1 files changed, 104 insertions, 0 deletions
diff --git a/interpolate.c b/interpolate.c
new file mode 100644
index 0000000000..6ef53f2465
--- /dev/null
+++ b/interpolate.c
@@ -0,0 +1,104 @@
+/*
+ * Copyright 2006 Jon Loeliger
+ */
+
+#include "git-compat-util.h"
+#include "interpolate.h"
+
+
+void interp_set_entry(struct interp *table, int slot, const char *value)
+{
+	char *oldval = table[slot].value;
+	char *newval = NULL;
+
+	if (oldval)
+		free(oldval);
+
+	if (value)
+		newval = xstrdup(value);
+
+	table[slot].value = newval;
+}
+
+
+void interp_clear_table(struct interp *table, int ninterps)
+{
+	int i;
+
+	for (i = 0; i < ninterps; i++) {
+		interp_set_entry(table, i, NULL);
+	}
+}
+
+
+/*
+ * Convert a NUL-terminated string in buffer orig
+ * into the supplied buffer, result, whose length is reslen,
+ * performing substitutions on %-named sub-strings from
+ * the table, interps, with ninterps entries.
+ *
+ * Example interps:
+ *    {
+ *        { "%H", "example.org"},
+ *        { "%port", "123"},
+ *        { "%%", "%"},
+ *    }
+ *
+ * Returns the length of the substituted string (not including the final \0).
+ * Like with snprintf, if the result is >= reslen, then it overflowed.
+ */
+
+unsigned long interpolate(char *result, unsigned long reslen,
+		const char *orig,
+		const struct interp *interps, int ninterps)
+{
+	const char *src = orig;
+	char *dest = result;
+	unsigned long newlen = 0;
+	const char *name, *value;
+	unsigned long namelen, valuelen;
+	int i;
+	char c;
+
+	while ((c = *src)) {
+		if (c == '%') {
+			/* Try to match an interpolation string. */
+			for (i = 0; i < ninterps; i++) {
+				name = interps[i].name;
+				namelen = strlen(name);
+				if (strncmp(src, name, namelen) == 0)
+					break;
+			}
+
+			/* Check for valid interpolation. */
+			if (i < ninterps) {
+				value = interps[i].value;
+				if (!value) {
+					src += namelen;
+					continue;
+				}
+
+				valuelen = strlen(value);
+				if (newlen + valuelen < reslen) {
+					/* Substitute. */
+					memcpy(dest, value, valuelen);
+					dest += valuelen;
+				}
+				newlen += valuelen;
+				src += namelen;
+				continue;
+			}
+		}
+		/* Straight copy one non-interpolation character. */
+		if (newlen + 1 < reslen)
+			*dest++ = *src;
+		src++;
+		newlen++;
+	}
+
+	/* XXX: the previous loop always keep room for the ending NUL,
+	   we just need to check if there was room for a NUL in the first place */
+	if (reslen > 0)
+		*dest = '\0';
+	return newlen;
+}