This adds the --ignore-case option, which makes rsync compare filenames
in a case-insensitive manner.

To use this patch, run these commands for a successful build:

    patch -p1 <patches/ignore-case.diff
    ./configure                            (optional if already run)
    make

TODO:

 - Make this code handle multibyte character encodings, and honor the
   --iconv setting when converting case.

--- old/exclude.c
+++ new/exclude.c
@@ -32,6 +32,7 @@ extern int io_error;
 extern int local_server;
 extern int prune_empty_dirs;
 extern int ignore_perishable;
+extern int ignore_case;
 extern int delete_mode;
 extern int delete_excluded;
 extern int cvs_exclude;
@@ -583,16 +584,17 @@ static int rule_matches(char *name, stru
 		if (litmatch_array(pattern, strings, slash_handling))
 			return ret_match;
 	} else if (anchored_match) {
-		if (strcmp(name, pattern) == 0)
+		if ((ignore_case ? strcasecmp(name, pattern)
+				 : strcmp(name, pattern)) == 0)
 			return ret_match;
 	} else {
 		int l1 = strlen(name);
 		int l2 = strlen(pattern);
-		if (l2 <= l1 &&
-		    strcmp(name+(l1-l2),pattern) == 0 &&
-		    (l1==l2 || name[l1-(l2+1)] == '/')) {
+		if (l2 <= l1
+		 && (ignore_case ? strcasecmp(name + (l1-l2), pattern)
+				 : strcmp(name + (l1-l2), pattern)) == 0
+		 && (l1 == l2 || name[l1 - (l2+1)] == '/'))
 			return ret_match;
-		}
 	}
 
 	return !ret_match;
--- old/flist.c
+++ new/flist.c
@@ -35,6 +35,7 @@ extern int inc_recurse;
 extern int do_progress;
 extern int always_checksum;
 extern int module_id;
+extern int ignore_case;
 extern int ignore_errors;
 extern int numeric_ids;
 extern int recurse;
@@ -2494,6 +2495,7 @@ int f_name_cmp(const struct file_struct 
 {
 	int dif;
 	const uchar *c1, *c2;
+	uchar ch1, ch2;
 	enum fnc_state state1, state2;
 	enum fnc_type type1, type2;
 	enum fnc_type t_path = protocol_version >= 29 ? t_PATH : t_ITEM;
@@ -2604,7 +2606,15 @@ int f_name_cmp(const struct file_struct 
 			if (type1 != type2)
 				return type1 == t_PATH ? 1 : -1;
 		}
-	} while ((dif = (int)*c1++ - (int)*c2++) == 0);
+		ch1 = CVAL(c1++, 0);
+		ch2 = CVAL(c2++, 0);
+		if (ignore_case) {
+			if (islower(ch1))
+				ch1 = toupper(ch1);
+			if (islower(ch2))
+				ch2 = toupper(ch2);
+		}
+	} while ((dif = ch1 - ch2) == 0);
 
 	return dif;
 }
--- old/lib/wildmatch.c
+++ new/lib/wildmatch.c
@@ -53,6 +53,8 @@
 #define ISUPPER(c) (ISASCII(c) && isupper(c))
 #define ISXDIGIT(c) (ISASCII(c) && isxdigit(c))
 
+extern int ignore_case;
+
 #ifdef WILD_TEST_ITERATIONS
 int wildmatch_iteration_count;
 #endif
@@ -72,6 +74,8 @@ static int dowild(const uchar *p, const 
     for ( ; (p_ch = *p) != '\0'; text++, p++) {
 	int matched, special;
 	uchar t_ch, prev_ch;
+	if (ignore_case && ISUPPER(p_ch))
+	    p_ch = tolower(p_ch);
 	while ((t_ch = *text) == '\0') {
 	    if (*a == NULL) {
 		if (p_ch != '*')
@@ -237,12 +241,21 @@ static int dowild(const uchar *p, const 
  * of "text" and any strings in array "a". */
 static int doliteral(const uchar *s, const uchar *text, const uchar*const *a)
 {
+    uchar s_ch, t_ch;
     for ( ; *s != '\0'; text++, s++) {
 	while (*text == '\0') {
 	    if ((text = *a++) == NULL)
 		return FALSE;
 	}
-	if (*text != *s)
+	s_ch = *s;
+	t_ch = *text;
+	if (ignore_case) {
+	    if (ISUPPER(s_ch))
+		s_ch = tolower(s_ch);
+	    if (ISUPPER(t_ch))
+		t_ch = tolower(t_ch);
+	}
+	if (t_ch != s_ch)
 	    return FALSE;
     }
 
