From b697d0594268023c24db5855130f8f6af28b250b Mon Sep 17 00:00:00 2001
From: "B. Watson" <urchlay@slackware.uk>
Date: Thu, 4 Dec 2025 16:15:27 -0500
Subject: alf and unalf: Detect dup Atari filenames.

---
 src/Makefile  |  4 ++--
 src/alf.c     |  1 +
 src/dupname.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 src/dupname.h |  1 +
 src/sanity.c  |  8 ++++++--
 5 files changed, 54 insertions(+), 4 deletions(-)
 create mode 100644 src/dupname.c
 create mode 100644 src/dupname.h

(limited to 'src')

diff --git a/src/Makefile b/src/Makefile
index 45016a9..7ebbb71 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -43,9 +43,9 @@ CFLAGS=-DVERSION='"$(VERSION)"' -Wall -I../f65 $(COPT)
 BINS=alf alfsum unalf
 MANS=alf.1 alfsum.1 unalf.1
 
-UNALF_OBJS=unalf.o io.o listalf.o extract.o f65.o glob.o opts.o usage.o self.o asmcode.o sanity.o
+UNALF_OBJS=unalf.o io.o listalf.o extract.o f65.o glob.o opts.o usage.o self.o asmcode.o sanity.o dupname.o
 ALFSUM_OBJS=alfsum.o self.o
-ALF_OBJS=alf.o self.o alfusage.o sanity.o crunch.o
+ALF_OBJS=alf.o self.o alfusage.o sanity.o crunch.o dupname.o
 
 .PHONY: all clean install crosswin windows windows-upload realclean
 
diff --git a/src/alf.c b/src/alf.c
index 702837e..d485ab1 100644
--- a/src/alf.c
+++ b/src/alf.c
@@ -12,6 +12,7 @@
 #include "sanity.h"
 #include "self.h"
 #include "crunch.h"
+#include "dupname.h"
 
 int opt_append = 0;
 int opt_overwrite = 0;
diff --git a/src/dupname.c b/src/dupname.c
new file mode 100644
index 0000000..532e14c
--- /dev/null
+++ b/src/dupname.c
@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+
+/* only check this many filenames */
+#define MAX_FNAMES 1024
+
+/* FILENAME.EXT\0 = 13 */
+#define FNAME_LEN 13
+
+// #define DUPNAME_DEBUG
+
+static char filenames[MAX_FNAMES][FNAME_LEN];
+static int fncount;
+
+/* linear search, slow, but only happens once at startup */
+int is_dup_filename(const char *newname) {
+	int i;
+
+	for(i = 0; i < fncount; i++)
+		if(strncmp(newname, filenames[i], FNAME_LEN - 1) == 0)
+			return 1;
+
+	strncpy(filenames[fncount++], newname, FNAME_LEN - 1);
+
+	return 0;
+}
+
+#ifdef DUPNAME_DEBUG
+int main(int argc, char **argv) {
+	int i;
+
+	while(++argv, --argc)
+		printf("%s: %d\n", *argv, is_dup_filename(*argv));
+
+	printf("filenames[]\n");
+
+	for(i = 0; i < fncount; i++)
+		printf("   %s\n", filenames[i]);
+
+	return 0;
+}
+#endif
diff --git a/src/dupname.h b/src/dupname.h
new file mode 100644
index 0000000..f051c22
--- /dev/null
+++ b/src/dupname.h
@@ -0,0 +1 @@
+int is_dup_filename(const char *newname);
diff --git a/src/sanity.c b/src/sanity.c
index df3cbe2..c542aec 100644
--- a/src/sanity.c
+++ b/src/sanity.c
@@ -1,6 +1,7 @@
 #include <stdio.h>
 #include <string.h>
 #include "u816.h"
+#include "dupname.h"
 
 extern const char *self;
 
@@ -64,6 +65,9 @@ void sanity_check_filename(const char *fname) {
 		bad_atari_filename(fname, "invalid characters.");
 	else if(uscore)
 		fprintf(stderr, "%s: filename has underscore, OK on Sparta/MyDOS, not Atari DOS 2.x\n", self);
-}
-
 
+	if(is_dup_filename(fname)) {
+		fprintf(stderr, "%s: warning: duplicate Atari filename %s\n",
+				self, fname);
+	}
+}
-- 
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