1 files changed, 151 insertions, 0 deletions
diff --git a/src/port/pgstrcasecmp.c b/src/port/pgstrcasecmp.c
new file mode 100644
index 0000000..fc7ee91
--- /dev/null
+++ b/src/port/pgstrcasecmp.c
@@ -0,0 +1,151 @@
+/*-------------------------------------------------------------------------
+ *
+ * pgstrcasecmp.c
+ *	   Portable SQL-like case-independent comparisons and conversions.
+ *
+ * SQL99 specifies Unicode-aware case normalization, which we don't yet
+ * have the infrastructure for.  Instead we use tolower() to provide a
+ * locale-aware translation.  However, there are some locales where this
+ * is not right either (eg, Turkish may do strange things with 'i' and
+ * 'I').  Our current compromise is to use tolower() for characters with
+ * the high bit set, and use an ASCII-only downcasing for 7-bit
+ * characters.
+ *
+ * NB: this code should match downcase_truncate_identifier() in scansup.c.
+ *
+ * We also provide strict ASCII-only case conversion functions, which can
+ * be used to implement C/POSIX case folding semantics no matter what the
+ * C library thinks the locale is.
+ *
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ *
+ * src/port/pgstrcasecmp.c
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "c.h"
+
+#include <ctype.h>
+
+
+/*
+ * Case-independent comparison of two null-terminated strings.
+ */
+int
+pg_strcasecmp(const char *s1, const char *s2)
+{
+	for (;;)
+	{
+		unsigned char ch1 = (unsigned char) *s1++;
+		unsigned char ch2 = (unsigned char) *s2++;
+
+		if (ch1 != ch2)
+		{
+			if (ch1 >= 'A' && ch1 <= 'Z')
+				ch1 += 'a' - 'A';
+			else if (IS_HIGHBIT_SET(ch1) && isupper(ch1))
+				ch1 = tolower(ch1);
+
+			if (ch2 >= 'A' && ch2 <= 'Z')
+				ch2 += 'a' - 'A';
+			else if (IS_HIGHBIT_SET(ch2) && isupper(ch2))
+				ch2 = tolower(ch2);
+
+			if (ch1 != ch2)
+				return (int) ch1 - (int) ch2;
+		}
+		if (ch1 == 0)
+			break;
+	}
+	return 0;
+}
+
+/*
+ * Case-independent comparison of two not-necessarily-null-terminated strings.
+ * At most n bytes will be examined from each string.
+ */
+int
+pg_strncasecmp(const char *s1, const char *s2, size_t n)
+{
+	while (n-- > 0)
+	{
+		unsigned char ch1 = (unsigned char) *s1++;
+		unsigned char ch2 = (unsigned char) *s2++;
+
+		if (ch1 != ch2)
+		{
+			if (ch1 >= 'A' && ch1 <= 'Z')
+				ch1 += 'a' - 'A';
+			else if (IS_HIGHBIT_SET(ch1) && isupper(ch1))
+				ch1 = tolower(ch1);
+
+			if (ch2 >= 'A' && ch2 <= 'Z')
+				ch2 += 'a' - 'A';
+			else if (IS_HIGHBIT_SET(ch2) && isupper(ch2))
+				ch2 = tolower(ch2);
+
+			if (ch1 != ch2)
+				return (int) ch1 - (int) ch2;
+		}
+		if (ch1 == 0)
+			break;
+	}
+	return 0;
+}
+
+/*
+ * Fold a character to upper case.
+ *
+ * Unlike some versions of toupper(), this is safe to apply to characters
+ * that aren't lower case letters.  Note however that the whole thing is
+ * a bit bogus for multibyte character sets.
+ */
+unsigned char
+pg_toupper(unsigned char ch)
+{
+	if (ch >= 'a' && ch <= 'z')
+		ch += 'A' - 'a';
+	else if (IS_HIGHBIT_SET(ch) && islower(ch))
+		ch = toupper(ch);
+	return ch;
+}
+
+/*
+ * Fold a character to lower case.
+ *
+ * Unlike some versions of tolower(), this is safe to apply to characters
+ * that aren't upper case letters.  Note however that the whole thing is
+ * a bit bogus for multibyte character sets.
+ */
+unsigned char
+pg_tolower(unsigned char ch)
+{
+	if (ch >= 'A' && ch <= 'Z')
+		ch += 'a' - 'A';
+	else if (IS_HIGHBIT_SET(ch) && isupper(ch))
+		ch = tolower(ch);
+	return ch;
+}
+
+/*
+ * Fold a character to upper case, following C/POSIX locale rules.
+ */
+unsigned char
+pg_ascii_toupper(unsigned char ch)
+{
+	if (ch >= 'a' && ch <= 'z')
+		ch += 'A' - 'a';
+	return ch;
+}
+
+/*
+ * Fold a character to lower case, following C/POSIX locale rules.
+ */
+unsigned char
+pg_ascii_tolower(unsigned char ch)
+{
+	if (ch >= 'A' && ch <= 'Z')
+		ch += 'a' - 'A';
+	return ch;
+}