LibC: Implement fnmatch

userspace/libraries/LibC/CMakeLists.txt

@@ -10,6 +10,7 @@ set(LIBC_SOURCES
 	errno.cpp
 	fcntl.cpp
 	fenv.cpp
+	fnmatch.cpp
 	ftw.cpp
 	grp.cpp
 	ifaddrs.cpp

userspace/libraries/LibC/fnmatch.cpp

@@ -0,0 +1,80 @@
+#include <fnmatch.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+static int fnmatch_impl(const char* pattern, const char* string, int flags, bool leading)
+{
+	while (*pattern)
+	{
+		if ((flags & FNM_PERIOD) && leading && *string == '.' && *pattern != '.')
+			return FNM_NOMATCH;
+		leading = false;
+
+		switch (*pattern)
+		{
+			case '*':
+			{
+				const char* ptr = strchrnul(string, (flags & FNM_PATHNAME) ? '/' : '0');
+				while (ptr >= string)
+					if (fnmatch_impl(pattern + 1, ptr--, flags, false) == 0)
+						return 0;
+				return FNM_NOMATCH;
+			}
+			case '[':
+			{
+				if (strchr(pattern, ']') == nullptr)
+					break;
+				pattern++;
+
+				const bool negate = (*pattern == '!');
+				if (negate)
+					pattern++;
+
+				uint8_t ch;
+				uint32_t bitmap[0x100 / 8] {};
+				while ((ch = *pattern++) != ']')
+					bitmap[ch / 32] |= 1 << (ch % 32);
+
+				ch = *string++;
+				if (!!(bitmap[ch / 32] & (1 << (ch % 32))) == negate)
+					return FNM_NOMATCH;
+
+				continue;
+			}
+			case '?':
+			{
+				if (*string == '\0')
+					return FNM_NOMATCH;
+				if ((flags & FNM_PATHNAME) && *string == '/')
+					return FNM_NOMATCH;
+				pattern++;
+				string++;
+				continue;
+			}
+			case '\\':
+			{
+				if (!(flags & FNM_NOESCAPE))
+					pattern++;
+				break;
+			}
+		}
+
+		if (*pattern == '\0')
+			break;
+
+		if (*pattern != *string)
+			return FNM_NOMATCH;
+		if ((flags & FNM_PATHNAME) && *string == '/')
+			leading = true;
+		pattern++;
+		string++;
+	}
+
+	return *string ? FNM_NOMATCH : 0;
+}
+
+int fnmatch(const char* pattern, const char* string, int flags)
+{
+	return fnmatch_impl(pattern, string, flags, true);
+}