Add libcompat fallback implementation for fnmatch

This has basically been copied over from Musl and slightly modifed.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 305 insertions, 0 deletions

diff --git a/lib/compat/fnmatch.c b/lib/compat/fnmatch.c
new file mode 100644
index 0000000..ed4dde1
--- /dev/null
+++ b/lib/compat/fnmatch.c
@@ -0,0 +1,305 @@
+/*
+ * An implementation of what I call the "Sea of Stars" algorithm for
+ * POSIX fnmatch(). The basic idea is that we factor the pattern into
+ * a head component (which we match first and can reject without ever
+ * measuring the length of the string), an optional tail component
+ * (which only exists if the pattern contains at least one star), and
+ * an optional "sea of stars", a set of star-separated components
+ * between the head and tail. After the head and tail matches have
+ * been removed from the input string, the components in the "sea of
+ * stars" are matched sequentially by searching for their first
+ * occurrence past the end of the previous match.
+ *
+ * - Rich Felker, April 2012
+ */
+
+#include "compat.h"
+
+#include <string.h>
+#include <stdlib.h>
+
+#ifndef HAVE_FNMATCH
+#define END 0
+#define UNMATCHABLE -2
+#define BRACKET -3
+#define QUESTION -4
+#define STAR -5
+
+static int str_next(const char *str, size_t n, size_t *step)
+{
+	if (!n) {
+		*step = 0;
+		return 0;
+	}
+	if (str[0] >= 128U) {
+		wchar_t wc;
+		int k = mbtowc(&wc, str, n);
+		if (k<0) {
+			*step = 1;
+			return -1;
+		}
+		*step = k;
+		return wc;
+	}
+	*step = 1;
+	return str[0];
+}
+
+static int pat_next(const char *pat, size_t m, size_t *step)
+{
+	int esc = 0;
+	if (!m || !*pat) {
+		*step = 0;
+		return END;
+	}
+	*step = 1;
+	if (pat[0]=='\\' && pat[1]) {
+		*step = 2;
+		pat++;
+		esc = 1;
+		goto escaped;
+	}
+	if (pat[0]=='[') {
+		size_t k = 1;
+		if (k<m) if (pat[k] == '^' || pat[k] == '!') k++;
+		if (k<m) if (pat[k] == ']') k++;
+		for (; k<m && pat[k] && pat[k]!=']'; k++) {
+			if (k+1<m && pat[k+1] && pat[k]=='[' && (pat[k+1]==':' || pat[k+1]=='.' || pat[k+1]=='=')) {
+				int z = pat[k+1];
+				k+=2;
+				if (k<m && pat[k]) k++;
+				while (k<m && pat[k] && (pat[k-1]!=z || pat[k]!=']')) k++;
+				if (k==m || !pat[k]) break;
+			}
+		}
+		if (k==m || !pat[k]) {
+			*step = 1;
+			return '[';
+		}
+		*step = k+1;
+		return BRACKET;
+	}
+	if (pat[0] == '*')
+		return STAR;
+	if (pat[0] == '?')
+		return QUESTION;
+escaped:
+	if (pat[0] >= 128U) {
+		wchar_t wc;
+		int k = mbtowc(&wc, pat, m);
+		if (k<0) {
+			*step = 0;
+			return UNMATCHABLE;
+		}
+		*step = k + esc;
+		return wc;
+	}
+	return pat[0];
+}
+
+static int match_bracket(const char *p, int k, int kfold)
+{
+	wchar_t wc;
+	int inv = 0;
+	p++;
+	if (*p=='^' || *p=='!') {
+		inv = 1;
+		p++;
+	}
+	if (*p==']') {
+		if (k==']') return !inv;
+		p++;
+	} else if (*p=='-') {
+		if (k=='-') return !inv;
+		p++;
+	}
+	wc = p[-1];
+	for (; *p != ']'; p++) {
+		if (p[0]=='-' && p[1]!=']') {
+			wchar_t wc2;
+			int l = mbtowc(&wc2, p+1, 4);
+			if (l < 0) return 0;
+			if (wc <= wc2)
+				if ((unsigned)k-wc <= wc2-wc ||
+				    (unsigned)kfold-wc <= wc2-wc)
+					return !inv;
+			p += l-1;
+			continue;
+		}
+		if (p[0]=='[' && (p[1]==':' || p[1]=='.' || p[1]=='=')) {
+			const char *p0 = p+2;
+			int z = p[1];
+			p+=3;
+			while (p[-1]!=z || p[0]!=']') p++;
+			if (z == ':' && p-1-p0 < 16) {
+				char buf[16];
+				memcpy(buf, p0, p-1-p0);
+				buf[p-1-p0] = 0;
+				if (iswctype(k, wctype(buf)) ||
+				    iswctype(kfold, wctype(buf)))
+					return !inv;
+			}
+			continue;
+		}
+		if (*p < 128U) {
+			wc = (unsigned char)*p;
+		} else {
+			int l = mbtowc(&wc, p, 4);
+			if (l < 0) return 0;
+			p += l-1;
+		}
+		if (wc==k || wc==kfold) return !inv;