@@ -288,10 +301,14 @@ static const uchar *trailing_N_elements(
 int wildmatch(const char *pattern, const char *text)
 {
     static const uchar *nomore[1]; /* A NULL pointer. */
+    int ret;
 #ifdef WILD_TEST_ITERATIONS
     wildmatch_iteration_count = 0;
 #endif
-    return dowild((const uchar*)pattern, (const uchar*)text, nomore) == TRUE;
+    force_lower_case = ignore_case;
+    ret = dowild((const uchar*)pattern, (const uchar*)text, nomore) == TRUE;
+    force_lower_case = 0;
+    return ret;
 }
 
 /* Match the "pattern" against the forced-to-lower-case "text" string. */
@@ -331,12 +348,14 @@ int wildmatch_array(const char *pattern,
     if (!text)
 	return FALSE;
 
+    force_lower_case = ignore_case;
+
     if ((matched = dowild(p, text, a)) != TRUE && where < 0
      && matched != ABORT_ALL) {
 	while (1) {
 	    if (*text == '\0') {
 		if ((text = (uchar*)*a++) == NULL)
-		    return FALSE;
+		    break;
 		continue;
 	    }
 	    if (*text++ == '/' && (matched = dowild(p, text, a)) != FALSE
@@ -344,6 +363,9 @@ int wildmatch_array(const char *pattern,
 		break;
 	}
     }
+
+    force_lower_case = 0;
+
     return matched == TRUE;
 }
 
--- old/options.c
+++ new/options.c
@@ -114,6 +114,7 @@ OFF_T max_size = 0;
 OFF_T min_size = 0;
 int ignore_errors = 0;
 int modify_window = 0;
+int ignore_case = 0;
 int blocking_io = -1;
 int checksum_seed = 0;
 int inplace = 0;
@@ -396,6 +397,7 @@ void usage(enum logcode F)
   rprintf(F,"     --exclude-from=FILE     read exclude patterns from FILE\n");
   rprintf(F,"     --include=PATTERN       don't exclude files matching PATTERN\n");
   rprintf(F,"     --include-from=FILE     read include patterns from FILE\n");
+  rprintf(F,"     --ignore-case           ignore case when comparing filenames\n");
   rprintf(F,"     --files-from=FILE       read list of source-file names from FILE\n");
   rprintf(F," -0, --from0                 all *-from/filter files are delimited by 0s\n");
   rprintf(F," -s, --protect-args          no space-splitting; only wildcard special-chars\n");
@@ -593,6 +595,8 @@ static struct poptOption long_options[] 
   {"read-batch",       0,  POPT_ARG_STRING, &batch_name, OPT_READ_BATCH, 0, 0 },
   {"write-batch",      0,  POPT_ARG_STRING, &batch_name, OPT_WRITE_BATCH, 0, 0 },
   {"only-write-batch", 0,  POPT_ARG_STRING, &batch_name, OPT_ONLY_WRITE_BATCH, 0, 0 },
+  {"ignore-case",      0,  POPT_ARG_VAL,    &ignore_case, 1, 0, 0 },
+  {"no-ignore-case",   0,  POPT_ARG_VAL,    &ignore_case, 0, 0, 0 },
   {"files-from",       0,  POPT_ARG_STRING, &files_from, 0, 0, 0 },
   {"from0",           '0', POPT_ARG_VAL,    &eol_nulls, 1, 0, 0},
   {"no-from0",         0,  POPT_ARG_VAL,    &eol_nulls, 0, 0, 0},
@@ -1907,6 +1911,9 @@ void server_options(char **args, int *ar
 		args[ac++] = arg;
 	}
 
+	if (ignore_case)
+		args[ac++] = "--ignore-case";
+
 	if (partial_dir && am_sender) {
 		if (partial_dir != tmp_partialdir) {
 			args[ac++] = "--partial-dir";
--- old/wildtest.c
+++ new/wildtest.c
@@ -31,6 +31,7 @@ int fnmatch_errors = 0;
 #endif
 
 int wildmatch_errors = 0;
+int ignore_case = 0;
 
 typedef char bool;