if (c == '\\' && !(flags & EXTRACT_RETAIN_ESCAPE)) {
+ backslash = true;
+ break;
+ } else {
+ if (!GREEDY_REALLOC(s, allocated, sz+2))
+ return -ENOMEM;
+
+ s[sz++] = c;
+ }
+ }
+
+ } else {
+ for (;; (*p)++, c = **p) {
+ if (c == 0)
+ goto finish_force_terminate;
+ else if (IN_SET(c, '\'', '"') && (flags & EXTRACT_QUOTES)) {
+ quote = c;
+ break;
+ } else if (c == '\\' && !(flags & EXTRACT_RETAIN_ESCAPE)) {
+ backslash = true;
+ break;
+ } else if (strchr(separators, c)) {
+ if (flags & EXTRACT_DONT_COALESCE_SEPARATORS) {
+ (*p)++;
+ goto finish_force_next;
+ }
+ /* Skip additional coalesced separators. */
+ for (;; (*p)++, c = **p) {
+ if (c == 0)
+ goto finish_force_terminate;
+ if (!strchr(separators, c))
+ break;
+ }
+ goto finish;
+
+ } else {
+ if (!GREEDY_REALLOC(s, allocated, sz+2))
+ return -ENOMEM;
+
+ s[sz++] = c;
+ }
+ }
+ }
+ }
+
+finish_force_terminate:
+ *p = NULL;
+finish:
+ if (!s) {
+ *p = NULL;
+ *ret = NULL;
+ return 0;
+ }
+
+finish_force_next:
+ s[sz] = 0;
+ *ret = TAKE_PTR(s);
+
+ return 1;
+}
+
+int extract_first_word_and_warn(
+ const char **p,
+ char **ret,
+ const char *separators,
+ ExtractFlags flags,
+ const char *unit,
+ const char *filename,
+ unsigned line,
+ const char *rvalue) {
+
+ /* Try to unquote it, if it fails, warn about it and try again
+ * but this time using EXTRACT_CUNESCAPE_RELAX to keep the
+ * backslashes verbatim in invalid escape sequences. */
+
+ const char *save;
+ int r;
+
+ save = *p;
+ r = extract_first_word(p, ret, separators, flags);
+ if (r >= 0)
+ return r;
+
+ if (r == -EINVAL && !(flags & EXTRACT_CUNESCAPE_RELAX)) {
+
+ /* Retry it with EXTRACT_CUNESCAPE_RELAX. */
+ *p = save;
+ r = extract_first_word(p, ret, separators, flags|EXTRACT_CUNESCAPE_RELAX);
+ if (r >= 0) {
+ /* It worked this time, hence it must have been an invalid escape sequence. */
+ log_syntax(unit, LOG_WARNING, filename, line, EINVAL, "Ignoring unknown escape sequences: \"%s\"", *ret);
+ return r;
+ }
+
+ /* If it's still EINVAL; then it must be unbalanced quoting, report this. */
+ if (r == -EINVAL)
+ return log_syntax(unit, LOG_ERR, filename, line, r, "Unbalanced quoting, ignoring: \"%s\"", rvalue);
+ }
+
+ /* Can be any error, report it */
+ return log_syntax(unit, LOG_ERR, filename, line, r, "Unable to decode word \"%s\", ignoring: %m", rvalue);
+}
+
+/* We pass ExtractFlags as unsigned int (to avoid undefined behaviour when passing
+ * an object that undergoes default argument promotion as an argument to va_start).
+ * Let's make sure that ExtractFlags fits into an unsigned int. */
+assert_cc(sizeof(enum ExtractFlags) <= sizeof(unsigned));
+
+int extract_many_words(const char **p, const char *separators, unsigned flags, ...) {
+ va_list ap;
+ char **l;
+ int n = 0, i, c, r;
+
+ /* Parses a number of words from a string, stripping any
+ * quotes if necessary. */
+
+ assert(p);
+
+ /* Count how many words are expected */
+ va_start(ap, flags);
+ for (;;) {
+ if (!va_arg(ap, char **))
+ break;
+ n++;
+ }
+ va_end(ap);
+
+ if (n <= 0)
+ return 0;
+
+ /* Read all words into a temporary array */
+ l = newa0(char*, n);
+ for (c = 0; c < n; c++) {
+
+ r = extract_first_word(p, &l[c], separators, flags);
+ if (r < 0) {
+ int j;
+
+ for (j = 0; j < c; j++)
+ free(l[j]);
+
+ return r;
+ }
+
+ if (r == 0)
+ break;
+ }
+
+ /* If we managed to parse all words, return them in the passed
+ * in parameters */
+ va_start(ap, flags);
+ for (i = 0; i < n; i++) {
+ char **v;
+
+ v = va_arg(ap, char **);
+ assert(v);
+
+ *v = l[i];
+ }
+ va_end(ap);
+
+ return c;
+}
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