+	}
+	return inv;
+}
+
+static int fnmatch_internal(const char *pat, size_t m, const char *str, size_t n)
+{
+	const char *p, *ptail, *endpat;
+	const char *s, *stail, *endstr;
+	size_t pinc, sinc, tailcnt=0;
+	int c, k, kfold;
+
+	for (;;) {
+		switch ((c = pat_next(pat, m, &pinc))) {
+		case UNMATCHABLE:
+			return FNM_NOMATCH;
+		case STAR:
+			pat++;
+			m--;
+			break;
+		default:
+			k = str_next(str, n, &sinc);
+			if (k <= 0)
+				return (c==END) ? 0 : FNM_NOMATCH;
+			str += sinc;
+			n -= sinc;
+			kfold = k;
+			if (c == BRACKET) {
+				if (!match_bracket(pat, k, kfold))
+					return FNM_NOMATCH;
+			} else if (c != QUESTION && k != c && kfold != c) {
+				return FNM_NOMATCH;
+			}
+			pat+=pinc;
+			m-=pinc;
+			continue;
+		}
+		break;
+	}
+
+	/* Compute real pat length if it was initially unknown/-1 */
+	m = strnlen(pat, m);
+	endpat = pat + m;
+
+	/* Find the last * in pat and count chars needed after it */
+	for (p=ptail=pat; p<endpat; p+=pinc) {
+		switch (pat_next(p, endpat-p, &pinc)) {
+		case UNMATCHABLE:
+			return FNM_NOMATCH;
+		case STAR:
+			tailcnt=0;
+			ptail = p+1;
+			break;
+		default:
+			tailcnt++;
+			break;
+		}
+	}
+
+	/* Past this point we need not check for UNMATCHABLE in pat,
+	 * because all of pat has already been parsed once. */
+
+	/* Compute real str length if it was initially unknown/-1 */
+	n = strnlen(str, n);
+	endstr = str + n;
+	if (n < tailcnt) return FNM_NOMATCH;
+
+	/* Find the final tailcnt chars of str, accounting for UTF-8.
+	 * On illegal sequences we may get it wrong, but in that case
+	 * we necessarily have a matching failure anyway. */
+	for (s=endstr; s>str && tailcnt; tailcnt--) {
+		if (s[-1] < 128U || MB_CUR_MAX==1) s--;
+		else while ((unsigned char)*--s-0x80U<0x40 && s>str);
+	}
+	if (tailcnt) return FNM_NOMATCH;
+	stail = s;
+
+	/* Check that the pat and str tails match */
+	p = ptail;
+	for (;;) {
+		c = pat_next(p, endpat-p, &pinc);
+		p += pinc;
+		if ((k = str_next(s, endstr-s, &sinc)) <= 0) {
+			if (c != END) return FNM_NOMATCH;
+			break;
+		}
+		s += sinc;
+		kfold = k;
+		if (c == BRACKET) {
+			if (!match_bracket(p-pinc, k, kfold))
+				return FNM_NOMATCH;
+		} else if (c != QUESTION && k != c && kfold != c) {
+			return FNM_NOMATCH;
+		}
+	}
+
+	/* We're all done with the tails now, so throw them out */
+	endstr = stail;
+	endpat = ptail;
+
+	/* Match pattern components until there are none left */
+	while (pat<endpat) {
+		p = pat;
+		s = str;
+		for (;;) {
+			c = pat_next(p, endpat-p, &pinc);
+			p += pinc;
+			/* Encountering * completes/commits a component */
+			if (c == STAR) {
+				pat = p;
+				str = s;
+				break;
+			}
+			k = str_next(s, endstr-s, &sinc);
+			if (!k)
+				return FNM_NOMATCH;
+			kfold = k;
+			if (c == BRACKET) {
+				if (!match_bracket(p-pinc, k, kfold))
+					break;
+			} else if (c != QUESTION && k != c && kfold != c) {
+				break;
+			}
+			s += sinc;
+		}
+		if (c == STAR) continue;
+		/* If we failed, advance str, by 1 char if it's a valid
+		 * char, or past all invalid bytes otherwise. */
+		k = str_next(str, endstr-str, &sinc);
+		if (k > 0) str += sinc;
+		else for (str++; str_next(str, endstr-str, &sinc)<0; str++);
+	}
+
+	return 0;
+}
+
+int fnmatch(const char *pat, const char *str, int flags)
+{
+	const char *s, *p;
+	size_t inc;
+	int c;
+	if (flags & FNM_PATHNAME) for (;;) {
+		for (s=str; *s && *s!='/'; s++);
+		for (p=pat; (c=pat_next(p, -1, &inc))!=END && c!='/'; p+=inc);
+		if (c!=*s)
+			return FNM_NOMATCH;
+		if (fnmatch_internal(pat, p-pat, str, s-str))
+			return FNM_NOMATCH;
+		if (!c) return 0;
+		str = s+1;
+		pat = p+inc;
+	}
+	return fnmatch_internal(pat, -1, str, -1);
+}
+#endif /* HAVE_FNMATCH */